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Accumulative Weekly External and Internal Load Relative to Match Load in Elite Male Youth Soccer Players

Vicente de Dios-Álvarez, Pello Alkain, Julen Castellano, and Ezequiel Rey

Purpose: The aim of this study was 2-fold: (1) to assess and compare the external and internal load of elite young soccer players during competitive microcycles and (2) to describe the training/match ratios (TMr) in elite male youth soccer players. Method: Twenty-one youth soccer players were monitored using a 10-Hz global positioning system. Total distance covered, running distance (RD), high-speed RD, sprint distance, number of accelerations and decelerations, player load, and rated perceived exertion were recorded during training sessions and matches. The TMr was calculated for each load measure. All variables were also normalized dividing the load per minute of activity. Results: The RD, high-speed running, and sprint distance were higher 3 days before the match and 2 days before match compared with the rest of the training sessions. However, accelerations, decelerations, and player load were higher 4 days before match than other sessions. Besides this, the TMr of RD, high-speed running, and sprint distance were associated with lower values than the TMr of total distance covered, accelerations, decelerations, and player load. The match constituted the highest load during competitive microcycle. Conclusions: The present data support the idea that youth soccer coaches and practitioners must consider relative training load according to match demands to better manage and evaluate player periodization.

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Karate Training Improves Metabolic Health in Overweight and Obese Adolescents: A Randomized Clinical Trial

Fabricio de Souza, Luciano Acordi da Silva, Gisele Santinoni Ferreira, Márcia Mendonça Marcos de Souza, Franciane Bobinski, Juliete Palandi, Chaiana Esmeraldino Mendes Marcon, Daniel Fernandes Martins, Fabiana Schuelter-Trevisol, and Daisson José Trevisol

Purpose: This study evaluated the effects of 12 weeks of karate training on cardiometabolic parameters, oxidative stress, and inflammation in adolescents with overweight and obesity. Method: Seventy adolescents were randomized into 2 groups: control received nutritional and psychological interventions once a week for 12 weeks, and treatment received nutritional and psychological interventions once a week, plus 3 karate sessions per week, for 12 weeks. The main outcome measure was improvement in cardiometabolic parameters, oxidative stress, and inflammation. Results: After the intervention period, the treatment group showed a reduction in resting heart rate (77.86 [10.89]), high-density lipoprotein cholesterol (40.86 [8.31]), and triglycerides (75.18 [32.29]) and an increase in low-density lipoprotein cholesterol (95.64 [42.53]) in relation to pretraining. Regarding oxidative stress markers, there was a reduction in protein carbonylation (0.07 [0.06]) and nitric oxide (1.39 [1.11]) and an increase in superoxide dismutase (0.68 [0.31]) and glutathione (0.11 [0.08]) compared with pretraining. With respect to inflammation, adiponectin increased (14.54 [5.36]) after the intervention when compared with preintervention. Conclusion: The study concluded that the intervention may improve cardiometabolic parameters, oxidative stress, and inflammation in adolescents with overweight and obesity. Long-term effects need to be evaluated.

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Feasibility of the Mothers and Daughters Moving Together Physical Activity Intervention

Deirdre Dlugonski, Lacey Schwab, and Katrina D. DuBose

Purpose: Preschool-aged children, especially girls, have low levels of physical activity that may be influenced through parent role modeling. Evidence for mother–daughter interventions that include preschool-aged children is sparse. The primary purpose of this study was to examine the feasibility of recruitment procedures, protocol compliance, and participant retention for the Mothers and Daughters Moving Together intervention. The secondary aim was to provide initial estimates of the intervention effect on mother–daughter and family physical activity co-participation, moderate to vigorous physical activity, and maternal physical activity enjoyment and support. Method: This nonrandomized feasibility study included mother–daughter (2–5 y) dyads who self-selected into the intervention (n = 21 dyads) or comparison (n = 10 dyads) group. Results: The recruitment rate was 41.9% (31 enrolled/74 interested). Intervention group mother–daughter dyads attended 57% of intervention sessions. Among the whole sample, 70% to 80% of participants (mothers and daughters) had at least 4 valid days of accelerometer data at preintervention and postintervention. The retention rate was 90% (28/31 dyads completed the study). Initial estimates of intervention effect indicated small, positive changes for mother–daughter physical activity co-participation, and maternal physical activity support and enjoyment. Conclusions: This study provides valuable information that should be confirmed using an adequately powered and randomized study design.

