Sweat mineral loss from whole body, patch and arm bag in white and black girls

Abstract

The objective of this study was to compare the loss of minerals in sweat between black and white girls by using four different methods of sweat collection. Sweat was collected from 36 girls during two three-week metabolic studies where they were fed either 1.3 or 4 g of Na/d in a crossover design. Sweat was collected by: 1) 24-h whole body; 2) 24-h back patch; 3) 30-min exercise with patches on the back; and 4) 30-min exercise with arm bags. Sweat losses of sodium, potassium, calcium, and magnesium were similar between races when whole body and patch methods were used. However, while consuming the high-Na diet, black girls excreted less (p<0.05) sodium than white girls when sweat was collected by arm bags during a 30-min exercise period. Projecting the excretion of sweat from the 24-h patch technique to the whole body technique overly exaggerated the loss of minerals. In conclusion, this study suggests that whole body measurements are more accurate than collecting sweat from a small area of the body and is the preferred method. Racial differences were apparent while consuming a high sodium diet and exercising.