Sport-based physical activity intervention on body weight in children and adolescents: a meta-analysis

Controversial results reported in past research pertaining to the effectiveness of sport-based physical activity interventions on weight loss. The purpose of this study was to assess the impact of sport-based physical activity intervention on body weight in children and adolescents using a meta-analysis. Academic Search Complete, Education Source, ERIC, Medline, ProQuest, PsycINFO and SportDiscus databases were searched from January 2000 to April 2015. Eighteen studies met following inclusion criteria: sport-based intervention studies; subjects aged 6–18 years; reported body weight; published in peer-reviewed journals written in English. The mean intervention duration was 17.72 weeks. The overall effect size (ES) was 0.52 (Cohen’s d (ES) = 0.52, 95% CI = 0.08, 0.95, P = 0.021), using a random effects model. Moderator analyses results showed that the Q statistic for the sport type (individual sport or team sport, Qbetween (Q_b) = 14.52, df = 1, P = 0.001) and diet control (Qbetween (Q_b) = 8.85, df = 1, P = 0.001), explained the heterogeneity of ESs. Our study showed that there was a moderate overall effect of sport-based physical activity intervention on body weight reduction. The team sport type (ES = 1.05, 95% CI = 0.44, 1.66) and diet control group (ES = 0.84, 95% CI = 0.26, 1.41) appeared to be more effective in reducing body weight.     

Quality of life perception of basketball master athletes: association with physical activity level and sports injuries

This study aimed to verify the prevalence and characteristics of sports injuries (SI) and determine the association between the physical activity level (PA) and SI with perception of health-related quality of life (HRQoL) in Brazilian basketball master athletes. A cross-sectional study was conducted with 410 male master athletes, between 35 and 85 years of age (mean 52.26, SD ±11.83). The HRQoL was assessed using the Medical Outcomes Study – Short Form-36. The PA was evaluated using the International Physical Activity Questionnaire. Information regarding SI was collected using the Reported Morbidity Survey. Poisson regression, as estimated by the prevalence ratio (PR), was used as a measure of the association of PA and SI with HRQoL. The majority of athletes showed a high SI prevalence (58.3%) and reported one injury (67.8%) that occurred during training (61.1%) and primarily affected a lower limb (74.6%). The adjusted regression models showed a positive association of PA with the Functional Capacity (PR = 1.46, 95% confidence interval [CI] = 1.12–1.90) and Physical Component (PR = 1.32, 95% CI = 1.03–1.70) of HRQoL. Furthermore, the SI were negatively associated with HRQoL in Functional Capacity (PR = 1.85, 95% CI = 1.51–2.27), Physical Aspects (PR = 3.99, 95% CI = 3.08–5.18), Pain (PR = 1.65, 95% CI = 1.26–2.16), Social Functioning (PR = 1.79, 95% CI = 1.41–2.27), Emotional Aspects (PR = 4.40, 95% CI = 3.35–5.78), Mental Health domains (PR = 1.37, 95% CI = 1.06–1.68), Physical Component (PR = 2.35, 95% CI = 1.90–2.90) and Mental Component (PR = 2.65, 95% CI = 2.14–3.29). These results highlighted that master athletes showed a high SI prevalence, primarily in the lower limbs. PA positively correlates with the physical HRQoL domain, whereas SI may decrease the HRQoL levels of both physical and mental domains.     

Effects of glucose–fructose versus glucose ingestion on stride characteristics during prolonged treadmill running

Scarce research has examined the effects of carbohydrate composition on running stride characteristics. On two occasions, 14 males and 6 females completed a 120-min sub-maximal run followed by a 4-mile time trial. Participants consumed glucose (GLU) or glucose–fructose (GLU–FRU) beverages supplying 1.3 g/min carbohydrate. Substrate use, psychological affect [Feeling Scale (FS)], and stride characteristics (stride frequency, stride length, and contact time) were assessed. Effects were expressed as Cohen’s d (90% confidence limits [90% CL]). CLs for stride frequency differences at 53 min (90% CL = 0.04–0.21) and 113 min (90% CL = 0.02–0.24) did not cover 0, indicating a positive effect of GLU–FRU. However, effect sizes were small (d = 0.13) and likely-to-very-likely trivial. Energy expenditure differences at sub-maximal end were very likely trivial (d = 0.08; 90% CL = 0.00–0.17), while FS ratings were possibly higher for GLU–FRU at 50 (d = 0.19; 90% CL = ?0.10–0.48) and 110 min (d = 0.16; 90% CL = ?0.13–0.45). During the time trial, stride length was possibly higher with GLU–FRU (d = 0.13; 90% CL = ?0.08–0.33). Glucose–fructose co-ingestion has no significant effect on stride characteristics during constant-velocity running but may result in slightly higher stride length during self-paced running.     

