The Influence of Exercise Intensity on Postexercise Baroreflex Sensitivity

Purpose: The purpose of this study was to investigate the influence of exercise intensity on postexercise supine and tilt baroreflex sensitivity (BRS). Method: Nine healthy, active men performed 2 conditions of interval cycling of 40% maximal work rate (WR_max) and 75% WR_max of matched work done and a control condition of no exercise in a counterbalanced order. BRS outcome measures were determined at preexercise and postexercise up to +24 hr in supine and tilt positions. R-R interval and blood pressure data were collected over consecutive 10-min periods and were analyzed by Fast Fourier transformation analysis. Results: A fully repeated analysis of variance revealed a significant interaction (p < .05) between time and condition in supine for BRS_αLF, F(3, 134) = 5.19, p < .05, ES = .39, and BRS_TFTG, F(3, 134) = 5.65, p < .05, ES = .41, and in tilt for BRS_UpUp, F(3, 134) = 3.54, p < .05, ES = .31, BRS_DownDown, F(3, 134) = 5.94, p < .05, ES = .43, BRS_αLF, F(4, 134) = 6.23, p < .05, ES = .44, and BRS_TFTG, F(4, 134) = 9.22, p < .05, ES = .54. There were significant differences (p < .05) between condition comparisons at +15 min and between control and 75% WR_max and between the 40% WR_max and 75% WR_max conditions at +60 min. At +15 min, BRS was lower in the 75% WR_max condition compared with the 40% WR_max condition and the control condition, and it was lower in the 40% WR_max condition than in the control condition. Conclusion: The findings demonstrate an intensity-dependent relationship in the BRS response following exercise.     

Impact of a physical education-based behavioural skill training program on cognitive antecedents and exercise and sport behaviour among adolescents: a cluster-randomized controlled trial

ABSTRACT

Background: School-based physical education has been associated with a multitude of potential learning outcomes. Representatives of a public health perspective suggest that promoting physical activity in and outside the context of school is an important endeavour. While the importance of behavioural skill training to improve (motor) learning is well documented in both general and physical education, the promotion of behavioural skills to foster physically active lifestyles constitutes a rather neglected area in physical education research.

Purpose: To examine whether a standardized physical education-based behavioural skill training program has the potential to positively impact on adolescents’ self-reported exercise and sport participation, as well as cognitive antecedents involved in the regulation of exercise and sport behaviour.

Research design: Cluster-randomized controlled trial.

Methods: A sample of 143 secondary school students (50% girls, aged 14–18 years) attending academic high schools in German-speaking Switzerland were assigned class-wise to the intervention (behavioural skill training) and control condition (conventional physical education lessons). Data were assessed prior and after completion of the 7-week intervention program, which was composed of four 20-min lessons and two reflection phases. Exercise and sport behaviour and cognitive antecedents (exercise/sport intention, motivation, implementation intentions, coping planning, self-efficacy) were assessed via self-reports. A multilevel mixed effects linear regression procedure was used to test the main hypotheses. The regression analyses were adjusted for clustering of school classes, and controlled for baseline levels of the outcome measure and potential confounders.

Results: Compared to a control condition, the intervention program resulted in significant improvements with regard to introjected motivation (p?<?.05), coping planning (p?<?.001) and self-efficacy (p?<?.01). The intervention also had a positive impact on adolescents’ self-reported sport/exercise behaviour (p?<?.001). Improvements in exercise/sport intention (p?<?.05), coping planning (p?<?.01), and self-efficacy (p?<?.01) were associated with increased levels of self-reported exercise/sport participation.

Conclusion: Behavioural skill training as part of compulsory physical education has the potential to improve cognitive antecedents of exercise and sport behaviour and to foster adolescents’ exercise and sport participation. Enhancing behavioural skills might be one way in which school physical education can contribute to the creation of more physically active lifestyles among adolescents.     

