Early rehabilitative exercise training in the recovery from pediatric burn

Abstract

Purpose: The purpose of this study was to determine the effects of early outpatient exercise on muscle mass, function, and fractional synthetic rate in severely burned children.

Methods: Forty-seven children with ≥40% total body surface area burn performed a 12-wk standard of care rehabilitation (SOC, n = 23) or rehabilitative exercise training (RET, n = 24) immediately after hospital discharge. Dual-energy x-ray absorptiometry was used to assess lean body mass (LBM) at discharge, posttreatment, and 12 months post-burn. Muscle function was evaluated with a Biodex Isokinetic Dynamometer, and peak aerobic fitness (V˙O2peak) was measured using a modified Bruce treadmill protocol posttreatment. Stable isotope infusion studies were performed in a subset of patients (SOC, n = 13; RET, n = 11) at discharge and posttreatment to determine mixed-muscle fractional synthetic rate.

Results: Relative peak torque (RET, 138 ± 9 N·m·kg, vs SOC, 106 ± 9 N·m·kg) and V˙O2peak (RET, 32 ± 1 mL·kg·min, vs SOC, 28 ± 1 mL·kg·min) were greater at posttreatment with RET compared with those with SOC. In addition, RET increased whole-body (9% ± 2%) and leg (17% ± 3%) LBM compared with SOC. Furthermore, the percentage change in whole-body (18% ± 3%) and leg (31% ± 4%) LBM from discharge to 12 months post-burn was greater with RET compared to SOC. Muscle fractional synthetic rate decreased from discharge to posttreatment in both groups (6.9% ± 1.1% per day vs 3.4 ± 0.4% per day); however, no differences were observed between treatment groups at each time point.

Conclusions: Early outpatient exercise training implemented at hospital discharge represents an effective intervention to improve muscle mass and function after severe burn injury.

Trial registration: ClinicalTrials.gov NCT00675714.

Figure 1. Effect of rehabilitative exercise training (RET) on muscle function in severely burned children

(A) Absolute peak torque (N·m) was assessed post-treatment using the Biodex isokinetic dynamometer at 150 ° · sec⁻¹. (B) Relative peak torque (N · m · kg⁻¹) was assessed post-treatment using the Biodex isokinetic dynamometer at 150 ° · sec⁻¹. (C) Peak aerobic fitness (VO₂peak) (ml · kg⁻¹ · min⁻¹) was assessed post-treatment using a modified Bruce treadmill protocol. SOC: N=23, RET: N=24. Values are means ± standard error. Abbreviations: N · m, newton-meter. kg, kilogram. SOC, standard of care. RET, rehabilitative exercise training.

Figure 2. Effect of rehabilitative exercise training (RET) on changes in whole-body and regional lean body mass (LBM) in severely burned children

(A) Percentage change in LBM was assessed by dual-energy X-ray absorptiometry (DEXA) at discharge to post-treatment. SOC: N=23, RET: N=24. (B) Percentage change in LBM was assessed by DEXA at discharge to 12 months post-burn. SOC: N=18, RET: N=21. Values are means ± standard error. Abbreviations: SOC, standard of care. RET, rehabilitative exercise training.

Figure 3. Effect of rehabilitative exercise training (RET) on muscle fractional synthetic rate in severely burned children

Muscle fractional synthetic rate is presented as the percent per day (% · d⁻¹). SOC: N=13; RET: N=11. Values are means ± standard error. Significant main effect of time (P = 0.004). Abbreviations: SOC, standard of care. RET, rehabilitative exercise training. ME, Main effect.