Sports, Volume 8, Issue 11 (November 2020) – 11 articles

Background The purpose of the study was to examine differences in objectively measured moderate-to-vigorous physical activity (MVPA min/day) and sedentary time (SED min/day) between different time domains as school hours, leisure time, and weekends. An additional objective addressed causal association between body mass and MVPA. Methods. The study sample consisted of 2015 subjects (51% girls) aged 6–12 years (9.46 ± 1.76) from the Health Oriented Pedagogical Project (HOPP) in south-east Norway. Six days of MVPA min/day and SED min/day were measured using accelerometers and presented as daily averages. The differences in physical activity (PA) were investigated between the time domains of school-hours, leisure time and weekends by age and sex. Data were analyzed using one-and two-way ANOVA. Results. The relative contribution of the different time domains in overall PA was found. Daily average of MVPA min/day and SED min/day differed significantly across the three time domains. The average weekend SED was 56 ± 3.45 and 82 ± 4.12 min/day less when compared with school hours and leisure time, respectively. On average children spent 27 ± 2.74 min/day less in MVPA during school hours, compared with leisure time (p < 0.001), and spent by 38 ± 2.10 min/day more during weekends compared to school hours (p < 0.001). Boys were more physically active than girls, and less time was spent in MVPA with age. Conclusion. With the objective of increasing PA in a child population, the findings indicate that PA intervention programs should target children with higher body mass, girls more than boys, older children more than younger, and during school hours and leisure time more than on weekends. Full article

Bodybuilding is a sport that requires adequate training strategies in order to maximize skeletal muscle hypertrophy. The purpose of the present review was to perform a narrative assessment of the training routines designed for muscle hypertrophy used by bodybuilders. A search was carried out in the databases Pubmed/MEDLINE, Scielo, EBSCO, LILACS, SportDiscus, Web of Science, and CINAHL with the words “Resistance training” and “hypertrophy” in bodybuilders and their variations that involve the respective outcomes. Fourteen studies were identified that investigated the long-term training routines of bodybuilders. These studies demonstrate a pattern in the training organization, whereby there is a separation of training into four distinct periods: off-season, pre-contest, peak week, and post-contest. Each period has a specific spectrum of intensity load, total training volume, and exercise type (multi- or single-joint). We conclude that bodybuilding competitors employed a higher intensity load, lower number of repetitions, and longer rest intervals in the off-season than pre-contest. Full article

Background: Benefits of sprint interval training performed in hypoxia (SIH) compared to normoxia (SIN) have been assessed by studies mostly conducted around 3000 m of simulated altitude. The present study aims to determine whether SIH at an altitude as high as 4000 m can elicit greater adaptations than the same training at 2000 m, 3000 m or sea-level. Methods: Thirty well-trained endurance male athletes (18–35 years old) participated in a six-week repeated sprint interval training program (30 s all-out sprint, 4 min 30 s recovery; 4–9 repetitions, 2 sessions/week) at sea-level (SL, n = 8), 2000 m (F_iO₂ 16.7%, n = 8), 3000 m (F_iO₂ 14.5%, n = 7) or 4000 m (F_iO₂ 13.0%, n = 7). Aerobic and anaerobic exercise components were evaluated by an incremental exercise test, a 600 kJ time trial and a Wingate test before and after the training program. Results: After training, peak power output (PPO) during the incremental exercise test increased (~6%) without differences between groups. The lactate threshold assessed by Dmax increased at 2000 m (+14 ± 12 W) and 4000 m (+12 ± 11 W) but did not change at SL and 3000 m. Mean power during the Wingate test increased at SL, 2000 m and 4000 m, although peak power increased only at 4000 m (+38 ± 38 W). Conclusions: The present study indicates that SIH using 30 s sprints is as efficient as SIN for improving aerobic and anaerobic qualities. Additional benefits such as lactate-related adaptations were found only in SIH and Wingate peak power only increased at 4000 m. This finding is of particular interest for disciplines requiring high power output, such as in very explosive sports. Full article

