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Mehrez Hammami, Rodrigo Ramirez-Campillo, Nawel Gaamouri, Gaith Aloui, Roy J. Shephard and Mohamed Souhaiel Chelly

Purpose: To analyze the effects of a 9-week plyometric training program on the sprint times (5, 10, 20, and 30 m), change-of-direction speed (modified T test and modified Illinois test), jumping (squat jump, countermovement jump, countermovement jump with arms, and horizontal 5-jump test), upper-body strength (right and left handgrip, back extensor strength, and medicine ball throw), and balance (Y and stork balance tests) of female handball players. Methods: Athletes were randomly divided into experimental (n = 21; age = 13.5 [0.3] y) and control (n = 20; age = 13.3 [0.3] y) groups. Training exercises and matches were performed together, but the experimental group replaced a part of their normal regimen by biweekly upper- and lower-limb plyometric training. Results: Both groups improved performance, but to a greater extent in the experimental group compared with controls for 20- and 30-m sprint times (Δ% = 9.6, P < .05, d = 0.557 and Δ% = 20.9, P < .001, d = 1.07, respectively), change of direction (T test: P < .01, Δ% = 14.5, d = 0.993 and Illinois test: P < .01, Δ% = 7.9, d = 0.769), vertical and horizontal jumping (P < .05), all measures of upper-limb strength (P < .001), and left-leg stork balance (P < .001, Δ% = 49.9, d = 1.07). Conclusions: A plyometric training program allows female junior handball players to improve important components of their physical performance.

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Robyn F. Madden, Kelly A. Erdman, Jane Shearer, Lawrence L. Spriet, Reed Ferber, Ash T. Kolstad, Jessica L. Bigg, Alexander S.D. Gamble and Lauren C. Benson

Purpose: To determine the effects of low-dose caffeine supplementation (3 mg/kg body mass) consumed 1 h before the experiment on rating of perceived exertion (RPE), skills performance (SP), and physicality in male college ice hockey players. Methods: Using a double-blind, placebo-controlled, randomized crossover experimental design, 15 college ice hockey players participated in SP trials and 14 participated in scrimmage (SC) trials on a total of 4 d, with prescribed ice hockey tasks occurring after a 1-h high-intensity practice. In the SP trials, time to complete and error rate for each drill of the validated Western Hockey League Combines Testing Standard were recorded. Peak head accelerations, trunk contacts, and offensive performance were quantified during the SC trials using accelerometery and video analysis. RPE was assessed in both the SP and SC trials. Results: RPE was significantly greater in the caffeine (11.3 [2.0]) than placebo (9.9 [1.9]) condition postpractice (P = .002), with a trend toward greater RPE in caffeine (16.9 [1.8]) than placebo (15.7 [2.8]) post-SC (P = .05). There was a greater number of peak head accelerations in the caffeine (4.35 [0.24]) than placebo (4.14 [0.24]) condition (P = .028). Performance times, error rate, and RPE were not different between intervention conditions during the SP trials (P > .05). Conclusions: A low dose of caffeine has limited impact on sport-specific skill performance and RPE but may enhance physicality during ice hockey SCs.

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Simona Bar-Haim, Ronit Aviram, Anat Shkedy Rabani, Akram Amro, Ibtisam Nammourah, Muhammed Al-Jarrah, Yoav Raanan, Jack A. Loeppky and Netta Harries

Purpose: Exercise interventions have been shown to increase motor capacities in adolescents with cerebral palsy; however, how they affect habitual physical activity (HPA) and sedentary behavior is unclear. The main objective was to correlate changes in HPA with changes in mobility capacity following exercise interventions. Methods: A total of 54 participants (aged 12–20 y) with bilateral spastic cerebral palsy at Gross Motor Function Classification System (GMFCS) levels II and III received 4 months of group progressive resistance training or treadmill training. Mobility measurements and HPA (averaged over 96 h) were made before and after interventions. Results: Averaged baseline mobility and HPA measures and improvements in each after both interventions were positively correlated in all participants. Percentage of sedentary/awake time decreased 2%, with significant increases in HPA measures of step count (16%), walk time (14%), and upright time (9%). Mobility measures and HPA changes were quite similar between Gross Motor Function Classification System levels, but improvement in HPA after group progressive resistance training was greater than after treadmill training (12% vs 4%) and correlated with mobility improvement. Conclusions: Mobility capacity improved after these interventions and was clearly associated with improved HPA. The group progressive resistance training intervention seems preferable to improve HPA, perhaps related to greater social interaction and motivation provided by group training.

