In a warm or hot environment, it is particularly important for an adult performing physical labor or exercising to drink plenty of liquid, so as to maintain proper functioning and correct bodily condition.
Hydration and physical activity: staying on top form
Water is an essential exercise partner, to counteract the negative effects of dehydration on performance and health. Adequate hydration before and during physical activity helps regulate temperature, replace fluid loss and, afterward, restore complete water balance(1).
The main conditions leading to a fluid deficit are high ambient temperature, high humidity, restricted fluid availability and clothing that traps heat and perspiration. Consequences include decrease of blood volume, increased heart rate, hampered thermoregulation and lowered exercise capacity.
When the environmental temperature exceeds 30°C, dehydration leads to a 2% loss of body weight and decreased endurance and skill. A 3% drop in body weight results in a decline of muscular power and strength. The more physically active a person is, the greater is the amount of water needed to maintain balance and sustain performance.
Except for those engaging in a very prolonged endurance exercise (> 2-3 hours) in a warm environment, there is no need to add large amounts of minerals to the fluids ingested before, during and after exercise. More water than minerals is lost during perspiration so proper fluid replacement should focus on water, not minerals.
For short periods of exercise (60 minutes or less), there is no evidence that ingestion of carbohydrates has any effect on fatigue or performance. Evidence does show, however, that carbohydrate intake postpones fatigue and increases endurance for exercise lasting around 90 minutes or more(2).
Healthy hydration in the workplace
Individuals performing intense physical labor in warm or hot environments can suffer from dehydration on a daily basis. Lack of hydration may adversely influence decision-making and cognitive performance and contribute to a decline in productivity as well as increase the risk of work-related accidents(3).
Education is essential to helping workers maintain proper hydration during and after a work shift. Those working in a hot environment should be informed about hydration assessment, signs and dangers of dehydration and strategies for maintaining hydration while working. Adequate bathroom facilities also help workers manage their hydration during shifts.
Workers can maintain healthy water balance by arriving onsite well hydrated, keeping a full water bottle/container at hand at all times and drinking during breaks and meals.
Sources: (1) Sawka et al. Exercise and fluid replacement. Medicine and Science in Sports and Exercise 2007, 39 (2): 377-390; (2) Péronnet F. Healthy Hydration for physical activity, Nutrition Today 2010, 45 (6S): S41-S44; (3) Kenefick et al. Hydration at the work site. Journal of the American College of Nutrition 2007, 26 (5): 597S-603S Miller et al. Hydration, Hydration, Hydration. Ann Occup Hyg 2010, 54 (2): 134-136