The Effect of CHAMP on Physical Activity and Lesson Context in Preschoolers: A Feasibility Study

Purpose: This feasibility study compared the effects of 2 movement programs, traditional and mastery climate (i.e., the Children’s Health Activity Motor Program [CHAMP]), on lesson context and children’s physical activity (PA) levels. A secondary aim was to examine sex differences in PA levels in both programs. Method: Seventy-two preschoolers served as participants and were assigned to a movement program. Physical activity levels and lesson context were assessed with the System for Observing Fitness Instruction Time. Results: Preschoolers in CHAMP spent more time walking (p < .05, d = 3.3), more time in moderate-to-vigorous PA (MVPA; p < .05, d = 3.6), and less time standing (p < .05, d = 3.8) compared with those in a traditional movement program. Boys in both programs spent less time standing (p < .05, d = 4.8) and more time in vigorous activity (p < .05, d = 5.8) and MVPA (p < .05, d = 4.4) compared with girls. During CHAMP, children spent less time engaged in management and knowledge (p < .05, d = 1.4, and p < .001, d = 0.9, respectively) and more time in skill practice (p < .05, d = 1.5). Conclusion: The findings support that participation in CHAMP elicits more MVPA in preschool-age children compared with a traditional movement program. The Children’s Health Activity Motor Program provided children with more class time devoted to skill practice. The program appears to be an innovative approach that is beneficial for PA engagement and could contribute positively to children’s health.     

Multiplicative Measurements of a Trait Anxiety Scale as Predictors of Burnout

The purpose of the present study was to investigate whether combining the two dimensions of anxiety (i.e., intensity and direction) by using a multiplicative model would strengthen the prediction of burnout. Collegiate athletes (N = 157) completed the Athlete Burnout Questionnaire as well as a trait version of the Competitive State Anxiety Inventory-2D. Three separate hierarchical regression analyses with four blocks were conducted to predict each one of the burnout subscales from anxiety intensity and direction while controlling for gender. The multiplicative variable for cognitive anxiety was a significant predictor of reduced sense of accomplishment (p < .01). Self-confidence was the only directional scale that predicted reduced sense of accomplishment, emotional/physical exhaustion, and devaluation (p < .01). In addition, gender was found to predict overall burnout in all three subscales as a control variable (p < .05). Conclusions and applied implications are drawn based on the results.     

Effectiveness of Physical Activity Interventions for Preschoolers: A Meta-Analysis

Purpose: The purpose of the meta-analysis was to examine the effectiveness of physical activity interventions on physical activity participation among preschoolers. A secondary purpose was to investigate the influence of several possible moderator variables (e.g., intervention length, location, leadership, type) on moderate-to-vigorous physical activity (MVPA). Method: Nine databases were systematically searched for physical activity interventions. Studies were included if they contained statistics necessary to compute an effect size (ES), were written in or translated into English, examined physical activity in preschoolers, incorporated a physical activity intervention, and targeted preschool-aged children. Fifteen studies satisfied these criteria. ESs were calculated using a random-effects model. Results: Results indicated that overall, interventions had a small-to-moderate effect on general physical activity (Hedges g = 0.44, p < .05, n = 73 ESs) and a moderate effect on MVPA (Hedges g = 0.51, p < .05, n = 39 ESs). The greatest effects for MVPA were identified for interventions that were less than 4 weeks in duration, were offered in an early-learning environment, were led by teachers, involved outdoor activity, and incorporated unstructured activity. Conclusions: This meta-analysis provides an overview and synthesis of physical activity interventions and highlights effective strategies for future interventions aimed at increasing physical activity levels among preschoolers.     

