Cardiac autonomic dysfunction in school age children with overweight and obesity.

BACKGROUND AND AIMS: We investigated cardiac autonomic function in overweight and obese school-age children. METHODS AND RESULTS: Quantitative cross-sectional study conducted with children (n = 110) of both genders. Children were divided by normal weight (NW; n = 54), overweight (OW; n = 24) and obese (OB; n = 32). Systolic (SBP) and diastolic (DBP) blood pressure and electrocardiograms were recorded and analyzed for heart rate and the heart rate variability (HRV) in time (SDRR, RMSSD, PRR50, SD1 and SD2) and frequency domains (HF, LF and LF/HF). The OB group presented higher SBP (p ≤ 0.01) and DBP (p ≤ 0.01). For HRV, the OB group had a lower PRR50 (p ≤ 0.01) and HF (p ≤ 0.01), associated with higher LF (p ≤ 0.01). Moderate negative correlations were found between the HF, BMI (r = -0.37; p ≤ 0.01) and WC (r = -0.38; p ≤ 0.01). Positive moderate correlation were found between LF, LF/HF and BMI (LF: r = 0.32; p ≤ 0.01; LF/HF: r = 0.31; p ≤ 0.01) and WC (LF: r = 0.34; p ≤ 0.01; LF/HF: = 0.34; p ≤ 0.01). Multiple linear regression showed a positive association between body fat and the SDRR (ß: 0.48; CI: 0.2-4.2; p = 0.02). No differences were observed in cardiac electrical activity. CONCLUSION: Children with obesity but not overweight presented higher blood pressure and cardiac autonomic dysfunction, with sympathetic predominance on the heart rate. This fact was positively correlated with BMI and may be considered an important marker for cardiovascular risk in children.

Effects of Strength Training on Sleep Parameters of Adolescents: A Randomized Controlled Trial.

ABSTRACT: Santiago, LCS, Lyra, MJ, Germano-Soares, AH, Lins-Filho, OL, Queiroz, DR, Prazeres, TMP, Mello, MT, Pedrosa, RP, Falcão, APST, and Santos, MAM. Effects of strength training on sleep parameters of adolescents: a randomized controlled trial. J Strength Cond Res 36(5): 1222-1227, 2022-This study aimed to examine the effects of 12 weeks of strength training (ST) on sleep quality and daytime sleepiness in adolescents with sleep complaints. Thirty adolescents were randomly assigned to 2 groups: ST group (ST, n = 18) and control group (CG, n = 12). Anthropometric, body composition, one-repetition maximum test, and sleep parameters (Pittsburgh Sleep Quality Index [PSQI] and Epworth Sleepiness Scale [ESS]) were evaluated. Training consisted of 55 min·d-1 (3 times a week, for 12 weeks), 3 sets of 10-12 repetitions with a 1-minute rest interval between sets and exercises. Baseline and postintervention differences were analyzed using Generalized Estimating Equations and the effect size (ES) with Cohen's d coefficient. Significance was set at (p < 0.05). After 12 weeks of ST, a significant decrease in the PSQI score (7.3 ± 0.7 vs. 5.1 ± 0.6; ES = 4.10) was observed in the ST group, but not in the CG (6.3 ± 0.8 vs. 7.4 ± 0.7; ES = 1.53). A significant decrease in ESS score was found in the ST group (10.1 ± 0.7 vs. 8.2 ± 0.7; ES = 3.08), without differences in the CG (10.7 ± 0.8 vs. 11.0 ± 0.7; ES = 0.56). The ST group presented increased total sleep duration (h·min-1) (6.2 ± 0.2 vs. 6.9 ± 0.2; ES = 3.60), but not the CG (7.0 ± 0.2 vs. 6.8 ± 0.1; ES = 1.32). Individual analyses showed ≈67% of adolescents experienced a reduction in PSQI (8.3; confidence interval [CI] 95% 6.8-10.1) and ESS (8.3; CI 95% 6.7-9.9) scores after ST, whereas only ≈17% of control subjects presented reduced scores (PSQI [11.1; CI 95% 9.5-12.9] and ESS [11.0; CI 95% 9.4-12.6]). Strength training improved sleep quality and increased total sleep duration.

The influence of anthropometric variables, body composition, propulsive force and maturation on 50m freestyle swimming performance in junior swimmers: An allometric approach.

The purpose of the current article was to use allometric models to identify the best body size descriptors and other anthropometric variables, body composition, and offset maturity that might be associated with the youngsters' 50m personal-best (PB) swim speeds (m·s-1). Eighty-five competitive swimmers (male, n=50; 13.5±1.8 y; female, n=35; 12.6±1.8 y) participated in this study. Height, body mass, sitting height, arm span, skinfolds, arm muscle area (AMA), and maturity offset were assessed. Swimming performance was taken as the PB time recorded in competition, and the propulsive force of their arm (PFA) was assessed by the tied swimming test. The multiplicative allometric model relating 50m PB swim speeds (m·s-1) to all the predictor variables found percentage body fat as a negative [(BF%) ß= -.121±.036; P=0.001], and PFA (PFA ß=.108±.033; P=0.001) and the girl's arm span (ß=.850±.301; P=0.006), all log-transformed, as positive significant predictors of log-transformed swim speed. The adjusted coefficient of determination, Radj2 was 54.8% with the log-transformed error ratio being 0.094 or 9.8%, having taken antilogs. The study revealed, using an allometric approach, that body fatness and PFA were significant contributors to 50m freestyle swim performance in young swimmers.

Are there gross motor coordination spurts during mid-childhood?

OBJECTIVES: The aims of this study were (1) to identify the timing of the mid-growth spurt (MGS) in stature in children and (2) to identify gross motor coordination (GMC) spurts when aligned by the age of attainment of the MGS (aMGS). METHODS: Stature, weight, and GMC were measured in 245 Portuguese children followed annually from 6 to 10 years. GMC was assessed and to estimate children's MGS in stature as well as GMC spurts in each of the four tests aligned by aMGS, we used a nonsmoothed polynomial methodology. RESULTS: In boys, the aMGS was attained at 7.8 years, whereas in girls it was 8.0 years. In boys, the peak MGS was 6.2 cm∙yr-1 and in girls it was 6.4 cm∙yr-1 . In boys, the peak for walking backwards (WB) occurred 18 months before aMGS (14.9-points∙yr-1 ), jumping sideways (JS) was 12 months after aMGS (13.5-points∙yr-1 ), hopping on one leg (HO) was 18 months before aMGS (11.7-points∙yr-1 ), and shifting platform (SP) was 12 months before aMGS (6.8-points∙yr-1 ). In girls, WB spurts occurred 12 months after aMGS (13.3-points∙yr-1 ), JS was 12 months before aMGS (10.5-points∙yr-1 ), HO was coincident with aMGS (10.4-points∙yr-1 ), and SP was 18 as well as 12 months before aMGS (7.2-points∙yr-1 ). No differences were observed in the mean peak spurts between sexes in the GMC tests. CONCLUSIONS: Boys and girls reached their MGS in stature at about the same chronological age. Spurts in GMC did not express themselves in the same biological timing relative to aMGS in stature, and there are sex differences.