Purpose: This study examined tissue oxygen saturation (StO 2 ) of the vastus lateralis (VL) muscles of chronic stroke survivors during a graded exercise test (GXT). We hypothesized the reduction in StO 2 will be blunted in the paretic vs. non-paretic VL during a maximum-effort GXT.
Methods: Chronic stroke survivors performed a GXT and StO 2 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 StO 2 between the paretic and non-paretic VL (65±9% vs. 68±7%, respectively, p=0.32). The maximum change in StO 2 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). VO 2 Peak was associated with the magnitude of the VL StO 2 change during (r 2 =0.54, p<0.0001) and after (r 2 =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 VO 2 Peak.