Proceedings, 2019, EEVFA 2019

Aim: Our previous studies have shown that the post-exercise urine lactate concentration is a reliable exercise biomarker under controlled post-exercise hydration conditions. However, the reliability of the urine lactate concentration has been examined only after brief maximal exercise. As a result, there is no information about the reliability of this biomarker after prolonged submaximal exercise. Thus, the aim of the present study was to examine the reliability of the urine lactate concentration after interval exercise of alternating intensity under controlled or ad libitum hydration during exercise. Material & Method: Twenty-eight physically active adults (16 men and 12 women) performed three identical 45-min running tests (2 sets of 22.5 min with 3 min rest interval) on the treadmill with alternating speed and inclination at 19–24 °C, spaced three days apart. The participants drank the same amount of water during exercise in two of tests and ad libitum in the other test, in random, counterbalanced order. Blood samples were collected before exercise and 1, 3, as well as 5 min post-exercise. The highest lactate value among the post-exercise samples of each individual was recorded as his/her peak post-exercise value. Urine samples were collected before exercise and 10 as well as 60 min post-exercise and the average value of the post-exercise samples was recorded. Blood and urine lactate were analyzed spectrophotometrically. Results: The peak post-exercise blood lactate concentration was 5.5 1.7 mmol/L (mean SD throughout) for men and 4.7 1.8 mmol/L for women. The post-exercise urine lactate concentration was 1.6 1.0 mmol/L for men and 1.5 1.0 mmol/L for women. The reliability of the blood lactate concentration at the three tests was high (ICC 077–0.88), being higher under controlled hydration. However, the reliability of the urine lactate concentration was low or non-significant (ICC 0.29–0.36). Conclusions: The urine lactate concentration after prolonged submaximal exercise was lower than the corresponding blood lactate concentration and showed unsatisfactory reliability regardless of the hydration pattern during exercise. Thus, it cannot be used as a biomarker for this kind of exercise. Full article

AIM: Cold exposure and exercise may increase thermogenic capacity of white adipose tissue (WAT), which could subsequently enhance energy expenditure and body weight loss. We aimed to identify possible alterations in uncoupling protein 1 (UCP1)—the main biomarker of thermogenic activation—in human WAT due to both cold exposure and exercise, as well as the link between environmental temperature and thermogenic capacity of human WAT. MATERIAL & METHOD: We conducted four human experimental studies and two systematic reviews and meta-analyses—PROSPERO registration CRD42019120116, CRD42019120213. RESULTS: UCP1 mRNA was higher in winter than in summer [t(30) = 2.232, p = 0.03] in human WAT and our meta-analysis showed a main effect of cold exposure on human UCP1 mRNA [standard mean difference (Std-md) = 1.81, confidence interval (CI) = 0.50–3.13, p = 0.007]. However, UCP1 mRNA/protein expressions displayed no associations with %fat mass or BMI (p > 0.05, Cohen’s f² < 0.20). Both a 2-hour cooling and a non-cooling protocol preceding the positron emission tomography/computed tomography (PET/CT) measurements revealed no association between environmental temperature and standardised uptake value (SUVmax) of human WAT, as well as no mean differences in SUVmax-WAT-activity between winter and summer. An 8-week exercise program had no effect on UCP1 of human WAT or on body composition. Our meta-analysis also revealed: (a) no effect of chronic exercise on human UCP1 mRNA, (b) a main effect of chronic exercise on UCP1 protein concentrations (Std-md = 0.59, CI = 0.03–1.16, p = 0.04) and UCP1 mRNA (Std-md = 1.76, CI = 0.48–3.04, p = 0.007) in WAT of normal diet animals, c) a main effect of chronic exercise on UCP1 mRNA (Std-md = 2.94, CI = 0.24–5.65, p = 0.03) and UCP1 protein concentrations (Std-md = 2.06, CI = 0.07–4.05, p = 0.04) of high-fat diet animals. CONCLUSIONS: Cold exposure represents a main stimulus for increased thermogenic capacity in human white adipocytes; however, this may have no impact on body weight loss. Chronic exercise may represent no major stimulus for UCP1 induced in human white adipocytes, while in animals it increases UCP1 gene independently of their diet. Therefore, evidence from animal studies regarding UCP1 gene activation in white adipocytes may not be applicable in humans. Finally, the identification of human WAT thermogenic capacity via PET/CT examination may be optimal with both a cooling and a non-cooling protocol.
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Aim: Regular swimming training is gaining popularity among adults for health and competition. The acute effects of high-intensity interval swimming are largely unknown in such populations. Thus, the aim of the present study was to evaluate the effects of swimming training sets of maximal intensity and different volumes on blood metabolic markers in master swimmers. Material & Method: Twenty-one master swimmers (11 females and 10 males), aged 40.5 (7.4) years, completed two freestyle swimming sets of 4 × 50 m and 4 × 25 m at maximal intensity and a work-to-rest ratio of 1:1 on different days, in random and counterbalanced order. Blood samples were taken before, immediately after and one hour after exercise for determination of glucose and uric acid (at all three time-points, spectrophotometrically), as well as irisin, insulin, glucagon, and cortisol (pre- and immediately post-exercise, through enzyme immunoassays), in plasma. Data were analyzed through three-way analysis of variance (set × time × gender). Statistical significance was declared when p < 0.05. Results: Glucose was higher immediately post-exercise compared to pre- and 1 h post-exercise (p < 0.001). Uric acid increased 1 h post-exercise (p < 0.001) and exhibited a time × gender interaction (p = 0.029) due to a larger increase in males. Irisin showed a time × gender interaction (p = 0.028), as exercise caused an increase in females and a decrease in males. Insulin increased with exercise (p < 0.001) and was higher in females (p = 0.016). Set × time interactions found in glucose, uric acid, and insulin denoted larger increases with the 4 × 50 set (p < 0.05). Glucagon increased with exercise (p = 0.014). Cortisol increased with exercise in males and more with the 4 × 50 set, as set × time and time × gender interactions and a main effect of time were found (p < 0.05). Conclusions: Interval swimming training sets of maximal intensity induced increases in plasma glucose, uric acid, insulin, glucagon, and cortisol in master swimmers. The larger set volume induced larger increases, which may have implications for the magnitude of the desired adaptations to training. Full article

AIM: The purpose of this study was to validate the physiological responses and biomechanical parameters during continuous swimming at intensity corresponding to lactate threshold previously calculated by an intermittent, progressively increasing speed test (7 × 200-m). MATERIAL & METHOD: Nine competitive male and female swimmers (age, 19.2 ± 2.3 years; height, 175.3 ± 7.5 cm; body mass, 67.6 ± 8.7 kg; VO₂max, 46.5 ± 15.6 mL/kg/min) performed a 7 × 200-m front crawl test reaching maximum speed in the last effort. Blood lactate concentration (BL) and oxygen uptake (VO₂) were determined after each repetition, while heart rate (HR) was recorded continuously. Stroke rate (SR) and stroke length (SL) were measured in each 200-m effort. The speed at lactate threshold (sLT) was calculated using the individual speed vs. BL, and subsequently BL, VO₂, HR, SR, and SL corresponding to sLT were calculated (BL-sLT, VO₂-sLT, HR-sLT, SR-sLT, and SL-sLT). On a subsequent day, swimmers performed 30-min continuous swimming (T30) with a constant speed corresponding to sLT. BL, V0₂, HR, SR, and SL (BL-T30, V0₂-T30, HR-T30, SR-T30, and SL-T30) were measured in the 10th and 30th minutes of the T30 test, and the mean values were used for the statistical analysis. RESULTS: The speed corresponding to sLT was not different from the speed at T30 (1.33 ± 0.08 vs. 1.32 ± 0.09 m/s, p > 0.05). There was no difference between tests in VO₂ (VO₂-sLT, 34.9 ± 13.3 vs. VO₂-T30, 32.1 ± 11.4 ml/kg/min, p = 0.47). However, not all swimmers were able to complete T30 at sLT, and BL, HR, and SR were higher, while SL was lower at the end of T30 compared to sLT (BL-sLT, 3.47 ± 0.60 mmol/L vs. BL-T30, 5.28 ± 3.15 mmol/L, p = 0.05; HR-sLT, 163 ± 10 vs. HR-T30, 171 ± 11 b/min, p = 0.03; SR-sLT, 28.0 ± 4.0 vs. SR-T30, 33.8 ± 3.2 strokes/min, p < 0.001; SL-sLT, 2.6 ± 0.4 vs. SL-T30, 2.4 ± 0.3 m/cycles, p < 0.001). A Bland-and-Altman plot indicated agreement between 7 × 200 and T30 in BL (bias 1.8 ± 2.4 mmol/L), VO₂ (bias −2.9 ± 11.4 ml/kg/min), HR (bias 10.3 ± 12 b/min), SR (bias 5.3 ± 3.4 strokes/min), and SL (bias −0.3 ± 0.2 m/cycle), but the range of physiological and biomechanical data variations was large. CONCLUSIONS: Continuous swimming at speed corresponding to lactate threshold may not show the same physiological and biomechanical responses as those predicted by a progressively increasing speed test of 7 × 200-m.
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AIM: There is some evidence to suggest that exercise in the evening, compared with exercise in the morning, has a more beneficial impact on glycemia in patients with type 2 diabetes (T2D). The aim of this study was to examine a possible acute effect of aerobic exercise performed at different times of day on blood glucose levels during and after exercise in patients with T2D. MATERIAL & METHOD: Eight male T2D patients (61.8 ± 6.9 yrs, 27.7 ± 3.1 kg/m², HbA1c: 6.5 ± 1.1%; mean ± SD), who did not receive insulin, performed 60-min cycling at about 75% maximal heart rate (HRmax) either at 10:30 (Morning-M), or at 17:30 (Evening-E), or 30-min cycling at 10:30 and 30-min cycling at 17:30 (ME). A control condition (C) was also included where volunteers did not exercise but had their blood glucose measured at day-time intervals similar to the time intervals of the three exercise trials. Two days before each condition no physical activity was allowed, while the day before and on the day of each trial participants controlled their diet. RESULTS: Compared to resting levels, blood glucose at the end of exercise decreased at similar levels in M (20 ± 12%), E (28 ± 14%), in the morning of ME (21 ± 10%) and in the evening of ME (26 ± 19%) (p > 0.05). Also, heart rate, blood lactate and rate of perceived exertion responses during exercise were similar between the 3 exercise conditions. Mean area under the blood glucose-time curve over the two-hour post-exercise period in exercise trials, and at similar time intervals in C, was different only between the morning in C (15,173 ± 1830 mg/dL•120 min) and the evening in ME (11,681 ± 1526 mg/dL•120 min, p = 0.045). In addition, overnight fasting serum glucose the morning after each trial was similar between conditions (p > 0.05). CONCLUSIONS: No acute effect of cycling at about 75% HRmax was observed on glycemia in patients with T2D when exercise was performed at different times of day.
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Aim: To explore the effect of a combat swimming training program (CSTP), with and without equipment, on swimming performance. Material & Method: 45 male army officer cadets volunteered to participate in the study and were randomly divided into three groups: a control group (CG) and two experimental groups. The experimental groups participated in a 4-week combat swimming training program with equipment (CSTPE) or without equipment (CSTPS). Prior to and after the CSTP, all groups performed a 400-m and a 4 × 50-m swimming task, and the time to complete the task, peak blood lactate, and peak heart rate were measured. Results: The time to complete the 400-m and 4 × 50-m trials improved significantly only in the CSTPE group (490 ± 66 s pre and 463 ± 50 s post for 400 m; and 205 ± 28 s pre and 192 ± 19 s post for 4 × 50 m; p < 0.05), while the CG and CTSPS groups did not improve their time significantly in either trial. All groups presented similar peak lactate and peak heart rate values. Conclusions: The results suggest that only the CSTPE group improved swimming performance in both the 400-m and 4 × 50-m trials. Full article

