Alterations in Aerobic Exercise Performance and Gait Economy Following High-Intensity Dynamic Stepping Training in Persons With Subacute Stroke

Abstract

Background and Purpose Impairments in metabolic capacity and economy (O2cost) are hallmark characteristics of locomotor dysfunction following stroke. High-intensity (aerobic) training has been shown to improve peak oxygen consumption in this population, with fewer reports of changes in O2cost. However, inconsistent gains in walking function are observed, particularly in persons with subacute stroke, with minimal associations with gains in metabolic parameters. The purpose of this study was to evaluate changes in aerobic exercise performance in participants with subacute stroke following high-intensity, variable stepping training as compared to conventional therapy. Methods A secondary analysis was performed from a randomized controlled trial (RCT ) comparing high-intensity training to conventional interventions, and a pilot study that formed the basis for the RCT. Participants 1–6 months post-stroke received ≤40 sessions of high intensity variable stepping training (n=21) or conventional interventions (n=12). Assessments were performed at baseline (BSL), post-training and 2–3 month follow-up, and included changes in submaximal VO2 (VO2submax) and O2cost at fastest possible treadmill speeds and peak speeds at BSL testing. Results Significant improvements were observed in VO2submax with less consistent decreases in O2cost, although individual responses varied substantially. Combined changes in both VO2submax and VO2 at matched peak BSL speeds revealed stronger correlations to improvements in walking function as compared to either measure alone. Conclusions High-intensity stepping training may elicit significant improvements in VO2submax, while changes in both peak capacity and economy better reflect gains in walking function. Providing such training to improve locomotor and aerobic exercise performance may increase the efficiency of rehabilitation sessions. See Video Abstract available for more insights from the authors (see supplemental digital content).

Effects of Training Intensity on Locomotor Performance in Individuals With Chronic Spinal Cord Injury: A Randomized Crossover Study

“…With determination of maximum age-predicted HR (208-(0.7*age), the goal of high-intensity LT was to maintain HRs within 70–85% of predicted maximum HR (HRmax) 35,36 while low-intensity training targeted 50–65% HRmax; these HR ranges approximate those observed during conventional physical therapy 35,42 . If targeted HR zones could not be achieved during training, the Rating of Perceived Exertion (RPE) scale 43,44 was also utilized as a secondary measure of intensity, with targeted ratings of 15–17 (“hard” to “very hard”) for the high–intensity LT protocol and 11–13 (below “somewhat hard”) for low-intensity LT protocol 17,26,35 .…”

“…Gait efficiency was estimated by comparing VO 2 at the highest matched treadmill speeds from pre- to post-testing (VO 2 match). In addition, comparisons of VO 2 peak and VO 2 match at post-testing (VO 2 peak-match) were calculated as a more precise estimate of combined changes in metabolic capacity and efficiency that may be better correlated with walking outcomes 26 . For overground measures, gait economy, or the cost of transport (O 2 cost, ml O 2 /kg/m), was evaluated during the 6MWT, and calculated by averaging data from the last 3 minutes of the 6MWT; this measure reflects the rate of O 2 consumption per unit distance, and has been shown to improve under certain training conditions 32,46 .…”

“…In patients with other acute-onset neurological injuries (i.e., patients post-stroke) , LT performed at moderate to high intensities (i.e., up to 85% of maximum HR) has been shown to improve walking function as compared to lower-intensity interventions, 32,33 even when the amount of practice is controlled 17,18 . While gains in cardiopulmonary capacity have been observed with such training 26 , improvements in neuromuscular impairments 34 and walking function 35,36 have also been demonstrated.…”

Strategies to Achieve High Intensity Gait Training in a Clinical Setting: A Case Study

“…This CPG promotes high intensity gait training (HIGT) as a highly recommended intervention to improve gait speed and walking distance [2]. A literature review of HIGT by this author further supported the efficacy of HIGT to improve walking [3][4][5][6]. Despite the ample evidence of the benefits of HIGT, there remains a gap in the literature regarding its clinical feasibility.…”

“…Despite the ample evidence of the benefits of HIGT, there remains a gap in the literature regarding its clinical feasibility. Training paradigms in the literature often span up to 40 visits across 10 weeks for 30-60 mins per session [4][5][6]. This is not consistent with typical clinical practice and lengths of stay.…”