Marcella A. Raney, Abbie L. Bowers, and Amanda L. Rissberger
Background: Green schoolyard renovations lead to immediate positive changes in moderate to vigorous physical activity (MVPA) and social behavior. This pilot study examines whether these benefits are equally distributed across gender and age and maintained 16 months postgreening. Methods: Physical activity and social interactions during recess were recorded at control (n = 389) and experimental (n = 642) Title I urban elementary schools with direct observation and accelerometers. Results: Activity profiles were similar to 4-month postgreening and to baseline for experimental girls and boys, respectively. There was no difference in MVPA minutes between sexes (girls = 11.8; 95% confidence interval [CI], 11.1 to 12.5]; boys = 12.8; 95% CI, 12.0 to 13.4) and no difference in sitting minutes between age groups (first to fourth = 2.0; 95% CI, 1.5 to 2.6; fifth to sixth = 1.8; 95% CI, 1.1 to 2.4) in green areas. Experimental students spent more time in MVPA (11.2 min; 95% CI, 10.6 to 11.8 vs 8.9 min; 95% CI, 8.3 to 9.3), in small groups (10.6 min; 95% CI, 10.2 to 11.0 vs 9.2 min; 95% CI, 8.5 to 9.9), and engaged in more prosocial interactions (5.5; 95% CI, 5.1 to 6.3 vs 3.7; 95% CI, 3.0 to 4.2) than control students. Conclusions: Green schoolyard renovations result in persistent changes to recess behavior that are characteristic of a more collaborative community and counteract age-related declines in MVPA, particularly for girls.
Fernando G. Beltrami and Timothy D. Noakes
Purpose: This study aimecd to investigate whether elite athletes could reach higher values of maximal oxygen uptake (
Ana C. Santos-Mariano, Fabiano Tomazini, Cintia Rodacki, Romulo Bertuzzi, Fernando De-Oliveira, and Adriano E. Lima-Silva
Purpose: To investigate the effects of caffeine (CAF) on performance during high- and long-jump competitions. Methods: Using a crossover and double-blind design, 6 well-trained high jumpers and 6 well-trained long jumpers performed a simulation of a high- and long-jump competition 60 minutes after ingesting a capsule containing either 5 mg·kg−1 body mass of anhydrous CAF or a placebo. The high jumps were video recorded for kinematic analysis. The velocity during the approach run of the long jump was also monitored using photocells. Results: CAF improved jump performance (ie, the highest bar height overlap increased by 5.1% [2.3%], P = .008), as well as enhancing the height displacement of the central body mass (+1.3% [1.7%], P = .004) compared with the placebo. CAF had no ergogenic effect on jump distance (P = .722); however, CAF increased the velocity during the last 10 m of the long jump (P = .019), and the percentage of “foul jumps” was higher than that expected by chance in the CAF group (80.5% [12.5%], χ2 = 13.44, P < .001) but not in the cellulose condition (58.3% [22.9%], χ2 = 1.48, P = .224). Conclusion: CAF ingestion (5 mg·kg−1 body mass) improves high-jump performance but seems to negatively influence technical aspects during the approach run of the long jump, resulting in no improvement in long-jump performance. Thus, CAF can be useful for jumpers, but the specificity of the jump competition must be taken into account.
Adrien Vachon, Nicolas Berryman, Iñigo Mujika, Jean-Baptiste Paquet, and Laurent Bosquet
Purpose: To investigate the relationship between physical fitness and repeated high-intensity effort (RHIE) ability in elite rugby union players, depending on playing position. Method: Thirty-nine players underwent a fitness testing battery composed of a body composition assessment, upper-body strength (1-repetition maximum bench press and 1-repetition maximum bench row), lower-body strength (6-repetition maximum back squat), and power (countermovement jump, countermovement jump with arms, and 20-m sprint), as well as aerobic fitness (Bronco test) and RHIE tests over a 1-week period. Pearson linear correlations were used to quantify relationships between fitness tests and the RHIE performance outcomes (total sprint time [TST] and percentage decrement [%D]). Thereafter, a stepwise multiple regression model was used to verify the influence of physical fitness measures on RHIE ability. Results: TST was strongly to very strongly associated to body fat (BF, r = .82, P < .01), the 20-m sprint (r = .86, P < .01), countermovement jump (r = −.72, P < .01), and Bronco test (r = .90, P < .01). These fitness outcomes were related to %D, with moderate to strong associations (.82 > ∣r∣ > .54, P < .01). By playing position, similar associations were observed in forwards, but RHIE ability was only related to the 20-m sprint in backs (r = .53, P < .05). The RHIE performance model equations were TST = 13.69 + 0.01 × BF + 0.08 × Bronco + 10.20 × 20 m and %D = −14.34 + 0.11 × BF +0.18 × Bronco − 9.92 × 20 m. These models explain 88.8% and 68.2% of the variance, respectively. Conclusion: Body composition, lower-body power, and aerobic fitness were highly related with RHIE ability. However, backs expressed a different profile than forwards, suggesting that further research with larger sample sizes is needed to better understand the fitness determinants of backs’ RHIE ability.
