Reliability of near-infrared spectroscopy measures of cerebral oxygenation and blood volume during handgrip exercise in nondisabled and traumatic brain-injured subjects.

We compared the test-retest reliability of near-infrared spectroscopy (NIRS) measures of cerebral oxygenation and blood volume during a rhythmic handgrip exercise in 13 nondisabled subjects and 25 subjects with moderate to severe traumatic brain injury (TBI). Subjects with TBI (average Glasgow Coma Scale score = 4.2, average time since injury = 21 mo) had completed an acute brain injury rehabilitation program. After 2 min of rest, each subject performed 60 s of maximal rhythmic handgrip contractions with the right hand in two trials 24 to 48 h apart. We used NIRS to measure cerebral oxygenation and blood volume responses from the left prefrontal lobe. Both groups' cerebral oxygenation and blood volume increased during handgrip contractions. The change in cerebral oxygenation was significantly lower in subjects with TBI compared with nondisabled subjects. Intraclass correlations between the two trials for cerebral oxygenation and blood volume were 0.83 and 0.80, respectively, in nondisabled subjects and 0.70 and 0.64, respectively, in subjects with TBI. The findings indicate that NIRS is a reliable noninvasive technique for evaluating cerebral oxygenation and blood volume changes during motor function. NIRS can be useful in monitoring recovery of cerebral oxygenation during rehabilitation of patients with TBI.

Effects of circuit training on body composition and peak cardiorespiratory responses in patients with moderate to severe traumatic brain injury.

OBJECTIVE: To examine the time course of the changes in body composition and peak cardiorespiratory fitness resulting from routine brain injury rehabilitation program (BIRP) activities and circuit training in patients with moderate to severe traumatic brain injury (TBI). DESIGN: Time-series design spanning 18 weeks. Trials T1 and T2 were completed in weeks 1 and 2, respectively, to establish reliability of the measurements, followed by trial 3 (T3) 4 weeks later to evaluate changes resulting from the BIRP. SETTING: A BIRP in a community rehabilitation hospital. PARTICIPANTS: Fourteen inpatients with moderate to severe acquired TBI (Glasgow Coma Scale score, 4.6+/-1.4; time since injury, 17.2+/-17 mo). INTERVENTIONS: Twelve-week circuit-training program designed to enhance muscular strength and endurance and aerobic fitness. Subjects were tested midway (T4) through the program and at the end (T5) of 12 weeks. The patients completed an average of 32 supervised sessions, each lasting 1 hour. MAIN OUTCOME MEASURES: Changes in body composition and peak cardiorespiratory responses. RESULTS: No significant changes were observed in the body mass or percentage body fat during the study. The peak values of power output, oxygen uptake, and ventilation rate increased significantly as a result of training, with no concomitant increases in peak heart rate or blood lactate (T5>T3, T2, T1; P <.05). No significant changes were evident midway through training. CONCLUSIONS: In a heterogeneous sample of patients with moderate to severe TBI, (1) body composition and peak cardiorespiratory responses remained fairly stable during 6 weeks of BIRP activities, (2) improvements in peak cardiorespiratory fitness required more than 6 weeks of circuit training, and (3) a 12-week course of circuit training without controlling caloric intake was not effective in reducing body weight or percentage body fat.

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.