Effect of betaine supplementation on power performance and fatigue

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to examine the efficacy of 15 days of betaine supplementation on muscle endurance, power performance and rate of fatigue in active college-aged men.</p> <p>Methods</p> <p>Twenty-four male subjects were randomly assigned to one of two groups. The first group (BET; 20.4 ± 1.3 years; height: 176.8 ± 6.6 cm; body mass: 77.8 ± 13.4 kg) consumed the supplement daily, and the second group (PL; 21.4 ± 4.7 years; height: 181.3 ± 5.9 cm; body mass: 83.3 ± 5.2 kg) consumed a placebo. Subjects were tested prior to the onset of supplementation (T1) and 7 (T2) and 14 days (T3) following supplementation. Each testing period occurred over a 2-day period. During day one of testing subjects performed a vertical jump power (VJP) and a bench press throw (BPT) power test. In addition, subjects were required to perform as many repetitions as possible with 75% of their 1-RM in both the squat and bench press exercises. Both peak and mean power was assessed on each repetition. On day two of testing subjects performed two 30-sec Wingate anaerobic power tests (WAnT), each test separated by a 5-min active rest.</p> <p>Results</p> <p>No differences were seen at T2 or T3 in the repetitions performed to exhaustion or in the number of repetitions performed at 90% of both peak and mean power between the groups in the bench press exercise. The number of repetitions performed in the squat exercise for BET was significantly greater (p < 0.05) than that seen for PL at T2. The number of repetitions performed at 90% or greater of peak power in the squat exercise was significantly greater for BET at both T2 and T3 than PL. No differences in any power assessment (VJP, BPT, WAnT) was seen between the groups</p> <p>Conclusion</p> <p>Two-weeks of betaine supplementation in active, college males appeared to improve muscle endurance of the squat exercise, and increase the quality of repetitions performed.</p

Conhecimento individual e Sociedade em Piaget: implicações para a investigação psicológica

Este artigo pretende ser uma reconstrução histórica das categorias utilizadas por Piaget para o estudo das relações entre os conhecimentos individuais e a sociedade. Serão examinadas as vicissitudes sofridas por conceitos, tais como autismo, egocentrismo, sociocentrismo, ideologia e marco epistêmico. O esforço principal dirige-se para o estabelecimento do sentido que eles foram adquirindo no curso da reelaboração teórica das idéias clássicas de Durkheim e das discussões e intercâmbios com seus contemporâneos, como Lucien Goldmann e Rolando García. Particularmente, fixa-se uma orientação que vai de uma perspectiva fortemente imanentista e objetivista – de ruptura entre ciência e sociocentrismo –, até uma versão mais aberta e histórica de “ciência com ideologia”. Finalmente, trata-se de avaliar criticamente as conseqüências dessas idéias para a investigação psicológica, referente ao desenvolvimento das idéias morais e institucionais das crianças. A este respeito são evocadas algumas discussões atuais originadas, em diferentes correntes de pensamento

A Comparison of Warm-up Effects on Maximal Aerobic Exercise Performance in Children

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Thermogenic effect of meltdown RTD™ energy drink in young healthy women: a double blind, cross-over design study

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A 47-Year Comparison of Lower Body Muscular Power in Spanish Boys: A Short Report

This article belongs to the Special Issue Health Promotion in Children and Adolescents through Sport and Physical Activities—2nd Edition[Abstract] Much of the evidence examining temporal trends in fitness among youth has found a decrease in measures of muscular strength and muscular power over recent decades. The aim of this study was to examine trends in lower body muscular power in Spanish boys over 47 years. In 1969 140 boys (10–11 years; body mass index = 19.24, SD = 2.91 kg/m2) and in 2016, 113 boys (10–11 years; body mass index = 19.20, SD = 3.15 kg/m2) were recruited. Lower body power was assessed using the vertical jump (VJ) and standing long jump (SLJ) tests. Significant differences and a large effect size were shown between groups in the SLJ (p = 0.001; d = 0.94) and the VJ (p = 0.001; d = 0.66). SLJ data in 1969 were higher (1.52 m, SD = 0.19) when compared to the 2016 data (1.34 m, SD = 0.18). The VJ performance of the 1969 sample was also higher (25.95 cm; SD = 6.58) than the 2016 sample (21.56 cm; SD = 4.72). SLJ and VJ performance of the 2016 group decreased 11.8% and 16.9%, respectively. There were no significant differences between groups in body mass index. The results indicate a secular decline in lower body muscular power in 10–11-year-old Spanish boys with no significant changes in body mass index over the 47-year study period

