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Purpose: The authors examined associations between preschoolers’ daily glycemic variability, parents’ report of hypoglycemia fear, and preschoolers’ daily moderate to vigorous physical activity (MVPA) and sedentary behavior (SB) in 25 families of preschoolers with type 1 diabetes. Methods: Parents completed a valid measure of hypoglycemia fear, and their child wore an accelerometer for up to 7 days. Parents provided glucose data from their child’s devices. The authors used multiple regression and multilevel modeling to analyze their data. Results: Preschoolers (mean age 4.2 [1.7] y; 50% boys) engaged in a mean of 154.5 (59.6) and 339.2 (85.1) minutes of MVPA and SB per day, respectively, and parents reported relatively low levels of hypoglycemia worry and avoidance behaviors. Preschoolers’ SB (r = .19, P = .02) and MVPA (r = −.20, P = .01) levels were significantly correlated with parental hypoglycemia worry scores but not with parents’ hypoglycemia behavior scores (P = .15 and P = .92, respectively). While multilevel models did not show an association between MVPA and preschoolers’ glycemic variability, preschoolers who engaged in more daily SB experienced higher glycemic variability (P = .04). Conclusions: Research exploring MVPA, SB, and parental hypoglycemia fear in preschoolers with type 1 diabetes could have important clinical implications because it may reveal modifiable treatment targets that can impact preschoolers’ health and activity patterns.

Purpose: To assess the short-term reliability of measurement instruments to quantify the acute psychophysiological response to load in adolescent soccer players in relation to biological maturity. Methods : Data were collected from 108 U12 to U17 soccer players on 2 consecutive weeks (pre, n = 32; at, n = 34; and post, n = 42 estimated peak height velocity). Measurements consisted of the Short Recovery and Stress Scale, a countermovement jump, assessment of leg stiffness, and a submaximal run to assess exercise heart rate and heart rate recovery. Test–retest reliability was assessed with the coefficient of variation (CV) and intraclass correlation coefficient (ICC). Results : Items of the Short Recovery and Stress Scale showed poor reliability across maturity groups (CV = 7.0%–53.5%; ICC = .28 to .79). Only few countermovement jump variables (jump height, concentric impulse, and concentric velocity) possessed good reliability. For most variables of the countermovement jump, reliability was better for the post peak height velocity group followed by at-peak height velocity and prepeak height velocity. Very high levels of reliability across maturity groups were observed for exercise heart rate (CV < 1.8%; ICC > .94), while heart rate recovery was more variable (CV < 16.5%; ICC > .48). Conclusion : Results suggest that the majority of investigated variables have poor reliability, questioning their ability to detect small, yet meaningful changes in acute responses to load in adolescent soccer players.

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.

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.

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.

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 N^ω-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). N^ω-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.

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.

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.