Little is known about the relationship among training, energy expenditure, muscle volume, and fitness in prepubertal girls. Because physical activity is high in prepubertal children, we hypothesized that there would be no effect of training. Forty pre- and early pubertal (mean age 9.1 +/- 0.1 yr) nonobese girls enrolled in a 5 day/wk summer school program for 5 wk and were randomized to control (n = 20) or training groups (n = 20; 1.5 h/day, endurance-type exercise). Total energy expenditure (TEE) was measured using doubly labeled water, thigh muscle volume using magnetic resonance imaging, and peak O(2) uptake (VO(2 peak)) using cycle ergometry. TEE was significantly greater (17%, P < 0.02) in the training girls. Training increased thigh muscle volume (+4.3 +/- 0.9%, P < 0.005) and VO(2 peak) (+9.5 +/- 6%, P < 0.05), effects surprisingly similar to those observed in adolescent girls using the same protocol (Eliakim A, Barstow TJ, Brasel JA, Ajie H, Lee W-NP, Renslo R, Berman N, and Cooper DM, J Pediatr 129: 537-543, 1996). We further compared these two sample populations: thigh muscle volume per weight was much lower in adolescent compared with prepubertal girls (17.0 +/- 0.3 vs. 27.8 +/- 0.6 ml/kg body mass; P < 0.001), and allometric analysis revealed remarkably low scaling factors relating muscle volume (0.34 +/- 0.05, P < 0.0001), TEE (0.24 +/- 0. 06, P < 0.0004), and VO(2 peak) (0.28 +/- 0.07, P < 0.0001) to body mass in all subjects. Muscle and cardiorespiratory functions were quite responsive to brief training in prepubertal girls. Moreover, a retrospective, cross-sectional analysis suggests that increases in muscle mass and VO(2 peak) may be depressed in nonobese American girls as they mature.
Objective:To determine the effects of Vicoprofen® and ibuprofen on aerobic performance, agility, and pain after exercise-induced muscle damage.Design:Double-blind randomized, placebo-controlled, repeated-dose clinical trial.Setting:Human-performance and sports-medicine laboratory.Participants:36 healthy men.Methods and Measures:Baseline testing was performed, 72 hours after which subjects performed eccentric exercise to induce muscle damage. They were evaluated for pain 24 hours postdamage and placed randomly into 3 groups: Vicoprofen (VIC), ibuprofen, or placebo (P). Postdamage testing was performed every day for 5 days. Subjects performed an economy run and a t-agility test to determine exercise performance.Results:The drugs had no significant effect on performance throughout the 5-day evaluation period. Pain was lower at days 4 and 5 in the VIC group than in P.Conclusions:It appears that Vicoprofen reduced pain after muscle damage, but the drug interventions did not enhance performance in aerobic and agility tasks.
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