Factors associated with early career progression in professional Australian Football players

This study examined the association between individual and team characteristics and the probability of being offered a second contract in professional Australian Football. Contract status was obtained from the AFL for players who were drafted in the AFL National Draft between 1999 and 2013 (n = 999). Individual player characteristics were retrieved from the AFL while variables relating to performance were accessed online via Champion Data®. A binary logistic regression examined the influence of each characteristic on the probability of a professional Australian Football player receiving a second contract. Receiver operating characteristic (ROC) curves and the associated AUC were used to assess the discriminant ability of both a training (n = 938) and test data set (n = 61). The characteristics that influenced the probability of receiving a second contract included first year debut (pr 0.606), draft order (pr – 0.126), draft year (pr 0.059), games played (pr 1.848), team state (pr 0.458), rising star nomination (pr 1.553) and team ladder position (pr ?0.043) (χ² (8) = 198.28, p < 0.001). The ROC curve demonstrated an AUC of 82.4% (training) and 76.0% (test). A combination of individual and team based characteristics are associated with early career progression in professional Australian Football.     

Comparison of athletic movement between elite junior and senior Australian football players

This study compared the athletic movement skill between elite Under-18 (U18) Australian football (AF) and senior Australian Football League (AFL) players. The U18 sample (n = 13; 17.7 ± 0.6 years) were representatives of an elite talent development programme. The AFL players were classified accordingly; Group 1 (1–4 AFL seasons; n = 20; 21.2 ± 1.9 years) and Group 2 (>5 AFL seasons; n = 14; 26.3 ± 2.6 years). Participants performed an athletic movement skill assessment, inclusive of five foundational movements. Each movement was scored across three assessment points using a three-point scale. Total score for each movement (maximum of nine) and overall score (maximum of 63) were used as criteria. Multivariate analysis of variance (MANOVA) was used to test the effect of developmental group (three levels) on the criteria. Receiver operating curves were built to examine the discriminant capability of the overall score. A significant effect of developmental group was noted, with the U18 sample having a lower mean total score for four of the five movements. Overall scores of 49/63 and 50/63 discriminated the elite U18 sample from Group 1 and Group 2, respectively. U18 players may have less developed athletic movement skills when compared to their senior AFL counterparts.     

Factors associated with physical activity referral completion and health outcomes

Abstract

Participant socio-demographic characteristics and referral reason were investigated in relation to completion and health outcomes in a Primary Care Physical Activity Referral Scheme using a prospective population-based longitudinal design. Participants (n = 1735) were recruited over a 2-year period. A three-stage binary logistic regression analysis identified the factors associated with the outcomes of completion (model 1), body mass reduction (model 2) and blood pressure reduction (model 3). Participant's age, gender, ethnicity, occupation and referral reason were the independent variables for model 1, with the variables of completion added in model 2 and completion and body mass reduction added in model 3. Logistic regression analysis revealed that increasing age is associated with the likelihood of completion (Odds Ratio, OR = 1.019; Confidence Interval, CI = 1.008–1.030; P = 0.001). Participants with a pulmonary condition are less likely to complete (OR = 0.546; CI = 0.346–0.860; P < 0.01) compared to those referred for cardiovascular conditions. For ethnicity, in comparison to the white category, patients in the mixed category are significantly more likely to achieve a reduction in body mass (OR = 3.991; CI = 1.191–13.373; P < 0.05). Those who complete are more likely to achieve a reduction in body mass (OR = 3.541; CI = 2.721–4.608; P < 0.001). When compared to the unemployed category, the skilled manual category had an increased likelihood of achieving a reduction in blood pressure (OR = 1.875; CI = 1.044–3.227; P < 0.05). Participants who completed also demonstrated an increased likelihood of a reduction in blood pressure (OR = 1.680; CI = 1.250–2.003; P < 0.001). Furthermore, those participants who achieved a reduction in body mass had an increased likelihood of achieving a reduction in blood pressure (OR = 1.292; CI = 1.008–1.641; P < 0.05). Completion is associated with health outcomes of reduced body mass and blood pressure.     

