Feasibility Of Overground High-intensity Interval Training (hit) In Persons With Chronic Stroke

Abstract

Evidence suggests that treadmill (TM) HIT can be safe and effective as a rehabilitation tool in persons with stroke. However, translation to overground walking can be limited and no studies have tested overground (OG) HIT. PURPOSE: To compare training speeds and HR responses for TM HIT and OG HIT in persons with chronic stroke. METHODS: Ten subjects (mean ± SD) 59.8 ± 6.8 years old and 2.4 ± 1.7 years post stroke with comfortable gait speed of 0.41 ± 0.35 m/s and fast gait speed of 0.56 ± 0.56 m/s participated and passed a symptom-limited GXT. Subjects performed 12 sessions of HIT over 4 weeks, alternating short and long interval HIT sessions. Both HIT protocols included 10 minutes of overground HIT (OG1), then 20 minutes of treadmill HIT, followed by another 10 minutes of overground HIT (OG2). Short interval HIT involved 30s bursts at maximum safe speed and 30-60s rest periods. Long interval HIT involved 4-min bursts at ~90% of peak heart rate (HRpeak) from the GXT and 3-min recovery periods at ~70% HRpeak. Variables recorded included gait training speeds and mean and max heart rate. OG1 and OG2 data were combined to control for warm up and cardiovascular drift effects. Mixed effects models were used to compare TM and OG exercise responses, while accounting for repeated measures from the same participant. RESULTS: All participants completed 12 sessions and no serious adverse events occurred. With the short interval protocol, OG HIT elicited significantly slower gait training speeds than TM HIT (0.75 vs. 0.90 m/s, p<0.0001), with lower mean HR (78.4 vs 82.9 %HRpeak, p<0.0001) and max HR (89.2 vs. 97.0 %HRpeak, p<0.0001). With the long interval protocol, OG HIT elicited significantly faster gait training speeds than TM HIT (0.66 vs. 0.51 m/s, p<0.0001) with similar mean HR (81.2 vs 81.9 %HRpeak, p=0.10) and lower max HR (92.7 vs. 95.8 %HRpeak, p<0.0001). CONCLUSIONS: OG HIT appears to be reasonably feasible and safe in chronic stroke. Mean OG HIT speeds were 34% and 18% faster than baseline fastest gait speed for short and long interval HIT, respectively. For short interval HIT, it may be optimal to combine the task specificity of overground training with the higher speeds and intensity of treadmill training. For long interval HIT, treadmill training does not appear to provide the same intensity benefit and overground training alone may be superior.