AIM: This study examined the effects of a high-intensity, short-duration supplementary strength-power training program on neuromuscular performance and sport-specific skills of young female “Gymnastics for All” athletes. MATERIAL & METHOD: Twenty-four female “Gymnastics for all” athletes aged 13 ± 2 years, with at least two years of competitive-level training experience, took part in this study. Participants were divided into training (TG, n = 13) and control groups (CG, n = 11), who completed the same 3-day per week gymnastics training program over 10 weeks, with the TG completing a supplementary 7–9 min long strength-power program at the end of each training session. This training program consisted of two rounds of strength and power exercises for arms and legs, executed in a circuit fashion with 1-min rest between rounds. The exercises used included plyometrics for upper and lower body using body weight resistance, as well as strength-power exercises using elastic bands and light kettle bells. Participants performed each exercise at maximum voluntary effort, as fast and as hard as possible. Initially, six different exercises were performed per round (15 s work and 15 s rest), while the number of exercises per round was gradually decreased to four and the duration of each exercise was increased to 30 s (with 30 s rest). Data were analyzed using mixed-model 2-way ANOVA (group × time). RESULTS: After 10 weeks of training the TG improved countermovement jump performance with one leg (by 11.9 ± 2.8%, p = 0.001) and two legs (by 7.1 ± 2.7%, p = 0.026), drop jump performance (by 11.9 ± 2.8%, p = 0.002), single-leg jumping agility (by 12.9 ± 1.5%, p = 0.001), sport-specific performance, i.e., repeated rondats (by 8.2 ± 2.1%, p = 0.004), but not 10-m sprint performance (2.5 ± 1.7%, p = 0.23). There was no change in these neuromuscular performance parameters in the CG (p = 0.13 to 0.94). CONCLUSIONS: The results of this study show that this supplementary strength-power program performed for only 7–9 min at the end of each session improved neuromuscular and sport-specific performance after 10 weeks of training.
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AIM: Although high-intensity interval sets are routinely used in the training regimen of competitive swimmers, information about the acute metabolic effects of such sets is lacking. Thus, the aim of the present study was to evaluate the effects of swimming training sets of maximal intensity and different volumes on blood metabolic markers in adolescent swimmers. MATERIAL & METHOD: Twenty-four adolescent competitive swimmers (12 female and 12 male) completed two training sets of 8 × 50 m and 8 × 25 m. Both sets were performed in freestyle, at maximal intensity and at a work-to-rest ratio of 1:1. They were spaced one week apart and were performed in a random and counterbalanced order. Blood samples were taken before, immediately after and one hour after both sets for the determination of glucose and uric acid (at all three time-points, spectrophotometrically), as well as irisin, insulin, glucagon, and cortisol (in pre- and immediately post-exercise samples, through enzyme immunoassays), in plasma. Three-way analysis of variance (set × time × gender) was used for the statistical analysis. The level of statistical significance was set at α = 0.05. RESULTS: Glucose was higher immediately post-exercise compared to pre- and 1 h post-exercise (p = 0.001). Uric acid was higher immediately and 1 h post-exercise (p < 0.001). Irisin exhibited a time × gender interaction (p = 0.005) due to the fact that exercise caused an increase in females and a decrease in males. Insulin, glucagon, and cortisol increased with exercise (p < 0.001). No gender effect was found for any of the markers except for uric acid, of which males had higher concentrations than females (p < 0.001). CONCLUSIONS: Maximal interval swimming sets induced remarkable increases in plasma glucose, uric acid, insulin, glucagon, and cortisol, suggesting a satisfactory metabolic effectiveness of such types of exercise training. Despite the difference in volume, the two training sets did not induce different metabolic responses in adolescent competitive swimmers. This is also true of blood lactate response, which has been presented previously. Full article

AIM: To investigate the effect of a combat swimming training program (CSTP), with and without equipment, on 1000-m combat swimming and shooting performance. MATERIAL & METHOD: 45 male army officer cadets volunteered to participate in the study and were randomly divided into three groups: a control group (CG) and two experimental groups. The experimental groups participated in a 4-week combat swimming training program with equipment (CSTPE) or without equipment (CSTPS). Prior to and after the training period, all participants performed a 1000-m combat swimming trial wearing full combat equipment. The time to complete the task, peak blood lactate, and peak heart rate were measured. Furthermore, before and immediately after the 1000-m trial, they performed a shooting test (10 shots) in standing position, using a shooting simulator; the holding stability, the center of gravity of shooting, and the relative triggering value were measured. RESULTS: The time to complete the 1000-m combat swimming trial improved in the CSTPE and CSTPS groups by 11,074 and 13,406 s, respectively (p < 0.001), while no change was noted in the CG. All groups presented similar peak lactate and peak heart rate values, but they had deteriorated shooting ability immediately after the 1000-m combat swimming trial. Both experimental groups showed similar shooting capability before and after the CSTP. CONCLUSIONS: The 1000-m combat swimming time was improved significantly after the CSTP, and this improvement was independent of the training mode implemented. Although fatigue seems to affect the shooting ability, the latter remained unaffected by the training regimen. Full article

AIM: Negative fluid balance before competition is used by some track-and-field athletes aiming to reduce body weight and increase jumping performance. However, the effects of body weight loss due to dehydration on fast and explosive muscle actions have not been fully explored. The purpose of this study was to investigate the effect of dehydration on weight-bearing and non-weight-bearing explosive movements. MATERIAL & METHOD: Nine athletes took part in this study (5 females and 4 males, 20–23 years old). Participants were familiarized with the procedures and measurements of the study, recorded their normal dietary and fluid intake for 3 days, and took part in two randomly assigned conditions. On one condition, carbohydrate intake was reduced by 70% and water intake by 50% of their habitual diet on the day preceding the measurements (dehydration). On the other condition, the habitual diet and fluid intake were followed (habitual hydration). Prior to the performance measurements in each condition, body weight (BW) and urine specific gravity were measured. After a standardized 15-min warm-up, the following assessments were performed: countermovement jump (CMJ), maximum isometric leg press force, and rate of force development (RFD), 10-, 20-, and 30-m sprint performance, and six 30-m sprints interspersed with 25 s of rest. RESULTS: Mild dehydration (1.1 ± 1.1% BW) was achieved, which was confirmed by almost two-fold higher thirst ratings compared with habitual hydration (p < 0.002) and a trend for higher urine specific gravity (habitual hydration: 1025 ± 5 vs. dehydration: 1032 ± 7 mg/mL, p = 0.054). CMJ performance, expressed as relative power, was similar in habitual hydration and dehydration (38.5 ± 4.6 vs. 39.0 ± 3.6 W/kg BW, p = 0.14). Also, 20-m, 30-m, and repeated-sprint performance were similar in the two conditions, but 10-m sprint performance was impaired by 3.2 ± 0.13% (p = 0.019) in dehydration. Moreover, although maximum isometric leg press force was unaffected, RFD was lower in dehydration at 0–150 ms (by 13.3%; p = 0.05), 0–200 ms (by 11.8%; p = 0.03), and 0–250 ms (by 11.2%; p = 0.03). CONCLUSION: Mild dehydration did not affect maximum force or power output, but decreased acceleration and RFD. The decreases in RFD may be linked with the lower acceleration ability in these athletes. Full article

