Sports, Volume 8, Issue 6 (June 2020) – 16 articles

This study aimed to assess the effects of repeated menthol mouth swilling upon strength and power performance. Nineteen (10 male) participants completed familiarisation and experimental trials of repeated menthol mouth swilling (0.1% concentration) or control (no swill) in a randomised crossover design. Participants performed an isometric mid-thigh pull (IMTP; peak and mean force; N), vertical jump (peak; cm) and six second sprint (peak and mean power; W) under each condition. Participants completed three efforts per exercise task interspersed with three-minute recoveries. Mean best values were analysed via a two-way mixed repeated measures ANOVA, and differences reported as effect sizes ± 95% confidence intervals, with accompanying descriptors and p values. Differences in peak IMTP values were unclear between familiarisation and experimental trials, and between menthol and control conditions. Mean IMTP force differed between familiarisation and control (0.51; −0.15 to 1.14; p = 0.001) and familiarisation and menthol conditions (0.50; −0.15 to 1.14; p = 0.002) by a small degree, but were unclear between control and menthol conditions. Unclear differences were also noted on vertical jump performance compared to familiarisation and between experimental conditions, with repeated six second peak and average power performance also showing unclear effects across all comparisons. We conclude that repeated menthol mouth swilling does not improve strength or power performance. Full article

The effects of different factors—such as age, sex, performance level, and athletic shoe features—on postural balance in athletes remain unclear. The main objective of our study is to identify the features of postural stability in athletes of different age, sex, performance level, and using different types of athletic shoes. This study assessed postural stability in athletes (n = 936, 6–47 years) in a normal bipedal stance with eyes open (EO) and eyes closed (EC). Postural stability was evaluated based on the center of pressure (COP), sway area (AS), and velocity (VCP) while standing on a stabiloplatform. Children (6–12 years) and teen athletes (13–17 years) showed reduced AS-EO (p < 0.01) and VCP-EO (p < 0.01) compared to control (n = 225, 7–30 years). In male and female athletes aged 18+, only VCP-EC was lower versus control. In females (13–17 and 18+), VCP-EO and EC were lower than in males (p < 0.05). Only in the Shooting group, the athletes’ performance levels had an effect on VCP-EO (p = 0.020). Long use of rigid athletic shoes with stiff ankle support was associated with reduced posture stability. Postural stability in athletes was mostly influenced by the athlete‘s age, and, to a lesser extent, by their sex, performance level, and athlete shoe features. Full article

Appropriate levels of motor competence are an integrated part of individuals’ health-related fitness, and physical education is proposed as an important context for developing a broad range of motor skills. The aim of the current study was to apply meta-analyses to assess the effectiveness of curriculum-based physical education on the development of the overall motor competence of children and adolescents. Studies were located by searching seven databases and included according to predefined criteria. Random effects models using the standardized effect size (Hedges’ g) were used to aggregate results, including an examination of heterogeneity and inconsistency. The meta-analysis included 20 studies, and a total of 38 effect sizes were calculated. A statistically significant improvement in motor competence following curriculum-based physical education compared to active control groups was observed in children and adolescents (g = −0.69, 95% CI −0.91 to −0.46, n = 23). Participants’ ages, total time for physical education intervention, and type of motor competence assessment did not appear to be statistically significant moderators of effect size. Physical education with various curricula can, therefore, increase overall motor competence in children and adolescents. Full article

