title: Seasonal variation of trace element loss to sweat during exercise in males.
abstract: OBJECTIVE
  To clarify the seasonal differences of the trace element excretion in sweat, the trace element concentration in sweat and their loss during exercise were compared between summer and winter.
  
  
  METHODS
  Sweat samples were collected from ten healthy adult males. Bicycle ergometer exercise was conducted by each subject at a heart rate of 140 beats/min for 1 hour, in summer and in winter. Sweat was collected by the arm bag method.
  
  
  RESULTS
  Concentrations of major (Na, K, Ca, and Mg) and trace elements (Zn, Cu, Fe, Ni, Mn, and Cr) in sweat tended to be lower in summer than in winter, and significantly lower concentrations of Mg (p<0.01), Na, Cu, and Mn (p<0.05) were found in summer. The sweat volume in summer (0.90 L) was 1.7-fold larger than that in winter (0.52 L) (p<0.01). The amount of loss of each element to sweat calculated from the concentrations in sweat and sweat volume showed no significant difference between summer and winter.
  
  
  CONCLUSIONS
  It is suggested that there was no significant difference in the amount of loss of trace elements in sweat due to exercise between summer and winter.
authors: Department of Health and Physical Education, Nippon Dental University, 1-9-20 Fujimi, Chiyoda-ku, 102-8159, Tokyo, Japan, ahoshi@tokyo.ndu.ac.jp.
authors: Akio
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authors: Hoshi
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authors: Kobayashi
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