Effects of β-Hydroxy β-Methylbutyric Supplementation in Combination with Conservative Non-Invasive Treatments in Athletes with Patellar Tendinopathy: A Pilot Study

The aim of the present study was to analyze the effect of conservative non-invasive treatments based on eccentric training, stretching and extracorporeal shock wave therapy (ESWT) supplemented with β-Hydroxy β-methylbutyric (HMB) or placebo (PLAC) on body composition, pain and muscular function (jump ability, muscular power and muscular strength) in athletes with patellar tendinopathy (PT). In a double-blind randomized trial, 8 athletes (4 males and 4 females) performed a physical rehabilitation for 4 weeks. They were randomly divided into two experimental groups (two males and two females in each one) that ingested HMB (HMBG) or PLAC (PLACG). In pre- and post-intervention were assessed body composition, pain, countermovement jump (CMJ), back-squat (BS) for analyzing peak power (W) (PPPP), load (kg) associated to PPPP (PPKG) and mean velocity (m/s) (PPMV) in addition to a 5-RM leg extension tests. An interaction intervention·supplementation (p = 0.049; Ƞ2p = 0.774) was observed in the height reached in the CMJ as an intervention effect in PPPP detected for the HMBG (p = 0.049). In addition, an enhancement in PPKG (p = 0.028; Ƞ2p = 0.842) was detected in the intervention, but not in PPMV, as an increase in the intervention in the 5-RM test (p = 0.001; Ƞ2p = 0.981) was observed. No changes were noted on body composition or pain (p > 0.05). The combination of eccentric training with stretching and ESWT increased concentric muscular power and strength after 4 weeks without changes in body lean mass or pain. In addition, HMB supplementation could enhance the power muscular performance in athletes with PT, optimizing the intervention adaptions.

The Effects of an Eight Week Plyometric-based Program on Motor Performance Skills and Muscular Power in 7–8-Year-Old Primary School Students

Background of Study: Competence in motor performance skills is important in enabling children to be physically literate. Plyometric-based training has been suggested as an effective means to enhance motor performance skills in young athletes. However, no studies have reported the effects of a whole body plyometric-based program integrated into physical education on motor performance skills with young children. Objective: This study aims to examine the effect of a plyometric-based program on primary school students’ motor performance skills, upper and lower body muscular power, and reactive strength index. Method: The sample was composed of 61 primary school students, 29 girls and 32 boys, aged 7–8 years old, from two second-grade Physical Education (PE) classes. Both groups participated in their regular eight-week PE lessons (50-minute classes twice a week). During the study, the plyometric group performed a plyometric-based program in the 15-minute warmup of each class, while the comparison group performed regular warmup activities. Student’s motor performance skill proficiency, reactive strength index, lower and upper body muscular power were assessed before and after the eight weeks of PE lessons. The data were analysed using a two-way analysis of variance, followed by pairwise comparisons with the Bonferroni adjustment. Results: The data analysis indicated significant increases in motor performance skill proficiency, upper and lower body muscular power in the plyometric group vs comparison group (p ≤ 0.05). Conclusion: These results suggest that including a plyometric-based program in the PE warmup phase of the lessons may improve motor performance skills and muscular power in primary school students.

Heart failure compromises muscle power of lower limbs of sedentary elderly people

Purpose. To analyze and to compare the absolute and relative muscle power of the lower limbs in sedentary elderly subjects with and without heart failure. Methods. The study included 36 elderly subjects (72 ± 6.5 years, 76.8 ± 4.8 kg, 171 ± 9.4 cm) divided into two groups: sixteen patients with heart failure versus twenty patients with coronary artery disease, but without heart failure. The muscle power of the lower limbs was assessed with a half-squat exercise; three repetitions were performed with three seconds of the interval between repetitions as fast as possible in the concentric phase. For the statistical analysis, unpaired Student's t-tests were used to compare the absolute and relative muscular power between groups. Results. Subjects without heart failure had significantly greater absolute (362 ± 18.5 W vs. 438 ± 22.3 W, p = 0.015) and relative (4.6 ± 0.2 W / kg vs. 5.9 ± 0.2 W / Kg, p = 0.001) muscle power versus subjects with heart failure. Conclusion. Heart failure harms the muscular power of the lower limbs in the elderly, which may influence the prognosis and evolution of the disease and capacity functional.