Research describing the match and specific positional demands during match play in women’s collegiate soccer is limited. The purpose of the study was to quantify the match demands of National Collegiate Athletic Association (NCAA) Division III soccer and assess position differences in movement kinematics, heart rate (HR), and energy expenditure. Twenty-five Division III women soccer players (height: 1.61 ± 0.3 m; body mass: 66.7 ± 7.5 kg; fat-free mass: 50.3 ± 6.5 kg; body fat%: 25.6 ± 5.1%) were equipped with a wearable global positioning system to assess the demands of 22 matches throughout a season. Players were categorized by position (goal keepers (GK), center defenders (CB), flank players (FP), forwards (F), and center midfielders (CM)). Players covered 9807 ± 2588 m and 1019 ± 552 m at high speeds (>249.6 m·m⁻¹), with an overall average speed of 62.85 ± 14.7 m·m⁻¹. This resulted in a mean HR of 74.2 ± 6% HR max and energy expenditure of 1259 ± 309 kcal. Significant and meaningful differences in movement kinematics were observed across position groups. CM covered the most distance resulting in the highest training load. FP covered the most distance at high speeds and mean HR values were highest in CM, CB, and FP positions. Full article

The activity of the transverse abdominal (TrA) muscle affects the stabilization of the trunk. It is known that after a stroke, people experience problems in performing daily activities. The purpose of this study was to examine whether there are differences in the transversus abdominal thickness between the two sides of the body in individuals with hemiparesis and controls. Eight patients with hemiparesis and nine controls matched for age and body mass index were examined by musculoskeletal ultrasound in four conditions: a) At rest, b) abdominal hollowing maneuver from the supine position, c) bridge, and d) abdominal hollowing maneuver from the bridge position. In each of the above conditions, the symmetry index was calculated as the absolute value of the difference in thickness between the two sides. Analysis of variance showed a lower TrA thickness at rest and exercise in patients compared to the control group (p < 0.05). Further, patients showed a lower contraction thickness ratio during exercise compared to controls (p < 0.05). The absolute symmetry of the TrA thickness was 12.59 ± 6.43% to 19.31 ± 10.43% in patients and it was significantly greater than the control group (3.01 ± 2.47% to 4.47 ± 2.87%). According to the above results, it seems that transverse abdominal activation exercises are particularly useful for improving the stability of patients with hemiparesis, as long as they are located and adapted to the deficit of each patient. Full article

This study explored the physical and fitness characteristics of elite professional rugby union players and examined the relationships between these characteristics within forwards and backs. Thirty-nine elite professional rugby union players from the New Zealand Super Rugby Championship participated in this study. Body composition was measured using dual-energy X-ray absorptiometry alongside anthropometrics. Fitness characteristics included various strength, power, speed, and aerobic fitness measures. Forwards were significantly (p ≤ 0.01) taller and heavier than backs, and possessed greater lean mass, fat mass, fat percentage, bone mass, and skinfolds. Forwards demonstrated greater strength and absolute power measures than backs (p = 0.02), but were slower and possessed less aerobic fitness (p ≤ 0.01). Skinfolds demonstrated very large correlations with relative power (r = −0.84) and speed (r = 0.75) measures within forwards, while backs demonstrated large correlations between skinfolds and aerobic fitness (r = −0.54). Fat mass and fat percentage demonstrated very large correlations with speed (r = 0.71) and aerobic fitness (r = −0.70) measures within forwards. Skinfolds, fat mass, and fat percentage relate strongly to key fitness characteristics required for elite professional rugby union performance. Individual and positional monitoring is important due to the clear differences between positions. Full article

We aimed to determine whether an Athletics Injury Prevention Programme (AIPP), targeting the most common athletics injuries, can reduce the occurrence of injury complaints that lead to restrictions in athletics participation (participation restriction injury complaints) in the short (12 weeks) and long (40 weeks) terms. For our 40-week prospective cohort study (level of evidence 2), we invited inter-regional and national-level athletes to regularly perform the AIPP, which included 8 exercises addressing core stability, hamstring, leg and pelvic muscles strengthening and stretching, and balance exercises. A Cox regression was used to analyse the influence of AIPP on the occurrence of participation restriction injury complaint, adjusted to sex, age, height, body mass, discipline, and history of injury complaints during the preceding season, individual response rate, mean weekly training time, mean weekly number of competition, presented by hazard ratio (HR) with 95% confidence interval (95% CI). At 12 weeks (n = 62 athletes), the AIPP was significantly associated with a lower risk of participation restriction injury complaint HR = 0.36 (95% CI: 0.15 to 0.86), p = 0.02 and HR = 0.29 (95% CI: 0.12 to 0.73), p = 0.009, with cumulative weeks and cumulative training time as time scale, respectively, while at 40 weeks (n = 53 athletes) there was no significant association. An 8-exercise injury prevention programme can effectively help to reduce occurrence of injury complaints that would restrict an athlete’s participation in athletics in the short term. Full article

