The Effects of Exercise Serum From Prepubertal Girls and Women on In Vitro Myoblast and Osteoblast Proliferation and Differentiation

Purpose: In girls and women, the authors studied the effects of an acute bout of low-impact, moderate-intensity exercise serum on myoblast and osteoblast proliferation in vitro. Methods: A total of 12 pre/early pubertal girls (8–10 y old) and 12 women (20–30 y old) cycled at 60% VO2max for 1 hour followed by 1-hour recovery. Blood samples were collected at rest, mid-exercise, end of exercise, mid-recovery, and end of recovery. C2C12 myoblasts and MC3T3E1 osteoblasts were incubated with serum from each time point for 1 hour, then monitored for 24 hours (myoblasts) or 36 hours (osteoblasts) to examine proliferation. Cells were also monitored for 6 days (myoblasts) to examine myotube formation and 21 days (osteoblasts) to examine mineralization. Results: Exercise did not affect myoblast or osteoblast proliferation. Girls exhibited lower cell proliferation relative to women at end of exercise (osteoblasts, P = .041; myoblasts, P = .029) and mid-recovery (osteoblasts, P = .010). Mineralization was lower at end of recovery relative to rest (P = .014) in both girls and women. Myotube formation was not affected by exercise or group. Conclusion: The systemic environment following one acute bout of low-impact moderate-intensity exercise in girls and women does not elicit osteoblast or myoblast activity in vitro. Differences in myoblast and osteoblast proliferation between girls and women may be influenced by maturation.

Carbohydrate Drink Use During 30 Minutes of Variable-Intensity Exercise Has No Effect on Exercise Performance in Premenarchal Girls

Purpose: This study examined the physiological, perceptual, and performance effects of a 6% carbohydrate (CHO) drink during variable-intensity exercise (VIE) and a postexercise test in premenarchal girls. Methods: A total of 10 girls (10.4 [0.7] y) participated in the study. VO2peak was assessed, and the girls were familiarized with VIE and performance during the first visit. The trial order (CHO and placebo) was randomly assigned for subsequent visits. The drinks were given before VIE bouts and 1-minute performance (9 mL/kg total). Two 15-minute bouts of VIE were completed (10 repeated sequences of 20%, 55%, and 95% power at VO2peak and maximal sprints) before a 1-minute performance sprint. Results: The mean power, peak power, heart rate (HR), %HRpeak, and rating of perceived exertion during VIE did not differ between trials. However, the peak power decreased, and the rating of perceived exertion increased from the first to the second bout. During the 1-minute performance, there were no differences between the trial (CHO vs placebo) for HR (190 [9] vs 189 [9] bpm), %HRpeak (97.0% [3.2%] vs 96.6% [3.0%]), rating of perceived exertion (7.8 [2.3] vs 8.1 [1.9]), peak power (238 [70] vs 235 [60] W), fatigue index (54.7% [10.0%] vs 55.9% [12.8%]), or total work (9.4 [2.6] vs 9.4 [2.1] kJ). Conclusion: CHO supplementation did not alter physiological, perceptual, or performance responses during 30 minutes of VIE or postexercise sprint performance in premenarchal girls.

Low Muscular Strength, Weight Status, and Metabolic Syndrome in Adolescents: National Health and Nutrition Examination Survey 2011–2014

Purpose: To investigate the association between muscular strength and metabolic syndrome (MetS), with a specific focus on the role of weight status, using a nationally representative sample of US youth. Methods: The analysis included 409 boys and 415 girls from the 2011 to 2014 National Health and Nutrition Examination Survey between 12 and 18 years of age. The prevalence of MetS was defined using age- and sex-specific criteria for abdominal obesity, elevated triglycerides, blood pressure, fasting glucose, and low high-density lipoprotein (HDL) cholesterol. Strength was assessed via handgrip dynamometer and expressed as age- and sex-specific z scores of relative strength. Low strength was defined as a relative strength below the 25th percentile. Analyses controlled for age, sex, race/ethnicity, physical activity, and weight status. Results: The sample prevalence of MetS was approximately 5.3%. However, MetS prevalence was 18.5% in overweight/obese youth with low strength. The adjusted odds of MetS were 3.1 (95% confidence interval, 1.5–6.3, P < .001) times higher for overweight/obese youth with low strength versus sufficient strength. Conclusion: Muscular strength is predictive of adolescent MetS, specifically in those with unhealthy weight status. Approximately one in 5 overweight/obese youth with low strength had MetS. These findings highlight the relevance of muscular strength in youth cardiometabolic morbidities.