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Skin Blood Flow Responses to Acetylcholine, Local Heating, and to 60% VO2max exercise with and without Nitric Oxide inhibition, in Boys vs. Girls

Raffaele Joseph Massarotto, Gary J. Hodges, Alexandra Woloschuk, Deborah D. O’Leary, Raffy Dotan, and Bareket Falk

Purpose: To determine sex-related differences in the skin blood flow (SkBF) response to exercise, local heating, and acetylcholine (ACh) in children, and to assess nitric oxide contribution to the SkBF response. Methods: Forearm SkBF during local heating (44°C), ACh iontophoresis, and exercise (30-min cycling and 60% of maximum oxygen consumption) was assessed, using laser Doppler fluxmetry, in 12 boys and 12 girls (7–13 y old), with and without nitric oxide synthase inhibition, using Nω-nitro-L-arginine methyl ester iontophoresis. Results: Local-heating-induced and ACh-induced SkBF increase were not different between boys and girls (local heating: 1445% [900%] and 1432% [582%] of baseline, P = .57; ACh: 673% [434%] and 558% [405%] of baseline, respectively, P = .18). Exercise-induced increase in SkBF was greater in boys than girls (528% [290%] and 374% [192%] of baseline, respectively, P = .03). Nω-nitro-L-arginine methyl ester blunted the SkBF response to ACh and during exercise (P < .001), with no difference between sexes. Conclusion: SkBF responses to ACh and local heat stimuli were similar in boys and girls, while the increase in SkBF during exercise was greater in boys. The apparent role of nitric oxide was not different between boys and girls. It is suggested that the greater SkBF response in boys during exercise was related to greater relative heat production and dissipation needs at this exercise intensity. The response to body size-related workload should be further examined.

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Speed Improves With Eccentric Hamstring Training in Athletes of Different Maturity Status

Raouf Hammami, Javier Gene-Morales, Ammar Nebigh, Haithem Rebai, and Juan C. Colado

Purpose: To investigate the effects of an eccentric hamstring strength training program (EHT) on sprint performance (10-, 20-, and 30-m sprint times) and change of direction speed (4 × 5-m shuttle run and T-Half test) in male European handball athletes at 2 maturity statuses (prepeak and postpeak height velocity [PHV]). Methods: Forty-five participants (12.68 [1.58] y) were divided into pre-PHV and post-PHV and randomly allocated to a control or intervention group, which performed a guided 2 day per week 6-week EHT of 5 exercises. A mixed-model (within- and between-factor) analysis of variance was conducted. Results: A significant effect (P < .05) of the interaction time × maturity × training was observed in the T-Half, 10, and 30 m tests. Both intervention groups significantly improved in all the tests, except in the 20 m sprint and the post-PHV in the 10 m sprint. Improvements ranged between 0.93% and 5.74% (effect size: 0.07–0.79). Both control groups yielded no improvements in almost all the tests. The improvements of both groups undergoing the intervention (pre-PHV and post-PHV) were not significantly different (only a tendency in the 10 m sprint). Conclusion: An EHT program combined with European-handball training improve change of direction and sprint performance in pre-PHV and post-PHV male players. Professionals training European handball and similar team-sport athletes should consider including EHT regardless of athlete’s maturity.

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Fitness Changes in Adolescent Girls Following In-School Combined Aerobic and Resistance Exercise: Interaction With Birthweight

Daniel Dylan Cohen, Javier Carreño, Paul Anthony Camacho, Johanna Otero, Daniel Martinez, Jose Lopez-Lopez, Gavin R. Sandercock, and Patricio Lopez-Jaramillo