Countermovement Jump with the Help of Wings in 16-Year-Old Volleyball Players

Vertical jump is combined with the assessment of the strength and strength of the muscles of the lower extremities that are fundamental components of the volleyball game's work.The Countermovement Jump with arm (CMJA) test as a specific specifically for the assessment of the offensive force of volleyball players.Methods: Female (F) - Males (M) average volleyball players were tested in CMJA at the GFRP; Force(F max), Power(P max) and gravity shift relationship Jump Height(JH). Anthropometric measurements of volleyball players were also developed; Body Height (BH cm), Body Mass (BMI% kg/m²), Body Weight (BW kg). Results: The differences between the two groups found in the study resulted in significant differences in BH cm (F-172, M-187.3), BW kg (F- 62.2, M -79.3), BMI kg / m² (F-21.1, M -22.6), Jump place in JP cm (F-266, M-310), Jump Attack in JA cm (F-274, M-321). But even the data captured by the Leonardo platform in the CMJA test gives us a noticeable difference between the two groups; (F-6.4,M-4.5), P max (F-3.08, M-4.78) and diff P max Left - Right(F-2.59,M-0.56),V max m/%(F-5.2,M-4.4). Conclusion: The results obtained suggest changes to the performance of volleyball players in "vertical jump" in the parameters of force, speed, and power. These indicators are valid for any trainer or volleyball player to implement a detailed and specific training program for the further development of the physical qualities of volleyball players, especially vertical tipping in gaining the lower extremity muscular power.

Relationship between Biological, Training, and Physical Fitness Variables in the Expression of Performance in Non-Professional Runners

Sports performance is a multifactorial trait that can be associated with individual and environmental characteristics. In this study, the sample comprised 35 male runners, enrolled in the “InTrack” project. Information regarding variables related to runners’ training was obtained via an online questionnaire, while anthropometric and body composition variables, as well as physical fitness components (muscular power, isometric strength, local muscular endurance, agility, and aerobic capacity) were measured, and a global physical fitness score (based on physical fitness components measured) was computed. The Weltman test (3200 m) was used to estimate runners’ pace and their stride frequency. Linear regression was used, taking the running pace as dependent variable. The final model, comprising biological, physical fitness, spatiotemporal, and training variables, explained 86% of the running performance variance. Muscular power (β = −1.02; 95% CI = (−1.69)–(−0.35)), abdominal muscle endurance (β = −4.81; 95% CI = (−7.52)–(−2.10)), isometric strength (β = −422.95; 95% CI = (−689.65)–(−156.25)), global physical fitness (β = 27.14; 95% CI = 9.52–45.03), and stride frequency (β = −2.99; 95% CI = (−4.29)–(−1.69)) were significantly associated with performance, meaning that better results in tests and increasing the stride frequency leads to better performance. Individual characteristics and physical fitness components were demonstrated to be significant predictors for running performance.

