The effect of ambient temperature deception on perceived exertion and physiological variables during fixed-intensity cycling in the heat

David N. Borg, Ian B. Stewart, Joseph Costello, Chris C. Drovandi, Geoffrey G. Minett

Research output: Contribution to conferenceAbstractpeer-review

Abstract

Perceived exertion is thought to play an important role in the regulation of exercise. Borg’s 15-point (6-20) rating of perceived exertion (RPE) scale is the standard method for measuring whole-body perceptions of exertion. Despite the simplicity of its measurement, the precise factors which modulate the RPE are unclear, with multiple physiological and psychological inputs and environmental factors all thought to contribute. The covert manipulation of body and ambient temperature (Ta) by means of deception has previously been shown to lower RPE when cycling in the heat compared to a condition where accurate temperature feedback was provided. The current study examined the effect of only Ta deception on the RPE and physiological variables during fixed-rate cycling performance in the heat. It was hypothesised that the direction of deception (told Ta was higher or lower) would lead to the same direction change in RPE with no change in physiological variables.

Eleven male recreational cyclists [mean±standard deviation; age: 26.8±4.1 years; height: 184.5±8.0 cm; body mass: 81.1±13.3 kg; VO2peak: 53.3±6.1 ml·kg-1·min-1; VO2peak power: 382±66 W; 4±1 training sessions·wk; 347±203 training min·wk] completed 30 min of cycling at 50% VO2peakpower, once in a thermoneutral environment (CON: 24 °C; 60% RH) and three times in the heat(33 °C; 60% RH). During one of the hot trials, cyclists were informed of the true Ta. In the other two hot trials, participants were told the Ta was either 5 °C hotter (DECHIGH: 38 °C) or 5 °C cooler (DECLOW: 28 °C). During trials, RPE, respiratory gas exchange, heart rate, rectal and skin temperature were recorded at 5 min intervals,and voluntary force and activation of the quadriceps were assessed pre-and post-cycling. All variables were compared using a two-way repeated measures ANOVA (condition x time). Where significance was obtained, Tukey’s Honestly Significant Difference post hoc test was undertaken.

All participants reported being unaware of the Ta deception. RPE responses were significantly (P<0.05) higher in each of HOT (13.0±1.5), DECLOW (13.0±1.7) and DECHIGH (13.1±1.8) compared to CON (11.8±1.5); but no differences between HOT, DECLOW and DECHIGH were observed. Similarly, all physiological variables were significantly different (P<0.05) in HOT, DECLOW and DECHIGH compared to CON, but no differences were observed between HOT, DECLOW and DECHIGH. Voluntary force and activation were not different between CON, HOT, DECLOW and DECHIGH.Despite the successful deception of Ta, RPE responses and physiological variables remained unaffected during 30 min of fixed intensity cycling in the heat. This study suggests that the use of Ta alone does not provide a strong enough stimulus to alter RPE or physiology during fixed-intensity exercise in the heat.
Original languageEnglish
Pages155
Number of pages1
Publication statusPublished - 1 Nov 2017
EventThe 17th International Conference on Environmental Ergonomics (ICEE 2017, Kobe) - Kobe, Japan
Duration: 12 Nov 201717 Nov 2017

Conference

ConferenceThe 17th International Conference on Environmental Ergonomics (ICEE 2017, Kobe)
Country/TerritoryJapan
CityKobe
Period12/11/1717/11/17

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