Reliability of peak cardiorespiratory responses in patients with moderate to severe traumatic brain injury

OBJECTIVE: To examine the test-retest reliability of acute physiologic responses in patients with traumatic brain injury (TBI). DESIGN: Repeated measures within 1 week. SETTING: Brain injury rehabilitation program and community rehabilitation hospital. PARTICIPANTS: Thirty-six inpatients or their legal guardians. INTERVENTIONS: Each patient performed a symptom-limited incremental cycle ergometer test to voluntary fatigue on 2 separate occasions within 1 week. MAIN OUTCOME MEASURES: Peak values of power output and cardiorespiratory responses measured with a metabolic cart interfaced with an electrocardiogram. RESULTS: Intraclass correlations between the 2 trials were as follows: power output,.96; absolute oxygen uptake,.98; relative oxygen uptake,.97; heart rate,.82; ventilation rate,.96; and respiratory exchange ratio,.81. Bland-Altman plots showed that all data points were within the 95% confidence limits of the mean value of the 2 trials for each variable. CONCLUSIONS: The reliability of the peak cardiorespiratory responses during non-weight-bearing exercise was high in patients with TBI in a controlled laboratory setting. Therefore, aerobic exercise programs can be accurately prescribed, and changes resulting from such interventions can be confidently evaluated in this population.