This study aimed to clarify whether changes in the fatigue status of elite athletes during a precompetition period could be evaluated using morning heart rate variability (HRV) indices. Eight Japanese National Badminton Team players (age, 23.0 ± 2.8 years) participated in this study. HRV and subjective fatigue were measured during the first (days 1–4: Phase 1) and the second half (days 5–8: Phase 2) of an 8-day national team training camp. The global and parasympathetic HRV indices were as follows: standard deviation of all R-R intervals (SDNN) (Phase 1, 87.5 ms; Phase 2, 104.3 ms; p < 0.05), root mean square of the successive R-R interval differences (RMSSD) (Phase 1, 66.6 ms; Phase 2, 103.6 ms; p < 0.05), and high-frequency component power (HF) (Phase 1, 1412.0 ms²; Phase 2, 3318.5 ms²; p < 0.05). All the aforementioned indices increased significantly from Phase 1 to Phase 2. Significant correlations were observed between the change in subjective fatigue and changes in SDNN, RMSSD, and HF (ρ = −0.80, p = 0.017; ρ = −0.77, p = 0.027; and ρ = −0.80, p = 0.017, respectively). Measuring morning HRV indices may be effective for objectively evaluating changes in the fatigue status of elite athletes during a precompetition period. Full article

Background: The work of a coach can be stressful, and little is known about how volunteer coaches in child and youth soccer perceive stress. Therefore, the overall aim of this study was to explore perceptions of stress among Swedish volunteer youth soccer coaches. Methods: An online questionnaire was distributed to 1514 soccer coaches of which 688 (78% men and 22% women; 4% < 30 years, 34% 31–40 years; 57% 41–50 years and 5% > 51 years) with non-profit positions responded. Results: Findings indicate that participants in general do not feel excessively stressed by being a volunteer youth soccer coach (M = 2.20; SD = 0.93; Min = 1; Max = 5), and no significant differences in perceived stress level were found based on gender, age, ethnicity, educational level or occupation. Multiple regression analysis showed that demands from employment (β = 0.24, p < 0.001), difficulty catching up with the family (β = 0.22, p < 0.001), not having enough time to plan activities (β = 0.13, p < 0.001), feeling pressured when selecting the team (β = 0.09, p = 0.013) and own demands to achieve good results (β = 0.07, p = 0.045), significantly contributed to perceptions of stress among the investigated youth sport coaches. Conclusions: The results shed light on the important aim that sport clubs develop holistic strategies when recruiting and retaining coaches and for other functions concerning child and youth soccer teams. Full article

Some controversy exists as to the most efficacious method of training to achieve enhanced levels of sport performance. Controversy concerning the efficacy of periodization and especially block periodization (BP) likely stems from the use of poorly or untrained subjects versus trained who may differ in their responses to a stimulus. The purpose of this study was to investigate the effect of training status on performance outcomes resulting from 11 weeks of BP training. Fifteen males were recruited for this study and placed into strong (age = 24.3 ± 1.9 years., body mass (BM) = 87.7 ± 8.7 kg, squat: body mass = 1.96 ± 0.16), moderate (age = 25.3 ± 2.7 years., body mass = 100.2 ± 15.5 kg, squat: body mass = 1.46 ± 0.14), or weak (age = 23.2 ± 3.9 yrs., body mass = 83.5 ± 17.1 kg, squat: body mass = 1.17 ± 0.07) groups based on relative strength. Testing was completed at baseline, and after each block which consisted of 1 repetition maximum (1RM) squat, 0 kg static jump (SJ), 0 kg countermovement jump (CMJ), 20 kg SJ, and 20 kg CMJ. Absolute and relative strength were strongly correlated with rates of improvement for absolute strength, relative strength, 0 kg, and 20 kg vertical jumps. All subjects substantially improved back squat (p < 0.001), relative back squat (p < 0.001) with large–very large effect sizes between groups for percent change favoring the weak group over the moderate and strong group for all performance variables. All subjects showed statistically significant improvements in 0 kg SJ (p < 0.001), 0 kg CMJ (p < 0.001), 20 kg SJ (p = 0.002), and 20 kg CMJ (p < 0.001). Statistically significant between group differences were noted for both 20 kg SJ (p = 0.01) and 20 kg CMJ (p = 0.043) with the strong group statistically greater jump heights than the weak group. The results of this study indicate BP training is effective in improving strength and explosive ability. Additionally, training status may substantially alter the response to a resistance training program. Full article

The purpose of this study was to compare how 6 weeks of strength- vs. plyometric training, which were matched upon direction of motion and workload, influences change of direction (COD) performance. Twenty-one experienced male soccer players (age: 22.2 ± 2.7) were pair-matched into a strength- (n = 10) and a plyometric (n = 11) training group. CODs of 45°, 90°, 135° and 180° performed from either a 4 m or 20 m approach distance were compared before and after intervention. Results showed no significant difference between groups. Significant effects were only found within the plyometric training group (−3.2% to −4.6%) in 90°, 135° and 180° CODs from 4 m and a 180° COD from a 20 m approach distance. Individual changes in COD performances showed that with the 4 m approach at least 55% and 81% of the strength and plyometric training group, respectively, improved COD performance, while with the 20 m approach at least 66% of both groups improved performance. This study showed that the plyometric training program can improve most CODs, with angles over 90°, although this is dependent on the distance approaching the COD. Considering the limited time of implementing physical conditioning, in addition to regular soccer practice in most soccer environments, the current plyometric training program can be advantageous in improving CODs at maximal intensity. Full article