Sense of extension force and angle of the knee joint are correlated between two generations of men

Numerous motor abilities depend on the activity of proprioceptors, which has been suggested to be genetically determined. To test this hypothesis, the control of torque generated by knee extensors and knee position was studied in 30 father–son pairs both before and immediately after running. After stabilisation of the participant in a sitting position, the knee joint of his dominant leg was flexed to 90°, and the maximal voluntary torque (MVT) of the dominant knee extensors under static conditions was measured. The participant then tried five times to produce 50% of the MVT. Next, the participant extended the knee to 45° five times without visual control. Significant correlations between the reproducibility of successive trials for groups of fathers and their sons were found. The correlation coefficients for the repeatability of the knee extension torque were 0.69 (confidence interval [CI] = 0.45–0.84; P < 0.01) and 0.75 (CI = 0.54–0.87; P < 0.01) before and after the fatiguing exercise, respectively, whereas the coefficient for the reproducibility of positioning the knee was 0.49 (CI = 0.16–0.72; P < 0.01) after the fatiguing exercise. Our results indicate a significant influence of hereditary factors on the control of limb torque and position.     

The impact of in-season national team soccer play on injury and player availability in a professional club

This study investigated the impact of in-season national team duty on injury rates and player availability in a professional soccer club. Time-loss injuries and exposure time during club and national team duties were recorded prospectively over 5 seasons (2009–2014). A time-loss injury was sustained by 37.7% of squad members participating in national duty, all injuries occurring in match-play. The incidence (per 1000 h exposure) for national team player match-play injuries did not differ (P = 0.608) to that for all players in club competitions: 48.0 (95% CI 20.9–75.5) vs. 41.9 (95% CI 36.5–47.4), incidence rate ratio = 1.2 (CI: 0.8–2.4). The majority (58%) of national team injuries resulted in a layoff ≤1 week. Of all working days lost to injury generally, 5.2% were lost through injury on national duty. Injury incidence in the week following national duty was comparable (P = 0.818) in players participating or not: 7.8 (95% CI 3.6–12.0) vs. 7.1 (95% CI: 4.6–9.6), incidence rate ratio = 1.1 (CI: 0.7–2.7). While approximately 40% of participating players incurred a time-loss injury on national duty, no training injuries were sustained and injuries made up a negligible part of overall club working days lost to injury. Following duty, players had a similar injury risk to peers without national obligations.     

The effects of mental fatigue on cricket-relevant performance among elite players

This study investigated the effects of a mentally fatiguing test on physical tasks among elite cricketers. In a cross-over design, 10 elite male cricket players from a professional club performed a cricket run-two test, a Batak Lite reaction time test and a Yo-Yo-Intermittent Recovery Level 1 (Yo-Yo-IR1) test, providing a rating of perceived exertion (RPE) after completing a 30-min Stroop test (mental fatigue condition) or 30-min control condition. Perceived fatigue was assessed before and after the two conditions and motivation was measured before testing. There were post-treatment differences in the perception of mental fatigue (P < 0.001; d = ?7.82, 95% CIs = ?9.05–6.66; most likely). Cricket run-two (P = 0.002; d = ?0.51, 95% CIs = ?0.72–0.30; very likely), Yo-Yo-IR1 distance (P = 0.023; d = 0.39, 95% CIs = 0.14–0.64; likely) and RPE (P = 0.001; d = ?1.82, 95% CIs = ?2.49–1.14; most likely) were negatively affected by mental fatigue. The Batak Lite test was not affected (P = 0.137), yet a moderate (d = 0.41, 95% CIs = ?0.05–0.87) change was likely. Mental fatigue, induced by an app-based Stroop test, negatively affected cricket-relevant performance.     

