RESUMEN
The purpose of this study was to evaluate the effects of human head hair on thermoregulation during exercise carried out under solar radiation. 10 healthy male subjects (mean±SD: 25.1±2.5 yr; height: 176.2±4.0 cm; weight: 73.7±6.7 kg; VO(2max) 56.2±5.3 mLO(2)·kg (-1)·min (-1)) took part in 2 1 h-long trials of continuous exercise on a treadmill at 50% VO2(max) under solar radiation that were separated by at least 2 days. Whereas for the first trial they retained their natural head hair (HAIR), in the second trial their hair was totally shaved (NOHAIR). Several properties were measured, including environmental heat stress (Wet Bulb Globe Temperature index - WBGT, °C), heart rate, rectal temperature, skin temperature, head temperature, and global sweat rate. The main findings were that whereas there was a lower sweat rate in the HAIR condition (HAIR: 7.08±0.79 vs. NOHAIR: 7.67±0.79 g·m (-2)·min (-1); p=0.03), there were no significant differences in any of the other variables between the HAIR and NOHAIR trials. In conclusion, the presence of head hair resulted in a lower sweat rate.
Asunto(s)
Regulación de la Temperatura Corporal/fisiología , Ejercicio Físico/fisiología , Cabello/fisiología , Sudoración/fisiología , Adulto , Prueba de Esfuerzo , Cabeza , Humanos , Masculino , Carrera , Luz Solar , Adulto JovenRESUMEN
BACKGROUND: Temperament relates to emotions and the prevailing mood or affective temperament. Uric acid (UA) is the end-product of purine metabolism and has been associated with psychological features such as high energy/drive, positive affect, achievement, good performance, higher social status and leadership. METHODS: 129 subjects (44 males, 85 females) completed with the Combined Emotional and Affective Temperaments Scale, serum UA levels and a general health questionnaire. RESULTS: In the whole sample, serum UA levels were significantly correlated with disinhibition (r=0.36, p<0.001) and drive (r=0.25, p<0.01), but not with control, anger or any of the affective temperament scores. Among males, we found correlations at trend level (p>0.05 and <0.07) for control (r=0.27), irritable (r=0.29) and hyperthymic (r=0.27) affective temperaments. Among females, a significant correlation was found only with disinhibition (r=0.34, p=0.001). The top tertile of males (serum UA>6.0 mg/ml, n=16) had significantly higher drive (29.9+/-5.9x26.0+/-3.6, p=0.01) and higher control at trend level (21.2+/-3.1x19.3+/-2.9, p=0.054) than other males. Among women, the top tertile (serum UA>4.0 mg/ml, n=29) showed higher disinhibition scores (20.7+/-4.9x17.9+/-3.6, p<0.01) and more frequent choices of hyperthymic (8/26x6/59, p=0.023) and irritable temperaments (7/26x5/59, p=0.031) than the rest of the sample. Controlling for daily intake of meat and grains, which could lead to higher UA levels, did not change these results. LIMITATIONS: Small sample size for males. CONCLUSIONS: Externalized traits of temperament are associated with higher serum UA levels both in men and women.