Reciprocal Longitudinal Relationship Between Fitness, Fatness, and Metabolic Syndrome in Brazilian Children and Adolescents: A 3-Year Longitudinal Study

Purpose: To verify the reciprocal longitudinal relationships between cardiorespiratory fitness (CRF), percentage body fat (%body fat), and metabolic syndrome in Brazilian primary school students. Method: This longitudinal study involved 420 children and adolescents followed for 3 years (2011–2014). The continuous Metabolic Syndrome (cMetSyn) score was calculated by summing adjusted z scores of glucose, systolic blood pressure, total cholesterol/high-density lipoprotein cholesterol ratio, triglycerides, and waist circumference. The CRF was assessed using running/walking tests, and %body fat was assessed through sex-specific 2-site skinfold thickness. Cross-lagged panel models were used to analyze longitudinal reciprocal relationships between CRF and %body fat with cMetSyn. Results: Results indicated that 2011 %body fat significantly predicted both 2014 CRF scores and 2014 cMetSyn scores (P < .001); however, 2011 CRF only predicted 2014 %body fat (P < .001) but not 2014 cMetSyn (P = .103). Furthermore, 2011 cMetSyn predicted 2014 %body fat (P = .002). The model explained 36%, 48%, and 37% of the variance in 2014 CRF, %body fat, and cMetSyn, respectively. Conclusion: The results suggest a reciprocal inverse relationship between %body fat and metabolic syndrome risk and that %body fat may play a more important role in the risk of developing metabolic syndrome compared with CRF.

Impact of COVID-19 on School-Aged Male and Female Health-Related Fitness Markers

Purpose: The purpose of this study was to examine the impact of the Coronavirus disease 2019 on male and female anthropometric variables and physical performance. Methods: This study utilized a mixed (time [PRE vs POST], gender [male vs female]) methods design to examine changes in the body mass index and physical fitness performance measures prior to and following closures. Data were collected from 264 third through eighth graders. This sample consisted of 131 males and 133 females. The data was collected through anthropometric (body mass index) and physical performance measures and was analyzed with separate 2 × 2 mixed-factorial analyses of variance (time [PRE, POST] × gender [male, female]). Results: The findings indicated both males and females exhibited mean increases in the body mass index (+10.6%; 18.8–20.8 kg·m−2, P < .001, partial η2 = .627) and decreases in push-ups (−35.6%; 7.3–4.7 repetitions, P < .001, partial η2 = .371), sit-ups (−19.4%; 22.7–18.3 repetitions, P < .001, partial η2 = .420), and the Progressive Aerobic Cardiovascular Endurance Run test (−26.7%; 31.4–22.4 laps, P < .001, partial η2 = .644) scores from PRE to POST. Conclusion: The results of this study demonstrate that both males and females exhibited significant anthropometric and physical performance losses during the Coronavirus disease 2019 shutdown.

The Effect of Growth Hormone Treatment on Physical Performance Indices in Children With Idiopathic Short Stature

Purpose: To examine the effect of growth hormone (GH) treatment on physical performance in children with idiopathic short stature and normal GH secretion. Materials and Methods: A total of 24 children participated in the study (13 GH-treated, 11 non-treated, aged 8–13 y, 11 males and 13 females, Tanner stage 1–2). Participants performed a battery of motor skill performance tests (Eurofit), as well as the Wingate anaerobic test. Results: No statistically significant differences in any of the Eurofit physical fitness test results (eg, 20-m shuttle run 33.0 [15.1] vs 25.1 [21.0] laps in treated and nontreated participants, respectively, P = .25) or the Wingate anaerobic test were found between the groups (eg, peak power 5.0 [2.9] vs 3.9 [2.6] watts/kg in treated and nontreated participants, respectively, P = .2). Conclusions: Therapeutic usage of exogenous GH for pre and early pubertal children with idiopathic short stature and normal GH secretion was not associated with beneficial effects on physical performance indices. This suggests that the use of GH as a potential performance enhancing agent, in this age group, at least at commonly used doses, is not advantageous.

