title: Seasonal variation of non-shivering thermogenesis (NST) during mild cold exposure.
abstract: BACKGROUND
  The physiological function of non-shivering thermogenesis (NST) has been investigated in recent years, and some studies have discussed the importance of NST with respect to human cold adaptation. The present study aimed to clarify individual and seasonal variations in NST that occurred as a result of mild cold exposure.
  
  
  METHODS
  Seventeen male university students participated in the present study during summer and winter. The climate chamber used was programmed so that ambient temperature dropped from 28°C to 16°C over an 80-min period. Physiological parameters of test subjects were recorded during the experiments.
  
  
  RESULTS
  Increases in oxygen intake (VO2) during cold exposure were significantly greater without shivering in winter than they were in summer. Respiratory exchange ratio (RER) was significantly lower during thermoneutral baseline and cold exposure in winter than it was during the same periods in summer. In addition, there was a significant negative correlation between ΔVO2 and ΔRER.
  
  
  CONCLUSIONS
  Increase of VO2 without shivering indicated increase of NST, and decrease of RER depends on the metabolization of fat in winter. These results suggested that NST activity was activated by seasonal acclimatization, and individual variation of NST depends on individual variation of fat metabolism.
authors: Takayuki
authors: T
authors: Nishimura
authors: Midori
authors: M
authors: Motoi
authors: Yuka
authors: Y
authors: Egashira
authors: Damee
authors: D
authors: Choi
authors: Kiyoshi
authors: K
authors: Aoyagi
authors: Shigeki
authors: S
authors: Watanuki
mesh_terms: D000064:Acclimatization / Q000502:physiology*; D000328:Adult; D000704:Analysis of Variance; D001831:Body Temperature / Q000502:physiology*; D003080:Cold Temperature; D004576:Electromyography; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012621:Seasons; D022722:Thermogenesis / Q000502:physiology*; D055815:Young Adult