Relative age effects in Australian Football League National Draftees

Abstract

This study examined the birth distribution for adolescent (i.e. <20 years) and mature age players (i.e. ≥20 years) selected in the Australian Football League (AFL) National Draft between 2001 and 2012. Birth-date information was accessed for all first time AFL national draftees and players were then classified as either adolescent (N = 736) or mature age (N = 70) draftees. Chi-squared analysis showed a clear bias in the birth distribution of adolescent draftees towards players born in the first part of the classification period for both quartile (P < 0.001) and half-year (P < 0.001) compared to the Australian national population. There was a reverse relative age effect (RAE) for mature age draftees, with a significant bias towards players born in the latter part of the selection period for both quartile (P = 0.047) and half-year (P = 0.028) compared to the Australian national population. The selection bias towards relatively older players in adolescent AFL draftees may be related to advanced physical and psychological maturity, and exposure to higher-level coaching compared to their younger counterparts. The reverse RAE in mature age draftees is a novel finding and supports the need for strategies to encourage continued participation pathways for talented Australian football players born later in the selection year.     

Getting to the top: an analysis of 25 years of career rankings trajectories for professional women’s tennis

Official rankings are the most common measure of success in professional women’s tennis. Despite their importance for earning potential and tournament seeding, little is known about ranking trajectories of female players and their influence on career success. Our objective was to conduct a comprehensive study of the career progression of elite female tennis talent. The study examined the ranking trajectories of the top 250 female professionals between 1990 and 2015. Using regression modelling of yearly peak rankings, we found a strong association between the shape of the ranking trajectory and the highest career ranking earned. Players with the highest career peak ranking were the youngest when first ranked. For example, top 10 players were first ranked at age 15.5 years (99% CI = 14.8–15.9), 1.2 years (99% CI = 0.8–1.5) earlier than top 51–100 players. Top 10 players were also ranked in the top 100 longer than other players, holding a top 100 ranking until a mean age of 29.0 years (99% CI = 27.8–30.3) compared with age 24.4 years (99% CI = 23.7–25.2) for top 51–100 players. Ranking trajectories were more distinct with respect to player age than years from first ranking. The present study’s findings will be instructive for players, coaches, and administrators in setting goals and assessing athlete development in women’s tennis.     

The Acute Exercise-Induced Inflammatory Response: A Comparison of Young-Adult Smokers and Nonsmokers

Purpose: This study examined postexercise inflammatory and leukocyte responses in smokers and nonsmokers, as well as the effects of cigarette smoking on the acute postexercise inflammatory and leukocyte response in habitual smokers. Method: Eleven recreationally active male smokers and 11 nonsmokers matched for age and aerobic fitness were familiarized and underwent baseline fitness testing. Participants then completed 40 min of cycling at 50% peak aerobic workload. Smokers performed 2 randomized exercise sessions, including an acute postexercise smoking condition (2 cigarettes in 15 min of 12 mg tar and 1 mg nicotine) and a no-smoking condition, while nonsmokers performed 1 exercise session without smoking. Venous blood was obtained preexercise and postexercise for analysis of interleukin (IL)-6, IL-1 receptor antagonist (ra), tumor necrosis factor-alpha (TNF-α), and c-reactive protein (CRP). Results: No differences existed between groups for resting CRP (d = 0.25–0.46; p = .374–.617). Despite no baseline difference (d = 0.03–0.07; p = .141–.70), exercise-induced increases were observed for IL-1 ra in smokers (d = 0.50; p = .024–.033), which was not observed in the never-smoker group. No between-group difference was observed for IL-6 across all points (d = 0.09–0.5; p = .102–.728); however, all groups observed significant within-group change (d = 0.27–1.09; p = .001–.042). Further, TNF-α for smokers smoking was elevated above both smokers not smoking and nonsmokers at baseline and across the protocol (d = 1.20–1.80; d = 0.20–1.0; p = .001–.035). Additionally, a marked postexercise increase in leukocyte and neutrophil concentrations was evident in smokers smoking compared with nonsmokers and smokers not smoking as indicated by a moderate-to-large effect size (d = 0.72; d = 0.78). Conclusion: Consequently, male smokers exhibit an altered postexercise proinflammatory profile compared with age- and fitness-matched nonsmokers.     