Effects of High-Intensity Interval Training on the Vascular and Autonomic Components of the Baroreflex at Rest in Adolescents

Purpose: In a sample of healthy adolescents, the authors aimed to investigate the effects of high-intensity interval exercise (HIIE) training and detraining on baroreflex sensitivity (BRS) and it’s vascular and autonomic components at rest. Methods: Nineteen volunteers were randomly allocated to (1) 4 weeks HIIE training performed 3 times per week or (2) a control condition with no intervention for the same duration as HIIE training. PRE, POST, and following 2 weeks of detraining resting supine heart rate and blood pressure were measured, and a cross-spectral method (integrated gain [gain in low frequency]) was used to determine BRS gain. Arterial compliance (AC) was assessed as the BRS vascular component. LFgain divided by AC (LFgain/AC) was used as the autonomic determinant of BRS. Results: The HIIE training was completed with 100% compliance. HIIE did not change resting gain in low frequency (LFgain) (P = .66; effect size = 0.21), AC (P = .44; effect size = 0.36), or LFgain/AC (P = .68; effect size = 0.19) compared to control. Conclusion: Four weeks of HIIE training does not change BRS and its autonomic and vascular determinant in a sample of healthy adolescents at rest.

Improved Motor Proficiency and Quality of Life in Youth With Prader–Willi Syndrome and Obesity 6 Months After Completing a Parent-Led, Game-Based Intervention

Purpose: To determine changes and potential differences in physical activity (PA), gross motor proficiency (MP), and health parameters after a 6-month follow-up (FU) period following participation in a parent-led PA intervention in youth with or without Prader–Willi syndrome (PWS). Methods: About 42 youth with PWS and 65 youth without PWS but with obesity (body fat percentage >95th percentile for age and sex), aged 8–16 years, participated. The intervention included preplanned PA sessions containing playground and console-based video games scheduled 4 days per week for 24 weeks. Families received training and curriculum materials. PA (accelerometry), MP (Bruininks–Oseretsky Test of MP), and health-related quality of life were obtained before (PRE), after completing the intervention (POST), and at FU. Results: There were no significant changes in PA at any time point. At FU and POST, participants showed higher bilateral coordination (PRE = 9.3 [0.4], POST = 11.7 [0.5], and FU = 11.1 [0.6]); speed and agility (PRE = 9.2 [0.4], POST = 10.8 [0.4], and FU = 11.5 [0.5]); and strength (PRE = 8.0 [0.3], POST = 9.2 [0.3], and FU = 9.2 [0.3]) than at PRE. At FU (80.3 [2.1]) and POST (79.8 [1.7]), youth without PWS showed higher health-related quality of life than PRE (75.0 [1.8]). Conclusion: The improvements in MP and health-related quality of life at FU suggest long-term durability of intervention outcomes.

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

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.

Cardiovascular Effects of Aerobic Exercise With Self-Selected or Predetermined Intensity in Adolescents With Obesity

This study compared the effects of self-selected exercise intensity (SEI) versus predetermined exercise intensity (PEI) on blood pressure (BP) and arterial stiffness in adolescents with obesity. A total of 37 adolescents, 14.7 (1.6) years old, body mass index ≥95th percentile were randomly allocated into SEI (n = 18; 12 boys) or PEI (n = 19; 13 boys). Both groups exercised for 35 minutes on a treadmill, 3 times per week, for 12 weeks. The SEI could set the speed at the beginning of the sessions and make changes every 5 minutes. The PEI adolescents were trained at an intensity set at 60% to 70% of heart rate reserve. Brachial and central BP, pulse pressure, augmentation index, and carotid–femoral pulse wave were determined at baseline and after 12 weeks. Both groups reduced brachial systolic BP (SEI, Δ = −9 mm Hg; PEI, Δ = −4 mm Hg; P < .01), central systolic BP (SEI, Δ = −4 mm Hg; PEI, Δ = −4 mm Hg; P = .01), and central pulse pressure (SEI, Δ = −4 mm Hg; PEI, Δ = −3 mm Hg; P = .02) without differences between groups. No changes in the augmentation index and carotid–femoral pulse wave were observed in either group. The SEI induced similar changes in various cardiovascular outcomes compared with PEI in adolescents with obesity.