Exertional symptoms and exercise capacity in individuals with brain injury.

Purpose: To examine factors affecting cycling exercise performance in individuals with acquired brain injury.

Methods: Thirty individuals with acquired brain injury and 18 sedentary controls (SC) participated. Heart rate, bicycle power output and rating of perceived exertional (RPE) were recorded, throughout incremental cycle ergometer exercise. The SC group and 18 moderately impaired individuals from the ABI group performed a 25-W (B25) protocol. The remaining 12 individuals performed a 10-W protocol (B10).

Results: The B10 group terminated exercise at the lowest RPE, percentage age predicted maximal heart rate (% APMHR) and bicycle power output, followed by the B25 and then the SC group (RPE: Kruskal - Wallis test P < 0.001, %APMHR and bicycle power output: one-way ANOVA P < 0.01). RPE was correlated with %APMHR and percentage of peak bicycle output (B10 group: R2 0.1 to 0.67; B25 group: 0.69 - 0.83; SC group: 0.76 - 0.91). There was no difference in RPE at the same relative work intensity between the B25 and the sedentary control group (P > 0.05). Forward regression analysis revealed fatigue levels were predictive of %APMHR at test termination (beta = -0.411, P < 0.05) and quadriceps strength was predictive of peak bicycle power output (beta = 0.612, P < 0.05).

Conclusions: Individuals with brain injury terminated exercise at lower exercise intensities but rated exertion no differently from healthy individuals. General fatigue levels predicted %APMHR and quadriceps strength predicted peak bicycle power output.