Effects of exercise training on resting energy expenditure and lean mass during pediatric burn rehabilitation

Abstract

Severe burns cause profound hormonal and metabolic disturbances resulting in hypermetabolism, reflected in extreme elevation of resting energy expenditure (REE) and extensive skeletal muscle catabolism. Aerobic and resistive exercise programs during rehabilitation have shown substantial benefits, although whether such training potentially exacerbates basal metabolism is unknown. Therefore, the effects of exercise training on REE during the rehabilitation of severely burned pediatric patients were examined. Children with 40% total body surface area burns and greater were enrolled at admission to the burn intensive care unit to participate in a 12-week, hospital-based exercise program (EX) or a home-based standard of care program (SOC), commencing 6 months after injury. Twenty-one patients (aged 7-17 years) were enrolled and randomized to SOC (n = 10) or EX (n = 11). Age, sex, and total body surface area burned were similar. Mean change (+/-standard deviation) in REE, normalized to individual lean body mass, was almost negligible between SOC and EX group patients (SOC, 0.03 +/- 17.40% vs EX, 0.01 +/- 26.38%). A significant increase in lean body mass was found for EX patients (SOC, 2.06 +/- 3.17% vs EX, 8.75 +/- 5.65%; P = .004), which persisted when normalized to height (SOC, 0.70 +/- 2.39% vs EX, 6.14 +/- 6.46%; P = .02). Peak torque also improved significantly more in EX patients (SOC, 12.29 +/- 16.49% vs EX, 54.31 +/- 44.25%; P = .02), reflecting improved strength. Exercise training significantly enhanced lean mass and strength, without observed exacerbation of postburn hypermetabolism. Therefore, the use of exercise conditioning as a safe and effective component of pediatric burn rehabilitation is advocated.

Figure 1

Study design flowchart with time-points and testing performed. Following randomization and acute care, patients participated in either a 12-week standard of care program or aerobic and resistance exercise program commencing at 6-months post-injury following baseline testing, with end-point testing completed at 9-months.

Figure 2

Change in Resting Energy Expenditure (REE) expressed as percentage of predicted value during the 6 to 9 month post-burn study period. Standard of care (SOC) and exercise (EX) patient group results shown as individual percentage change. Horizontal line represents group mean. A statistically significant difference between patient groups was not demonstrated.

Figure 3

Change in Lean Body Mass (LBM) Index (LBM normalized to inverse of height-squared) during the 6 to 9 month post-burn study period. Standard of care (SOC) and exercise (EX) patient group results shown as individual percentage change. Horizontal line represents group mean. * Indicates statistically significant difference to SOC patient group observed (p <0.05).

Figure 4

Change in Peak Torque normalized to Lean Body Mass Index (PKT/LBM Index) during the 6 to 9 month post-burn study period. Standard of care (SOC) and exercise (EX) patient group results shown as individual percentage change. Horizontal line represents group mean. * Indicates statistically significant difference to SOC patient group observed (p <0.05).