Post-stroke hemiparesis often leads to a vicious cycle of limited activity, deconditioning, and poor cardiovascular health. Accumulating evidence suggests that exercise intensity is a critical factor determining gains in aerobic capacity, cardiovascular protection and functional recovery after stroke. High-intensity interval training (HIT) is a strategy that augments exercise intensity using bursts of concentrated effort alternated with recovery periods. However, there was previously no stroke-specific evidence to guide HIT protocol selection.
Purpose: To compare within-session exercise responses between three different HIT protocols for persons with chronic (> 6 months post) stroke.
Methods: Nineteen ambulatory persons with chronic stroke performed three different one-day HIT sessions in randomized order, approximately one week apart. HIT involved repeated 30 second bursts of treadmill walking at maximum tolerated speed, alternated with rest periods. The 3 HIT protocols were different based on length of the rest periods: 30 seconds (P30), 60 seconds (P60) or 120 seconds (P120). Exercise tolerance, oxygen uptake (VO2), heart rate (HR), peak treadmill speed and step count were measured.
Results: P30 achieved the highest mean VO2, HR and step count, but with reduced exercise tolerance and lower treadmill speed than P60 or P120 (P30: 70.9% VO2peak, 76.1% HR reserve, 1619 steps, 1.03 m/s; P60: 63.3% VO2peak, 63.1% HR reserve, 1370 steps, 1.13 m/s; P120: 47.5% VO2peak, 46.3% HR reserve, 1091 steps, 1.10m/s). P60 achieved similar treadmill speed and exercise tolerance to P120 with higher mean VO2, HR and step count.
Conclusion: For treadmill HIT in chronic stroke, a combination of P30 and P60 may optimize aerobic intensity, treadmill speed and stepping repetition, potentially leading to greater improvements in aerobic capacity and gait outcomes in future studies.
(C) 2014 American College of Sports Medicine