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Purpose: To examine the effect of normobaric hypoxia on pulmonary oxygen uptake ( ${\dot{\mathrm{V}}\mathrm{O}}_2$ ) and muscle oxygenation kinetics during incremental and moderate-intensity exercise in children. Methods: Eight prepubertal boys (9–11 y) performed incremental cycle tests to exhaustion in both normoxia and hypoxia (fraction of inspired O₂ of 15%) followed by repeat 6-minute transitions of moderate-intensity exercise in each condition over subsequent visits. Results: Maximal oxygen uptake ( ${\dot{\mathrm{V}}\mathrm{O}}_2\max$ ) was reduced in hypoxia compared with normoxia (1.69 [0.20] vs 1.87 [0.26] L·min⁻¹, P = .028), although the gas exchange threshold was not altered in absolute terms (P = .33) or relative to ${\dot{\mathrm{V}}\mathrm{O}}_2\max$ (P = .78). During moderate-intensity exercise, the phase II ${\dot{\mathrm{V}}\mathrm{O}}_2$ time constant (τ) was increased in hypoxia (18 [9] vs 24 [8] s, P = .025), with deoxyhemoglobin τ unchanged (17 [8] vs 16 [6], P ≥ .28). Conclusions: In prepubertal boys, hypoxia reduced ${\dot{\mathrm{V}}\mathrm{O}}_2\max$ and slowed ${\dot{\mathrm{V}}\mathrm{O}}_2$ phase II kinetics during moderate-intensity exercise, despite unchanged deoxyhemoglobin kinetics. These data suggest an oxygen delivery dependence of ${\dot{\mathrm{V}}\mathrm{O}}_2\max$ and moderate-intensity ${\dot{\mathrm{V}}\mathrm{O}}_2$ kinetics under conditions of reduced oxygen availability in prepubertal boys.

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.

Purpose: The aim of this study was to explore the interday reliability of mechanical variables obtained from the horizontal and vertical force–velocity (FV) profiles in adolescent female basketball players. If found to be reliable, the associations between FV parameters (theoretical maximal force, velocity, and power), squat jump (SJ) height, 30-m sprint, and change of direction (COD) times were evaluated. Methods: After familiarization, SJ against incremental loads, 30-m sprint, and 505-COD tests were obtained twice in 36 adolescent female basketball players (age = 15.4 [1.2] y). Results: Reliability for vertical FV parameters was unacceptable, whereas 505-COD times and FV horizontal parameters (except for theoretical maximal power) showed a moderate to high reliability. 505-COD time was correlated with FV horizontal parameters (range: r = −.821, −.451), and a large association was observed with both SJ height (r = −.678, −.600) and 30-m sprint time (r = .813, .858). Conclusions: Due to low levels of strength, our athletes were not adequately prepared to obtain a reliable vertical FV profile. Practitioners can expect acceptable reliability of the horizontal FV profile. Given the association between COD performance and SJ height and 30-m sprint time, we encouraged practitioners with limited equipment at their disposal to use COD and/or 30-m sprint tests.

Purpose: Inflammation regulation is important for obesity management and prevention of obesity-related diseases. This cross-sectional study aimed to analyze the independent and combined associations of physical activity and screen time with biomarkers of inflammation in children and adolescents with overweight/obesity. Method: A total of 1289 children and adolescents with overweight/obesity were included from the 2015 to 2018 National Health and Nutrition Examination Survey. Multivariable linear regressions were conducted for the association analyses. Results: For the independent associations, a negative dose-dependent relationship was demonstrated between physical activity and inflammatory biomarker high-sensitivity C-reactive protein (hsCRP) in adolescents with overweight/obesity (P < .001) but not children; screen time was not associated with hsCRP in both children and adolescents. No significant association was found between physical activity or screen time with other inflammatory biomarkers. For the combined associations, there was an interaction between physical activity and screen time on hsCRP in adolescents with overweight/obesity (P = .014). In addition, the negative association between physical activity and hsCRP was greater in boys compared with girls and in Hispanic and non-Hispanic Black individuals compared with non-Hispanic White individuals. Conclusion: This study demonstrated a combined association of physical activity and screen time with inflammatory biomarker hsCRP in adolescents with overweight/obesity.