Maximal muscular power: lessons from sprint cycling

Maximal muscular power production is of fundamental importance to human functional capacity and feats of performance. Here, we present a synthesis of literature pertaining to physiological systems that limit maximal muscular power during cyclic actions characteristic of locomotor behaviours, and how they adapt to training. Maximal, cyclic muscular power is known to be the main determinant of sprint cycling performance, and therefore we present this synthesis in the context of sprint cycling. Cyclical power is interactively constrained by force-velocity properties (i.e. maximum force and maximum shortening velocity), activation-relaxation kinetics and muscle coordination across the continuum of cycle frequencies, with the relative influence of each factor being frequency dependent. Muscle cross-sectional area and fibre composition appear to be the most prominent properties influencing maximal muscular power and the power-frequency relationship. Due to the role of muscle fibre composition in determining maximum shortening velocity and activation-relaxation kinetics, it remains unclear how improvable these properties are with training. Increases in maximal muscular power may therefore arise primarily from improvements in maximum force production and neuromuscular coordination via appropriate training. Because maximal efforts may need to be sustained for ~15-60 s within sprint cycling competition, the ability to attenuate fatigue-related power loss is also critical to performance. Within this context, the fatigued state is characterised by impairments in force-velocity properties and activation-relaxation kinetics. A suppression and leftward shift of the power-frequency relationship is subsequently observed. It is not clear if rates of power loss can be improved with training, even in the presence adaptations associated with fatigue-resistance. Increasing maximum power may be most efficacious for improving sustained power during brief maximal efforts, although the inclusion of sprint interval training likely remains beneficial. Therefore, evidence from sprint cycling indicates that brief maximal muscular power production under cyclical conditions can be readily improved via appropriate training, with direct implications for sprint cycling as well as other athletic and health-related pursuits.

EFFECT OF HIGH AND LOW FLEXIBILITY ON AGILITY, ACCELERATION SPEED AND VERTICAL JUMP PERFORMANCE OF VOLLEYBALL PLAYERS

This study aimed to assess the effect of high and low levels of flexibility on key performance indicators of volleyball performance. Eighty-four volleyball players (n=84; mean±SD; decimal age: 16.57±1.51; height (cm): 176.23±8.77; body mass (kg): 66.14±11.79) were selected for the study. The design of the study was cross-sectional and to measure selected variables i.e. agility, lower body muscular power, and acceleration speed; 6×10 m shuttle run, countermovement jump (with arm swing) test and 20 m sprint test (standing start) were used. To measure the flexibility level of the players, sit and reach test was used. Shapiro-Wilk normality test was conducted to check the distribution of data and the Levine test was applied to check homogeneity of the variance in data. Participants were divided into two groups i.e. High Flexibility Group (HFG) and Low Flexibility Group (LFG) using k-means cluster analysis and independent t-test was applied to find the differences between HFG and LFG. The level of significance was set at p < 0.05. Results showed statistically significant difference between HFG and LFG in agility, acceleration speed and lower body muscular power and, based on the results, it was concluded coaches should include flexibility training in the regular training programme. The results obtained supported the rationale that baseline flexibility may influence the performance of volleyball players. <p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0778/a.php" alt="Hit counter" /></p>

Effect of Dry-Land Core Training on Physical Fitness and Swimming Performance in Adolescent Elite Swimmers

Background: We aimed to investigate the effect of a 12-week dry-land core training program on physical fitness and swimming performance in elite adolescent swimmers. Methods: Thirty subjects were selected and assigned to the core training group (CTG, n=15) and the traditional weight training group (WTG, n=15) in Seoul, Korea, between Sep and Dec 2016. The field fitness test was performed to determine the isotonic maximum muscular strength (one repetition maximum of deadlift and cable pulldown), anaerobic power (Wingate test), core stability (sports-specific endurance plank), core muscular power (front abdominal power, side abdominal power), muscular endurance of limbs (push-up, endurance jump), and swim performance improvement (personal record). Differences between groups after the exercise intervention were analyzed using two-way analysis of variance with repeated measures. Results: There were no significant interactions in isotonic maximum strength, anaerobic power (mean power, fatigue index), core muscular power, muscular endurance of limbs (endurance jump), and swim record improvement (P>0.05). The anaerobic peak power (P<0.001), sports-specific endurance plank test (P<0.001), and push-up test (P<0.001) showed significant interaction effects. Conclusion: The 12-week dry-land core training program resulted in statistically significant improvements in anaerobic power, core stability, upper extremity muscular endurance, and swimming performance.