Effect of exercise‐induced muscle damage on vascular function and skeletal muscle microvascular deoxygenation

This paper investigated the effects of unaccustomed eccentric exercise‐induced muscle damage ( EIMD ) on macro‐ and microvascular function. We tested the hypotheses that resting local and systemic endothelial‐dependent flow‐mediated dilation ( FMD ) and microvascular reactivity would decrease,V ˙ O 2 maxwould be altered, and that during ramp exercise, peripheral O 2 extraction, evaluated via near‐infrared‐derived spectroscopy ( NIRS ) derived deoxygenated hemoglobin + myoglobin ([ HH b]), would be distorted following EIMD . In 13 participants, measurements were performed prior to (Pre) and 48 h after a bout of knee extensor eccentric exercise designed to elicit localized muscle damage (Post). Flow‐mediated dilation and postocclusive reactive hyperemic responses measured in the superficial femoral artery served as a measurement of local vascular function relative to the damaged tissue, while the brachial artery served as an index of nonlocal, systemic, vascular function. During ramp‐incremental exercise on a cycle ergometer, [ HH b] and tissue saturation ( TSI %) in the m. vastus lateralis were measured. Superficial femoral artery FMD significantly decreased following EIMD (pre 6.75 ± 3.89%; post 4.01 ± 2.90%; P  < 0.05), while brachial artery FMD showed no change. The [ HH b] and TSI % amplitudes were not different following EIMD ([ HH b]: pre, 16.9 ± 4.7; post 17.7 ± 4.9; TSI %: pre, 71.0 ± 19.7; post 71.0 ± 19.7; all P  > 0.05). At each progressive increase in workload (i.e., 0–100% peak), the [ HH b] and TOI % responses were similar pre‐ and 48 h post‐ EIMD ( P  > 0.05). Additionally,V ˙ O 2 maxwas similar at pre‐ (3.0 ± 0.67 L min −1 ) to 48 h post (2.96 ± 0.60 L min −1 )‐ EIMD ( P  > 0.05). Results suggest that moderate eccentric muscle damage leads to impaired local, but not systemic, macrovascular dysfunction.