Quantification of Tissue Oxygen Saturation in the Vastus Lateralis Muscle of Chronic Stroke Survivors during a Graded Exercise Test.

ABSTRACT

Purpose: This study examined tissue oxygen saturation (StO2) of the vastus lateralis (VL) muscles of chronic stroke survivors during a graded exercise test (GXT). We hypothesized the reduction in StO2 will be blunted in the paretic vs. non-paretic VL during a maximum-effort GXT. Methods: Chronic stroke survivors performed a GXT and StO2 of the VL in each leg was measured using near infrared spectroscopy. Twenty-six stroke survivors performed a GXT. Results: At rest, there was no difference in StO2 between the paretic and non-paretic VL (65±9% vs. 68±7%, respectively, p=0.32). The maximum change in StO2 from rest during the GXT was greater in the non-paretic vs. the paretic VL (-16±14% vs. -9±10%, respectively, p<0.001). The magnitude of the oxygen resaturation response was also greater in the non-paretic vs. the paretic VL (29±23% vs. 18±15%, respectively, p<0.001). VO2 Peak was associated with the magnitude of the VL StO2 change during (r2=0.54, p<0.0001) and after (r2=0.56, p<0.001) the GXT. Conclusions: During a GXT there is a blunted oxygen desaturation response in the paretic vs. the non-paretic VL of chronic stroke survivors. In the paretic VL there was a positive correlation between the oxygen desaturation response during the GXT and VO2 Peak.