AIM: Τhe mechanisms underpinning long-term changes in muscle architectural characteristics and joint range of motion (ROM) following static stretching in humans remain under question, and data are sparse for growing athletes. It is possible that the characteristics of the stretching protocols used in previous training studies were not adequate to induce significant changes. An alternative approach would be to compare populations with different chronic flexibility training backgrounds. Thus, the purpose of this study was to examine differences in gastrocnemius medialis (GM) architectural characteristics at rest and during 1 min of static stretching between child athletes with different flexibility training backgrounds. MATERIAL & METHOD: Ten female rhythmic gymnasts (RG; age. 9.0 ± 0.7 years) were compared to six volleyball athletes (VA; age, 9.0 ± 0.6 years). Fascicle length, pennation angle and muscle thickness at the medial and distal part of GM, and ankle ROM were measured at rest and during 1 min of static stretching using ultrasonography. Data were analysed using two-way ANOVA for repeated measures on two factors (time x sport). RESULTS: At rest, RG displayed similar fascicle length compared to VA at the medial (4.19 ± 0.37 vs. 4.24 ± 0.54 cm, respectively, p = 0.841) and the distal part of GM (4.25 ± 0.35 vs. 4.18 ± 0.65 cm, respectively, p = 0.780). Pennation angle and muscle thickness were also similar in the two groups at the medial (p = 0.519 and p = 0.216, respectively) and the distal part of the gastrocnemius (p = 0.998 and p = 0.433, respectively). Ankle angle before stretching was greater in RG compared with VA (120.9 ± 4.2 vs. 110.9 ± 5.8°, respectively, p = 0.001). During the 1 min of static stretching, RG displayed greater fascicle elongation compared to the VA at the medial (5.86 ± 0.29 vs 5.52 ± 0.53 cm, p = 0.048) and the distal part (6.09 ± 0.49 vs 5.15 ± 0.65 cm, p = 0.013), as well as greater maximal ankle dorsiflexion (p < 0.001) and muscle tendon junction displacement (p < 0.001). No differences were found between groups in pennation angle (p > 0.458) and muscle thickness (p ˃ 0.237). CONCLUSIONS: Muscle architectural properties are similar at rest in child athletes with different flexibility backgrounds. However, muscle fascicle elongation is greater in rhythmic gymnasts compared to volleyball athletes and this may contribute to the greater ankle ROM observed in rhythmic gymnasts. Full article

AIM: Aging has been associated with reduced physical performance and morbidity. Living in a residential care home may be beneficial with regard to long-term medical assistance, but the diminished fundamental or instrumental daily activities further contribute to the deteriorated physical health and fall risk. Therefore, the aim of this study was to implement a motivation program to sustain and potentially increase physical activity in residential settings. MATERIAL & METHOD: Thirteen female residents of the Larissa Municipality Elderly Care Nursing Home (17% of bed capacity), 61-92 years old, with mild cognitive impairment (MMSE score 11-20) and diverse health conditions, participated in this pilot program. The intervention lasted from September 2018 to June 2019 and included two practical sessions of field walking, geriatric NHS workouts, plant care, and creative artwork per week. The quantitative and descriptive elements of STEADI battery were used to assess physical performance at the beginning and end of the intervention. RESULTS: All participants complied with gardening activities, half were in full compliance with the bi-weekly session schedule, and two adopted independent exercise activities. No participant was free of fall risk either at the beginning or at the end of the intervention, and 6 incidents were recorded concerning 5 people. One individual achieved finally the TUG goal of 12 s, but overall the shift of test performance did not reach statistical significance (p = 0.196). Leg strength and endurance score were above the average score for age in another case, and no significant change was observed during the study period (p = 0.738). Contrariwise, balance was significantly improved (p < 0.001), and half of the participants were able to complete the tandem or the single foot stand stage. CONCLUSIONS: A multidisciplinary approach may be effective in promoting physical performance indices, and STEADI tools are sensitive to such changes. However, seasonal infections, chronic conditions, and medication have a severe impact on leg strength and walking speed, and occasionally may mask the beneficial effect of exercise in the elderly, even to the point of an individual not being able to commence the assessment. Full article

AIM: Irisin is released in the circulation in response to exercise and may increase energy expenditure by stimulating the browning of white adipose tissue through UCP1 upregulation. We aimed to investigate the effects of treatment with human recombinant irisin on the metabolic profile of 3T3-L1 differentiated beige adipocytes. MATERIAL & METHOD: 3T3-L1 cells were differentiated into beige adipocytes in the presence of IBMX, dexamethazone and insulin in DMEM. To assess the mitochondrial respiration activity, an extracellular mitochondrial assay was performed after 2 h and 4 h of treatment with 20 nM irisin. UCP1 protein expression levels were assessed through Western blot analysis at baseline, 2 h, and 4 h. RESULTS: We observed that the oxygen consumption rate (OCR) of the differentiated cells was significantly reduced after 2 h of treatment compared to control, untreated cells (40.8 ± 34.1 vs. 71.6 ± 51.7 pmol/min/μg, p < 0.05, d = 0.69). Interestingly, OCR was rescued after 4 h of treatment (57.4 ± 49.2 pmol/min/μg, p < 0.05, d = 0.38). Similar results were observed for the proton leak-mediated respiration (baseline, 26.5 ± 15.1; 2 h, 8.7 ± 3.3; 4 h, 17.2 ± 2.3 pmol/min/μg, p > 0.05). The highest expression of UCP1 was observed after the 2-h treatment with irisin (Δ_{2 h—baseline} = 1.7-fold, Δ_{4 h—baseline} = 1.2-fold, p < 0.05). CONCLUSIONS: Based on these results, we conclude that treatment of beige adipocytes with irisin generated a reverse effect on the thermogenic process. Beige adipocytes are already highly metabolic active cells that work close to their maximal capacity. Further stimulation of the thermogenic pathway can decrease the metabolic profile of 3T3-L1 cells, which can be partially rescued after 4 h of stimulation. Full article

Aim: Warm-up activates muscular thermogenesis leading to enhanced athletic performance and reduced risk for exercise-induced injuries. However, very little is known about the thermo physiological responses of elite basketball players during the time spent on bench (BENCH) and consequently its impact on athletic performance in cool environments. Therefore, the purpose of this study was to investigate the impact of BENCH on the thermo physiological responses and athletic performance of elite basketball players. Material & Method: Six elite male basketball players (age, 24.9 ± 4.6 year; BMI, 25.5 ± 1.8 kg/m²) participated in the study. Following a 20-min warm up, the participants were randomly allocated in four different scenarios: (i) 9-min BENCH wearing basketball uniform, (ii) 9-min BENCH wearing basketball uniform and insulative clothing, (iii) 23-min BENCH wearing basketball uniform, and (iv) 23-min BENCH wearing basketball uniform and insulative clothing. The athletic performance of the participants was examined by conducting fitness test pre- and post-BENCH scenarios. Mean skin temperature (T_sk) was calculated from two sites (arm and thigh), while ambient temperature was recorded using a portable weather station. Results: Ambient temperature (16.8 ± 1.2 °C) ranged from 18.2 to 15.5 °C. We identified an increase of 1 °C in T_sk during 23-min BENCH scenarios (p < 0.05). Similarly, we found that counter-movement jump was significantly reduced after 23-min BENCH with basketball uniform (−2.8 cm) and 23-min BENCH with basketball uniform and insulative clothing (−3.4 cm, p < 0.05). On the other hand, there were no statistically significant differences in T_sk and athletic performance between the baseline and post 9-min BENCH measures (p > 0.05). Conclusions: The present study showed that 23 min of bench time reduces high-intensity players’ performance in both conditions (23 min bench time + basketball uniform, 23 min bench time + basketball uniform and insulative clothing) in cool environment. Thus, further studies are needed in order to identify factors causing impaired performance. Full article

AIM: progressively increasing swimming speed test (5 × 200 m) is used to calculate the speed corresponding to blood lactate concentration of 4 mmol/L (V4) and related physiological and biomechanical parameters. The purpose of this study was to compare the calculated by a 5 × 200-m test parameters with those obtained during an intermittent swimming training set (5 × 400-m) performed at constant speed corresponding to V4. MATERIAL & METHOD: Twelve competitive male swimmers (age, 19 ± 2 years; height, 178 ± 8 cm; body mass, 74.4 ± 10.1 kg) performed a 5 × 200-m front crawl test reaching maximum speed in the last effort. Blood lactate concentration (BL) was measured after each 200 m, and heart rate (HR), stroke rate (SR), and stroke length (SL) were determined during each 200 m. V4 was calculated by interpolation using the individual speed vs. BL, and subsequently HR, SR, SL corresponding to V4 were calculated (HR-V4, SR-V4, SL-V4). One week later, swimmers performed 5 × 400-m at constant speed corresponding to V4. During the 5 × 400-m test, BL (BL-5 × 400) was measured after the 1st, 3rd and 5th repetitions, while HR (HR-5 × 400) was recorded continuously. SR and SL were measured in each 400-m repetition, and mean values were calculated (SR-5 × 400 and SL-5 × 400). RESULTS: V4 and HR-V4 were not different from speed and HR-5 × 400 during the 5 × 400-m test (1.30 ± 0.10 vs. 1.29 ± 0.10 m/s; 160 ± 14 vs. 166 ± 13 b/min, both p > 0.05). BL-5 × 400 was not different from 4 mmol/L (4.9 ± 2.6 mmol/L, p > 0.05). SR was increased and SL was decreased during 5 × 400 m compared to the values corresponding to V4 (SR-V4, 28.9 ± 3.8 vs. SR-5 × 400, 34.5 ± 3.4 strokes/min; SL-V4, 2.38 ± 0.33 vs. SL-5 × 400, 2.25 ± 0.30 m/cycle, both p < 0.05). A Bland-and-Altman plot indicated agreement between variables obtained by the 5 × 200-m and 5 × 400-m tests but with great range of variation (bias: BL, −1.0 ± 2.6 mmol/L; HR, −7 ± 12 b/min; SR, −5.6 ± 3.3 strokes/min; SL, 0.13 ± 0.09 m/cycle). CONCLUSIONS: An intermittent, with progressively increasing speed, swimming test provides physiological information to coaches to apply during an intermittent constant-speed swimming training set at intensity corresponding to BL of 4 mmol/L with large inter-individual variability. It seems that the 5 × 200-m test does not provide valid results for the biomechanical parameters. Full article

