Muscle oxygenation of the paretic and nonparetic legs during and after exercise in chronic stroke: Implications for mobility

Abstract

BackgroundOxygen delivery and demand are reduced in the paretic leg of individuals after stroke. However, it is unknown how muscle oxygenation, the balance between delivery and utilization of oxygen at the muscle, is altered post‐stroke during aerobic exercise and how it relates to mobility.ObjectiveTo monitor muscle oxygenation changes between the paretic and nonparetic legs of individuals after stroke during treadmill exercise and the 6‐minute walk test and analyze the association with mobility.DesignCross‐sectional study.SettingCardiac rehabilitation program.PatientsEleven male participants were enrolled in the study. Ten men (30.8 ± 4.1 months post‐stroke; age 63.9 ± 13.9 years) with hemiparetic gait pattern finished the study.Methods or interventionsNot applicable.Main outcome measuresMuscle oxygenation was measured with near‐infrared spectroscopy placed on the vastus lateralis of each leg during treadmill exercise at the first ventilatory threshold and during a 6‐minute walk test.ResultsThe desaturation slope during treadmill exercise was significantly steeper (p = .047) in the paretic (−0.7 ± 0.6%/s) compared to the nonparetic leg (−0.3 ± 0.2%/s). There was no other significant difference between legs. The 6‐minute walk test distance was not correlated with 6‐minute walk test muscle oxygenation in either leg (paretic: r = 0.20, p = 0.590; nonparetic: r = 0.42, p = .232).ConclusionsAt the onset of treadmill exercise, the paretic leg was unable to effectively match the oxygen demand and extraction of the nonparetic leg, suggesting the need for an immediate cardiovascular warmup prior to initiating moderate intensity exercise in this population. Because the exercise desaturation rate is thought to indicate increased anaerobic metabolism and lactate production, efforts to delay rapid desaturation could improve the sustainability of activities of daily living and exercise.