Cardiorespiratory Capacity and Strength Remain Attenuated in Children with Severe Burn Injuries at Over 3 Years Postburn

Abstract

Objectives: To compare physical capacity and body composition between children with burn injuries at approximately 4 years postburn and healthy, fit children.

Study design: In this retrospective, case-control study, we analyzed the strength, aerobic capacity, and body composition of children with severe burn injuries (n = 40) at discharge, after completion of a 6- to 12-week rehabilitative exercise training program, and at 3-4 years postburn. Values were expressed as a relative percentage of those in age- and sex-matched children for comparison (n = 40 for discharge and postexercise; n = 40 for 3.5 years postburn).

Results: At discharge, lean body mass was 89% of that in children without burn injuries, and exercise rehabilitation restored this to 94% (P < .01). At 3.5 years postburn, lean body mass (94%), bone mineral content (89%), and bone mineral density (93%; each P ≤ .02) remained reduced, whereas total body fat was increased (148%, P = .01). Cardiorespiratory fitness remained lower in children with burn injuries both after exercise training (75%; P < .0001) and 3.5 years later (87%; P < .001). Peak torque (60%; P < .0001) and average power output (58%; P < .0001) were lower after discharge. Although exercise training improved these, they failed to reach levels achieved in healthy children without burns (83-84%; P < .0001) but were maintained at 85% and 82%, respectively, 3.5 years later (P < .0001).

Conclusions: Although the benefits of rehabilitative exercise training on strength and cardiorespiratory capacity are maintained at almost 4 years postburn, they are not restored fully to the levels of healthy children. Although the underlying mechanism of this phenomenon remains elusive, these findings suggest that future development of continuous exercise rehabilitation interventions after discharge may further narrow the gap in relation to healthy adolescents.

Keywords: body composition; exercise program; muscle strength; peak aerobic capacity; rehabilitation; standard of care.

Figure 1

Patient flow diagram. IRB: Institution review board; TBSA: total body surface area.

Figure 2

Cardiorespiratory fitness, as reflected by A, peak VO₂, and strength, as reflected by B, peak torque and C, average power. All are provided as non-normalized and LBM-normalized values. A/S matched, age- and sex-matched non-burned controls; DC, discharge; EX, exercise (^† p ≤ 0.01 vs. age- and sex-matched group, *p ≤ 0.001 vs. DC, ^‡ p ≤ 0.05 vs. post-EX training).