Aim: It is well documented that static stretching acutely increases range of motion (ROM) in a dose-dependent manner. However, most previous studies have utilized intermittent stretching protocols, and it is not known if intermittent and continuous stretches elicit different changes in joint ROM and, in particular, in flexibility-trained subjects. The aim of this study was to examine changes in hip joint ROM after an intermittent or a continuous static stretching protocol of equal total duration. Material & Method: Twenty-seven female subjects (age, 19.9 ± 3.0 years; height, 167.3 ± 6.1 cm; body mass, 58.2 ± 5.2 kg), 14 artistic and rhythmic gymnasts, and 13 recreationally active participants performed 3 min of intermittent (6 × 30 s with 30 s rest) or continuous stretching (3 min) of the hamstring muscles, with an intensity of 8–9 on a 10-point visual analogue scale. Hip joint ROM was measured for both legs after warm-up and immediately after stretching. The same individuals performed both conditions with alternate legs in a randomized, counterbalanced order. Data were analysed using mixed-model three-way ANOVA. Results: In the untrained participants, only intermittent stretching increased ROM by 13% (from 91.0 ± 7.2° to 102.4 ± 14.5°, p = 0.001), while continuous stretching did not affect ROM (from 92.4 ± 6.9° to 93.1 ± 9.2°, p = 0.99). In the trained participants, both stretching types equally increased ROM by ~6% (continuous, 140.9 ± 20.4° to 148.6 ± 18.8°, p = 0.047; intermittent, 141.8 ± 20.3° to 150.0 ± 18.8°, p = 0.029). Conclusions: The different effect of intermittent vs. continuous stretching on hip ROM between trained and untrained subjects suggests that stretching mode is an important variable when examining the acute effects of static stretching on ROM enhancement. Full article

AIM: Subclinical, low-grade, inflammation is one of the main pathophysiological mechanisms underlying the majority of chronic diseases. Ιt is therefore obvious that an inflammatory model, inducing inflammatory responses to humans in a regulated, specific, and non-harmful way, could greatly facilitate the assessment of redox and immune status. Exercise-induced muscle damage (EIMD) could serve as such a model; however, the kinetics of biomarkers may be substantially different according to the muscle groups examined. Therefore, the aim of this study was to assess the responses of selected inflammatory and redox biomarkers after eccentric-induced muscle damage in upper and lower limbs. MATERIAL & METHOD: Ten healthy, sedentary volunteers (5 males) performed, in a randomized and cross-over fashion, two discrete exercise protocols in lower (10 sets × 10 drop jumps from a height of 40 cm) and upper extremities (8 sets × 10 eccentric muscle contractions of the biceps at 90% of 1RM) separated by 6 weeks. Venous blood samples were collected pre-, immediately post-, 2, 24 and 48 h after the exercise protocols. Body composition was evaluated with dual-energy X-ray absorptiometry, blood cell count analysis by an automated hematology analyzer, CK, CRP and IL-6 by commercially available kits, while serum glutathione peroxidase (GPX3) by enzymatic assays adapted for microwell plates. RESULTS: A different pattern of response (time x protocol p < 0.05) was observed for CK, IL-6 and CRP, with lower limbs reaching the highest increases at 2 h post-exercise, while upper limbs at 24 and 48 h. A similar response between the two protocols was observed for WBC and neutrophils, with a transient 30% increase at 2 h (time p < 0.05). No effect of time or protocol was observed for GPX3. CONCLUSIONS: Kinetics of selected inflammatory and redox biomarkers follow different patterns depending on the muscle group tested. Thus, depending on the targeted muscle group, blood samples should be obtained at specific time points. The higher levels of CK, IL-6 and CRP at 24–48 h implies an augmented inflammatory response at upper limbs, probably due to a lower adaptation to eccentric exercise, indicating that EIMD of upper limbs is a better protocol for the assessment of the inflammatory status in humans. Full article

AIM: Sedentary lifestyle is related to many non-communicable diseases and psychological disorders. Family caregivers often have physical and psychological health problems, similar to those characterizing a sedentary lifestyle. The aim of this study was to determine the levels of physical activity, depression, anxiety, burden, and quality of life in Greek family caregivers of people with dementia and in non-caregiving controls, and to explore whether physical activity can affect their psychological health and quality of life. MATERIAL & METHOD: A cross-sectional survey was conducted including 159 volunteers, 100 family caregivers of people suffering from dementia, and 59 age- and gender-matched non-caregivers. Six questionnaires were provided to the caregivers and five to the non-caregivers, including a demographic questionnaire, a stress Scale-BAI, a depression scale-BDI, a quality of life scale (WHOQOL-BREF), a physical activity Questionnaire-RPAQ, and the scale of burden-ZBI, which was given only to caregivers. The two groups were compared in order to be revealed whether psychological and quality of life variables are related to or are independent of care. RESULTS: Caregivers appear to have a worse quality of life (p < 0.001) and lower levels of physical activity (p < 0.05) compared to age- and gender-matched non-caregivers. No significant differences were found between groups regarding anxiety and depression (p > 0.05). Interestingly, the less active caregivers and non-caregivers have a worse quality of life than the more active individuals (p < 0.05), while, particularly, the less active caregivers exhibited higher levels of depression compared with the more active caregivers (p < 0.05). On the other hand, it was found that higher levels of PA associate with lower levels of depression (r_P = −0.2, p < 0.05) and quality of life becomes better (r_P = 0.303, p < 0.001). Moreover, it was revealed that stress and depression levels, quality of life, and burden (caregivers) are correlated with each other in both groups (p < 0.01). CONCLUSIONS: Greek caregivers of people with dementia exhibited lower levels of physical activity and a worse quality of life than non-caregivers, while physical activity appeared to improve quality of life and depression in both groups. Full article

Aim: Maximum oxygen uptake (VO₂max), running economy, and lactate threshold (LT) velocity are interacting factors which determine the running speed that that can be sustained in an endurance event such as Athens marathon. The aim of this study was to examine the physiological characteristics and the race pace characteristics in relation to the aforementioned parameters of moderate (finish time < 240 min) and low-level runners (finish time > 240 min) of the Athens marathon race. Material & Method: 15 athletes (age, 41 ± 7 yrs; height, 174.5 ± 6.6 cm; and body mass, 72.8 ± 6.9 kg), who participated in the 2018 Athens marathon, performed an incremental test until exhaustion, 3 to 10 days before the race to determine VO₂max, maximal aerobic velocity (MAV), and the velocity at the 1^st LT. The athletes were divided into a moderate level (n = 8, finish time, 209.0 ± 10.4 min) and a low-level group (n = 7; finish time, 289.7 ± 25.1 min). Finish time was exported from the results posted on the official site of the organization. Results: For the whole sample, VO₂max was 52.4 ± 5.2 mL/kg/min, MAV 15.5 ± 1.4 km/h, and velocity at the 1^st LT 10.6 ± 1.4 km/h, corresponding to 68.0 ± 5.4% of MAV and to 75.0 ± 8.8% of VO₂max. The mean finish time was 246.7 ± 45.4 min, and the average running velocity 10.6 ± 1.9 km/h, which corresponded to 99.9 ± 7.5% of the velocity at the 1^st LT and 75.0 ± 8.8% of VO₂max. Moderate level, compared with the low-level athletes had higher (p < 0.05) VO₂max (55.5 ± 3.5 vs. 48.8 ± 4.8 mL/kg/min), MAV (16.5 ± 0.7 vs. 14.4 ± 1.2 km/h), and velocity at 1^st LT (11.6 ± 0.8 vs. 9.4 ± 1.0 km/h, corresponding to 70.5 ± 4.0 vs. 65.2 ± 5.6% of MAV). Medium-level athletes ran the marathon at a higher velocity (12.1 ± 0.6 vs. 8.8 ± 0.9 km/h), corresponding to a higher percentage of MAV (73.8 ± 2.6 vs. 61.3 ± 42%), 1^st LT (104.8 ± 4.8 vs. 94.2 ± 5.8%), and VO₂max (80.0 ± 7.8 vs. 69.3 ± 6.5%). Conclusions: These findings suggest that athletes of different levels run the Athens marathon at a rate corresponding to different percentages of key parameters of aerobic performance. It is recommended that the selected pace be applied individually according to each athlete’s level. Full article

