Reduced oxygen desaturation in the vastus lateralis of chronic stroke survivors during graded muscle contractions

ABSTRACT

Background

Few studies have examined changes in skeletal muscle physiology post-stroke. This study examined changes in tissue oxygen saturation (StO₂) of the vastus lateralis (VL) muscle of stroke survivors and age-matched control participants during maximal and submaximal isometric contractions of the knee extensor muscles.

Objectives

We hypothesized that tissue oxygen desaturation (ΔStO₂) during knee extensor muscle contractions would be less in the VL in the paretic vs. the non-paretic and control legs.

Methods

Ten chronic stroke survivors (>6 months post-stroke) with lower extremity muscle weakness and 10 age-matched controls completed this prospective cohort study. Maximum voluntary contractions (MVCs) of the knee extensor muscles were assessed with a Biodex dynamometer and StO₂ of the VL was measured using near-infrared spectroscopy.

Results

In the paretic leg of the stroke survivors little change in StO₂ of the VL was observed during an MVC (ΔStO₂ = -1.7 ± 1.8%) compared to the non-paretic (ΔStO₂ = -5.1 ± 6.1%; p < 0.05) and control legs (ΔStO₂ = -14.4 ± 8.8%; p < 0.05 vs. paretic and non-paretic leg). These differences remained when normalizing for strength differences between the legs. Compared to controls, both the paretic and non-paretic VL showed pronounced reductions in ΔStO₂ during ramp and hold contractions equal to 20%, 40%, or 60% of the MVC (p < 0.05 vs. controls at all load levels).

Conclusions

These results indicate that oxygen desaturation in response to isometric muscle contractions is impaired in both the paretic and non-paretic leg muscle of stroke survivors compared to age-matched controls, and these differences are independent of differences in muscle strength.

KEYWORDS:

• Stroke
• muscle Strengthening
• oxygen kinetics
• exercise
• Physical inactivity
• muscle function

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data generated or analyzed during this study are available from the corresponding author upon reasonable request.

Additional information

Funding

The project was supported by the National Center for Advancing Translational Sciences Grants UL1-TR-001436 and KL2-TR-001438 and by National Institute of Child Health and Human Development at the National Institutes of Health Grant R01HD099340.