Limb, sex, but not acute dietary capsaicin, modulate the near ‐infrared spectroscopy‐vascular occlusion test estimate of muscle metabolism

AbstractThe downward slope during the near-infrared spectroscopy (NIRS)-vascular occlusion test (NIRS-VOT) is purported as a simplified estimate of metabolism. Whether or not the NIRS-VOT exhibits sex- or limb-specificity or may be acutely altered remains to be elucidated. Thus, we investigated if there is limb- or sex specificity in tissue desaturation rates (DeO2) during a NIRS-VOT, and if acute dietary capsaicin may alter this estimate of muscle metabolism. Young healthy men (n = 25, 21 ± 4 years) and women (n = 20, 20 ± 1 years) ingested either placebo or capsaicin, in a counterbalanced, single-blind, crossover design after which a simplified NIRS-VOT was conducted to determine the DeO2 (%/s), as an estimate of oxidative muscle metabolism, in both the forearm (flexors) and thigh (vastus lateralis). There was a significant limb effect with the quadriceps having a greater DeO2 than the forearm ( −2.31 ± 1.34 vs. −1.78 ± 1.22%/s,p = 0.007,ηp2 = 0.19). There was a significant effect of sex on DeO2 (p = 0.005,ηp2 = 0.203) with men exhibiting a lesser DeO2 than women ( −1.73 ± 1.03 vs. −2.36 ± 1.32%/s, respectively). This manifested in significant interactions of limb*capsaicin (p = 0.001,ηp2 = 0.26) as well as limb*capsaicin*sex on DeO2 (p = 0.013,ηp2 = 0.16) being observed. Capsaicin does not clearly alter O2-dependent muscle metabolism, but there was apparent limb and sex specificity, inter...
Source: Physiological Reports - Category: Physiology Authors: Tags: ORIGINAL ARTICLE Source Type: research
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