AIM: Ballet dancers’ performance is based on the execution of complex technical skills that require an unusually large range of motion (ROM) and increased muscular power. Static stretching is commonly used to increase ROM, but it may induce a transient decrease in muscle power. However, this may depend on the population and stretching protocol. The purpose of this study was to compare the acute effect of a short (20 s) vs. a long (60 s) static stretching protocol on joint ROM and jumping performance in ballet dancers. MATERIAL & METHOD: Sixteen female professional ballet dancers (age, 25.9 ± 2.7; dancing experience, 19.6 ± 3.8 y) performed 5 days of testing using a single-leg stretching and jumping design. Baseline measurements of one-leg countermovement jump (CMJ) and a ballet technical jump with one leg (“temps levé”, TL) were performed on the first visit. On the other four visits, dancers stretched their hamstrings, quadriceps and plantar flexors for 20 or 60 s per muscle group and then performed a CMJ or a TL in a counterbalanced order. This combination of stretching and jumping resulted in four conditions: long stretch-CMJ, long stretch-TL, short stretch-CMJ and short stretch-TL. In all conditions, ankle joint ROM was measured at rest and immediately after stretching. RESULTS: ROM significantly increased following stretching (p = 0.01) with no difference between stretching protocols (p = 0.505). CMJ height decreased post-stretching following both stretching protocols (p = 0.01); however, the long-duration static stretching induced a larger decrease in jump height (p = 0.020). TL height remained unchanged after the short and the long stretching protocols (7.7 ± 2.1 to 7.4 ± 2.2 vs. 7.7 ± 2.1 to 7.2 ± 2.0 cm, respectively, p = 0.701). CONCLUSION: Both stretching protocols similarly increased ankle joint ROM and decreased one-leg CMJ height immediately post-stretching. Also, both stretching protocols did not decrease TL height, probably because dancers are able to compensate for the stretch-induced deficit in muscle power through motor coordination. Full article

AIM: The purpose of the present study was to investigate the correlation between acceleration and maximum running phase in 60-m sprint and vertical jump performance. Furthermore, to investigate the factors that affect the acceleration phase, maximum running phase, and overall 60-m sprint performance. MATERIAL & METHOD: Participants were 25 young amateur athletes, aged 18 ± 1 years, with body mass 64.64 ± 13.39 kg and body height 1.71 ± 0.11 m. We examined the correlation between the acceleration phase (0–30 m) and maximum running phase (30–60 m) and 60-m sprint performance, measured with photocells (Optojump), and vertical jump performance (take-off velocity, jump height, maximal velocity, maximal power), measured with a force plate (Bertec). Pearson correlation was used to examine the correlation between the forementioned parameters (SPSS, v. 21). RESULTS: There was a correlation between jump height and 60-m sprint performance (r = −0.713, p < 0.001), maximum running phase (r = −0.512, p = 0.15), and a weak correlation with acceleration phase (r = −0.495, p = 0.19). There was a correlation between take-off velocity and 60-m sprint performance (r = −0.732, p < 0.001), maximum running phase (r = −0.553, p = 0.08), and a weak correlation with acceleration phase (r = −0.472, p = 0.27). There was a weak correlation between maximal velocity, acceleration phase (r = 0.439, p = 0.41), and 60-m sprint performance (r = 0.438, p = 0.42). There was a correlation between maximal power and 60-m sprint performance (r = −0.739, p < 0.001), acceleration phase (p = −0.635, p = 0.02), and a weak correlation with maximum running phase (r = −0.437, p = 0.042). There was a correlation between 60-m sprint performance and maximum running phase (r = 0.792, p < 0.001) and acceleration phase (r = 0.596, p = 0.03). Finally, there was a correlation between body height and 60-m sprint performance (r = −0.738, p = 0.02) and maximum running phase (r = −0.666, p = 0.07). CONCLUSIONS: According to our results, 60-m sprint performance was highly correlated with body height, maximum running phase and all the vertical jump parameters (explosive power), except for maximal power, which had a high correlation with the acceleration phase (sprint acceleration). Full article

AIM: Rate of force development (RFD) of the leg extensor muscles is important for jumping performance. Static stretching has been shown to reduce explosive force generation, but little is known regarding changes in muscle architectural characteristics due to stretching and jumping performance alterations. Τhe aim of this study was to determine the effects of two different static stretching protocols (20 or 60 s) on gastrocnemius medialis (GM) muscle architectural characteristics and RFD during jumping in a population with long-term flexibility training background. MATERIAL & METHOD: Twelve female professional ballet dancers (age, 25.3 ± 2.2 years) performed 5 days of testing using a single leg stretching and jumping design. RFD during one-leg countermovement jump and jump height were measured on the first visit. On the other four visits, dancers stretched their hamstrings, quadriceps and plantar flexors for 20 or 60 s per muscle group, in a counterbalanced order. Immediately after stretching, RFD and jump height were measured. Fascicle length (FL), pennation angle (PA), and muscle thickness (MT) at the medial and the distal part of GM were assessed at rest and during static stretching for each protocol, using ultrasonography. RESULTS: There was a main effect of time for FL, PA, and MT (p < 0.01) with no difference between stretching protocols, at the medial and distal parts of GM, in FL (p = 0.373 and p = 0.651, respectively), PA (p = 0.724 and p = 0.477, respectively) and MT (p = 0.314 and p = 0.444, respectively). Greater FL elongation was observed at the medial compared to the distal part of GM (p = 0.013) during the long stretching protocol. RFD significantly decreased after the long stretching protocol (p = 0.019), while it remained unchanged in the short stretching protocol (p = 0.061). Significant correlations were found between resting FL at the medial part of GM and RFD (r = −0.645, p = 0.05) and between fascicle elongation at the medial part of GM and CMJ height (r = 0.717, p = 0.01). CONCLUSIONS: The long static stretching protocol induced non-uniform adaptations along GM length and decreased RFD, suggesting that prolonged stretching durations should be avoided immediately before activities requiring rapid force production. Full article

Aim: Soccer is characterized as an intense intermittent team sport. Heart rate (HR) is used to monitor the players’ training response, as well as to quantify microcycle and mesocycle training intensity during preseason and in-season periods. The purpose of the present study was to quantify the preseason training intensity distribution in elite soccer players and then examine the relationship between HR distribution and changes in aerobic fitness. Material & Method: Sixteen elite professional soccer players (age, 26.8 ± 3.8 years; weight, 77.8 ± 7.7 kg; height, 1.79 ± 0.06 m; mean ± SD) participated in the study. Aerobic fitness was evaluated with VO₂max, running velocity at VO₂max (v-VO₂max) during a laboratory incremental aerobic test and with the distance completed during an interval shuttle run test (ISRT), before and after preseason. HR of each player was measured using a short-range telemetry HR transmitter strap at 5-s intervals during all training sessions of the preseason. The absolute (min) and relative (%) time spent in high-intensity HR zone (90–100% of HRmax) during the preseason period was calculated for each player. Results: VO₂max and distances completed during ISRT improved significantly (p < 0.05) by 3.3 ± 2.1% and 29 ± 16%, respectively. The time (%) players spent in high-intensity training was significantly correlated (p < 0.01) with the changes (%) in distance completed during ISRT. Conclusions: These results provide useful information about the HR quantification during preseason in elite soccer players. Additionally, coaches have to take into consideration the time soccer players spend in high-intensity training for optimal endurance responses when planning and implementing the preseason training period. Full article

AIM: Salivary cortisol has been used in research for studying possible alterations in human mood after different types of exercise. Exercise intensity plays an important role in mood levels and salivary cortisol concentration. The purpose of the study was to find out if two swimming learning programs could affect the salivary cortisol concentration and the score of pleasure in children. MATERIAL & METHOD: Participants were 40 rookie swimmers, aged 9.0 ± 0.9 (mean ± SD). The children were divided into two groups, control (CG, n = 21) and experimental (EG, n = 19), who trained in a pool with a classic and an alternative swimming training program, respectively. Intervention duration was 8 weeks and the training took place 3 times per week. Measurements were taken in the 4th week, before and after a training session, when both groups provided 0.5 mL of saliva. Saliva samples were analyzed for cortisol through ELISA method. Before saliva sampling, the children answered a motivation questionnaire to find out the pleasure levels from participation in training. For the statistical analysis we used the Shapiro-Wilk test of normality, two-way ANOVA with repeated measures, and Mann-Whitney U test. Cortisol concentration and questionnaire scores were correlated through Spearman correlation analysis. The level of statistical significance was set at α = 0.05. RESULTS: Salivary cortisol concentrations decreased in both groups with exercise (p = 0.001). Additionally, EG had higher concentrations than CG (p = 0.007). CG had higher scores than EG in the motivation questionnaire (p = 0.001). Moreover, pleasure scores correlated significantly with cortisol concentrations in CG (ρ =0.485, p = 0.04). CONCLUSIONS: Low-intensity swimming training targeting on fun lowers salivary cortisol concentration. The questionnaire revealed that young swimmers need the opportunity and time to understand that they are expressed through training to feel more pleasure with sport, especially in EG. Full article