Acute Cardiometabolic Responses to Medicine Ball Interval Training in Children

International Journal of Exercise Science 11(4): 886-899, 2018. Medicine ball interval training (MBIT) has been found to be an effective exercise modality in fitness programs, yet the acute physiological responses to this type of this exercise in youth are unknown. The purpose of this study was to examine the acute cardiometabolic responses to MBIT in children. Fourteen children (mean age 10.1 ± 1.3 yr) were tested for peak oxygen uptake (VO2peak) on a treadmill and subsequently (\u3e 48 hours later) performed a progressive 10 min MBIT protocol of 5 exercises (EX): standing marches (EX1), alternating lunges (EX2), squat swings (EX3), chest passes (EX4) and double arm slams (EX5). A 2.3 kg medicine ball was used for all trials and each exercise was performed twice for 30 sec with a 30 sec rest interval between sets and exercises. Participants exercised while connected to a metabolic system and heart rate (HR) monitor. During the MBIT protocol, mean HR significantly (p\u3c0.05, η2= 0.89) increased from 121.5 ± 12.3 bpm during EX1 to 178.3 ± 9.4 bpm during EX5 and mean VO2 significantly (p\u3c0.05, η2= 0.88) increased from 15.5 ± 2.9 ml ×kg-1×min-1during EX1 to 34.9 ± 5.1 ml ×kg-1×min-1during EX5. Mean HR and VO2values during MBIT ranged from 61.1% to 89.6% of HRpeak and from 28.2% to 63.5% of VO2peak. These descriptive data indicate that MBIT can pose a moderate to vigorous cardiometabolic stimulus in children

Use of Heart Rate Index to Predict Oxygen Uptake – A Validation Study

International Journal of Exercise Science 13(7): 1705-1717, 2020. An equation that uses heart rate index (HRI) defined as HR/HRrest to predict oxygen uptake (VO2) in METs (e.g., METs = 6 × HRI ‒ 5) has been developed retrospectively from aggregate data of 60 published studies. However, the prediction error of this model as used by an individual has not been established. Therefore, the purpose of this study was to examine the predictive validity of the HRI equation by comparing submaximal and maximal VO2 predicted by the equation (VO2-Pred) with that measured by indirect calorimetry (VO2-Meas). Sixty healthy adults (age 20.5 ± 2.4 yr., body mass 69.4 ± 13.4 kg, height 1.7 ± 0.1 m) underwent a VO2max test and an experimental trial consisting of a 15-min resting measurement and three successive 10-min treadmill exercise bouts performed at 40%, 60% and 80% of VO2max. VO2 and HR were recorded during both the submaximal and maximal exercises and used to obtain VO2-Pred and VO2-Meas for each intensity and for VO2max. Validation was carried out by paired t-test, regression analysis, and Bland-Altman plots. A modest but significant (p \u3c 0.05) correlation was observed between VO2-Meas and VO2-Pred at 40% (r = 0.58), 60% (r = 0.53), and 80% of VO2max (r = 0.56) and at VO2max (r = 0.50). No differences between VO2-Pred and VO2-Meas were found at 40% (5.53 ± 1.21 vs. 5.28 ± 0.98 METs, respectively) of VO2max, but VO2-Pred was higher (p \u3c 0.05) than VO2-Meas at 60% (8.42 ± 1.77 vs. 7.96 ± 1.39 METs, respectively) and 80% (10.79 ± 2.13 vs. 10.29 ± 1.81 METs, respectively) of VO2max. In contrast, VO2-Pred was lower (p \u3c 0.05) than VO2-Meas at VO2max (12.32 ± 2.30 vs. 13.38 ± 2.24 METs, respectively). Standard errors of the estimate were 0.81, 1.20, 1.54, and 1.97 METs at 40%, 60%, 80% of VO2max and at VO2max, respectively. These results suggest that further investigation aimed to establish the accuracy of using HRI to predict VO2 is warranted

Factors influencing overweight children's commencement of and continuation in a resistance training program