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Llion A. Roberts, Johnpaul Caia, Lachlan P. James, Tannath J. Scott and Vincent G. Kelly

Purpose: External counterpulsation (ECP) has previously been used to treat cardiac patients via compression of the lower extremities during diastole to increase venous return and coronary perfusion. However, the effects of ECP on exercise performance and markers of recovery in elite athletes are largely unknown. Methods: On 2 separate occasions, 48 h apart, 7 elite National Rugby League players performed an identical 60-min field-based conditioning session followed by a 30-min period of either regular ECP treatment or placebo. Power measures during repeated cycle bouts and countermovement jump height and contraction time derivatives were measured at rest and 5 h postexercise. Saliva samples and venous blood samples were taken at rest, postexercise, and 5 h postexercise to assess stress, inflammation, and muscle damage. Results: After ECP treatment, cycling peak power output (P = .028; 11%) and accumulated peak power (P = .027; 14%) increased compared with the placebo condition. Postexercise plasma interleukin 1 receptor antagonist only increased after ECP (P = .024; 84%), and concentrations of plasma interleukin 1 receptor antagonist tended to be higher (P = .093; 76%) 5 h postexercise. Furthermore, testosterone-to-cortisol ratio was increased above baseline and placebo 5 h postexercise (P = .017–.029; 24–77%). The ratio of postexercise salivary α-amylase to immunoglobulin A decreased after treatment (P = .013; 50%) compared with the placebo control. Conclusions: Exercise performance and hormonal indicators of stress were improved and inflammation markers were reduced following acute ECP.

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Zeynep Hazar Kanik, Seyit Citaker, Canan Yilmaz Demirtas, Neslihan Celik Bukan, Bulent Celik and Gurkan Gunaydin

Objective: The purpose of this study was to examine the effects of Kinesio taping (KT) on delayed onset muscle soreness. Design: Randomized controlled study. Setting: Clinical laboratory. Participants: Fifty-four nonathletic volunteers were assigned randomly to KT (n = 27) and placebo KT (n = 27) groups. Interventions: The intense exercise protocol consisted of 100 consecutive drop jumps from a 0.60-m-high platform. Kinesio tape was applied with the fan technique on the quadriceps muscles in the KT group. The placebo KT group received the Kinesio tape with no technique and tension. Main Outcome Measure: Muscle soreness, maximal isometric quadriceps muscle strength, vertical jump height, and blood analyses (creatine kinase, lactate dehydrogenase, myoglobin, and C-reactive protein) were measured preexercise, immediately postexercise, 48 hours postexercise, and 72 hours postexercise. Results: There was a significant effect of time in all outcome measures (P < .05) except serum C-reactive protein level (P > .05). The intensity of muscle soreness was significantly lower in the KT group relative to the placebo KT group at 72 hours postexercise (P = .01). The serum creatine kinase level was significantly higher in the KT group compared with the placebo KT group at 72 hours postexercise (P = .01). There were no statistically significant differences between groups for the other outcome measures (P > .05). Conclusions: These findings indicate that KT intervention following the intense exercise protocol reduced muscle soreness. However, it had no effect on maximal quadriceps isometric strength and vertical jump height or serum lactate dehydrogenase, myoglobin, and C-reactive protein levels. Furthermore, KT application after intense exercise also increased serum creatine kinase levels.

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Marissa A. Kobayashi, Tae Kyoung Lee, Rafael O. Leite, Blanca Noriega Esquives, Guillermo Prado, Sarah E. Messiah and Sara M. St. George

Background: Previous literature has shown a negative relationship between parental stress and youth moderate to vigorous physical activity (MVPA). This study examined (1) the relationship between parental stress and adolescent MVPA, (2) the moderating role of family communication on this relationship, and (3) gender differences in these effects among overweight and obese Hispanic adolescents. Methods: Hispanic adolescents (N = 280, 52% female, 13.0 [0.8] y old, 44% obese, 12% severely obese) and their parents (88% female, 44.9 [6.5] y old) completed baseline measures for an efficacy trial. Adolescents self-reported MVPA in minutes per week for work, transportation, and recreation using a validated measure. Multiple regression analyses with interaction terms and multigroup methods were conducted. Results: There was a negative effect of parental stress on adolescent MVPA (β = −0.15, t = −2.018, P ≤ .05). This effect was moderated by family communication (β = 0.20, t = 2.471, P = .01), such that the association between parental stress and youth MVPA was stronger for adolescents with low levels of family communication. Furthermore, a multiple group model showed that the interaction was significant for boys (β = 0.27, t = 2.185, P = .03), but not for girls. Conclusions: Findings provide support that addressing parental stress and family communication may help facilitate MVPA among Hispanic boys, the most at-risk group for pediatric obesity.

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Anna M. Ifarraguerri, Danielle M. Torp, Abbey C. Thomas and Luke Donovan

Individuals with chronic ankle instability (CAI) have been shown to have increased lateral plantar pressure during walking which is thought to contribute to symptoms associated with CAI. The objective of this study was to determine whether real-time video feedback can reduce lateral plantar pressure in individuals with CAI. Twenty-six participants with CAI completed 30 s of treadmill walking while plantar pressure was measured using an in-shoe plantar pressure system (baseline). Next, participants completed an additional 30 s of treadmill walking while receiving video feedback (VID FB). During the VID FB condition, participants had a significant decrease in medial forefoot peak pressure and medial midfoot pressure-time integral; however, both changes were associated with small effect sizes. Real-time video feedback did not reduce lateral plantar pressure in individuals with CAI; therefore, other gait retraining strategies should be considered when treating patients with CAI.

