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

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.