<p>Abstract</p> <p>Background</p> <p>In light of the child overweight and obesity problem in Australia, resistance training programs have been trialled as an innovative way of assisting children increase lean body mass and reduce body fat. The purpose of this study was to investigate the factors influencing overweight children's participation in a resistance training trial program.</p> <p>Method</p> <p>Parent-child pairs who participated in the trial program were invited to take part in a follow-up individual interview to discuss their program experiences. In total, 22 semi-structured interviews were conducted with 11 parent-child pairs.</p> <p>Results</p> <p>The factors found to be most relevant to program commencement among parents were a desire for their child to lose weight and gain confidence, the proximity of the venue, and no cost for participation. For children, the most relevant factors were the opportunity to build strength and improve fitness and having supportive parents who facilitated program initiation. The factors most relevant to continuation for parents were the quality of the program management, being able to stay for the sessions, the child's improved weight status, coordination, and confidence, and no cost for participation. Weight loss and improved confidence were also motivators for continuation among the children, along with pleasant social interaction with peers and trainers and ongoing parental support.</p> <p>Conclusion</p> <p>Different factors variably influence program commencement and program continuation in both parents and children. This has important implications for future interventions that aim to successfully recruit and retain intervention participants.</p

Cardiometabolic responses of body-weight exercises with and without vibration

This investigation examined the interactive effect of body-weight (BW) exercises and vibration on cardiometabolic responses. Fourteen subjects performed a BW exercise protocol with (BW+V) and without (BW‒V) vibration in a randomized order. The BW exercise protocol consisted of three circuits of eight calisthenics-based exercises including prisoner squat, push-up, isometric squat, reverse dip, lunge, flutter kicks, isometric lunge, and T push-up. Vibratory frequency and amplitude were set at 40 Hz and 4 mm, respectively. Oxygen uptake (VO2), heart rate (HR), expired ventilation (VE), and blood lactate [La] were determined during the protocol and 30-minute recovery. The mean VO2 reached 48% and 50% of VO2max and the mean HR reached 80% and 83% of HRmax in BW‒V and BW+V, respectively. During the protocol, while the mean VE was greater (p=.031) in BW+V than BW‒V, no differences were seen for VO2 and HR between the two conditions. During recovery, while mean VO2 was greater (p=.002) in BW+V than BW-V, no differences were seen for VE and HR between the two conditions. [La] values were significantly elevated but remained similar between the two conditions. Exercise-specific VO2 was higher during the prisoner squat (p=.003) and isometric squat (p=.042) in BW+V than BW‒V, while no differences in VO2 were observed for all other exercises. Performing three circuits of eight BW exercises in a rapid-and-intense manner produced a sufficient increase in cardiometabolic responses. Metabolic potentiation associated with combining vibration with BW exercises seemed to be influenced by how the exercises were carried out on a vibration plate

The epidemiology of injuries across the weight-training sports

Background: Weight-training sports, including weightlifting, powerlifting, bodybuilding, strongman, Highland Games, and CrossFit, are weight-training sports that have separate divisions for males and females of a variety of ages, competitive standards, and bodyweight classes. These sports may be considered dangerous because of the heavy loads commonly used in training and competition. Objectives: Our objective was to systematically review the injury epidemiology of these weight-training sports, and, where possible, gain some insight into whether this may be affected by age, sex, competitive standard, and bodyweight class. Methods: We performed an electronic search using PubMed, SPORTDiscus, CINAHL, and Embase for injury epidemiology studies involving competitive athletes in these weight-training sports. Eligible studies included peer-reviewed journal articles only, with no limit placed on date or language of publication. We assessed the risk of bias in all studies using an adaption of the musculoskeletal injury review method. Results: Only five of the 20 eligible studies had a risk of bias score ≥75 %, meaning the risk of bias in these five studies was considered low. While 14 of the studies had sample sizes >100 participants, only four studies utilized a prospective design. Bodybuilding had the lowest injury rates (0.12–0.7 injuries per lifter per year; 0.24–1 injury per 1000 h), with strongman (4.5–6.1 injuries per 1000 h) and Highland Games (7.5 injuries per 1000 h) reporting the highest rates. The shoulder, lower back, knee, elbow, and wrist/hand were generally the most commonly injured anatomical locations; strains, tendinitis, and sprains were the most common injury type. Very few significant differences in any of the injury outcomes were observed as a function of age, sex, competitive standard, or bodyweight class. Conclusion: While the majority of the research we reviewed utilized retrospective designs, the weight-training sports appear to have relatively low rates of injury compared with common team sports. Future weight-training sport injury epidemiology research needs to be improved, particularly in terms of the use of prospective designs, diagnosis of injury, and changes in risk exposure