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Danny Lum and Tiago M. Barbosa

Purpose: To evaluate the effect of strength training on Olympic time-based sports (OTBS) time-trial performance and provide an estimate of the impact of type of strength training, age, training status, and training duration on OTBS time-trial performance. Methods: A search on 3 electronic databases was conducted. The analysis comprised 32 effects in 28 studies. Posttest time-trial performance of intervention and control group from each study was used to estimate the standardized magnitude of impact of strength training on OTBS time-trial performance. Results: Strength training had a moderate positive effect on OTBS time-trial performance (effect size = 0.59, P < .01). Subgroup meta-analysis showed that heavy weight training (effect size = 0.30, P = .01) produced a significant effect, whereas other modes did not induce significant effects. Training status as factorial covariate was significant for well-trained athletes (effect size = 0.62, P = .04), but not for other training levels. Meta-regression analysis yielded nonsignificant relationship with age of the participants recruited (β = −0.04; 95% confidence interval, −0.08 to 0.004; P = .07) and training duration (β = −0.05; 95% confidence interval, −0.11 to 0.02; P = .15) as continuous covariates. Conclusion: Heavy weight training is an effective method for improving OTBS time-trial performance. Strength training has greatest impact on well-trained athletes regardless of age and training duration.

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Carlos Marta, Ana R. Alves, Pedro T. Esteves, Natalina Casanova, Daniel Marinho, Henrique P. Neiva, Roberto Aguado-Jimenez, Alicia M. Alonso-Martínez, Mikel Izquierdo and Mário C. Marques

Purpose: The aim of this study was to determine the effects of an 8-week program of resistance training (RT) or suspension training (ST) on explosive strength in prepubescent boys. Methods: Fifty-seven boys aged 10–11 years were assigned to 2 training groups, RT or ST or a control group (no training program). Boys trained twice weekly for 8 weeks. Results: A significant interaction was reported with a large (P < .001, ηp2=.463), medium (P < .001, ηp2=.395), and small effect sized (P ≤ .001, ηp2=.218) in the 1-kg ball throw, 3-kg ball throw, and time-at-20-m test, respectively. There was no significant interaction in the countermovement vertical jump or the standing long jump. Changes from preintervention to postintervention for the 1-kg ball throw were 5.94% and 5.82% for the ST and RT, respectively, and 8.82% and 8.14% in the 3-kg ball throw for the ST and RT, respectively. The improvement in the 20-m sprint was 1.19% for the ST and 2.33% for the RT. Conclusion: Traditional RT and ST seem to be effective methods for improving explosive strength in prepubescent boys. ST could be considered as an alternative modality to optimize explosive strength training in school-based programs.

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Charlie Bowen, Kristian Weaver, Nicola Relph and Matt Greig

Context: Training exposure has been associated with injury epidemiology in elite youth soccer, where lower-limb musculoskeletal screening is commonly used to highlight injury risk. However, there has been little consideration of the relationship between lower-limb screening and the loading response to soccer activities. Objective: To quantify the efficacy of using screening tests to predict the loading elicited in soccer-specific activities and to develop a hierarchical ordering of musculoskeletal screening tests to identify test redundancy and inform practice. Design: Correlational. Setting: Professional soccer club academy. Participants: A total of 21 elite male soccer players aged 15.7 (0.9) years. Intervention: Players completed a battery of 5 screening tests (knee to wall, hip internal rotation, adductor squeeze, single-leg hop, and anterior reach) and a 25-minute standardized soccer session with a Global Positioning System unit placed at C7 to collect multiplanar PlayerLoad data. Main Outcome Measures: Baseline data on each screening test, along with uniaxial PlayerLoad in the mediolateral, anteroposterior, and vertical planes. Results: Stepwise hierarchical modeling of the screening tests revealed that dominant leg knee-to-wall distance was the most prevalent and powerful predictor of multiplanar PlayerLoad, accounting for up to 42% of variation in uniaxial loading. The adductor squeeze test was the least powerful predictor of PlayerLoad. Of note, one player who incurred a knee injury within 3 weeks of testing had shown a 20% reduction in knee-to-wall distance compared with peers, and elicited 23% greater PlayerLoad, supporting the hierarchical model. Conclusions: There was some evidence of redundancy in the screening battery, with implications for clinical choice. Hierarchical ordering and a concurrent case study highlight dominant leg knee-to-wall distance as the primary predictor of multiaxial loading in soccer. This has implications for the design and interpretation of screening data in elite youth soccer.