Sprint interval training versus moderate-intensity continuous training during inpatient rehabilitation after spinal cord injury: a randomized trial.

STUDY DESIGN: Randomized trial. OBJECTIVES: To evaluate the effectiveness of a 5-week sprint interval training (SIT) protocol on an arm-crank ergometer in individuals with sub-acute spinal cord injury (SCI). SETTING: Inpatient rehabilitation. METHODS: Individuals with SCI (N = 20; 9 tetraplegia/11 paraplegia; time since injury, 14-182 days; age, 46 ± 16 years; 15 M/5 F) were randomized to SIT or moderate-intensity continuous training (MICT). SIT consisted of 3 × 20 s. 'all-out' cycle sprints (≥100% peak power output) interspersed with 2 min of active recovery (10% peak power output; total time commitment, 10 mins). MICT involved 20 min of cycling (45% peak power output; total time commitment, 25 mins). Both training interventions were delivered 3 times/week for 5 weeks. Heart rate and Borg's Rating of Perceived Exertion (RPE; 6-20) were monitored throughout training sessions. Maximal and sub-maximal power outputs were assessed on an arm-crank ergometer. Exercise enjoyment, exercise self-efficacy, and pain were assessed at the end of the intervention. RESULTS: During training sessions, heart rate (135 bpm vs. 119 bpm; p = 0.05), peripheral RPE (16 vs. 12; p = 0.000), and central RPE (15 vs. 11; p = 0.004) responses were higher in the SIT group, yet total work performed was greater in MICT. Peak power output increased significantly with training (36%), with no difference between groups (39% vs. 33%; p = 0.524). Similarly, improvements in sub-maximal power output were not different across groups. There were no between-group differences in exercise enjoyment (p = 0.385), exercise self-efficacy (p = 0.930), or pain (p = 0780). CONCLUSIONS: Five weeks of SIT improved physical capacity to the same extent as MICT in individuals with sub-acute SCI, despite a significantly lower time commitment with SIT.