Aerobic Training with Hyperoxia in Patients with Mild/Severe Brain Injury

Background: Previous studies have shown that aerobic training can induce physiological benefits for brain injured patients. However these benefits seem to be limited. Compared with untrained subjects who follow the same training program, patients with brain injury have a reduced exercise capacity and have difficulty in reaching a high intensity exercise level. A possible alternative to help these patients is to conduct the training in hyperoxia (O2 supply). Studies with untrained subjects have shown that training in hyperoxia enhances the fitness performance. Thus, the purpose of this study was to measure the effects of an aerobic training in hyperoxia with brain-injured patients. Methods: Twelve patients were randomly assigned to either one of two aerobic training protocols: A) 100% O2; B) 20.9% O2 (room air). In both protocols training was on stationary bicycle, 2 sessions per week over 10 weeks. Each session lasted 25 min and was composed of 6 intervals with intensity ranging from 60 to 85% of the max HR. The first interesting result is that all patients were able to reach and sustain the 80-85% level of exercise. To measure the working capacity during the training, we recorded the workload (watts) reached at the third interval (80-85% of the HRmax) of each session. Results: A difference (P < 0.05) in the power output on the ergocycle was observed between the pre test (measured on the first week) and the post test (measured on the 6th week) for subjects trained in hyperoxia but no difference was observed for subjects trained in normoxia. However, no difference was observed in the 6 min walk test for all subjects before and after the aerobic training. There was no difference in oxygen consumption (submaximal test 85% HRmax) between the pre and post tests in both groups of subjects (P=0.18). Nonetheless, subjects trained in hyperoxia showed a 16% average increase in their VO2 (85% HRmax) compared with subjects in normoxia who had a 4% average decrease. Conclusion: Our results show that oxygen supply seems to accelerate the benefits of the aerobic training with brain injured patients. We believe that it is the combination of the training protocol (i.e. intervals) and the oxygen addition that induced the early benefits observed