Physiological Differences Between Heat Tolerant and Heat Intolerant Young Healthy Women

ABSTRACT

Purpose: Heat intolerance (HI) is determined in the Israel Defense Force according to a heat tolerance test (HTT) before returning to duty after an exertional heat stroke (EHS) event. Recently, increased numbers of female combatants resulted in an increased number of EHS cases among women and a higher percentage of heat intolerance (HI) individuals. We aimed to evaluate the differences between tolerance to heat among women performing an HTT in relation to their menstrual cycle phase. Method: Thirty-three female participants were sorted into two groups: HI and heat tolerant (HT) according to two HTTs performed during both the luteal and follicular phases of the menstrual cycle or while consuming and during a break from consuming contraceptives. Results: HT women had an 18% higher maximal oxygen uptake (p < .005, 95% CI [2.6,9.8]) and 1.2% lower skin temperature in the HTT at the during and follicular phases (p < .01, 95% CI [0.12,0.77]) and 1.7% lower at the off and luteal phases (p < .001, 95% CI [0.34,0.92]). The mean sweat rate was 14% lower among the HI group only at the HTT at the during and follicular phases (p < .05, 95% CI (3,88)]). Conclusion: We found that HT can be predicted using aerobic capacity and core body temperature. Moreover, during the luteal phase, women presented altered thermoregulation that decreased the probability of being HT. This emphasizes the importance of considering the HT/HI criteria in the HTT for women, according to their aerobic ability and menstrual-cycle phase.     

The Influence of Feedback on Competence,Motivation, Vitality,and Performance in a Throwing Task

Purpose: The purpose of this work is focused on the study of the effect that feedback has on competence valuation, perceived competence, autonomous motivation, vitality, and performance in a throwing task. Method: Thirty-five college students (26 men and 9 women), without previous experience in the task, participated in this study. The students were randomly assigned to three experimental conditions (positive, negative, and lack of feedback). Results: The results of this study point out that only those who received positive feedback before the handball throwing task, in contrast to those who received negative feedback or did not receive any feedback, showed increased levels of competence valuation (p < .05, Cliff’s delta effect size = ?.30), perceived competence (p < .001, Cliff’s delta effect size = ?.77), and autonomous motivation (p < .05, Cliff’s delta effect size = ?.48). This group also presented higher levels of perceived competence (p < .001, Cliff’s delta effect size = ?.84) and subjective vitality (p < .001, Cliff’s delta effect size = ?.80) than the group who received negative feedback after the throwing task. Those who received positive feedback also showed a higher throwing speed at the end of task than those who received negative feedback (p < 0.001, Cliff’s delta effect size = ?.71) or than those who did not receive any feedback (p < .05, Cliff’s delta effect size = ?.56). Conclusions: Competence valuation, perceived competence, autonomous motivation, subjective vitality, and throwing speed were favorably influenced by positive feedback. These results have important implications for the training style applied by coaches.     

Effects of Experience and Opponents on Pacing Behavior and 2-km Cycling Performance of Novice Youths

ABSTRACT

Purpose: To study the pacing behavior and performance of novice youth exercisers in a controlled laboratory setting. Method: Ten healthy participants (seven male, three female, 15.8 ± 1.0 years) completed four, 2-km trials on a Velotron cycling ergometer. Visit 1 was a familiarization trial. Visits 2 to 4 involved the following conditions, in randomized order: no opponent (NO), a virtual opponent (starting slow and finishing fast) (OP-SLOWFAST), and a virtual opponent (starting fast and finishing slow) (OP-FASTSLOW). Repeated measurement ANOVAs (p < .05) were used to examine differences in both pacing behavior and also performance related to power output, finishing- and split times, and RPE between the four successive visits and the three conditions. Expected performance outcome was measured using a questionnaire. Results: Power output increased (F_3,27 = 5.651, p = .004, η²_p = .386) and finishing time decreased (F_3,27 = 9.972, p < .001, η²_p = .526) between visit 1 and visits 2, 3 and 4. In comparison of the first and second visit, the difference between expected finish time and actual finishing time decreased by 66.2%, regardless of condition. The only significant difference observed in RPE score was reported at the 500 m point, where RPE was higher during visit 1 compared to visits 3 and 4, and during visit 2 compared to visit 4 (p < .05). No differences in pacing behavior, performance, or RPE were found between conditions (p > .05). Conclusion: Performance was improved by an increase in experience after one visit, parallel with the ability to anticipate future workload.     

