HONEST SWEAT
I was thrown out of an aerobics class years ago for pulling a groin muscle: it wasn’t mine. Another riveting personal detail is that I’m an Olympic sweater. Not the common or garden sweat that appears in the palms on a first date, or the glow that appears after 20 minutes on the treadmill, but a good two litres of liquid in an hour’s intense, high-energy workout. I don’t sweat; I leak.
Sweating is an essential physiological function. If you don’t sweat, you could die. Sweating lowers the body’s temperature, thus cooling you down. When the body’s temperature rises, the heart automatically beats faster to pump blood to all the organs, so as to absorb their heat.
As activity intensifies, the blood itself will grow too hot to cool the organs, and this triggers the sweat reflex.
The heat generated by exercise is significant. The increased energy needs of the body stimulate the combustion of more fuel, only about 25% of which is converted into an energy form which generates a better work capacity. Seventy-five percent is released in the form of heat. This explains the mandatory rise in body temperature that always accompanies exercise.
The body generates an incredible amount of heat energy, which is so powerful that it evaporates litres of sweat liquid. The capillaries just beneath the surface of the skin open up to enable heat raised by exercise to get closer to the surface, creating the flushed and red state many exercisers experience after working out.
In hard exercise, we can produce enough heat to evaporate litres in an hour (put that in a pot on the stove and witness how much heat is required to make all that liquid disappear!). For every litre of sweat that evaporates, up to 2500 kilojoules of heat energy may be released from the body.
Sweating is the process during which the water evaporating from the body surface produces the cooling effect on the skin, and on the blood which flows directly beneath it. If your body, which generates up to 15 times as much heat as in your resting state, doesn’t sweat properly, you can boil yourself alive!
The sweat mechanism is your body’s way of dissipating this heat over the entire surface of the skin (our largest organ) to facilitate this natural air-conditioning activity.
As sweat evaporates on the skin’s surface, it cools the body and prevents hyperthermia (that dangerous state in which an adult’s body temperature rises above 40 degrees Centigrade). The good news is that a fit person sweats more than his out-of-shape neighbour. His sweat mechanism is more finely tuned, as are all his other bodily systems, and when his core temperature starts to rise, he will immediately start to sweat in compensation. Naturally, evaporation may make this process invisible. Unfit people heat up more quickly but their sweat function takes longer to kick in. The fit are more efficient at cooling their bodies. Males sweat more than females. Archaic lore dictated that women merely ‘glowed’, but today, as real women replace males in the boardroom, they sweat heartily and healthily, too.
In humid climes extra care should be taken to prevent dehydration. Much of the liquid we lose in sweating comes from the blood. Because a good 70% of the body is composed of water, this can have potentially serious consequences. The male body averages about eleven pints of blood (we donate pints of blood and still call for a pint in the pub!), which weighs around 5 kg. If you sweat 2 kg or more during a hard workout, at least half of that water is from the blood, so your blood volume is lowered and your blood made less watery and more sluggish, and it doesn’t function as efficiently in carrying oxygen to the working muscles.
If you don’t rehydrate the body while you’re still active, oxygen-starved blood will continue to reach the muscles, but the flow of blood to the skin will decrease, as will sweating, in order to conserve water. With your body heat now increasing dangerously, and the essential sweating mechanism being prevented, you risk heat stroke and break down: you will be hot to the touch, but your skin will be dry.
Water, then, is the most vital ‘health food’ and supplement for any exerciser. You sweat liquid and your body needs to replace this regularly. Sip cool, not iced water (which passes more efficiently through the stomach and into the bloodstream) before, during and after exercise.
Don’t overdress or wear impermeable rubber or plastic outfits as these interfere with the air’s cooling convection process, which acts to evaporate the sweat on the skin’s surface. The ignorant, who think that one can sweat off fat, are deluded. They merely lose liquid, never fat, and the weight loss is merely temporary, until the liquid is replaced.
Little men on horses, or too-heavy boxers at the weigh-in, may force-sweat a temporary weight loss to make it through the preliminaries, but following suit will weaken you and put your blood plasma volume at risk. Dehydration is dangerous and saunas in climates like Durban’s are a curse, with foolish homeboys and girls playing at being Scandinavians and overloading already heated systems which have sweated during activity and certainly don’t need extra heat burdens.
The nonsense about flushing impurities and toxins out of the body is just that. You sweat liquid-not toxins or impurities. Your kidneys and liver take care of the heavies.
Saunas or hot showers after workouts should be avoided as the heat dilates your blood vessels. Blood often pools in the extremities immediately after strenuous exercise, and the heart and brain receive less blood, so one can experience dizziness and risk injury from falls.
Finally, don’t take extra salt to compensate for any sodium loss through sweating. Even though sweat tastes salty (‘Ah, a Chateau 69, a cheeky little number, with a mere hint of the smack of the ocean…’), there is almost never a shortage of sodium in the body, no matter how copiously you may perspire. Additional doses of salt only increase the body’s real lack-of fluid. The more salt you ingest, the more fluid the body needs.
So, train hard, sweat well, drink water regularly, and remember, exercise comes with a life-time guarantee!
drphil