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. 2025 Jan 1;57(1):181-191.
doi: 10.1249/MSS.0000000000003543. Epub 2024 Aug 20.

Metabolic Heat Production Modulates the Cardiovascular Drift-V̇O 2max Relationship Independent of Aerobic Fitness in Women

Tori Stone  1 , Sarah G Burnash  1 , Ryan L Earley  2 , Annie M Mulholland  1 , Hillary A Yoder, Hayley V Macdonald  1 , Mark T Richardson  1 , Jonathan E Wingo  1
Affiliations

Metabolic Heat Production Modulates the Cardiovascular Drift-V̇O 2max Relationship Independent of Aerobic Fitness in Women

Tori Stone et al. Med Sci Sports Exerc. .

Abstract

Introduction/purpose: The purpose of this study was to test the hypothesis that cardiovascular (CV) drift and associated decrements in maximal oxygen uptake (V̇O 2max ) are greater in high-fit compared with low-fit women during exercise at the same %V̇O 2max , but comparable at the same rate of metabolic heat production.

Methods: Six high-fit (HI) and six low-fit (LO) women cycled in 35°C for 15 or 45 min at the same relative intensity (60% V̇O 2max ; 15REL and 45REL) or fixed rate of heat production (500 W; 15FX and 45FX), immediately followed by a graded exercise test to measure V̇O 2max . The separate 15- and 45-min trials permitted measurements of V̇O 2max over the same time interval as CV drift.

Results: During 45REL, higher heat production in HI (496 ± 51 vs 364 ± 44 W in LO) resulted in greater end-exercise core temperature (38.7°C ± 0.4°C vs 38.2°C ± 0.1°C, P = 0.03), greater increases in HR (15 bpm (10%) vs 10 bpm (6%), P = 0.03) and decreases in stroke volume (11 mL per beat (16%) vs 5 mL per beat (8%), P = 0.001), and larger reductions in V̇O 2max (16% vs 5%, P = 0.04) compared with LO. During 45FX, temperature responses, CV drift, and decreased V̇O 2max were not different between groups (all P > 0.05), despite differences in %V̇O 2max (60% vs 75% for HI and LO, respectively).

Conclusions: We conclude metabolic heat production modulates the CV drift-V̇O 2max relationship, independent of fitness level. These results support previous findings showing the magnitude of CV drift is proportional to reductions in V̇O 2max .

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