Physical activity (PA) may improve brain development, cognition, concentration and academic performance. In this prospective controlled intervention study, we increased the level of PA in 338 children aged 6–8 years at study start, from the Swedish standard of 60 min per week to 200 min per week (40 min daily). The intervention continued in all nine compulsory school years until the students graduated between 2007–2012. All other 689,881 Swedish children who graduated the same years were included as a control group. We registered at graduation eligibility rate for upper secondary school and the final grade score (from 0 to 320 grade points). We also registered the same end points in the 295 students in the index school and in all other 471,926 Swedish students who graduated in 2003–2006, that is, those who graduated before the intervention study started. Before the intervention, academic performance was similar among children in the index school as for all other Swedish boys and girls. With the intervention, the eligibility rate increased for boys in the index school by 7.3 percentage points and the mean grade scores by 13.3 points. This should be compared with a decrease of 0.8 percentage points in eligibility rate and an increase by 2.7 points in grade score in other Swedish boys. No changes were seen for intervention girls, neither in eligibility rates or grade scores. By introducing daily school-based PA in compulsory school, more boys would probably reach the eligibility rate for higher education. Full article

The purpose of the study was to examine the differences in bilateral deficit (BLD) at different loadings during the half-squat jump (SJ) and horizontal countermovement jump (HCMJ) to determine if there is a relationship with linear sprint or change of direction (COD). The second goal was to check if fast players were more powerful in SJ and HCMJ than slow players in bilateral performance (BP). Twenty-seven male youth soccer players participated in the study. Players were divided in two groups, faster and slower, according to their sprint performance (10 and 40 m). BLD average power with body weight (BW) and 25%BW were significantly higher than 50%BW (p < 0.01). BLD during HCMJ was significantly higher than BLD during SJ with BW, 25%BW and 50%BW (p < 0.01). There were no statistical relationships between BLD and sprint or COD performance (p > 0.05). Fast players showed significantly higher SJ power with all the different loads and HCMJ than slow players (p < 0.01), and fast players lost more time executing COD-90° than slow players (p < 0.01). There were no statistical differences between fast and slow players in BLD. BLD seems to be dependent on motor task, contraction type and load and could not be a proper measure to estimate sprint and COD performance. Faster players are confirmed to be more powerful players than slow players, and decrements in COD could be a key benchmark to identify deficit between linear and COD performance. Full article

Studies evaluating the physical fitness levels of elite wrestlers during junior high school are limited. This study aimed to examine the body composition and physical fitness profiles of elite Japanese female wrestlers aged <12 years until >20 years. There were 114 elite female wrestlers enrolled. Measurements were conducted in the following age categories: <12 years (U-12), <15 years (U-15), <17 years (U-17: cadet), <20 years (U-20: junior), and >20 years (senior). Body composition variables consisted of body mass index (BMI), percent body fat, fat free mass, and fat free mass index (FFMI). Fitness measurements included grip strength, back strength, sit-up, rope-climbing, and endurance running tests. The wrestlers in this study demonstrated comparable or greater FFMI values (e.g., FFMI: 17.9 ± 0.4 kg/m² for light and 19.8 ± 0.9 kg/m² for heavy weight categories in U-20), when compared with young female wrestlers in previous studies, whereas stature, body mass, and BMI of the wrestlers in our study were unremarkable. Regarding the fitness assessment, a remarkable increase in back strength was observed after late puberty. An outstanding enhancement of muscle strength after late puberty, which is unlikely to occur in ordinary women, would be an important requirement to become the world’s top female wrestler. Full article

