ABSTRACT
Introduction:
Sweat and its consequent evaporation are essential for maintaining body temperature during the exercise.
Objective:
To evaluate the loss of calcium (Ca++), magnesium (Mg++) and iron (Fe++) in the sweat of runners and active individuals.
Methods:
Fifteen long-distance-runners {VO2máx = 68 ± 5.4 ml (kg.min)-1} and 15 non- athletes active subjects {VO 2máx = 50.3 ± 6.3 ml (kg.min)-1} with mean ages of 25.3 ± 2.4 and 23.1 ± 4.3 years, respectively. Both groups exercised for 80 minutes on a treadmill, with intensity of 75-85% of reserve heart rate, and ingested 3 ml of water/kg of body weight every 15 minutes. The environmental conditions of the test were 21.9 ± 1.5 °C and 89.2 ± 5.6% relative humidity for athletes and 21.8 ± 1.6 °C and 93.2 ± 3.5% RH for active individuals. The sweat samples were collected at regular intervals of 20 minutes in the chest, thoracic and lower back regions for further analysis of the minerals Ca++, Mg++ and Fe++ by atomic absorption spectrophotometer.
Results:
No significant differences were recorded for the minerals in relation to fitness level. There was a tendency for a decrease in Mg++ and Fe++ concentrations of sweat over the course of the exercise.
Conclusion:
In the environmental and exercise conditions studied, the conditioning does not interfere in the loss of Ca++, Mg++ and Fe++.
Keywords:
fluid therapy; minerals; exercise.