High-Intensity Interval Training in Individuals with Subacute Motor Incomplete Spinal Cord Injury: An Explorative...

Spinal cord injury (SCI) causes major functional limitations. The subacute phase offers a critical window to optimize recovery. High-intensity interval training (HIIT) may improve cardiorespiratory fitness (CRF) in chronic complete SCI, but evidence in subacute incomplete SCI is limited.

To evaluate the effects of 6 weeks of HIIT on CRF compared with usual care in subacute motor incomplete SCI.

In this explorative randomized controlled trial, participants with subacute incomplete SCI were assigned to HIIT or usual care. HIIT involved 2 to 3 weekly arm-ergometry sessions. Usual care consisted of individualized inpatient rehabilitation fitness, mainly focusing on strength training. Primary outcomes were relative peak oxygen uptake (VO₂peak) and absolute peak power output (PPO), measured by cardiopulmonary exercise testing. Pre-post changes across all participants were analyzed with the Wilcoxon signed-rank test and between-group differences with the Mann-Whitney U test.

Of 19 randomized participants, 7/10 completed HIIT (70%), and all 9 completed usual care (100%). Across groups, relative VO₂peak increased from 18.0 (12.5-23.7) to 20.3 (14.4-24.8) mL/kg/min and absolute PPO increased from 63 (35-75) to 73 (45-85) watts post intervention (both P _S = .003), with no between-group differences. A higher proportion of HIIT participants (57%) achieved clinically meaningful VO₂peak improvements compared with usual care (33%).

Inpatient rehabilitation, through HIIT or usual care, improved CRF in individuals with subacute motor incomplete SCI. Although between-group differences were not found, a greater proportion of HIIT participants achieved clinically meaningful CRF improvements, suggesting that HIIT may improve CRF in this population.