Its Cool to Sweat by Allan Bolton BHMS (Hons)
We all know people who sweat buckets when they exercise. and others who hardly shed a drop. So why do some people sweat more than others when exercising?
It is commonly believed that people who sweat a lot are out of shape, but in fact the opposite is true. Your sweat glands respond to exercise by becoming larger, allowing them to release more water and cool your body more effectively. This means as your fitness increases you sweat sooner and sweat more, and as a result, face less risk of overheating.
Sweating is an important process your body uses to dissipate heat. Even during moderate exercise, heat production can be ten times greater than at rest, and evaporation of sweat accounts for about 80% of this heat loss (compared to 20% at rest). When you are exercising, increases in your brain blood temperature causes the body's thermostat (the hypothalamus) to stimulate the body's millions of sweat glands into action. When sweat reaches the skin surface it evaporates, which in turn cools the surface blood supply.
Why do we sweat more in closed spaces full of people?
When you pack a room with warm exercising bodies, the air temperature and relative humidity increase significantly. This makes your body retain more heat, which in turn makes you sweat more. Low airflow and higher humidity reduces the rate that sweat evaporates, making it even harder for you to dissipate heat. It's because of this that you seem to sweat more - sweat drips off you as liquid rather than evaporating as vapour. The higher the ratio of people to space and the more enclosed the space is, the more likely you are to be a drip!
Why do some people get a red face from exercise, and others not?
You get a red face because your sweating mechanism isn't keeping pace with the heat you're producing. So your body directs more blood to the surface for cooling, hence the red face. As your fitness improves you start sweating earlier and you sweat more, which reduces your body's need to make you go red in the face. Don't worry if you are really fit and still go red, as some people redden regardless of fitness - this is a genetic factor
Do we sweat when exercising in the water? Regardless of where you exercise, if you get hot enough you sweat. Sweat produced while exercising in water doesn't cool you effectively because it doesn't evaporate - it's simply rinsed off by the water. When you're in the water, heat is mainly lost through direct body contact with water via conduction and convection. Just because you exercise in water doesn't mean that you don't need to replace fluids during and after exercise.
If I don't sweat much, does this mean I am not fit enough?
No, sweat rates vary a lot and change with fitness relative to the individual. So as your fitness increases so will your sweat rate, relative to how much you sweat now.
Should I drink more, the more I sweat?
Everyone should drink enough to replenish the fluids they use. It might seem natural to wait until you are thirsty to drink, but our thirst mechanism is only triggered when we are partly dehydrated. Our bodies are approximately 55% to 65% fluid, and when some of this fluid is lost through sweat, it affects our cardiovascular system and our ability to control temperature. If these fluids aren't replaced as they are lost there is a very real danger of cramps, exhaustion or heat stroke. One way to calculate your individual requirements is to weigh yourself before and after exercise, and replace each 0.5 kg of weight loss with 750 ml of water.
Courtesy of Network for Fitness Professionals - Network is a national rnembership association for the fitness Industry
Web site: www.globalfit.net