Effects of Cessation of a Structured and Supervised Exercise Conditioning Program on Lean Mass and Muscle Strength in Severely Burned Children

Suman OE, Herndon DN. Effects of cessation of a structured and supervised exercise conditioning program on lean mass and muscle strength in severely burned children. Objective: To determine whether the benefits of exercise by burned children are maintained 3 months after the exercise program is concluded. Design: Randomized, controlled prospective study. Setting: Pediatric burn hospital. Participants: Twenty severely burned children with a 40% or greater total body surface area burn, with main outcome measures completed before exercise training, immediately after 12 weeks of exercise training (intervention), and 12 weeks after training ended. Intervention: Randomization into a 12-week standard rehabilitation program at home (n=9) or a 12-week standard hospital rehabilitation program supplemented with an exercise-training program beginning 6 months after burn injury (n=11). Main Outcome Measures: Assessment of lean body mass (LBM) using dual-energy x-ray absorptiometry and of leg isokinetic muscle strength at a speed of 150°/s were done before, after the 12-week rehabilitation and exercise training program, and 3 months after the exercise program was completed (12mo postburn). The effects of exercise on the dependent variables were analyzed by repeated-measures analysis of variance. If we found a significant overall effect of time and/or intervention, we did a post hoc test for multiple comparison (Holm-Sidak). Results are expressed as mean ± standard error. Results: The mean percentage increase in LBM and muscle strength was significantly greater in the exercise group (6.4%±1.9%, 40.7%±8.6%, respectively) than in the no-exercise group (1.9%±2.6% vs 3.4%±4.5%, respectively). Three months after cessation of the exercise program, LBM remained relatively unchanged in the no-exercise group (3.5%±1.8%). In contrast, LBM in the exercise group increased significantly (10.7%±4.8%, P=.03). In addition, muscle strength further increased by 17.9%±10.1% in the exercise group versus 7.2%±3.4% in the no-exercise group, although neither percentage increase was significant (P=.08 for exercise vs P=.61 for no exercise). Absolute values in LBM and muscle strength for both groups at 12 months postburn continued to be below historical or concurrent age-matched, nonburned children. Conclusions: Participation in an exercise program resulted in a greater improvement in LBM and muscle strength in the exercise group than in the no-exercise group. Three months after the exercise training ended, there were persistent mild-to-moderate increases in LBM and muscle strength. Absolute levels continued to be below previously reported nonburned, age-matched values, however, which underscores the need for continued exercise to improve LBM and muscle strength in severely burned children.