Effects of heat acclimation on time perception

Maria Tamm; Ainika Jakobson; Merle Havik; Saima Timpmann; Andres Burk; Vahur Ööpik; Jüri Allik; Kairi Kreegipuu

doi:10.1016/j.ijpsycho.2014.11.004

Effects of heat acclimation on time perception

Int J Psychophysiol. 2015 Mar;95(3):261-9. doi: 10.1016/j.ijpsycho.2014.11.004. Epub 2014 Nov 15.

Authors

Maria Tamm¹, Ainika Jakobson², Merle Havik², Saima Timpmann³, Andres Burk³, Vahur Ööpik⁴, Jüri Allik⁵, Kairi Kreegipuu⁶

Affiliations

¹ Institute of Psychology, University of Tartu, Estonia; Doctoral School of Behavioural, Social and Health Sciences, University of Tartu, Estonia. Electronic address: maria.tamm@ut.ee.
² Institute of Psychology, University of Tartu, Estonia; Doctoral School of Behavioural, Social and Health Sciences, University of Tartu, Estonia.
³ Laboratory of Exercise Physiology, University of Tartu, Estonia.
⁴ Laboratory of Exercise Physiology, University of Tartu, Estonia; Doctoral School of Behavioural, Social and Health Sciences, University of Tartu, Estonia.
⁵ Institute of Psychology, University of Tartu, Estonia; Doctoral School of Behavioural, Social and Health Sciences, University of Tartu, Estonia; Estonian Academy of Sciences.
⁶ Institute of Psychology, University of Tartu, Estonia.

PMID: 25451787
DOI: 10.1016/j.ijpsycho.2014.11.004

Abstract

Cognitive performance is impaired during prolonged exercise in hot environment compared to temperate conditions. These effects are related to both peripheral markers of heats stress and alterations in CNS functioning. Repeated-exposure to heat stress results in physiological adaptations, and therefore improvement in exercise capacity and cognitive functioning are observed. The objective of the current study was to clarify the factors contributing to time perception under heat stress and examine the effect of heat acclimation. 20 young healthy male subjects completed three exercise tests on a treadmill: H1 (at 60% VO(2)peak until exhaustion at 42°C), N (at 22°C; duration equal to H1) and H2 (walk until exhaustion at 42°C) following a 10-day heat acclimation program. Core temperature (T(C)) and heart rate (HR), ratings of perceived fatigue and exertion were obtained continuously during the exercise, and blood samples of hormones were taken before, during and after the exercise test for estimating the prolactin, growth hormone and cortisol response to acute exercise-heat stress. Interval production task was performed before, during and after the exercise test. Lower rate of rise in core temperature, heart rate, hormone response and subjective ratings indicated that the subjects had successfully acclimated. Before heat acclimation, significant distortions in produced intervals occurred after 60 minutes of exercise relative to pre-trial coefficients, indicating speeded temporal processing. However, this effect was absent after in acclimated subjects. Blood prolactin concentration predicted temporal performance in both conditions. Heat acclimation slows down the increase in physiological measures, and improvement in temporal processing is also evident. The results are explained within the internal clock model in terms of the pacemaker-accumulator functioning.

Keywords: Core temperature; Heart rate; Heat acclimation; Internal clock; Interval production; Prolactin; Time perception.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Adaptation, Physiological
Adrenocorticotropic Hormone / blood
Adult
Body Temperature
Exercise Test
Fatigue
Growth Hormone / blood
Heart Rate / physiology
Hot Temperature*
Humans
Hydrocortisone / blood
Male
Oxygen Consumption
Physical Exertion / physiology
Prolactin / blood
Psychophysics
Regression Analysis
Time Factors
Time Perception / physiology*
Young Adult

Substances

Adrenocorticotropic Hormone
Prolactin
Growth Hormone
Hydrocortisone