Acute Effects of Speed-Dependent Interval Training Versus Continuous Training on Post-Stroke Locomotor Function

Abstract

The benefits of interval training (IT) compared to continuous training (CT) have been shown on a variety of functional and health-related outcomes. To date, the feasibility of IT has been demonstrated in individuals following stroke, though investigations of its effectiveness are still lacking. PURPOSE: To compare acute changes in locomotor function following single bouts of continuous (CT) and interval (IT) treadmill training, matched for total work, in ambulatory individuals with chronic stroke. METHODS: Participants completed 20 minute sessions of CT and IT treadmill exercise separated by a minimum of 48 hours. Overground self-selected walking speed (SSWS) was used for CT while IT involved a 1:1 ratio (1 min slow : 1 min fast walking) with the goal of fast walking at 150% of SSWS and slow walking at 50% of SSWS. If subjects could not achieve 150% SSWS then speed was reduced and slow walking speed was adjusted to ensure matched-work between conditions. Overground SSWS was assessed prior to, immediately following as well as 20, 40 and 60min post-training. Subjects also walked at self-selected speed on a split-belt, instrumented treadmill to collect ground-reaction force data at the same time points. RESULTS: Six subjects completed both sessions. Average CT treadmill speed was 0.92 m/s; average IT speeds were 0.57 m/s (slow) and 1.26 m/s (fast). Immediate post-training increases in SSWS were realized following CT (+6%) but not IT (-2%). SSWS following CT remained 6% faster than pre-training SSWS over time. In contrast, IT showed a delayed increase in speed with 7% improvement in SSWS at 20min, 11% at 40min, and 6% at 60min. Improvements in peak paretic propulsive (Pp) force were realized immediately post-training for the CT condition (+10.3 N; +21%) and persisted over time (20min +24%, 40m +23%, 60m +19%). IT improved peak Pp force immediately post-training (+6.9 N; +14%) and remained elevated post-training (20m +18%, 40m +16%, 60m +11%). CONCLUSION: These preliminary results suggest single bouts of IT and CT treadmill walking appear to elicit acute increases in SSWS as well as propulsive forces in individuals following stroke. The potentially greater relative improvements following IT suggest its potential effectiveness over CT if changing walking function is the goal. Funding source NIH COBRE Stroke Study P20-GM109040