Why the study?
Unaccustomed eccentric exercise leads to impaired microvascular function, but the underlying mechanisms involving oxidative stress and nitric oxide bioavailability are unknown.
Does acute ingestion of antioxidants or dietary nitrate improve impaired microvascular reactivity after eccentric muscle contractions in young adults?
Does acute ingestion of antioxidants or dietary nitrate improve impaired microvascular reactivity after eccentric muscle contractions in young adults?
Acute ingestion of antioxidants or dietary nitrate does not restore impaired microvascular reactivity following unaccustomed eccentric muscle contractions.
Impaired microvascular reactivity after eccentric exercise is unaffected by antioxidants or nitrate; leaves open structural mechanisms and clinical relevance.
Unaccustomed eccentric exercise leads to impaired microvascular function but the underlying mechanism is unknown. In this study, we evaluated the role of oxidative stress and of nitric oxide (NO) bioavailability. Thirty young men and women performed eccentric contractions of the tibialis anterior (TA) muscle (ECC), with the contralateral leg serving as nonexercising control (CON). Participants were randomized into three groups ingesting an antioxidant cocktail (AO), beetroot juice (BR) or placebo 46 h postexercise. At baseline and 48 h postexercise, hyperemic responses to brief muscle contractions and 5 min of cuff occlusion were assessed bilaterally in the TA muscles using blood oxygen level dependent (BOLD) magnetic resonance imaging. Eccentric contractions resulted in delayed time-to-peak (~22%; P < 0.001), blunted peak (~21%; P < 0.001) and prolonged time-to-half relaxation (~12%, P < 0.001) in the BOLD response to brief contractions, with no effects of AO or BR, and no changes in CON. Postocclusive time-to-peak was also delayed (~54%; P < 0.001) in ECC, with no effects of AO or BR, and no changes in CON. Impaired microvascular reactivity after eccentric contractions is confined to the exercised tissue, and is not restored with acute ingestion of AO or BR. Impairments in microvascular reactivity after unaccustomed eccentric contractions may result from structural changes within the microvasculature that can diminish muscle blood flow regulation during intermittent activities requiring prompt adjustments in oxygen delivery.
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Larsen et al. (2019) studied this question.
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