Purpose: This study examined the relationship between parent physical activity (PA) support and children’s motor skill development and PA during early childhood and explored the potential moderating effect of child PA and motor skills on these relationships. Methods: Participants (N = 589, 250 girls, mean_age = 4.93 [0.59] y) were part of a larger, longitudinal cohort study. Motor skills were assessed using the Movement Assessment Battery for Children—Second Edition. Moderate to vigorous PA (MVPA) was measured using ActiGraph accelerometers. Five items were used to measure parent support frequency (1 = none, 3 = 3–4 times, 5 = daily). Moderation analyses were conducted to examine the moderating effect of MVPA and motor skills on the relationship between parent support and motor skills and MVPA, respectively. Results: Parent support was significantly related to motor skills (B = 14.45, P = .007), and child MVPA significantly moderated this relationship (B = −0.17, P = .021). The relationship between parent support and child MVPA did not reach significance (B = 2.89, P = .051); however, motor skills had a significant moderating effect (B = −0.08, P = .022). Conclusions: These novel findings suggest parent PA support is related to child motor skills and PA during early childhood, but this relationship is context dependent. Child-level characteristics should be considered in future parent PA support research.

Purpose: The aim of this investigation was to assess alterations of pulmonary oxygen uptake ( ${\dot{\mathrm{V}}\mathrm{O}}_2$ ) and muscle deoxygenation on-kinetics during heavy-intensity cycling in youth cyclists over a period of 15 months. Methods: Eleven cyclists (initial age, 14.3 [1.6] y; peak ${\dot{\mathrm{V}}\mathrm{O}}_2$ , 62.2 [4.5] mL·min⁻¹·kg⁻¹) visited the laboratory twice on 3 occasions within 15 months. Participants performed an incremental ramp exercise test and a constant workrate test within the heavy-intensity domain during the first visit and second visit, respectively. Subsequently, parameter estimates of the ${\dot{\mathrm{V}}\mathrm{O}}_2$ and muscle deoxygenation on-kinetics were determined with mono-exponential models. Results: The ${\dot{\mathrm{V}}\mathrm{O}}_2$ phase II time constant decreased from occasion 1 (34 [4] s) to occasion 2 (30 [4] s, P = .005) and 3 (28 [4] s, P = .010). However, no significant alteration was observed between occasions 2 and 3 (P = .565). The ${\dot{\mathrm{V}}\mathrm{O}}_2$ slow component amplitude either expressed in absolute values (ie, L·min⁻¹) or relative to end exercise ${\dot{\mathrm{V}}\mathrm{O}}_2$ (ie, %) showed no significant changes throughout the study (P = .972 and .996). Furthermore, the muscle deoxygenation on-kinetic mean response time showed no significant changes throughout the study (18 [8], 18 [3], and 16 [5] s for occasions 1, 2, and 3, respectively; P = .279). Conclusion: These results indicate proportional enhancements of local muscle oxygen distribution and utilization, which both contributed to the speeding of the ${\dot{\mathrm{V}}\mathrm{O}}_2$ on-kinetics herein.

Background: Anthracycline-induced cardiotoxicity is a frequent complication that can occur at any stage of treatment, even in survivors. Objective: To determine maximum aerobic power, quality of life, and left ventricular ejection fraction in childhood cancer survivors treated with anthracyclines. Design: Cross-sectional, observational study. Methods: The left ventricular ejection fraction was obtained from the transthoracic echocardiogram report in the medical records. Each patient underwent a 6-minute walk test, assessment of maximum aerobic power on a cycle ergometer, and evaluation of perceived exertion using the EPInfant scale, and finally, their quality of life was evaluated using the pediatric quality of life inventory model. Results: A total of 12 patients were studied, with an average of 16.2 years of age. All patients exhibited a left ventricular ejection fraction >60%, the mean distance covered in the 6-minute walk test was 516.7 m, and the mean of the maximum aerobic power was 70 W. Low quality of life scores were obtained in the physical and psychosocial aspects. In the Pearson test, a weak correlation without statistical significance was found between all the variables studied. Conclusions: Simultaneously with the detection of cardiotoxicity in childhood cancer survivors, it is pertinent to perform physical evaluations as physical condition and cardiotoxicity seem to be issues that are not necessarily dependent.