1. The physiological and perceptual responses of restrictive heat loss attire in hot and temperate conditions
A. Willmott 1, C.A. James 2, O.R. Gibson 3, M. Hayes 1, J. Dekerle 1 & N.S. Maxwell 1 1 Centre for Sport and Exercise Science and Medicine (SESAME), University of Brighton, Eastbourne, UK.
2 National Sports Institute of Malaysia, Institut Sukan Negara, Bukit Jalil Stadium, Kuala Lumpur, Malaysia.
3 Centre for Human Performance, Exercise and Rehabilitation (CHPER), Brunel University London, UK.
Introduction
Results
Heat acclimation (HA), by definition(1), typically occurs within environmental chambers which may be impractical, precluding use of the intervention.
Alternative methods to induce physiological strain sufficient to acquire the HA phenotype include hot water bathing(2), sauna use(3), and restricting evaporative heat loss before(4), or during exercise(5).
PURPOSE: Investigate the efficacy of an inexpensive and practical sauna suit across hot and temperate conditions to induce equivalent physiological strain to HA.
HYPOTHESIS: Wearing a sauna suit in temperate conditions would elicit similar physiological strain to that of hot conditions without a sauna suit. Temperate conditions without the sauna suit, and hot conditions with the sauna suit would elicit the least & greatest physiological strain respectively.
Core temperature ∆ was higher in TEMPSAUNA (+1 .7 ±0.4 °C.hr-1), HOT (+1.9 ±0.5 °C.hr-1) and HOTSAUNA (+2.3 ±0.5 °C.hr-1) than TEMP (+1.3 ±0.3 °C.hr-1).  
Mean skin temperature was higher in HOT (34.8 ±0.9°C) and HOTSAUNA (36.0 ±0.8°C) than TEMP (32.2 ±1.8°C) and TEMPSAUNA (32.1 ±0.5°C).
Methods
Ten moderately trained individuals (6M, 4F; mass 69.4 ± 7.5 kg; stature 175 ± 9 cm; body fat, 19.2 ± 7.2 %).
4 randomised exercise sessions of 30min (15min at 2 W.kg-1 then 15min at 1 W.kg-1)
 Temperate (TEMP, 22°C & 45%)
Temperate whilst wearing a vinyl sauna suit (TEMPSAUNA, 22°C & 45%)
 Hot (HOT, 45°C & 20%)
 Hot whilst wearing a vinyl sauna suit (HOTSAUNA, 45°C & 20%)
a = TEMP vs HOTSAUNA.
d = TEMP, TEMPSAUNA vs HOT, HOTSAUNA.
f = HOT SAUNA vs TEMP, TEMPSAUNA.
b = TEMP vs HOT.
c = HOTSAUNA vs TEMP, TEMPSAUNA, HOT.
e = HOT vs HOTSAUNA.
g = TEMP vs TEMPSAUNA.
h = HOT vs HOT SAUNA
Peak HR was higher (p<0.05) in HOTSAUNA (171 ±18 b.min-1) than TEMP (151 ±20 b.min-1). There was no difference between TEMPSAUNA (155 ±23 b.min-1) and HOT (163 ±18 b.min-1) .
Fig 2. *
* Sweating increased (p<0.05) in TEMPSAUNA (0.9 ±0.2 L.hr-1), HOT (1.1 ±0.5 L.hr-1) and HOTSAUNA (1.5 ± 0.5L.hr-1) vs TEMP (0.6 ± 0.7L.hr-1).
# Perceived exertion was higher (p<0.05) in HOT (15 ±1) and HOTSAUNA (16 ±1) than TEMPSAUNA (14 ±1) and TEMP (14 ±1).
* Thermal Sensation was greater (p<0.05) in TEMPSAUNA (5.2 ±0.4), HOT (5.7 ±0.4) and HOTSAUNA (6.1 ±0.3) than TEMP (4.8 ±0.5).
* Thermal Comfort was greater (p<0.05) in TEMPSAUNA (3 ±1), HOT (3 ±1) and HOTSAUNA (4 ±1) than TEMP (2 ±1).
Conclusions
Wearing sauna suits to restrict heat loss during exercise in temperate conditions increases physiological strain and thermal perception to a comparable magnitude of equivalent exercise in a typical HA environment.
Such methods in hot conditions further increases physiological and perceptual strain and may make HA more efficient.
Wearing sauna suits during training in temperature conditions could be a viable alternative to environmental chambers.
1. Taylor NAS. Human Heat Adaptation. Compr Physiol Jan 17;4(325–65
2. Zurawlew MJ, Walsh NP, Fortes MB, Potter C. Post‐exercise hot water immersion induces heat acclimation and improves endurance exercise performance in the heat. Scand J Med Sci Sports Dec 1;26(7):745–754.
3. Scoon GSM, Hopkins WG, Mayhew S, Cotter JD. Effect of post-exercise sauna bathing on the endurance performance of competitive male runners. J Sci Med Sport Aug;10(4):259–62.
4. Mee J, Peters S, Doust J, Maxwell N. Restricted sweat evaporation preceding short term heat acclimation accelerates adaption in females. Extrem Physiol Med. BioMed Central Ltd; 2015 Sep 14;4(Suppl 1):A112.
5. Steele J, Ely B, Minson C. Over-dressing during exercise in temperate environmental conditions mimics physiological strain of exercise in the heat. International Journal of Exercise Science: Conference Proceedings p. 18.