Age differences in cardiac autonomic regulation during intermittent exercise in the heat

Eur J Appl Physiol. 2020 Feb;120(2):453-465. doi: 10.1007/s00421-019-04290-8. Epub 2020 Jan 1.


Purpose: This study aimed to detect potential differences in heart-rate variability (HRV) during a moderate-intensity intermittent exercise in the heat among physically active young (25.8 ± 1.9 years), middle-aged (43.5 ± 2.8 years), and older (62.9 ± 3.7 years) men.

Methods: Thirty-three participants (11/group) performed four successive bouts of 15-min cycling at a moderate fixed rate of metabolic heat production of ~ 400 W; each separated by a 15-min recovery with 1 h of final recovery in a hot and dry environment (35 °C, 20% relative humidity). Twelve HRV indices were computed that have been commonly described in the literature, and characterized various domains of the variability and complexity of heart rate.

Results: Cardiac autonomic regulation during intermittent exercise in the heat, as well as during pre-exercise rest and recovery was significantly affected by age, as changes were observed among the three different aged groups in five indices (p ≤ 0.05). Similarly, time influenced cardiac autonomic regulation as three indices showed changes across time (p ≤ 0.05) during intermittent exercise, whilst five indices displayed significant changes (p ≤ 0.05) during rest and recovery in the heat.

Conclusions: This study supports that moderate-intensity intermittent exercise in the heat is associated with significant cardiac autonomic dysregulation in older men, as compared to young and middle-aged men, yet it highlights the importance of developing preventative health strategies for heat-related illness in aged individuals.

Keywords: Ageing; Autonomic nervous system; Exercise; Heart-rate variability; Hot environment.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Aging*
  • Autonomic Nervous System / physiology*
  • Electromyography
  • Exercise
  • Female
  • Heart / innervation
  • Heart / physiology*
  • Hot Temperature
  • Humans
  • Resistance Training
  • Young Adult