Heat Production in Exercise
As in other mammals, humans produce more heat as they increase the intensity of muscular activity, such as that which takes place during exercise. The quantity of heat is roughly proportional to their size, strength, will and ability to work intensely.
As the brain overheats, thinking becomes fuzzy and the will degenerates, thus compromising optimal intensity of effort. Beyond this, excessive heat becomes a threat to life. This can be a critical situation for obese and/or elderly subjects. And specifically, heat is also a critical factor for certain medical conditions, such as multiple sclerosis.
The dissipation of heat is multi-factorial. The ideal combination of factors includes:
• Low ambient temperature (within reason)
• Low ambient humidity
• Ample ventilation.
The Body’s Evaporative System
Sweat glands reside in the skin all over the body. Increased temperature stimulates them to excrete sweat which is mostly water. This moisture, in the presence of dry air, evaporates. This evaporation is endothermic, which means that heat is acquired (in this case to the water vapor) during the process. Thus the heat is given up by the body.
The mechanics are as follows: The body conducts heat to the water. The water then leaves the inside of the body carrying the heat with it to the surface of the body. Then in a low-humidity atmosphere, the water evaporates, using the heat of the sweat as well as drawing more heat from the body to accomplish the evaporative process. Knowing the foregoing information, we can plan the ideal atmospheric controls for a workout.
• The first recommendation is to keep the room temperature about 68 degrees Fahrenheit and to maintain this with refrigerated air. Refrigerated air, by its very process, removes water vapor from the air as it cools.
• The second recommendation is to keep the subject well ventilated. In other words, use fans to constantly move the air onto the subject.
• The third recommendation regards workout apparel. Clothing should be close-fitting, not baggy or loose, but not tight as to be constrictive.
• The kind of fabric is also important. Avoid popular so-called “warm-up suits” of any kind, particularly those made of synthetic and water repellent fabrics that hold in heat and moisture.
• Avoid long leggings, long sleeves and tight closures, such as turtlenecks that tend to trap heat.
• Avoid Headgear, as heat dissipation is dramatically greater through the nape and scalp; it does not make much sense to cover or constrict these areas. For these same reasons turtleneck tops, scarves, wigs and high collars are to be avoided.
• Subjects who bundle up for a workout can’t be seriously interested in obtaining the best possible workout. That point in the workout where they normally become overheated and lose will and motivation will come sooner in the sequence of exercises because they dress warmly. They should not peel off their outer sweater as they warm up, but should instead start the workout pre-cooled, almost to the point of discomfort.
• As a threatening threshold of temperature is reached, the body starts processes to cool itself. In general, it is important to start the processes well before a damaging and critical temperature is reached—in the case of the workout—before heat rises to thwart the best exercise effect.
• When informing subjects that their sleeves are too long for efficient exercise, they invariably and instantly respond by rolling up their sleeves. This, of course, makes the situation worse, as the arms are then constricted and ventilation is blocked.
• Sometimes, subjects complain that the cold air in the gym gives them a sore throat. Note that this is not an actual infection-type sore throat. Their throat is merely dried and irritated due to the initial heavy ventilation of dry air produced by the refrigeration process—a kind of mild abrasion. It will go away after the first workout in most cases.
Four Reasons to Dress Briefly and Snugly During Exercise
• To Dissipate Heat
• To Enable Your Instructor to Visualize Alignment
• To Enable Your Instructor to Detect On/Offing
• To Minimize Hang-ups on the Equipment Leading to Injuries