Whether burn injury affects boys and men differently is currently unknown. To test the hypothesis that burned boys have lower exercise capacity and exercise training-induced responses compared with burned men, 40 young boys (12 ± 4 years, 149 ± 20 cm, 46 ± 18 kg) were matched to 35 adult men (33 ± 9 years, 174 ± 10 cm, 84 ± 16 kg) based on extent of burn injury (total body surface area burned, boys 46 ± 14% vs men 47 ± 30, P = .85) and length of hospital stay (boys 33 ± 23 vs men 41 ± 32 days, P = .23). Strength (peak torque) and cardiorespiratory fitness (peak VO2) were normalized to kg of lean body mass for group comparisons. Each group was also compared with normative age-sex matched values at discharge and after an aerobic and resistance exercise training (RET) program. A two-way factorial analysis of covariance assessed interaction and main effects of group and time. We found that boys and men showed similar pre-RET to post-RET increases in total lean (~4%) and fat (7%) mass (each P ≤ .008). Both groups had lower age-sex matched norm values at discharge for peak torque (boys 36%; men 51% of normative values) and peak VO2 (boys: 44; men: 59%; each P ≤ .0001). Boys strength were 13-15 per cent lower than men at discharge and after RET (main effect for group, P < .0001). Cardiorespiratory fitness improved to a greater extent in men (19%) compared with boys (10%) after the RET (group × time interaction, P = .011). These results show that at discharge and after RET, burn injury may have age-dependent effects and should be considered when evaluating efficacy and progress of the exercise program.

The burn injury does not have sex-dependent effects on LBM or exercise capacity in severely burn injured children. Differences in relative peak VO and peak HR suggest the need for burn specific exercise programs for improving the efficacy of a rehabilitation program.

BackgroundChildren with severe burn injury sometimes undergo exercise training as part of their rehabilitation. Others have reported that females have a 50% increased risk of death from burn injury compared to males. However, whether exercise capacity and exercise induced training adaptations differ between boys and girls is unknown.PurposeThis project tested the hypothesis that girls with burn injury would have lower strength and aerobic exercise capacity compared to burned boys, and that exercise training rehabilitation (RET) adaptations would likewise differ between groups.MethodsSeverely burned girls (n=25) and boys (n=26) were matched for age, body morphology (means±SD; 13±3 yrs, 150±15 cm, 53±14 kg; each P≥0.71) and for burn injury (54±20% total body surface area burn, P=0.82). Strength (peak torque) and cardiorespiratory fitness (peak VO2) were normalized to lean body mass (LBM) and analyzed as a relative percentage of age‐sex matched non‐burned children (girls 13 yrs, n=25, boys 13 yrs, n=26). Submaximal oxygen uptake (VO2) and heart rate (HR) were expressed as a percentage of peak values and compared to their sex‐ matched non‐burned counterpart during the first 4 stages of the modified Bruce protocol. At discharge (DC) and after an aerobic and resistance rehabilitation exercise training (RET) program, 2‐way factorial ANOVA assessed interaction and main effects of group × time for peak exercise and group × stage for submaximal exercise, with significance set at P<0.05.ResultsGirls had longer length of hospital stay (41±23 vs. 29±13 days, P=0.02). At DC and post‐RET, LBM was lower in burned and increased similarly after RET (DC 87.3% of non‐burned values, post‐RET 92.8%; Main effect, Time P=0.017). Peak torque was not different at DC and increased similarly after RET in both groups (DC, 56±17; after RET, 77±20%; Main effect, Time P<0.0001). Likewise, the improvement in peak VO2 was not different from DC to after RET between both groups (DC, 54±12 to RET, 67±13%; Main effect, Time; P<0.0001). Burned children exercise at greater percentage of their peak VO2 and peak HR during submaximal exercise compared to non‐burned children (Interaction, Group × Stage, P<0.0001; see Figure 1).ConclusionThese data indicate that the initial burn injury at DC or after RET does not have sex‐dependent effects on LBM, submaximal or peak exercise capacity. Exercise capacity is improved after exercise training but remains lower than non‐burned children. Differences in relative peak VO2 and peak HR may suggest the need for burn specific exercise programs for improving the efficacy and progress of a rehabilitation exercise program.Support or Funding InformationThis study was supported in part or totally by awards from NIH P50‐GM060338, NIH R01‐GM56687, R01 HD049471, 3R01HD049471‐12S1, SHC 84080, 71008, 84090, NIDILRR 90DP0043‐01‐00This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

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