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

Abstract

The dependence of sweat composition and acidity on sweating rate (SR) suggests that the lower SR in children compared to adults may be accompanied by a higher level of sweat lactate (Lac -) and ammonia (NH 3 ) and a lower sweat pH. Four groups (15 girls, 18 boys, 8 women, 8 men) cycled in the heat (42ºC, 20% relative humidity) at 50% VO 2max for two 20-min bouts with a 10-min rest before bout 1 and between bouts. Sweat was collected into plastic bags attached to the subject's lower back. During bout 1, sweat from girls and boys had higher Lac -concentrations (23.6 ± 1.2 and 21.2 ± 1.7 mM; P < 0.05) than sweat from women and men (18.2 ± 1.9 and 14.8 ± 1.6 mM, respectively), but Lac -was weakly associated with SR (P > 0.05; r = -0.27). Sweat Lac -concentration dropped during exercise bout 2, reaching similar levels among all groups (overall mean = 13.7 ± 0.4 mM). Children had a higher sweat NH 3 than adults during bout 1 (girls = 4.2 ± 0.4, boys = 4.6 ± 0.6, women = 2.7 ± 0.2, and men = 3.0 ± 0.2 mM; P < 0.05). This difference persisted through bout 2 only in females. On average, children's sweat pH was lower than that of adults (mean ± SEM, girls = 5.4 ± 0.2, boys = 5.0 ± 0.1, women = 6.2 ± 0.5, and men = 6.2 ± 0.4 for bout 1, and girls = 5.4 ± 0.2, boys = 6.5 ± 0.5, women = 5.2 ± 0.2, and men = 6.9 ± 0.4 for bout 2). This may have favored NH 3 transport from plasma to sweat as accounted for by a significant correlation between sweat NH 3 and H + (r = 0.56). Blood pH increased from rest (mean ± SEM; 7.3 ± 0.02) to the end of exercise (7.4 ± 0.01) without differences among groups. These results, however, are representative of sweat induced by moderate exercise in the absence of acidosis.

Penetration of nanoparticles and nanomaterials in the skin: Fiction or reality?

“…Sweat glands are coiled tubular glands that extend from SC to dermis or hypodermis (2–5 mm in length) and are involved in thermoregulation and excretion of acids and body wastes 4. Their serous fluid is a dilute, hypotonic aqueous mixture (pH 4.0–6.8) of organic acids, carbohydrates, amino acids, nitrogenous substances, vitamins, and electrolytes 84–88. Sweat is excreted at 2–20 nL/min speed from an orifice of 60–80 µm in diameter 4.…”

Kinetic changes in sweat lactate following fatigue during constant workload exercise

“…However, uncontrolled water intake may have little effect because we encouraged the participants to drink water before the test, and a previous report indicated that dehydration had no effect on the blood lactate acid curve (Van Schuylenbergh et al, 2005). Fourth, because this study included healthy college-aged male individuals, further research is needed in females and young athletes based on a sweat functional difference between genders (Frye & Kamon, 1983;Wyndham et al, 1965) and age (Meyer et al, 2007). Fifth, it is possible that psychological factors may negatively affect the three participants who were unable to proceed to Test 2.…”

Alternative matrices in forensic toxicology: a critical review

“…However, factors such as gender, age and physical exercise, may alter this value (which can range from 5.2 to 6.9). It is believed that the volume of sweat perspired daily by the whole body of an individual can amount to between 300 and 700 mL, under normal environmental conditions [74][75][76]. Depending on how sweat sample is collected, it can also include secretions generated by the sebaceous glands.…”