AIM: Research evidence suggests that physical exercise can be part of standard care for breast cancer (BC) patients, contributing to the prevention or reduction of the adverse effects of both the disease and cancer therapies on physiological and quality of life (QoL) parameters. The purpose of this study was to assess QoL and physical activity (PA) levels of BC female patients under chemotherapy and compare them with healthy controls. MATERIAL & METHOD: 159 females were recruited, 94 BC patients [age, 57.25 ± 13.59 yrs; height, 1.61 ± 0.05 m; mass, 69.49 ± 12.67 kg; body mass index (BMI), 26.63 ± 5.36 kg/m²] and 65 healthy women [age, 49.60 ± 7.80 yrs; height, 1.65 ± 0.04 m; mass, 69.04 ± 5.25 kg; BMI, 25.30 ± 3.95 kg/m²]. Levels of PA were self-estimated using the International Physical Activity Questionnaire. QoL was self-reported by the BC and control groups using the EORTCQLQ-C30 and the SF-36 Health Survey, respectively. RESULTS: BC patients exhibited a total energy expenditure of 2,200 ± 1,187 MET-min/week, of which 1,384 ± 592 were spent in moderate PAs, 773 ± 436 in walking and 43.34 ± 159 in vigorous PAs. On the other hand, 49.30% and 50.70% of the controls participated in high-intensity and moderate-intensity PAs, respectively. Moreover, controls and BC patients were spending 2.34 ± 1.05 h/day and 4.62 ± 2.58 h/day sitting, respectively. BC patients scored their QoL with 63.43 ± 20.63 and physical functioning (PF) with 71.48 ± 23.35, while their fatigue, pain, and dyspnea scores were 42.28 ± 20.54, 19.44 ± 24.40, and 25.93 ± 28.85, respectively. Negative correlations were found between QoL and fatigue (p < 0.01), PF and pain (p < 0.01), fatigue (p < 0.01) and dyspnea (p < 0.05), while a positive correlation was found between QoL and PF (p < 0.01). Healthy participants evaluated their QoL as excellent (10.30%), very good (55.17%), average (29.30%), and poor (3.40%). CONCLUSION: This study revealed that BC patients represented moderate to high levels of functioning and QoL and preferred PAs of moderate intensity. Moreover, a positive association was found between PF and QoL in BC patients, while their QoL and functional capacity were compromised by pain, dyspnea, and fatigue. Although the BC group used to participate in PAs, they accumulated many hours seated, and they were overweight, further supporting the need for these patients to follow the specific exercise recommendations, so as to optimize their benefits from exercise. Full article

AIM: The present study examined the influence of match location, quality of opposition team, and playing position on physical performance indicators of the 4-2-3-1 formation. MATERIAL & METHODS: Twenty-six games (with 184 player-observations and 17 players, who played the full 90 min) were recorded with a video system, and the physical demands of the players were analyzed according to their specific playing position (classified into wide defenders, central defenders, central midfielders, wide midfielders, and forwards). Match performance variables analyzed included total distance (TD), high-intensity running (HIR), very-high-intensity running (VHIR), and sprinting (SPR). RESULTS: There was a main effect of position on TD (F = 37.84, p < 0.001), HIR (F = 41.19, p < 0.001), VHIR (F = 27.89, p < 0.001), and SPR (F = 22.25, p < 0.001). Wide defenders covered the most SPR and—along with the central midfielders—the most VHIR. Central midfielders covered the most TD and HIR. Match location and opposition quality had interactive effects on TD (F = 12.96, p < 0.001), HIR (F = 8.33, p = 0.004) and VHIR (F = 8.17, p = 0.005). Competing against “weak” opponents, more TD, HIR, and VHIR were covered during home games compared to away games (p < 0.001). However, more TD was covered during away games against “strong” opponents compared to away games against “weak” opponents (p < 0.01). CONCLUSIONS: The current study supports more individualized specific intense-based drills (e.g., repeated sprint training) for wide defenders and more volume-based drills (e.g., long interval training) for central midfielders, whilst total weekly training load can be adjusted based on match location and quality of oppositions in the anticipated game-load. Full article

Aim: Increased hamstring and lower back flexibility may contribute to preventing muscle injuries. However, inconsistencies exist on whether dynamic or static stretching exercises should be routinely used prior to and after training sessions/games to improve performance and ameliorate muscle soreness. No studies so far evaluated whether “poor” or “good” levels of flexibility may influence fitness parameters in elite young soccer players. The purpose, therefore, of the present study was to examine the effect of lower back and hamstring flexibility on several fitness parameters in elite young soccer players. Material & Method: One hundred three young elite soccer players (U15, U17, U19 National team members) were initially evaluated, but only 81 met the cut-off criteria and were included in the statistical analysis. These 81 players were separated into two groups based on their sit-and-reach flexibility score. The players whose score was less than 22 cm were included in the low-flexibility (L-Flex) group (n = 52), and those whose reach score was above 28 cm were included in the high-flexibility (H-Flex) group (n = 29). A comparison of several fitness parameters between groups was performed using unpaired t test. Results: Sit-and-reach flexibility was significantly higher (p < 0.001) in H-Flex (31.5 ± 3 cm) compared with the L-Flex group (18 ± 5 cm). No differences between groups were observed in age, height, body weight, % body fat, maximum speeds (5–30 m), isokinetic parameters, maximum aerobic speed and VO₂max (p > 0.05). Countermovement jump (CMJ, p = 0.023) and CMJ with arm-swing (p = 0.005) were significantly better in the H-Flex compared with the L-Flex group. No correlation was observed between mean flexibility score and any other evaluated fitness parameters (p > 0.05). Conclusions: High level of sit-and-reach flexibility may contribute to enhancing neuromuscular explosiveness performance in young elite soccer players. However, the exact mechanism responsible for these results still need to be determined. Full article

AIM: Forward and backward sprint are two types of locomotion commonly used in sports. The purpose of the present study was to examine the acute effect of two post-activation potentiation sprint protocols, including the aforementioned types of locomotion, in subsequent 20-m sprint performance (SP) and the possible fatigue caused by them in preadolescent boys. MATERIAL & METHOD: Fourteen recreationally active preadolescent boys (aged 12.49 ± 0.52 years) volunteered to participate in the study. Boys’ SP was evaluated randomly on three non-consecutive days. SP was evaluated 4 min after (a) a typical warm-up (3 min jogging and dynamic stretching), (b) the typical warm-up followed by 3 x 10 m forward sprint and (c) the typical warm-up followed by 3 × 10 m backward sprint. Τhe Microgate Witty Wireless Training Timer was used for the evaluation of SP and the 10-degree OMNI scale for the evaluation of the rate of perceived exertion. RESULTS: ANOVA with repeated measures indicated no statistically significant effect of protocol on the 0–5, 0–10 and 0–20 m SP (p > 0.05). On the contrary, it was found that the protocols in which 3 × 10 m forward or backward sprint was incorporated caused statistically significant greater fatigue than the control protocol (p < 0.001), without any differences between them. CONCLUSIONS: The implementation of three 10-m sprints, either forward or backward, to a standard warm-up does not cause acute improvement in 20-m sprint performance in preadolescent boys, as both protocols cause greater fatigue than a typical warm-up. Therefore, their addition to warm-up of preadolescent boys is not recommended. Full article

AIM: Monitoring biochemical and hematologic parameters in athletes at regular intervals is essential for the evaluation, protection, and improvement of their health and performance. The aim of the study was to monitor and evaluate the biochemical and hematologic status of elite Greek track-and-field athletes included in the roster of the Hellenic Athletics Federation (SEGAS). MATERIAL AND METHOD: 162 athletes (87 female and 75 male), aged 15–38, provided 285 blood samples one to four times over two years. Parameters monitored included indices of the iron status (hemoglobin, hematocrit, iron, total iron-binding capacity, transferrin saturation, and ferritin), glucose, the lipidemic profile (triglycerides, total cholesterol, HDL cholesterol, and LDL cholesterol), indices of the protein status and renal function (urea and creatinine), creatine kinase (CK) as an index of muscle fiber damage, γ-glutamyl transferase as an index of liver damage, minerals (calcium and magnesium), vitamins (folate, B₁₂, and D), cortisol and testosterone (indices of catabolic–anabolic balance), and thyroid-stimulating hormone for checking thyroid function. RESULTS: Although most parameters were normal, there were several instances of alerting values. These included high iron in females (in 13% of cases); hyperglycemia (10%) and hypercholesterolemia (14%) in males; high (11%) or low (15%) folate in females; and low (18%) folate in males. In 48% of cases in females and 74% in males, CK was higher than the normal values for the general population, although only 5% and 9% of cases, respectively, were above the proposed values for athletes (Mougios, Brit J Sports Med 41: 674-678, 2007), suggesting increased muscle fiber damage. There was also high prevalence of excessive vitamin B₁₂ (41% in females and 32% in males) and vitamin D insufficiency (54% in females and 38% in males). Hypercortisolemia, indicative of high physical and/or mental stress, was manifest in 15% of cases in females and 9% in males, whereas 21% of cases in males had high testosterone. CONCLUSIONS: These findings suggest some problems of training overload, malnutrition, and excessive vitamin and mineral supplementation in elite Greek track-and-field athletes. Personalized advice and instructions are necessary to remedy the problems identified. Full article