Breast cancer survivors suffer from disproportionate cardiovascular disease risk compared to age-matched controls. Beyond direct cardiotoxic effects due to treatments such as chemotherapy and radiation, breast-cancer-related reductions in skeletal muscle mass, quality and oxidative capacity may further contribute to cardiovascular disease risk in this population by limiting the ability to engage in aerobic exercise—a known promoter of cardiovascular health. Indeed, 20–30% decreases in peak oxygen consumption are commonly observed in breast cancer survivors, which are indicative of exercise intolerance. Thus, breast-cancer-related skeletal muscle damage may reduce exercise-based opportunities for cardiovascular disease risk reduction. Resistance training is a potential strategy to improve skeletal muscle health in this population, which in turn may enhance the capacity to engage in aerobic exercise and reduce cardiovascular disease risk. Full article

We compared the effects of accentuated eccentric loading (AEL) on mechanical variables and agonist muscle activation using low (30% 1-repetition maximum (1RM)) and high (80% 1RM) upward-phase loading with AEL (100% 1RM during downward phase) to traditional loading schemes (T) in the bench press. Twelve resistance-trained men (26 ± 6 years; 1RM: 134 ± 33 kg) performed sets of two repetitions with three-minute intervals using loading schemes of 30AEL, 30T, 80AEL, and 80T. AEL was applied using weight releasers while force plates and a 3D motion-analysis system were used to measure mechanical variables. Electromyographic activity of the pectoralis major and triceps brachii muscles was also recorded. The greater downward-phase loads experienced during the AEL conditions allowed greater overall mean vertical forces (mean difference ( $\overline{x}$ _Diff): 118 N, p < 0.001), greater work ( $\overline{x}$ _Diff: 43 J, p < 0.001), and greater pectoralis major muscle activation ( $\overline{x}$ _Diff: 27 µV, p = 0.002) compared to the corresponding traditional loading schemes. However, there was little evidence of potentiation of the mechanical variables or muscle activity during the subsequent upward phases caused by the AEL schemes. It is possible that the use of weight releasers may disrupt lifting technique particularly during low AEL schemes thereby diminishing any benefits. Full article

Trunk stability functions play an important role in sport and everyday movements. The aim of this study was to analyze trunk strength, trunk muscles onset of activity, and rate of electromyographic rise (RER) in the case of self-inflicted and unexpected trunk loading. Thirty-two healthy young adults (16 elite kayakers/canoeists and 16 non-athletes) were measured with a multi-purpose diagnostic machine. Trunk strength was assessed in standing position. Trunk muscles onset of activity and RER were assessed through unexpected loading over the hands and rapid shoulder flexion, respectively. In comparison with non-athletes, kayakers/canoeists did not significantly differ in trunk strength and showed lower trunk extension/flexion strength ratio (p = 0.008). In general, trunk muscles onset of activity did not significantly differ between the groups. On the contrary, kayakers/canoeists showed higher RER mean values in all the observed muscles (p < 0.041), except in multifidus muscle during self-inflicted movements. Similarly, higher RER variability was observed in the majority of the observed muscles among kayakers/canoeists. Higher RER among kayakers/canoeists could represent a protective mechanism that ensures spine stability and prevents low back pain. Full article