Proper training methods may be used as an effective preventative measure for many of the musculoskeletal injuries sustained as a first responder that are inherent to the profession. The traditionally low fitness levels and poor exercise habits of city firefighters may predispose this population to an increased risk of chronic conditions, such as cardiovascular and metabolic disease. The purpose of this study was to analyze changes in the health and fitness parameters of professional firefighters across North Texas during a six-month training program. Twenty-two professional firefighters completed six months of group training, consisting of two training sessions per week. These individuals underwent a pre- and post-fitness testing protocol that consisted of body composition, range of motion, anaerobic power, muscular endurance, and cardiorespiratory fitness. Improvements (p < 0.05) in flexibility, anaerobic performance, fatigue index, muscular endurance, and aerobic fitness were found following the six-month training program. No differences in body composition or peak power were observed (p > 0.05). Six months of group exercise improves aerobic and anaerobic fitness, exercise tolerance, muscular endurance, and flexibility in firefighters. Full article

Easy-to-apply and quick methods for evaluate body composition are often preferred when assessing soccer teams. This study aimed to develop new equations for the somatotype quantification that would reduce the anthropometric measurements required by the Heath and Carter method, integrating the somatotype assessment to the bioelectrical impedance analysis (BIA). One hundred and seventy-six male elite soccer players (age 26.9 ± 4.5 years), registered in the Italian first division (Serie A), underwent anthropometric measurements and BIA. Endomorphy, mesomorphy, and ectomorphy were obtained according to the Heath and Carter method, while fat mass (FM) and fat free mass (FFM) estimated using a BIA-derived equation specific for athletes. The participants were randomly split into development (n = 117) and validation groups (n = 59, 1/3 of sample). The developed models including resistance²/stature, FM%, FFM, contracted arm and calf circumference, triceps, and supraspinal skinfolds had high predictive ability for endomorphy (R² = 0.83, Standard Error of Estimate (SEE) = 0.16) mesomorphy (R² = 0.80, SEE = 0.36), and ectomorphy (endomorphy (R² = 0.87, SEE = 0.22). Cross validation revealed R² of 0.80, 0.84, 0.87 for endomorphy, mesomorphy, and ectomorphy, respectively. The proposed strategy allows the integration of somatotype assessment to BIA in soccer players, reducing the number of instruments and measurements required by the Heath and Carter approach. Full article

This study aimed to examine the effects of short-term detraining on the strength, speed, and jump capacities of under-20 soccer players. Twenty-four elite under-20 soccer players from the same professional club were assessed pre and post 26 days of detraining. The measurements were performed in the following order: countermovement jump (CMJ); 10 m linear sprint velocity; and one-repetition maximum test (1RM) in the horizontal leg-press exercise. To analyze the differences between pre- and post-tests, a paired T-test was applied. The significance level was set as p < 0.05. Soccer players exhibited a significant increase in CMJ performance (p = 0.02) and no significant differences in 10 m sprint velocity and 1RM leg-press were found after the short-term training cessation (p = 0.61; p = 0.55, respectively). We demonstrated that a short-term detraining period was capable of promoting a significant increase in the vertical jump height without inducing negative effects on the strength and speed capabilities of elite under-20 soccer players. Practitioners and sport scientists should be aware of these findings to program more effective training strategies at the beginning of the subsequent training cycle. Full article

This study aimed to investigate the relationship between relative or absolute intensity and changes in range of motion and passive stiffness after static stretching. A total of 65 healthy young adults voluntarily participated in this study and performed static stretching of the plantar flexor-muscle for 120 s. Dorsiflexion range of motion and passive torque during passive dorsiflexion before and after stretching were assessed. We measured the passive torque at a given angle when the minimum angle was recorded before and after stretching. The angle during stretching was defined as the absolute intensity. Dorsiflexion range of motion before stretching was defined as 100%, and the ratio (%) of the angle during stretching was defined as the relative intensity. A significant correlation was found between absolute intensity and change in passive torque at a given angle (r = −0.342), but relative intensity and range of motion (r = 0.444) and passive torque at dorsiflexion range of motion (r = 0.259). A higher absolute intensity of stretching might be effective in changing the passive properties of the muscle-tendon unit. In contrast, a higher relative intensity might be effective in changing the range of motion, which could be contributed by stretch tolerance. Full article