February 21, 2020
Matt Mallette, PhD
Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, Ontario, Canada.
The KT committee is introducing a new format for Knowledge Translation articles with an emphasis on how current research may impact practitioners. This month’s article is written by Matt Mallette, PhD, Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, Ontario, Canada.
Matt Mallette completed his PhD in Environmental Ergonomics in 2019 from Brock University and is currently pursuing his postdoctoral work at Wilfrid Laurier University. Matt was chosen to lead this article owing to his PhD work examining neuromuscular adaptions following temperature manipulations. He is currently investigating sex-related differences in neuromuscular fatigue.
- Aerobic exercise performance is often seen to be greatest in cooler environmental temperatures (approx. range 3°C to 20°C) and core body temperature is neutral, as this reduces stress placed on the body.
- Very little research has looked at aerobic exercise performance in a cold environment when core temperature is reduced.
- As the body redirects blood flow away from the peripheral limbs in cold environments to minimize heat loss, supplemental oxygen may be able to provide more oxygen to the muscles and restore exercise performance.
How the study was done
- Twelve healthy male cyclists performed 15 km time-trials (TT) in three different temperature and oxygen conditions: neutral (23°C) temperature with normal air, cold (0°C) temperature with normal air, and cold temperature with supplemental oxygen (40% oxygen).
- Before starting the cold TTs, participants rested in 0°C air until their core body temperature was reduced by 0.5°C below baseline temperature while breathing normal air.
- During the TT, participants were blinded to the air condition while breathing either normal (room) air or air mixed with a higher percentage of oxygen.
- Oxygen content in the artery, muscle, and brain was non-invasively assessed throughout the TT.
What the researchers found
- TT performance was reduced by 2% in the cold with normal air condition compared to the neutral temperature condition.
- Supplemental oxygen in the cold condition restored exercise performance to neutral temperature levels.
- Arterial, muscle, and brain oxygenation were all greater in the supplemental oxygen condition compared to the normal air condition in the cold temperature, suggesting the impairment from the reduced core body temperature is due to reduced oxygen availability to the working muscles.
- Exercise performance is reduced when core body temperature is lowered by a small amount. However, it can be restored with supplemental oxygen.
- This work highlights the importance of maintaining core body temperature prior to the start of an event in cold environments, which can be achieved via an active warm-up and wearing insulative clothing while waiting for the event to start.
Take home message
- Exercise performance is impaired in a cold environment when core body temperature is reduced.
- Supplemental oxygen can restore performance to levels achieved at a neutral temperature.
Ferguson SAH, Eves ND, Roy BD, Hodges GJ, Cheung SS. Effects of mild whole body hypothermia on self-paced exercise performance. J Appl Physiol. 2018; 125: 479-485
This article is a summary of an article published in Applied Physiology, Nutrition & Metabolism. If you intend to cite any information in this article, please consult the original article and cite that source. This summary was written for the Canadian Society for Exercise Physiology and it has been reviewed by the CSEP Knowledge Translation Committee.