The aim of our study is to determine the first (LTP₁) and the second (LTP₂) lactate turn points during an incremental bicep curl test and to verify these turn points by ventilatory turn points (VT₁ and VT₂) and constant-load exercise tests. Twelve subjects performed a one-arm incremental bicep curl exercise (IET) after a one repetition maximum (1RM) test to calculate the step rate for the incremental exercise (1RM/45). Workload was increased every min at a rate of 30 reps/min until maximum. To verify LTPs, VT₁ and VT₂ were determined from spirometric data, and 30 min constant-load tests (CL) were performed at 5% P_max below and above turn points. Peak load in IET was 5.3 ± 0.9 kg (La_max: 2.20 ± 0.40 mmol·L⁻¹; HR_max: 135 ± 15 b·min⁻¹; VO_2max: 1.15 ± 0.30 L·min⁻¹). LTP₁ was detected at 1.9 ± 0.6 kg (La: 0.86 ± 0.36 mmol·L⁻¹; HR 90 ± 13 b·min⁻¹; VO₂: 0.50 ± 0.05 L·min⁻¹) and LTP₂ at 3.8 ± 0.7 kg (La: 1.38 ± 0.37 mmol·L⁻¹; 106 ± 10 b·min⁻¹; VO₂: 0.62 ± 0.11 L·min⁻¹). Constant-load tests showed a lactate steady-state in all tests except above LTP₂, with early termination after 16.5 ± 9.1 min. LTP₁ and LTP₂ could be determined in IET, which were not significantly different from VT₁/VT₂. Constant-load exercise validated the three-phase concept, and a steady-state was found at resting values below VT₁ and in all other tests except above LTP₂. It is suggested that the three-phase model is also applicable to small muscle group exercise. Full article

This investigation aimed to determine the countermovement jump (CMJ) neuromuscular performance (NMP) qualities that differentiate between athletes with high or low horizontal deceleration ability. Twenty-seven male university team sport athletes performed a CMJ on vertical axis force plates and a maximal horizontal deceleration following a 20 m maximal horizontal sprint acceleration. The instantaneous velocity throughout the maximal horizontal deceleration test was measured using a radar device. The deceleration ability was evaluated using the average deceleration (HDEC, m·s⁻²) and change in momentum—referred to as the horizontal braking impulse (HBI, N·s·kg⁻¹). Participants were dichotomised into high and low HDEC and HBI according to a median-split analysis, and CMJ variables calculated for the overall eccentric, eccentric-deceleration and concentric phases. When horizontal deceleration ability was defined by HDEC, the CMJ concentric (effect size (ES) = 0.95) and eccentric (ES = 0.72) peak forces were the variables with the largest difference between groups. However, when defined using HBI, the largest difference was the concentric (ES = 1.15) and eccentric (ES = −1.00) peak velocities. Only the concentric mean power was significantly different between the high and low groups for both HDEC (ES = 0.85) and HBI (ES = 0.96). These findings show that specific eccentric and concentric NMP qualities may underpin the horizontal deceleration abilities characterised by HDEC and HBI. Specific NMP training interventions may be beneficial to target improvements in either of these measures of horizontal deceleration abilities. Full article

The aim of this study was to investigate if the order of submaximal lactate threshold and maximal oxygen uptake testing would influence test outcomes. Twelve well-trained male cross-country skiers (mean age 19.6 years) performed two test sessions within a week in a within-subjects repeated measures with cross-over design study. A maximal oxygen uptake test (VO_2max) followed by a lactate threshold (LT) test and vice versa, were performed. The test data included VO₂, blood lactate (La^-_b), heart rate (HR), performance speed, Borg scale (RPE) at all stages and lactate accumulation throughout the whole test protocol including the breaks. No significant effect of testing order was found for: VO_2max (74.23 vs. 73.91 mL∙min⁻¹∙kg⁻¹), maximal HR (190.7 vs. 189.9 bpm) and speed at LT during uphill running. Three out of four common definitions of LT resulted in the same La^-_b at the last two steps, 11 and 12 km/h respectively, in the two protocols. It is worth noting that VO₂, HR and La^-_b were higher in the first two stages of the LT test when VO_2max was tested first in the protocol. Well-trained cross-country skiers conclusively attained a similar VO_2max and LT in both protocols, and the two tests did not seem to influence each other in terms of the degree of exhaustion that occurs in a single VO_2max or an incremental LT test. However, when using a curvilinear function to define the LT, it is important to know that the VO_2max test can influence levels of VO₂, HR and La^-_b at the first two stages of the LT test. Full article