Comparing self-report and mental chronometry measures of motor imagery ability

Abstract

The present study investigated the relationship between two of the most common measures of motor imagery ability, self-report ratings, and chronometric assessment. This was done for three types of imagery modalities: external visual imagery (EVI), internal visual imagery (IVI), and kinesthetic imagery (KI). Measures of imagery ability (i.e. self-report and mental chronometry) were also compared across skill levels. Participants (N?=?198) completed the Movement Imagery Questionnaire-3 (MIQ-3) to generate self-report ratings. Chronometric assessment was obtained by recording the duration of each MIQ-3 movement imaged and physically performed and then calculating a discrepancy score. There were no significant correlations between self-report and mental chronometry for any of the three motor imagery types (p?>?.05). When assessing the different types of motor imagery ability using self-report ratings, elite athletes had significantly higher KI than IVI, which was in turn significantly higher than EVI (p?<?.05). When assessing motor imagery ability using mental chronometry, there were no significant differences in imagery type (p?>?.05). Findings suggest both measures address different components of MI quality and should be used together to obtain a more comprehensive assessment of motor imagery ability.     

Student outcomes of the physical education and physical literacy (PEPL) approach: a pragmatic cluster randomised controlled trial of a multicomponent intervention to improve physical literacy in primary schools

ABSTRACT

Background: Health organisations such as the United Nations continue to place an expectation on school physical education (PE) programmes and wider school strategies to ensure students develop physical literacy and receive the well-established benefits of meeting physical activity guidelines. Barriers to meet this expectation such as lack of trained PE teachers, lack of time and greater emphasis on academic achievement are ongoing challenges to schools. The purpose of this study was to evaluate the impact of the multi-component Physical Education Physical Literacy (PEPL) intervention, designed to improve students’ fundamental movement skill, perceived physical abilities and level of physical activity.

Method: A qualified PE teacher implemented the PEPL intervention across seven schools, and another seven schools formed a control group as part of a randomised cluster-based trial. Grade 5 students (N?=?318, age 10.4 years?±?SD 0.4) completed assessments of physical activity, fundamental movement skill, attitudes towards PE, and self-perceptions of physical abilities before and after a 33-week intervention. Intervention effects were examined using general linear mixed models. Post-intervention focus groups with students were used to develop insights into experiences and outcomes.

Results: With no significant gender interactions, the PEPL approach led to enhanced object control skills (β?=?1.62; SE?=?0.61; p?=?0.008), with little evidence of any other fundamental movement skill improvements in excess of those in the control group. There was also modest evidence for an effect on accelerometer measured moderate-to-vigorous physical activity (MVPA) during school time (β?=?4.50; SE?=?2.39; p?=?0.058), but this was not accompanied by any significant intervention effect over the entire week. Questionnaires indicated students in the PEPL programme became less satisfied with their own sporting ability (β?=??0.20; SE?=?0.08; p?=?0.013) but qualitative data analyses suggested that they enjoyed the PEPL approach experience, becoming more motivated and confident in their physical abilities.

Conclusions: Evidence of enhanced object control skill, increased confidence and motivation to be physically active, and moderate evidence of more MVPA during school time, indicate that the introduction of the PEPL approach contributed to the development of student physical literacy. A decrease in perceived sporting competence warrants greater attention on student’s self-perceptions in future iterations of the intervention.

Trial registration: Australian New Zealand Clinical Trials Registry identifier: ACTRN12615000066583.     

