Sweat lactate in exercising children and adolescents of varying physical maturity

Abstract

This study attempts to explain some of the individual variability in sweating pattern by comparing prepubescents and pubescents. Sweating rate and muscular anaerobic capacity are higher in adults than in children; thus we hypothesized that sweat gland anaerobic metabolism, as reflected by lactate excretion, might be higher with advanced physical maturity (PM). Lactate concentration in sweat ([LAC]sw) was measured at various stages of PM in boys who exercised in the heat. The subjects were divided into three groups on the basis of Tanner staging: prepubertal (PP, n = 16), midpubertal (MP, n = 15), and late pubertal (LP, n = 5). Subjects cycled at 50% of maximal O2 uptake for three 20-min bouts, with 10-min rest periods, in 42 degrees C and 18% relative humidity. Sweat samples were harvested, and population density of activated sweat glands was determined after each exercise bout. [LAC]sw during bout 1 was higher in PP than in LP [PP = 22.2 +/- 2.2, MP = 19.5 +/- 1.4, LP = 14.3 +/- 1.3 (SE) mmol/l]. In all groups, [LAC]sw decreased during subsequent bouts, and there were no intergroup differences in [LAC]sw during bout 3 (PP = 11.2 +/- 0.4, MP = 10.6 +/- 0.5, LP = 9.7 +/- 0.2 mmol/l). [LAC]sw was inversely related to sweating rate. Lactate excretion rate per gland was greater with the increase in PM (PP = 61.0 +/- 8.2, MP = 79.1 +/- 11.3, LP = 99.9 +/- 11.0 pmol/min; P = 0.08).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of age and gender on sweat lactate and ammonia concentrations during exercise in the heat

“…A consistent finding of the present study was that Lac -dropped with exercise duration, which is in agreement with other studies in which subjects cycled at constant work rates (7,11,18,28,29). The drop in sweat Lac -could be due to the fact that, besides glycolysis, the sweat gland uses oxygen (oxidative phosphorylation) as a substrate for sweating (4,30).…”

“…The overall sweat Lac -of the boys (16.6 mM) and men (15.1 mM) in the present study agrees with those reported for boys (7) and men (6,11,18) performing similar exercise protocols. The mean sweat Lac -of women (14.3 mM) in the present study, however, was much lower than that of sedentary (100 mM) or fit (43 mM) women (8).…”

“…Although children's sweat Lac -after bout 1 was higher than that of adults, this cannot be accounted for by their lower SR. We found a negative but very weak association between SR and sweat Lac -(P > 0.05, r = -0.27, for all subjects). Such a relationship is not consistent since some investigators have reported an inverse correlation (7,8,24), while studies using single sweat glands have shown a significant positive correlation (14), or none at all (13).…”

“…To guarantee enough volume, sweat was collected into two plastic bags (one in each side) attached to the subjects' lower back as previously described (7,10). The format of the plastic bag was such that the skin area covered was equivalent in children and adults.…”

Construction of an Amperometric Lactate Biosensor Based on Immobilization of Lactate Dehydrogenase Nanoparticles onto Pencil Graphite Electrode

“…During this process, lactate generation rate is much higher than its consumption rate, thus creates a lactate concentration which is proportional to the level of physical exertion [3,4]. The circulation of lactate throughout the body is managed by monocarboxylate transporter and thus lactate can be traced in biological samples at typical conentration [5].…”