The influence of transient change of total body water on relative body fats based on three bioelectrical impedance analyses methods. Comparison between before and after exercise with sweat loss, and after drinking.
BACKGROUND
The purpose of this study was to clarify the influence of change of total body water caused by exercise and drinking, on relative body fat (%BF) based on three bioelectrical impedance analyses (BIA) methods, between hand and foot (H-F), between hand and hand (H-H), and between foot and foot (F-F).


METHODS
The subjects were 30 Japanese healthy young adults aged 18 to 23 years (15 males, 15 females). Measurements were made three times for each BIA method; before and after exercise with sweat, and after drinking, and also twice according to the under water weighing (UW) method, before exercise and after drinking. A pedaling exercise, with a bicycle ergometer, was used for 60 minutes as the exercise.


RESULTS
The relationship of %BF between the UW method and each BIA method was mid-range or more (r=0.765-0.839). However, %BF based on the H-F and F-F BIA methods were higher than that based on the UW method. After drinking, %BF of all the BIA methods were higher than the UW method. %BF of the BIA methods after exercise indicated values lower than those before exercise. %BF of the H-F and H-H BIA methods after drinking were a little higher than those before exercise, indicating that those measurements reflect a slight change of body water.


CONCLUSIONS
It was demonstrated that %BF of any BIA method reflect the change of body water caused by exercise, sweating, and drinking.
Demura
S
S
Faculty of Education, Kanazawa University, Japan. demura@ed.kanazawa-u.ac.jp
Yamaji
S
S
Goshi
F
F
Nagasawa
Y
Y
D000273:Adipose Tissue / Q000502:physiology*; D000293:Adolescent; D000328:Adult; D001823:Body Composition / Q000502:physiology*; D001834:Body Water / Q000502:physiology*; D004326:Drinking / Q000502:physiology; D017097:Electric Impedance; D015444:Exercise / Q000502:physiology*; D005260:Female; D005528:Foot; D006225:Hand; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D013546:Sweating / Q000502:physiology