Reliability and discriminative ability of a modified Wingate rowing test in 12- to 18-year-old rowers

Abstract

We evaluated (1) the test–retest reliability of the Wingate test conducted on a rowing ergometer, and (2) the sensitivity of this test in determining the differences in performance attained by 12- to 18-year-old rowers. Altogether, 297 male rowers aged 12.0–18.9 years (mean ± s: 14.8 ± 1.7) completed a maximal 30-s test on a rowing ergometer, and 80 rowers representing all age groups were retested after 5–7 days. No change was evident in participants' performance in terms of mean power output (P = 0.726; Cohen's d = 0.04), maximal power output (P = 0.567; Cohen's d = 0.06), and minimum power output (P = 0.318; Cohen's d = 0.11) in the second test. The intra-class correlation coefficients were high (≥0.973) and coefficients of variation were low (≤7.3%). A series of analyses of variance were used to compare the performances among 12- to 18-year-old rowers, and age-related increases in performance were evident (P < 0.001; Cohen's d = 1.91–1.96). The age-related increases in performance were similar, although reduced, when the effects of body mass were partitioned out when using analysis of covariance (P < 0.001; Cohen's d = 0.82–0.85). The results suggest that: (1) the described test is reliable and can be used for maximal-intensity exercise assessment in youth rowing, and (2) it discriminates performance among 12- to-18-year-old rowers.     

Comparison of three generations of ActiGraph™ activity monitors in children and adolescents

Abstract

In this study, we evaluated agreement among three generations of ActiGraph? accelerometers in children and adolescents. Twenty-nine participants (mean age = 14.2 ± 3.0 years) completed two laboratory-based activity sessions, each lasting 60 min. During each session, participants concurrently wore three different models of the ActiGraph? accelerometers (GT1M, GT3X, GT3X+). Agreement among the three models for vertical axis counts, vector magnitude counts, and time spent in moderate-to-vigorous physical exercise (MVPA) was evaluated by calculating intraclass correlation coefficients and Bland-Altman plots. The intraclass correlation coefficient for total vertical axis counts, total vector magnitude counts, and estimated MVPA was 0.994 (95% CI = 0.989–0.996), 0.981 (95% CI = 0.969–0.989), and 0.996 (95% CI = 0.989–0.998), respectively. Inter-monitor differences for total vertical axis and vector magnitude counts ranged from 0.3% to 1.5%, while inter-monitor differences for estimated MVPA were equal to or close to zero. On the basis of these findings, we conclude that there is strong agreement between the GT1M, GT3X, and GT3X+ activity monitors, thus making it acceptable for researchers and practitioners to use different ActiGraph? models within a given study.     

The effect of playing formation on high-intensity running and technical profiles in English FA Premier League soccer matches

Abstract

The aim of this study was to examine the effect of playing formation on high-intensity running and technical performance during elite soccer matches. Twenty English FA Premier League games were analysed using a multiple-camera computerized tracking system (n = 153 players). Overall ball possession did not differ (P > 0.05) between 4–4–2, 4–3–3 and 4–5–1 formations (50%, s = 7 vs. 49%, s = 8 vs. 44%, s = 6). No differences were observed in high-intensity running between 4–4–2, 4–3–3 and 4–5–1 formations. Compared with 4–4–2 and 4–3–3 formations, players in a 4–5–1 formation performed less very high-intensity running when their team was in possession (312 m, s = 196 vs. 433 m, s = 261 vs. 410 m, s = 270; P < 0.05) but more when their team was not in possession (547 m, s = 217 vs. 461 m, s = 156 vs. 459 m, s = 169; P < 0.05). Attackers in a 4–3–3 performed ～30% more (P < 0.05) high-intensity running than attackers in 4–4–2 and 4–5–1 formations. However, the fraction of successful passes was highest in a 4–4–2 (P < 0.05) compared with 4–3–3 and 4–5–1 formations. The results suggest that playing formation does not influence the overall activity profiles of players, except for attackers, but impacts on very high-intensity running activity with and without ball possession and some technical elements of performance.     

Network analysis of kick-in possession chains in elite Australian football

ABSTRACT

The study aim was to investigate ball movement patterns using network analysis techniques, to compare between successful and unsuccessful outcomes and teams in the Australian Football League (AFL). This analysis focused on possession chains starting from a kick-in (n = 1,720), drawn from all games played in the 2015 AFL Premiership season (18 teams, 206 games). Player interactions were quantified using four network metrics: cluster coefficient, degree centrality, network density, and entropy. Three-way ANOVA with Tukey post hoc and ω² effect sizes were calculated to assess whether differences existed between kick-in outcomes, ladder brackets, and match outcomes for each network metric. No significant differences were observed between ladder brackets or match outcomes for any network metric. More successful kick-in chains were characterised by lower density (ω² = 0.26, large effect; F(9, 1678) = 66.6, p < 0.00) and higher entropy (ω² = 0.17, large effect; F(9, 1678) = 39.6, p < 0.00). This suggests that chains resulting in successful kick-in outcomes exhibited lower interconnectedness, with a high number of players involved, and lower predictability in ball movement patterns. These findings have practical value for coaches and performance analysts and support further applications of network analysis in Australian football.     

