Association between the increase in brain temperature and physical performance at different exercise intensities and protocols in a temperate environment

There is evidence that brain temperature (Tbrain) provides a more sensitive index than other core body temperatures in determining physical performance. However, no study has addressed whether the association between performance and increases in Tbrain in a temperate environment is dependent upon exercise intensity, and this was the primary aim of the present study. Adult male Wistar rats were subjected to constant exercise at three different speeds (18, 21, and 24 m/min) until the onset of volitional fatigue. Tbrain was continuously measured by a thermistor inserted through a brain guide cannula. Exercise induced a speed-dependent increase in Tbrain, with the fastest speed associated with a higher rate of Tbrain increase. Rats subjected to constant exercise had similar Tbrain values at the time of fatigue, although a pronounced individual variability was observed (38.7-41.7°C). There were negative correlations between the rate of Tbrain increase and performance for all speeds that were studied. These results indicate that performance during constant exercise is negatively associated with the increase in Tbrain, particularly with its rate of increase. We then investigated how an incremental-speed protocol affected the association between the increase in Tbrain and performance. At volitional fatigue, Tbrain was lower during incremental exercise compared with the Tbrain resulting from constant exercise (39.3±0.3 vs 40.3±0.1°C; P<0.05), and no association between the rate of Tbrain increase and performance was observed. These findings suggest that the influence of Tbrain on performance under temperate conditions is dependent on exercise protocol.

Deseos en los adolescentes de la calle / Wishes in the adolescents street children

Identificar los 3 deseos más frecuentes de 42 adolescentes de ambos sexos entre 10 y 17 años, albergados en las casas "Abuelita Mami" y " Mi Tío Simón", de la Alcaldía de Caracas y compararlos con los deseos de 42 pacientes de la consulta de Medicina del Adolescente del Hospital J.M de Los Ríos en el lapso marzo-junio de 1997. El deseo más frecuente se relacionó con estudios (33 por ciento) en muchachos de la calle. Otros fueron buena salud (19,5 por ciento) en niños de consulta. Unión familiar y afecto: todos los grupos, especialmente muchachos de la calle (11,9 por ciento). Trabajar: muchachos de la calle (14,2 por ciento). Recreación: niños de la calle (14,2 por ciento). A ambos grupos se les aplicó un instrumento de autoevaluación, en el cual se solicita la descripción de tres deseos que se analizaron de acuerdo a orden de frecuencia por método porcentual. Los deseos fueron diferentes en ambos grupos de adolescentes. Los muchachos de la calle desean estudiar y trabajar. Es importante reinsertar a los muchachos de la calle a su núcleo familiar, debido a la carencia afectiva que manifiestan a través de los deseos