AIM: The aim of this study was to examine whether the addition of high-load resistance exercises to a high-intensity functional training (HIFT) program elicits further improvements in physical fitness-related parameters and body composition. Material & Method: Twenty recreationally active volunteers (8 male, 12 female; age, 30 ± 4 y; body mass, 65.8 ± 12.7 kg; height, 167 ± 7 cm) were randomly assigned to a HIFT-control (HIFT-C, n = 10) or HIFT-power group (HIFT-P, n = 10) and trained 3 times per week for 8 weeks. The HIFT-C protocol consisted of four rounds of an 8-exercise circuit (30:15 s work:rest, 2 min rest after round 2), which included clean-and-press jump box, TRX chest press, wall ball throws, burpees, repeated 10 m sprints, sumo squat-and-upright row (at 65% 1RM), and abdominal crunches. The HIFT-P group replaced the TRX chest press with bench chest press and the squat-and-upright row with squat at 80% 1RM. Before and after training, participants underwent evaluation of body composition, cardiorespiratory fitness (VO₂max), vertical jump, 1RM bench press, and maximum number of abdominal crunches in 1 min. Two-way repeated-measures ANOVA was used to analyze results. Statistical significance was set at p < 0.05. Results: After 8 weeks the following parameters improved in both groups: VO₂max (5.2 ± 5.4%, p = 0.003), squat jump (10.9 ± 9.8%, p < 0.001), countermovement jump (8.0 ± 6.0%, p < 0.001), bench press 1RM (18.6 ± 19.6%, p < 0.001), and body fat mass (0.82 ± 1.65 kg, p < 0.001). However, muscle mass increased only in HIFT-P (3.3 ± 2.3%, p = 0.002) and abdominal muscle endurance improved only in HIFT-C (16.2 ± 12.2%, p = 0.002). Conclusions: Short-term HIFT resulted in improvements in whole-body cardiorespiratory and neuromuscular fitness and reduction of body fat. The addition of high-load resistance exercises to a HIFT training program was well tolerated and resulted in increased muscle mass. Full article

AIM: Energy supply in artistic gymnastics is derived mainly through the anaerobic metabolism, due to the brief duration of the competitive routines. However, during training, gymnasts perform repetitive exercises and routines, which may require aerobic adaptations, in order to recover fast and maintain high quality of execution. To improve this aspect of fitness, coaches use high-intensity interval circuit training with sport-specific exercises. Despite the popularity of this training method, there is limited information regarding the demands placed on aerobic metabolism, especially in very young athletes. Thus, the aim of this study was to examine heart rate responses during a high-intensity functional training session in female child gymnasts, to indirectly assess the contribution of aerobic energy metabolism. MATERIAL & METHOD: Seventeen girls aged 9.8 ± 0.8 years (height, 1.38 ± 0.10 m; body mass, 33.7 ± 7.25 kg) performed two 5-min sets, each consisting of five rounds of five gymnastics exercises (5–7 s work and equal rest) executed at maximal effort. The two sets were separated by a 3-min recovery period. Prior to the main measurement, athletes performed a 20-m shuttle run test until exhaustion where maximum heart rate (HRmax) was measured and the maximum oxygen uptake (VO₂max) was estimated. Heart rate was continuously monitored during all sessions using a Polar team 2 system. RESULTS: VO₂max was 47.8 ± 3.0 mL kg^-1 min^-1 and HRmax was 207 ± 5 bpm. During the first set, peak HR was 192 ± 7 bpm and average HR was 171 ± 8 bpm (83% HRmax). During the second set, peak HR was 196 ± 8 bpm and average HR was increased to 186 ± 6 bpm (90% HRmax, p < 0.001 compared with set 1). The time during which HR was above 90% of HRmax was 2.0 ± 1.2min in set 1 and increased to 3.4 ± 1.7 min in set 2 (p < 0.01). HR recovery was similar after both sets, with HR decreasing by about 30% (to 139 ± 7 bpm and 134 ± 10 bpm) after 2 min (p < 0.001). CONCLUSION: These results suggest that high-intensity training using sport-specific exercises increases HR to levels above 90% HRmax for extended time periods. Thus, this type of training may be an appropriate stimulus for concurrent improvements in muscle strength/power and aerobic fitness. Full article

AIM: The present study was aimed at determining the effect of two different types of exercise (elite athletes playing football and ultramarathon runners on iron metabolism and, especially, the role of hepcidin in iron homeostasis. MATERIAL & METHOD: Two groups of athletes were investigated. The first group consisted of 19 male elite football athletes and the second group of 41 ultramarathon runners. In both cases, blood samples were taken pre-race (t1), immediately post-race (t2), and 24 hours post-race for football athletes or 36-48 hours post-race for ultramarathon athletes (t3). RESULTS: The iron levels in time t3 were found to have statistically significant decreases compared with the iron levels in pre-race and post-race period. Moreover, ferritin levels increased significantly in times t2 and t3. Hepcidin levels increased in time t2 in football players (from 27.45 ± 12.98 to 37.42 ± 13.74 ng/mL) and decreased in time t3. However, in ultramarathon runners, hepcidin levels significantly increased in time t2 (from 29.16 ± 10.92 to 58.81 ± 16.97 ng/mL) and remained increased in time t3 (37.69 ± 16.38 ng/mL), despite a trend for decrease. In football players, sTfR levels did not change, contrary to ultramarathon runners, where sTfR levels were found decreased in times t2 and t3. CONCLUSIONS: Iron metabolism in athletes can be impacted by the type of exercise. Ferritin is not a reliable marker for iron balance because, in the present study, it is more likely an acute-phase protein. The main regulator of iron homeostasis, hepcidin, increased, showing the body’s response to inflammation, by trapping iron in the macrophages and by altering iron absorption. Finally, a strenuous and prolonged exercise can lead to sports anemia. Full article

AIM: The aim of this study was to examine the relationship between the performance of men’s and women’s finalists in the 100-m finals of IAAF World Championship 2017 and the mechanical properties of horizontal force-velocity-power (FVP) profile produced by each athlete. MATERIAL & METHOD: The spatio-temporal data from the 16 finalist sprinters (8 men and 8 women with 10.04 ± 0.12 s and 10.97 ± 0.09 s 100-m performance, respectively), were obtained from recordings of the distance-time curve in men’s and women’s 100-m finals during the IAAF World Championships 2017. The variables of horizontal FVP profile were calculated in order to determine the relationship between horizontal FVP profile [theoretical maximal values of force (F0), velocity (V0), and power (Pmax), the proportion of the theoretical maximal effectiveness of force application in the forward direction (RFmax), the rate of decrease in the ratio of horizontal force (DRF)] and the 10-m split-time, as well as the sprint running performance of men’s and women’s finalists in 100-m race. RESULTS: Spearman’s correlation analysis revealed highly negative linear associations between Pmax (r = −0.87, r² = 0.76; p < 0.001), RFmax (r = −0.81, r² = 0.66; p < 0.001), V0 (r = −0.78, r² = 0.61; p < 0.001), and F0 (r = −0.66, r² = 0.44; p = 0.005) with 100-m performance. The 10-m split-time was highly negatively linearly associated with RFmax (r = −0.98, r² = 0.97; p < 0.001), F0 (r = −0.96, r² = 0.93; p < 0.001), Pmax (r = −0.96, r² = 0.91; p < 0.001), V0 (r = −0.62, r² = 0.38; p = 0.011). DRF was not correlated with 10-m split-time or 100-m performance (p > 0.05). CONCLUSION: The mechanical properties of FVP profile strongly influenced the 100-m performance of men’s and women’s world-class sprinters. This study highlights the importance of the technical capability of world-class athletes to effectively orient the horizontal force onto the supporting ground during the initial sprint-acceleration. Full article

AIM: Anaerobic interval sets are commonly used in the training program of swimmers competing in short-distance events. However, data regarding the way that these sets compare to the competitive events are lacking. The aim of this study was to examine if there are differences in speed, blood lactate, stroke rate (SR), and stroke index (SI) between an anaerobic set of 4 × 50 m maximal swimming with work-to-rest ratio of approximately 1:4 and the 100-m event in freestyle stroke. MATERIAL & METHOD: Twenty-seven competitive swimmers (11 males, 16 females), aged 16.1 ± 1.1 years, completed the two tests on different days, in a random counterbalanced order. In each test, blood lactate was measured before and repeatedly after exercise through a portable lactate analyzer. Time and SR were recorded for each 50 m of the tests, and speed and SI were subsequently calculated. Three-way analysis of variance (time × test × gender) and Pearson’s correlation analysis were used. The level of statistical significance was set at α = 0.05. RESULTS: Average speed was higher at 4 × 50 m compared to 100 m (1.62 ± 0.10 and 1.56 ± 0.10, respectively, p < 0.001) and was correlated between tests (r = 0.930, p < 0.001). Peak blood lactate after 4 × 50 m was higher compared to 100 m (14.8 ± 3.1 and 10.9 ± 3.3 mmol/L, respectively, p < 0.001) and was correlated between tests (r = 0.640, p < 0.001). Average SR was higher in 4 × 50 m compared to 100 m (47.0 ± 3.6 and 44.5 ± 3.2 cycles/min, respectively, p < 0.001) and was correlated between tests (r = 0.836, p < 0.001). Average SI did not differ but was correlated between tests (r = 0.937, p < 0.001). Males had higher SR and SI and were faster than females (p < 0.05) but did not differ from females regarding lactate. CONCLUSIONS: Based on the aforementioned differences and correlations, the 4 × 50 m training set could be used to improve the parameters that have impact on performance in the 100-m event. Full article