Purpose: To assess the efficacy of a supervised in-school combined resistance and aerobic training program in adolescent girls and investigate whether responses differ according to birthweight. Methods: Participants (girls aged 13–17 y) were randomized either to an intervention replacing physical education (PE) classes with 2 × 60-minute training sessions per week (n = 58) or to a control group that continued to attend 2 × 60 minutes per week of curriculum PE (n = 41). We measured muscular fitness (handgrip, standing long jump, and sit-ups), cardiorespiratory fitness (20-m shuttle run), skinfolds, and lean body mass preintervention and postintervention and determined effect size (Hedge’s g) differences between changes in these measures. We also compared changes within lower (<3000 g) and normal birthweight intervention and PE control subgroups. Results: The intervention group showed greater improvements in all the fitness measures and lean body mass (g = 0.22–0.48) and lower skinfold increases (g = 0.41) than PE controls. Within the intervention group, improvements in all fitness measures were larger in lower birthweight (g = 0.53–0.94) than in normal birthweight girls (g = 0.02–0.39). Conclusion: Replacing curriculum PE with supervised training improved muscular and cardiorespiratory fitness and body composition outcomes in adolescent females. Our findings suggest an enhanced adaptive response to training in participants with lower birthweight which warrants further investigation.

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Volume 33 (2021): Issue S1 (Dec 2021)

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Influence of Insulin Application Time and High-Intensity Intermittent Exercise on Hypoglycemic Risk in Adolescents With Type 1 Diabetes

Valderi de Abreu de Lima, Gabriel Ribeiro Cordeiro, Luis Paulo Gomes Mascarenhas, Suzana Nesi França, Juliana Pereira Decimo, Andréia Araújo Porchat de leão, Camila Kapp Fritz, and Neiva Leite

Purpose: The study analyzed the influence of exercise on hypoglycemia episodes postexercise and in the subsequent 24 hours in children and adolescents with type 1 diabetes. Methods: Thirty young people performed the same protocol of physical exercises for 1 hour (Ex1h) and 2 hours (Ex2h) after the administration of insulin. They performed 30 minutes of exercise on a cycle ergometer with a load of 60% of maximal oxygen uptake, interspersed with maximum intensity sprints lasting 10 seconds every 5 minutes. Results: Regarding the occurrence of hypoglycemia, in the 8 hours following the exercises, there was no occurrence in Ex1h (χ 2 = 0.001; P = .0001) and a greater proportion for Ex2h (n = 71 episodes, 53.8%), while Ex1h had a higher number of nocturnal hypoglycemic episodes (n = 60, 71.4%) compared with Ex2h (n = 31, 23.1%, χ 2 = 49.521, P = .0001), Ex1h triggered a lower number of hypoglycemia (n = 84) than Ex2h (n = 134, χ 2 = 11.504, P = .001). There was a greater reduction in the average amount of fast-acting insulin administered the day after Ex1h compared with Ex2h (P = .031). Conclusions: Intermittent exercise performed 1 hour after insulin administration shows a lower risk of hypoglycemia within 8 hours after exercise, as well as a reduction in insulin the following day.

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Validity of the Fitbit Ace and Moki Devices for Assessing Steps During Different Walking Conditions in Young Adolescents

Xiyao Sun, Stephanie A. Adams, Chuchu Li, Josephine N. Booth, Judy Robertson, and Samantha Fawkner

Purpose: Using wearable monitoring devices is increasingly ubiquitous, including among young people. However, there is limited evidence of the validity of devices which are aimed at children and adolescents. The purpose of this study was to evaluate the validity of Fitbit Ace and Moki monitors in healthy young adolescents. Methods: This cross-sectional study included 17 young adolescents (ages 11–13 y) ambulating between 3 different walking conditions (incidental [∼6 min], controlled, and treadmill [each 3 min], while wearing wrist-worn devices [Fitbit Ace, Moki] on each wrist [left and right, respectively]). Data from the devices were compared with observer counts (criterion). Bland–Altman plots and mean absolute percentage errors were computed. Results: Analyses identified that the Fitbit Ace showed higher levels of bias across conditions compared with the Moki device: (mean difference [SD]; Fitbit Ace: 30.0 [38.0], 3.0 [13.0], and 13.0 [23.0] steps and Moki: 1.0 [19.0], 4.0 [16.0], and 6.0 [14.0] steps, incidental, controlled, and treadmill, respectively). Mean absolute percentage errors ranged from 3.1% to 9.5% for the Fitbit Ace and 3.0% to 4.0% for the Moki device. Conclusion: The Fitbit Ace and Moki devices might not provide acceptable validity under all walking conditions, but the Moki provides more accurate estimates of incidental walking and might therefore be a good choice for free-living research or school-based interventions.

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Volume 33 (2021): Issue 4 (Nov 2021)