Search Results

The purpose of this study was to examine the time-of-day effects on short-term performances in boys. In a balanced and randomized study design, 20 boys performed four anaerobic tests of strength and power (grip strength, Squat-Jump, Five-jump and cycle Wingate tests) at 08:00, 14:00 and 18:00 hr on separate days. The results showed a time-of-day effect on oral temperature. Analysis of variance revealed a significant time-of-day effect for short-term performances for strength, cycle, and jump tests. The post hoc analysis revealed that performances improved significantly from morning to afternoon but no significant differences were noticed between 14:00 and 18:00 hr. The differences between the morning and the afternoon (the highest value measured either at 14:00 or at 18:00 hr) reached 5.9% for grip strength, 3.5% for the squat jump test, 5% for the five jump test, and 5.5% for P_peak and 6% for P_mean during the Wingate test. A significant positive correlation was found between temperature and short-term performances. In conclusion, a time-of-day effect in the child’s maximal short-term exercise performances exists in relation with core temperature. Such variations would have pronounced effects when expressed in training programs and competitions.

Purpose: The aim of this study was to examine whether cortical activity changes during exercise with increasing cognitive demands in preadolescent children. Method: Twenty healthy children (8.75 [0.91] y) performed one movement game, which was conducted with lower and higher cognitive demands. During a baseline measurement and both exercise conditions, cortical activity was recorded using a 64-channel electroencephalographic system, and heart rate was assessed. Ratings of perceived excertion and perceived cognitive engagement were examined after each condition. To analyze power spectral density in the theta, alpha-1, and alpha-2 frequency bands, an adaptive mixture independent component analysis was used to determine the spatiotemporal sources of cortical activity, and brain components were clustered to identify spatial clusters. Results: One-way repeated-measures analyses of variance revealed significant main effects for condition on theta in the prefrontal cluster, on alpha-1 in the prefrontal, central, bilateral motor, bilateral parieto-occipital, and occipital clusters, and on alpha-2 in the left motor, central, and left parieto-occipital clusters. Compared with the lower cognitive demand exercise, cortical activity was significantly higher in theta power in the prefrontal cluster and in alpha-1 power in the occipital cluster during the higher cognitive demand exercise. Conclusion: The present study shows that exercise complexity seems to influence cortical processing as it increased with increasing cognitive demands.

Purpose: To describe serum irisin and fibroblast growth factor-21 (FGF-21) concentrations in healthy female adolescents with different training activity patterns and their associations with bone mineral properties and metabolic markers. Methods: A total of 62 adolescent girls aged 14–18 years were recruited: 22 rhythmic gymnasts, 20 swimmers, and 20 untrained controls. Bone mineral characteristics by dual-energy X-ray absorptiometry, daily energy intake by dietary recall, serum irisin, FGF-21, undercarboxylated osteocalcin, and C-terminal telopeptide of type I collagen were measured in all girls. Results: Whole body and lumbar spine areal bone mineral density and lumbar spine bone mineral content were higher in the rhythmic gymnasts group compared with swimmers and untrained controls groups (P < .05). Serum irisin, FGF-21, undercarboxylated osteocalcin, and C-terminal telopeptide of type I collagen levels were not significantly different between the groups. In the rhythmic gymnasts group, serum FGF-21 concentration was positively correlated with lumbar spine areal bone mineral density independently of confounding factors (r = .51; P = .027). Conclusions: Serum irisin and FGF-21 levels were not different between adolescent eumenorrheic girls with different training activity patterns. FGF-21 was positively associated with lumbar spine areal bone mineral density, which predominantly consists of trabecular bone in adolescent rhythmic gymnasts.

Purpose: Exercise seems to influence taste, but the effect of exercise on specific tastes is still to be elucidated among youths. Methods: Athlete boys aged 14–16 years were recruited. Participants (n = 19) ages ranged 14.7 (0.7) years, weight 59.6 (7.8) kg, and height of 173.4 (7.9) cm. Distinct taste tests were administered using low and high concentrations of sweet, salty, and bitter solutions before and after a 30-minute aerobic exercise session (70%–90% of estimated maximal heart rate). McNemmar tests, standard paired t tests, Wilcoxon signed-rank tests, and Cohen d effect size tests were used to analyze taste identification, intensity, and appreciation. Results: There were no significant differences in taste identification capacities after exercise. Participants perceived more intense (P = .037) and appreciated better (P = .004) the low-concentration sweet solution after exercise. Taste appreciation was increased for the high-concentration sweet solution (P = .009) after exercise. Effect sizes were moderate (0.516–0.776). Possible effects were noted for the intensity of salty solutions (P = .0501 and .0543). Conclusion: Following an exercise session, participants had increased perceived intensity and appreciation of sweet solutions. This adds new insights into how exercise influences taste in youths, a topic less documented compared with adults, suggesting further research into its impact on dietary choices is needed.

This study examined differences in resting concentrations of markers of bone formation and resorption, and osteokines between female adolescent (12–16 y) swimmers, soccer players, and nonathletic controls. Resting, morning blood samples were obtained after an overnight fast from 20 swimmers, 20 soccer players, and 20 nonathletic controls, matched for age. carboxyl-terminal cross-linking telopeptide of type I collagen (CTX), amino-terminal propeptide of type I collagen (P1NP), total osteocalcin (OC), sclerostin, osteoprotegerin (OPG), and receptor activator of nuclear factor kappa B ligand (RANKL) were analyzed in serum. After controlling for percent body fat, there were no significant differences between swimmers and nonathletic controls in any of the measured markers. In contrast, soccer players had significantly higher P1NP (89.5 [25.6] ng·mL⁻¹), OC (57.6 [22.9] ng·mL⁻¹), and OPG (1052.5 [612.6] pg·mL⁻¹) compared with both swimmers (P1NP: 66.5 [20.9] ng·mL⁻¹; OC: 24.9 [12.5] ng·mL⁻¹; OPG: 275.2 [83.8] pg·mL⁻¹) and controls (P1NP: 58.5 [16.2] ng·mL⁻¹; OC: 23.2 [11.9] ng·mL⁻¹; OPG: 265.4 [97.6] pg·mL⁻¹), with no differences in CTX, sclerostin, and RANKL. These results suggest that bone formation is higher in adolescent females engaged in high-impact sports like soccer compared with swimmers and controls.