Influence of muscular contraction on vascular conductance during exercise above versus below critical power

Shane M. Hammer, Stephen T. Hammond, Shannon K. Parr, Andrew M. Alexander, Vanessa Rose G. Turpin, Zachary J. White, Kaylin D. Didier, Joshua R. Smith, Thomas J. Barstow, Carl J. Ade

Research output: Contribution to journalArticlepeer-review

Abstract

We tested the hypothesis that limb vascular conductance (LVC) would increase during the immediate recovery phase of dynamic exercise above, but not below, critical power (CP) indicating a threshold for muscular contraction-induced impedance of limb blood flow (LBF). CP (115 ± 26 W) was determined in 7 men and 7 women who subsequently performed ∼5 min of near-supine cycling exercise both below and above CP. LVC demonstrated a greater increase during immediate recovery and remained significantly higher following exercise above, compared to below, CP (all p < 0.001). Power output was associated with the immediate increases in LVC following exercise above, but not below, CP (p < 0.001; r = 0.85). Additionally, variance in percent LBF impedance was significantly lower above (CV: 10.7 %), compared to below (CV: 53.2 %), CP (p < 0.01). CP appears to represent a threshold above which the characteristics of LBF impedance by muscular contraction become intensity-dependent. These data suggest a critical level of LBF impedance relative to contraction intensity exists and, once attained, may promote the progressive metabolic and neuromuscular responses known to occur above CP.

Original languageEnglish (US)
Article number103718
JournalRespiratory Physiology and Neurobiology
Volume293
DOIs
StatePublished - Nov 2021

Keywords

  • Contraction impedance
  • Critical power
  • Limb blood flow
  • Vascular conductance

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology
  • Pulmonary and Respiratory Medicine

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