97 Six Months of Exercise Training and Aerobic Capacity in Well-Healed Burn Survivors: Effect of Body Surface Area Burned

Abstract

Aerobic exercise is an important component towards the full rehabilitation of burn survivors, yet aerobic capacity is reduced in this population. No studies have examined the benefits of long-term aerobic exercise training in well-healed burn survivors, particularly stratified by the severity of the burn injury. This study tested the hypothesis that a community-based 6-month exercise training regimen would improve aerobic capacity in burn survivors, with the magnitude of this improvement being influenced by body surface area (BSA) burned. Eleven unburned control subjects (34±8 y), 12 low BSA burn survivors (38±14 y; 27±7% BSA burned), and 11 high BSA burn survivors (39±12 y; 58±16% BSA burned) participated in a 6-month community-based aerobic exercise training regimen. Burn survivors were assessed a minimum of 2 years after the injury. Both prior to and after this exercise regimen, subjects performed steady-state cycle exercise (50 and 75 Watts) and two graded maximal cycle exercise tests, where maximal oxygen uptake (VO2max) was obtained. For both pre- and post-training periods, the greater of the two VO2max values was selected and analyzed. Exercise training improved VO2max in all groups (Control: 2.94±0.76 to 3.19±0.61 L/min; low burned: 2.24±0.52 to 2.48±0.54 L/min; high burned: 2.47±0.50 to 2.54±0.48 L/min; P<0.001 main effect of pre/post training), without any differences in the magnitude of the improvement between groups (P=0.27 for the interaction). Perhaps equally important was a ~10 beat per min lowering of heart rate post-exercise training in all groups during steady-state exercise of 50 and 75 Watts, demonstrating lower cardiovascular stress post-training at workloads that approximate activities of daily living (e.g., ~2 to 4 METS). These data demonstrate that well-healed burn survivors have the capability to appropriately improve their aerobic capacity through an aggressive long-term exercise training regimen. Counter to our hypothesis, there was no difference between the magnitude of the improvements in VO2max and the percent BSA burned, though the high burn group had an appreciably lower mean elevation in VO2max post-training. As a population, burn survivors have a reduced aerobic capacity relative to unburned peers, with these lower values being related to higher morbidity and all-cause mortality. Thus, without an intervention to improve aerobic capacity, burn survivors will experience the negative sequelae associated with a sedentary lifestyle. The present data demonstrate that burn survivors generally have the capability to improve their aerobic capacity via a long-term aerobic exercise regimen. Funded by: NIH - GM68865