Aim: Aerobic, resistance, or isometric exercise has been shown to reduce blood pressure (BP) in normotensive and hypertensive individuals. The aim of this study was to examine the acute effect of combining resistance and isometric exercise and the training effect of combining all 3 types (aerobic, resistance and isometric exercise) in hypertensive patients. Material & Method: Fourteen adults, six females and eight males (age, 55 ± 11 yrs; BMI, 31.0 ± 6.0 kg^.m²; body fat, 34 ± 14 %; waist circumference, 102 ± 18 cm; mean ± SD), with stage 1 and 2 hypertension performed a combined resistance and isometric exercise bout to examine the acute effect of exercise. Afterwards, volunteers were randomly divided into two groups of 7 participants each. One group performed 3 exercise sessions per week for 8 weeks (T). Training consisted of aerobic (45 min at 60–80% of maximal heart rate), resistance (3 sets of 10–15 repetitions at 60–80% of 1RM) and isometric (4 sets at 30% maximum handgrip strength for 2 min) exercise. The other group acted as a control group (C) and performed only isometric exercise at 5% of maximum handgrip strength for 2 min. Results: After the resistance-isometric exercise bout the average systolic (SBP), diastolic (DBP) and mean arterial blood pressure (MBP) over one hour post-exercise were reduced by 11 ± 2 mm Hg, 6 ± 1 mm Hg and 8 ± 1 mm Hg, respectively, compared to pre-exercise levels (p < 0.001). After 8 weeks of training in the T group SBP, DBP and MBP were reduced by 16 ± 4 mm Hg, 10 ± 3 mm Hg and 12 ± 3 mm Hg, respectively, compared to pre-training (p < 0.05). These values were higher (p < 0.05) than the corresponding values in the C group, where no changes were observed (SBP, 2 ± 1 mm Hg; DBP, 0 ± 1 mm Hg; MBP, 1 ± 1 mm Hg; p > 0.05). Conclusions: One bout of resistance-isometric exercise acutely reduced SBP, DBP, and MBP over one hour post-exercise, while 8 weeks of training that combined aerobic, resistance, and isometric exercise also reduced SBP, DBP, and MBP in adult patients with stage 1 and 2 hypertension. Full article

Aim: Aging is associated with declines in functional capacity and cognitive function. The aim of the present study was to examine, for the first time, the effects of a high-dose omega-3 and omega-6 fatty acid supplementation, in combination with antioxidant vitamins, on functional capacity and cognitive function in older adults with cognitive impairment, over a 6-month period in a randomized, double-blind, placebo-controlled design. Material & Method: Thirty-six older adults with cognitive impairment (aged 79.3 ± 7.6 yrs, 22 females) were randomized to receive either a formula containing a mixture of omega-3 and omega-6 fatty acids with antioxidant vitamins or placebo for six months. Participants completed assessments of functional capacity, cognitive function, and various aspects of quality of life at baseline and following three and six months of supplementation. Functional capacity was evaluated using two sit-to-stand tests (STS-5, STS-60), the timed-up-and-go test (TUG), the 6-min walk test (6MWT), and the handgrip strength test. Cognitive function was evaluated through the Addenbrooke’s Cognitive Examination Revised (ACE-R) and the Mini Mental State Examination (MMSE), whilst health-related quality of life, sleep quality, daily sleepiness, and fatigue were assessed by specific questionnaires. A linear mixed model with a random effect for participant was used to evaluate differences in the dependent variables between the supplementation and placebo groups throughout time, whilst it was adjusted for age and education of the participants. Results: A significant interaction between supplementation and time was found on functional capacity (6MWT and STS-60; p = 0.028 and p = 0.032, respectively), cognitive function (ACER and MMSE; p < 0.001 and p = 0.011, respectively), fatigue (p < 0.001), physical health component (p = 0.007), and daily sleepiness (p = 0.007), showing a favorable improvement for the participants receiving the nutritional supplement. Conclusions: The results of the present study showed that high-dose omega fatty acid and antioxidant vitamin supplementation improves functional capacity and cognitive function in older adults with cognitive impairment. Thus, this novel approach appears promising for reducing cognitive decline and frailty in the elderly. Full article

Aim: Pulmonary rehabilitation (PR) is an important and safe intervention which can improve health indicators and quality of life. The purpose of our study was to investigate the effect of 8 weeks of PR in patients with pulmonary embolism (PE) during (tele)rehabilitation and self-selected exercise (SSE) versus supervised exercise in a rehabilitation center (SE). Material & Method: 14 patients with PE participated in our study (age, 50.7 ± 15.1 yrs; BMI, 30.0 ± 3.3 kg/m²; male, 78.6%) and were divided into two groups (SSE, n = 7, vs. SE, n = 7). Inclusion criteria were diagnosis of PE > 6 months and weekly exercise ≤ 100 min. For each patient, demographics, characteristics of PE episodes, follow-up after the thromboembolic event, and echocardiography were recorded. Before and after the PR program we recorded anthropometric characteristics and questioners [Quality of life (SF-36) and Pittsburg sleep quality index (PSQI)], and we performed blood sampling for NT-proBNB measurement. Patients underwent cardiopulmonary exercise testing until exhausting.The PR exercise program included the following: SE, 3/w, 30-min intermittent exercise 1/1 in cycle ergometer at 70% VO₂max calculated from heart rate, 10-min respiratory physiotherapy, and 10-min strength exercises; SSE, 50-min walking at 60% VO₂max, 10-min (tele)respiratory physiotherapy and 10-min strength exercise. Results: The SSE group differed in mean arterial pressure at the end of ergospirometry pre- and post-PR (87.6 ± 3.3 vs. 95.0 ± 5.5 mmHg, p< 0.05). All patients showed differences pre-and post-PR in SF-36 (general health, 57.5 ± 14.9 vs. 63.8 ± 20.5 p< 0.05; physical health, 63.8 ± 189 vs. 75.6 ± 14.5, p< 0.05) and PSQI (cannot get to sleep within 30 min, 5.3 ± 2.2 vs. 3.5 ± 1.7, p< 0.05; enthusiasm, 1.3 ± 0.7 vs. 0.3 ± 0.5 p< 0.05) but we observed no differences between groups. The ΝΤ-proBNB (73.8 ± 11.8 vs. 104.0 ± 55.7 pg/mL) and ergospirometry parameters were not significantly different pre- and post-PR or between groups. Conclusions: PR may present a safe intervention in patients with PE. Post-PR results are similar in patients with SE and SSE. Full article

Aim: The purpose of the present study was to (1) investigate the cross-sectional (baseline) and longitudinal (12 months) effects of football (weight-bearing sport), swimming and cycling (non-weight-bearing sports), and an active control group on bone turnover markers in adolescent males and (2) examine the effect of a 9-month progressive jumping intervention programme on bone turnover in the sports groups of adolescent males. Materials & Methods: A total of 105 adolescent males (30 footballers, 37 swimmers, 26 cyclists, and 12 active controls), aged 12 to 14 years at baseline, were measured at baseline (T0), after 1 year of sport-specific training (T1) and following a 9-month progressive jumping intervention programme (T2). Bone turnover was measured using serum N-terminal propeptide of procollagen type I (PINP) as bone formation marker and isomer of the carboxy-terminal telopeptide of type 1 collagen (CTX-I) as bone resorption marker. Bone turnover rate and balance were estimated using the multiple of medians logarithmic equations of PINP and CTX-I. Results: At T0 there were no significant differences between groups in any of the biochemical markers. At T1 PINP was significantly higher in footballers than swimmers (3.3%) and cyclists (6.0%). Cyclists had significantly lower PINP (5.1%) and CTX-I (14.8%) than controls. In swimmers, there was a significant decrease in PINP (5.8%) and a significant increase in CTX-I (9.8%) from T0 to T1. In cyclists, PINP significantly decreased (7.2%) and CTX-I non-significantly increased (4.3%) from T0 to T1. At T2, PINP was reduced in all non-intervention sport groups (4.4% in swimmers, 3.3% in footballers, and 4.2% in cyclists). CTX-I was reduced by 3.8% in swimmers and cyclists who did not perform the intervention. Conclusions: The present study showed that at baseline there were no differences between groups in bone turnover, but after 1 year of sport-specific training bone turnover was significantly improved in footballers and controls compared to swimmers and cyclists. Following the 9-month jumping intervention bone turnover significant declined in the intervention groups of cycling and swimming. By contrast, bone formation significantly decreased in footballers and the control groups, and bone resorption significantly decreased in the non-intervention groups of cycling and swimming. Full article

AIM: The critical role of nutrition in athletes’ performance is widely accepted, and water polo players are no exception. However, there are no studies about their adequate knowledge of proper nutrition. Thus, the purpose of this study was to assess the nutritional knowledge of water polo players. MATERIAL & METHOD: We examined 30 male and 11 female water polo players of the A1 Greek national league, aged 16-37. Participants answered the “General Nutrition Knowledge Questionnaire” (Kliemann et al., Eur J Clin Nutr 70: 1174–1180, 2016) consisting of 86 questions on general nutrition knowledge. Results were analyzed with descriptive statistics and with the χ² test to examine gender differences. RESULTS: Participants answered correctly 59% and incorrectly 41% of the questions. The majority of false answers were about the role of fruits and vegetables, body composition, fats, nutritional supplements, salt, the energy content of food, micronutrients, sugar-containing foods, alcohol, the glycemic index, and whole-grain foods. Males performed significantly better in 2 questions compared to females (which combination of vegetables had more vitamins and which of chip choices is lower in fat). CONCLUSIONS: Water polo players had satisfactory knowledge on general nutrition, with males performing slightly better than females. However, they should receive further education on nutrition by experts in order to clarify misconceptions that still exist. Full article