Biomechanical Contributions to Alterations in Peak Metabolic Capacity and Efficiency Following Locomotor Training in Individuals After Stroke.

Abstract

Importance Changes in peak metabolic capacity (Vo2peak) and gait efficiency at matched speeds (Vo2match) are often observed in individuals after stroke following locomotor training, although it is uncertain how those changes are achieved. Objective The objective of this study was to evaluate the effects of locomotor training on changes in Vo2peak and Vo2match in individuals after stroke and their associations with changes in locomotor kinematics and kinetics. Design This study was a secondary analysis of a randomized trial. Setting The setting was an outpatient clinic/laboratory. Participants Participants were individuals >6 months after stroke with self-selected walking speeds of Interventions Participants were randomized to receive ≤30 sessions of locomotor training at higher intensities (>70% of heart rate reserve) either in variable contexts (multiple tasks/environments) or during forward walking (treadmill/overground) or at lower intensities ( Main outcomes and measures As changes in Vo2match masked gains in Vo2peak, both measures were evaluated during graded exercise tests and their difference calculated (Vo2gain), with subsequent determination of associations with changes in locomotor kinematics and kinetics. Between-group differences in changes in metabolic and biomechanical outcomes were evaluated using 1-way analyses of variance, with subsequent correlation and stepwise regression analyses. Results Data from 45 participants with baseline and posttraining data indicated no between-group differences in changes in Vo2peak or Vo2match. However, larger changes in Vo2gain were observed following either higher-intensity paradigm, consistent with faster treadmill speeds. Correlation and regression analyses revealed limited associations with changes in Vo2peak, with greater associations between Vo2gain and selected spatiotemporal parameters, joint kinematics, and nonparetic joint powers. Conversely, changes in Vo2match were associated primarily with paretic ankle powers. Conclusions High-intensity training resulted in significant improvements in Vo2gain, which were related to improvements in multiple biomechanical variables at higher treadmill speeds, while gains in gait efficiency were related to improved paretic limb power. Relevance Alterations in peak metabolic capacity and efficiency are associated with distinct biomechanical changes.