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.