Peter Leo, James Spragg, Iñigo Mujika, Andrea Giorgi, Dan Lorang, Dieter Simon, and Justin S. Lawley
Purpose: The aim of this study was to compare the power profile, internal and external workloads, and racing performance between U23 and professional cyclists and between varying rider types across 2 editions of a professional multistage race. Methods: Nine U23 cyclists from a Union Cycliste Internationale “Continental Team” (age 20.8 [0.9] y; body mass 71.2 [6.3] kg) and 8 professional cyclists (28.1 [3.2] y; 63.0 [4.6] kg) participated in this study. Rider types were defined as all-rounders, general classification (GC) riders, and domestiques. Data were collected during 2 editions of a 5-day professional multistage race and split into the following 4 categories: power profile, external and internal workloads, and race performance. Results: The professional group, including domestiques and GC riders, recorded higher relative power profile values after certain amounts of total work (1000–3000 kJ) than the U23 group or all-rounders (P ≤ .001–.049). No significant differences were found for external workload measures between U23 and professional cyclists, nor among rider types. Internal workloads were higher in U23 cyclists and all-rounders (P ≤ .001–.043) compared with professionals, domestiques, and GC riders, respectively. The power profile significantly predicted percentage general classification and Union Cycliste Internationale points (R 2 = .90–.99), whereas external and internal workloads did not. Conclusion: These findings reveal that the power profile represents a practical tool to discriminate between professionals and U23 cyclists as well as rider types. The power profile after 1000 to 3000 kJ of total work could be used by practitioners to evaluate the readiness of U23 cyclists to move into the professional ranks, as well as differentiate between rider types.
Stefan Altmann, Rainer Neumann, Sascha Härtel, Alexander Woll, and Martin Buchheit
Purpose: To assess the value of monitoring changes in fitness in professional soccer players, using changes in heart rate at submaximal intensity (HR12km/h) over the velocity at a lactate concentration of 4 mmol/L (v4mmol/L). The authors reexamined (1) a range of threshold magnitudes, which may improve detecting substantial individual changes and (2) the agreement between changes in these 2 variables. Methods: On at least 2 occasions during different moments of the season, 97 professional soccer players from Germany (first, second, and fourth division) completed an incremental test to determine HR12km/h and v4mmol/L. Optimal thresholds for changes in HR12km/h and v4mmol/L were assessed, using various methods (eg, smallest worthwhile change + typical error [TE], successive reiterations approach). Agreement between both variable changes was examined for the whole sample (225 comparisons), 4 different subgroups (depending on the moment of the season), and in an individual over 6 years (n = 23 tests). Results: Changes of 4.5% and 6.0% for HR12km/h and v4mmol/L, respectively, were rated as optimal to indicate substantial changes in fitness. Depending on the (sub)groups analyzed, these thresholds yielded 0% to 2% full mismatches, 22% to 38% partial agreements, and 60% to 78% full agreements in terms of fitness change interpretation between both variables. Conclusions: When lactate sampling during incremental tests is not possible, practitioners willing to monitor adult professional soccer players’ (Germany; first, second, and fourth division) training status can confidently implement short, 3-minute submaximal runs, with 4.5% changes in HR12km/h being indicative of true substantial fitness changes, with 60% to 78% accuracy. Future studies should investigate the potential role of confounding factors of HR12km/h to improve changes in fitness prediction.
Genevieve F. Dunton, Daniel Chu, Christine H. Naya, Britni R. Belcher, and Tyler B. Mason
Background: Psychological stress has adverse effects on health-related behaviors, yet longitudinal research is lacking. Research examined how children’s and mothers’ perceived stress are associated with children’s physical activity and sedentary behavior trajectories across 3 years. Methods: Mothers and their children (N = 186 dyads; 8–12 y at baseline, 57% Hispanic) completed 6 assessments across 3 years. Children and mothers self-reported perceived stress using the Stress in Children Scale and Perceived Stress Scale, respectively. Children’s moderate to vigorous physical activity (MVPA) and sedentary behavior were assessed using accelerometers. Mixed models examined interactions of mothers’ and children’s perceived stress by time elapsed in the study on children’s MVPA and sedentary behavior. Results: The perceived stress × time elapsed interactions were significant for children’s MVPA and sedentary behavior (Ps < .05). Higher average perceived stress in mothers was associated with greater decreases in children’s MVPA and increases in children’s sedentary behavior. The child stress × time elapsed interactions was significant for children’s MVPA (P < .05) but not sedentary behavior. Higher average perceived stress in children was associated with smaller decreases in children’s MVPA. Conclusion: Interventions to promote physical activity and reduce screen time in children should mitigate the effects of psychological stress, especially among mothers, on these behaviors.