Average acceleration and intensity gradient of primary school children and associations with indicators of health and well-being

ABSTRACT

Average acceleration (AvAcc) and intensity gradient (IG) have been proposed as standardised metrics describing physical activity (PA) volume and intensity, respectively. We examined hypothesised between-group PA differences in AvAcc and IG, and their associations with health and well-being indicators in children. ActiGraph GT9X wrist accelerometers were worn for 24-h·d^?1 over 7days by 145 children aged 9–10. Raw accelerations were averaged per 5-s epoch to represent AvAcc over 24-h. IG represented the relationship between log values for intensity and time. Moderate-to-vigorous PA (MVPA) was estimated using youth cutpoints. BMI z-scores, waist-to-height ratio (WHtR), peak oxygen uptake (VO₂peak), Metabolic Syndrome risk (MetS score), and well-being were assessed cross-sectionally, and 8-weeks later. Hypothesised between-group differences were consistently observed for IG only (p < .001). AvAcc was strongly correlated with MVPA (r = 0.96), while moderate correlations were observed between IG and MVPA (r = 0.50) and AvAcc (r = 0.54). IG was significantly associated with health indicators, independent of AvAcc (p < .001). AvAcc was associated with well-being, independent of IG (p < .05). IG was significantly associated with WHtR (p < .01) and MetS score (p < .05) at 8-weeks follow-up. IG is sensitive as a gauge of PA intensity that is independent of total PA volume, and which relates to important health indicators in children.     

Factors affecting sports involvement in a school-based youth cohort: Implications for long-term athletic development

ABSTRACT

The aim of the present study was to determine the factors affecting sports involvement in a school-based adolescent population. The cross-sectional cohort study assessed anthropometry, physical capacities and motor competence in 501 boys (aged 10–16 y), from junior (10–12 y) and senior (13–16 y) cohorts. Sports participation data was collected from junior participants. Multivariate analysis of covariance revealed moderate maturity, anthropometry, physical capacity and motor competence differences between sports in the senior cohort (F = 2.616, p < 0.001, η² = .08), but not in the junior cohort. Furthermore, differences in physical fitness were revealed between playing levels (F = 2.616, p < 0.001, η² = .08), with a discriminant analysis correctly classifying 73% of participants using aerobic fitness and vertical jump measures. Representative level participants engaged in more structured training and commenced organised competition at a later age (F = 4.332, p < 0.001, η² = .21). This study’s findings are twofold: 1) physical and motor competence profiles differ more between sports with increasing age, and 2) participants at a higher level of competition report delayed engagement in their main sport. As a result, schools may be the ideal environment in which to provide children and adolescents with the opportunity to sample different sports.     

Resting Bradycardia,Enhanced Postexercise Heart Rate Recovery and Cardiorespiratory Fitness in Recreational Ballroom Dancers

Purpose: In a cross-sectional study design, we evaluated the resting heart rate (HR_baseline) and exercise and postexercise stress test-related chronotropic responses in male practitioners of recreational ballroom dancing (BD; n = 25, M_age = 26.6 ± 6.1 years) compared to a control group of insufficiently active nondancers (CG; n = 25, M_age = 25.9 ± 4.5 years). Method: All participants underwent a submaximal exercise test. At 85% of the maximal predicted HR, the recovery protocol was started, and heart rate recovery (HRR) was recorded during 1-min intervals for 5 min. Results: Compared with CG, BD showed lower HR_baseline (70 beats per minute [bpm] vs. 62 bpm, respectively, U = 143, p < .05, ES = .46), lower preexercise HR (94 bpm vs. 86 bpm, U = 157, p < .05, ES = .42), longer exercise test duration (346 s vs. 420 s, U = 95.5, p < .05, ES = .59), and higher HRR for 5 min postexercise (U = 1.29–1.89, p < .05, ES = .33–.50) as follows: 1st min (32 bpm vs. 40 bpm), 2nd min (45 bpm vs. 53 bpm), 3rd min (51 bpm vs. 58 bpm), 4th min (55 bpm vs. 59 bpm), and 5th min (59 bpm vs. 63 bpm). The coefficient of HRR from the 1st min to the 5th min postexercise was similar in both groups (U = 229–311, p > .05, ES = < .10–.22). Conclusion: Heightened cardiovascular functional status characterized by favorable enhanced chronotropic dynamics appears to occur in practitioners of recreational ballroom dancing, which suggests that this modality of exercise may result in health benefits.     