How Much Does Experience Matter in NCAA Division I Volleyball? A Retrospective Study

Purpose: To evaluate the relationship between years of collegiate playing experience and success of NCAA Division I volleyball programs. Methods: Data were gathered from the 2010–2015 seasons for each volleyball program in the “power five” conferences. Players that were involved in at least 66% of the sets were selected for analysis. Each player’s years of college experience were tabulated and a team average experience score was created. This score was correlated with the end of season Ratings Percentage Index (RPI). Years with a significant correlation between success and experience were further analyzed for differences in on-court statistics by years of experience. Results: The range for team average experience score was 2.52–2.66. Only the 2012 season showed a moderate correlation between the team average score and RPI (ρ = ?0.421, p = .001), indicating that more experienced teams finished with a higher national ranking. Within this year, teams with more experience had a statistically significant (p < .05) higher season win percentage, higher conference win percentage, higher hitting percentage, more kills/set, and more assists/set than teams with low or only moderate experience. Conclusions: These data suggest that more collegiate playing experience does not always result in a significantly more successful season, but trends indicate that a relationship does exist between experience and success. In the one year that showed significance, more experienced teams had more favorable statistics related to skills that terminate play (e.g., kills) rather than ball control skills (e.g., digs and passing).     

Acceleratory match-play demands of a Super Rugby team over a competitive season

The match-play demands of rugby union have increased over time, and these demands should be quantified so as to provide a basis for optimal player loading during training. The primary aim of this article was to quantify accelerations, decelerations, impacts and aggregated body demands during the first half of match-play in a Super Rugby team. The secondary aim was to determine whether these characteristics are position-specific. Thirty-three players were monitored for 14 matches using global positioning system units with inbuilt microtechnology. Players were grouped according to positional roles and data were analysed for those who completed the entire duration of the first half of a given match. Forwards sustained more (d = 0.44) high-intensity impacts and greater (d = 0.26) aggregated body demands, while backs had more moderate (d = 0.55) and heavy accelerations (d = 0.76), and moderate (d = 0.23) and heavy decelerations (d = 0.54). These differences suggest that conditioning and recovery strategies should reflect the physical demands placed on players in different playing positions. Forwards should be conditioned with a focus on impacts and require longer recovery for the same duration of playing time, whereas conditioning for backs should emphasise rapid accelerations and decelerations.     

Physical activity levels during youth sport practice: does coach training or experience have an influence?

This study examined moderate-to-vigorous physical activity (MVPA) levels in youth during flag football practice and compared youth MVPA in practices led by trained or untrained, and by experienced or inexperienced, coaches. Boys (n = 111, mean age = 7.9 ± 1.2 years) from 14 recreation-level flag football teams wore an accelerometer during two practices. Each team’s volunteer head coach reported prior training and coaching experience. Mixed-model team-adjusted means showed the proportion of practice time spent in sedentary (13 ± 1%), MVPA (34 ± 2%) and vigorous (12 ± 1%) activity. Practice contributed ~20 min of MVPA towards public health guidelines. There was no significant difference in percentage time spent in MVPA between teams with trained (mean = 33.3%, 95% CI = 29.4%, 37.2%) and untrained coaches (mean = 35.9%, 95% CI = 25.5%, 42.4%) or between experienced (mean = 34.1%, 95% CI = 30.2%, 38.0%) and inexperienced coaches (mean = 33.8, 95% CI = 27.9%, 39.7%). Although sport provides a setting for youth to accrue MVPA, two-thirds of practice was spent sedentarily or in light activity. Participation in a coach training programme was not associated with higher MVPA. Further research is needed to inform volunteer coach training programmes that provide coaches with skills necessary to increase the percentage of practice time spent in MVPA.