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Concurrent adaptations in maximal aerobic capacity, heat tolerance, microvascular blood flow and oxygen extraction following heat acclimation and ischemic preconditioning

Lookup NU author(s): Dr Owen JeffriesORCiD



This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


We investigated the effects of: 1) Ischemic pre-conditioning (IPC) plus a concurrent five-day heat acclimation + IPC (IPC+HA), 2) five-day HA with sham IPC (HA), or 3) control (CON) on thermoneutral measurements of endurance performance, resting measures of skeletal muscle oxygenation and blood flow. Twenty-nine participants were randomly allocated to three groups, which included: 1) five-days of repeated leg occlusion (4 x 5-min) IPC at limb occlusive pressure, plus fixed-intensity (55% O2max) cycling HA at ~36°C/40% humidity; 2) HA plus sham IPC (20 mmHg) or 3) or CON (thermoneutral 55% O2max plus sham IPC). In IPC+HA and HA, there were increases in maximal oxygen consumption ( O2max) (7.8% and 5.4%, respectively; P < 0.05), ventilatory threshold (VT) (5.6% and 2.4%, respectively, P < 0.05), delta efficiency (DE) (2.0% and 1.4%, respectively; P < 0.05) and maximum oxygen pulse (O2pulse-Max) (7.0% and 6.9%, respectively; P < 0.05) during an exhaustive incremental test. There were no changes for CON (P > 0.05). Changes (P < 0.05) in resting core temperature (TC), muscle oxygen consumption (mO2), and limb blood flow (LBF) were also found pre-to-post intervention among the HA and IPC+HA groups, but not in CON (P > 0.05). Five-days of either HA or IPC+HA can enhance markers of endurance performance in cooler environments, alongside improved muscle oxygen extraction, blood flow, exercising muscle efficiency and O2 pulse at higher intensities, thus suggesting the occurrence of peripheral adaptation. Both HA and IPC+HA enhance the adaptation of endurance capacity, which might partly relate to peripheral changes.

Publication metadata

Author(s): Waldron M, Papavasileiou G, Jeffries O, Nevola V, Heffernan SM, Kilduff L, Tallent J

Publication type: Article

Publication status: Published

Journal: Journal of Thermal Biology

Year: 2020

Volume: 93

Print publication date: 01/10/2020

Online publication date: 08/09/2020

Acceptance date: 28/08/2020

Date deposited: 23/10/2020

ISSN (print): 0306-4565

ISSN (electronic): 1879-0992

Publisher: Elsevier Ltd


DOI: 10.1016/j.jtherbio.2020.102724


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