Relative Age Effect,Biological Maturation,and Coaches’ Efficacy Expectations in Young Male Soccer Players

Purpose: The talent identification and selection process in young male soccer players is mainly focused on anthropometrics and physical performance, but social factors are also considered in this process. The purpose of this study was to test the existence of the relative age effect and its possible influence on anthropometrics and physical performance and to analyze coaches’ efficacy expectations. Method: Data for 564 young male soccer players (M_age = 13.7 ± 1.5 years; M_weight = 53.7 ± 11.6 kg; M_height = 160.2 ± 11.6 cm) included their birth quartile, maturity status, anthropometrics, a physical test battery, and coaches’ efficacy expectations. Results: Early-born players were overrepresented (p < .05). Early-born players were not statistically taller, heavier, or better at physical performance (p > .05) when maturation and chronological age were controlled as confounding factors. However, coaches expected more from early-born players (p < .05), and the inferential analysis showed likely to very likely worthwhile differences between the coaches’ expectations for players born in the first quartile of the year and those born in the fourth quartile of the year. Conclusions: Anthropometrical and physical performance variables were not affected by birth quartile, and coaches’ efficacy expectations were related to the relative age effect.     

Children’s metabolic expenditure during object projection skill performance: New insight for activity intensity relativity

Objective: To examine children’s energy expenditure (EE) during object projection skill performance at three intensity intervals. Methods: Children’s (42, Mage = 8.1) average metabolic equivalents of task (METs) were calculated using a COSMED K4b2 while they repeatedly performed blocks of kicking, throwing (overhand), and striking (two-handed) during 6, 12, and 30-s interval conditions. A repeated-measures analysis of covariance examined differences in METs while controlling for skill level. Results: Data indicated a main effect for interval condition (df = 2, 123, F = 94.36, p <.001, η2 = .605). Post hoc t-tests demonstrated decreasing performance interval times yielded progressively higher METs (p <.001) across the three conditions (30s = 4.5±0.8 METs, 12s = 6.3±1.3, 6s = 8.3±1.6). There also was a main effect for sex (df = 1,120, F = 52.28, p <.001 η2 = .305). Boys demonstrated higher METs at each performance interval (p <.001). Conclusion: Skill practice with a maximum of one trial every 30s resulted in the equivalent of at least moderate physical activity (>4.0 METs) and intervals of 6s demonstrated vigorous physical activity (>7.0 METs). Practicing/performing object projection skills, even at intervals that allow for adequate instruction and feedback (i.e., 1 trial/30s), promotes MVPA in children.     

The relationship between meeting of recommendations on physical activity for health and perceived work ability among white-collar workers

Objective: The aim of this study was to evaluate the association between meeting recommendations on physical activity for health in leisure-time and the ability to work among Polish white-collar workers. Methods: The study used a cross-sectional design with a convenience sample of 360 white-collar workers. Participants recorded 7-day physical activity logs, including form, duration and intensity of leisure-time physical activities. The results were compared to health recommendations. A standardized Work Ability Index (WAI) questionnaire was used in assessing the ability to work. Results: Participants who met health recommendations achieved higher scores of the WAI (mean score?=?41.93) in comparison to those who were not sufficiently physically active (mean score?=?39.35) (p?Conclusions: Meeting leisure-time physical activity recommendations (especially the criterion of vigorous physical activity) is significantly related to higher self-assessed ability to work among white-collar workers.     

The moderating effect of physical activity on the relationship between bullying and mental health among sexual and gender minority youth

