title: Exercising in a hot environment: which T-shirt to wear?
abstract: OBJECTIVE
  The aim of this study was to investigate thermoregulatory, cardiorespiratory, metabolic, and perceptual responses while running in a hot environment (31.7° ± 1.0°C; 42% ± 3% relative humidity) and wearing T-shirts made from different fiber types.
  
  
  METHODS
  Eight well-trained men performed 4 tests wearing either a T-shirt made of 100% polyester with 4, 6, or 8 channels, or one made of 100% cotton. Each test consisted of 30 minutes running at 70% of peak oxygen uptake, followed by a ramp test to exhaustion and 15 minutes of recovery.
  
  
  RESULTS
  There were no differences in skin, core, and body temperatures between fiber types during submaximal and high-intensity running (best P = .08). During recovery, body temperature and shivering/sweating sensations were lower when wearing 4- and 6-channel fibers (P ≤ .04) compared with cotton. The relative humidity at the chest and back were lower for all polyester T-shirts compared with cotton during and after submaximal and maximal running (P ≤ .007). Heart rate (best P = .10), oxygen uptake (P = .95), respiratory exchange ratio (best P = .93), ventilation (best P = .99), and blood lactate concentration (best P = .97) did not differ between the fiber types. Nor were any differences in time to exhaustion (best P = .76), ratings of perceived exertion (best P = .09), thermal sensation (best P = .07), or sensation of clothing wetness (best P = .36) discovered.
  
  
  CONCLUSIONS
  Although statistical analysis revealed lower shivering/sweating sensations while wearing 4- and 6-channel fiber shirts during recovery, with an improved chest and back microenvironment for all polyester T-shirts, the question remains whether these differences are of any practical relevance because the performance of the well-trained men was unaffected.
authors.affiliation: Department of Sport Science, University of Wuppertal, Wuppertal, Germany (Dr Sperlich, Mr Born, and Ms Lefter). Electronic address: sperlich@uni-wuppertal.de.
authors.forename: Billy
authors.initials: B
authors.lastname: Sperlich
authors.forename: Dennis-Peter
authors.initials: DP
authors.lastname: Born
authors.forename: Marie Denise
authors.initials: MD
authors.lastname: Lefter
authors.forename: Hans-Christer
authors.initials: HC
authors.lastname: Holmberg
mesh_terms: D000328:Adult; D001833:Body Temperature Regulation / Q000502:physiology*; D003020:Clothing; D004734:Energy Metabolism; D006358:Hot Temperature / Q000009:adverse effects*; D006801:Humans; D008297:Male; D010465:Perception / Q000502:physiology; D013997:Time Factors
keywords: clothing; fiber; heat stress; high intensity; microenvironment; thermoregulation