BackgroundSexual and gender minority youth frequently experience bullying, which often contributes to higher depressive symptoms and lower self-esteem. Given that physical activity (PA) can mitigate depressive symptoms and improve self-esteem, we examined the moderating effect of PA on the relationship between bullying and mental health among sexual and gender minority youth.MethodsData from the Lesbian, Gay, Bisexual, Transgender, and Queer National Teen Survey (n = 9890) were analyzed. Hierarchical regression analyses examined the influence of history and frequency of being bullied, PA, and the interaction of these variables on depressive symptoms and self-esteem. Simple slopes analyses were used to probe significant interactions.ResultsResults indicated the importance of accounting for bullying history when examining effects of PA on mental health. PA was negatively related to depression (t = –4.18, p < 0.001) and positively related to self-esteem (t = 12.11, p < 0.001). Bullying frequency was positively related to depression (t = 19.35, p < 0.001) and negatively related to self-esteem (t = –12.46, p < 0.001). There was a significant interaction between bullying frequency and PA for depression (t = 4.45, p < 0.001) and self-esteem (t = –4.69, p < 0.001). Post hoc analyses suggested that the positive effects of PA on mental health may be limited to those not bullied because it had a negligible effect on those who were bullied.ConclusionResults suggest that sexual and gender minority youth exercise interventions aiming to improve mental health should first address bullying history; otherwise, their effectiveness may be limited to those who have been bullied.     

Validity of Activity Trackers in Estimating Energy Expenditure During High-Intensity Functional Training

ABSTRACT

Purpose: The purpose of this study was to evaluate the agreement of five commercially available accelerometers in estimating energy expenditure while performing an acute bout of high-intensity functional training (HIFT). Methods: Participants (n = 47; average age: 28.5 ± 11.6 years) consisted of recreationally active, healthy adults. Each participant completed a session of HIFT: a 15-minute workout consisting of 12 repetitions each of air-squats, sit-ups, push-ups, lunges, pull-ups, steps-ups, and high-knees; performed circuit-style by completing as many rounds as possible. During this session, each participant wore the Cosmed K4b2 portable metabolic analyzer (PMA) and five different accelerometers (ActiGraph GT3X, Nike Fuelband, Fitbit One, Fitbit Charge HR, and Jawbone UP Move). Results: Four of the five activity trackers reported lower (p < .05) total EE values compared to the PMA during the acute bout of HIFT. The waist-mounted device (ActiGraph, 182.55 ± 37.93 kcal) was not significantly different from, and most closely estimated caloric expenditure compared to the PMA (144.99 ± 37.13 kcal) (p = .056). A repeated-measures ANOVA showed that all activity trackers were significantly different from the reference measure (PMA) (p < .05). Systematic relative agreement between the activity trackers was calculated, exhibiting a significant ICC = 0.426 (F [46,230] = 5.446 [p < .05]). Conclusion: The wrist- and hip-mounted activity trackers did not accurately assess energy expenditure during HIFT exercise. With the exception of the ActiGraph GT3X, the remaining four activity trackers showed inaccurate estimates of the amount of kilocalories expended during the HIFT exercise bout compared to the PMA.     

The relative age effect among elite youth competitive swimmers

Abstract

The aim of this study was to analyse the relative age effect (RAE) in competitive swimming. The best 50 Portuguese swimmers (12- to 18-year-olds) for the main individual swimming pool events of both genders were considered. Analysis was conducted on 7813 swimming event participants, taking account of respective swimmer birth dates and the Fédération Internationale de Natation points gained. Differences in the distribution of birth dates by quarter year were determined using the Chi-square. A one-way analysis of variance ANOVA was used to test for differences measured in points between individuals by quarterly birth year intervals. A two-way analysis of variance ANOVA was also conducted to test the interaction between gender and seasonal birth date with regard to performance. The results show an inequitable distribution (p<0.01) of birth dates by quarter for almost all age groups and both genders. However, the distribution of birth dates by quarter for each considered swim event shows that RAE seems to exist only for 12-year-old females and 12- to 15-year-old males. Analysing mean swimming performance, post-hoc results (p<0.01) show no consistency in RAE. Higher performance occurs among older swimmers only in 100 m butterfly (female 1998, 1st≠2nd quarter, p=0.003). The results also show no interaction between gender and seasonal birth date (p<0.01). Findings of this study show that a higher number of swimmers, particular males, are born in the first two quarters of the year, although there is mostly no effect of seasonal birth date on performance differences within the top 50 swimmers.