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To investigate the uniform's responsibility for the heat load that players carry, Dr. Mathews set up a controlled experiment. His subjects were seven volunteers, all football players, of various heights and weights, five in their late teens and two in their 20s. The procedure followed was to test each under four different conditions, and in various orders. The first condition required the subject to put on, a scrub suit (a loose-fitting, well-ventilated cotton pajama) and run on a treadmill moving at six miles an hour for 20 minutes. As the subject ran, his temperature, heart rate, water loss, the amount of oxygen he used and the total amount of air he breathed were recorded minute by minute. Then, while the subject rested, the recordings were continued for 30 minutes more. Later the subject wore a complete football uniform, including the helmet, except for rib pads and football shoes (sneakers were substituted). Once again recordings were made of his physiological reactions as he ran at six miles an hour on the treadmill and as he later rested.
For the third condition the process was repeated, except that the subject, again wearing a scrub suit, ran at eight miles an hour for 20 minutes and rested for 30. Finally he performed in the same manner while wearing the football uniform.
Taking as the norm for each subject the reactions recorded while he ran wearing the scrub suit and comparing these reactions with those when the subject wore the uniform, the research team found that the uniform imposed a considerable burden. The subject's heart rate, rate of oxygen use and the total air intake shot up markedly. But even more dramatic were the rises in body temperature and the amount of water loss. When subjects ran the treadmill at eight miles an hour, their average rise in temperature was 33% higher when they wore uniforms than when they wore scrub suits. The average jump in water loss, by the same comparison, was 63%. In addition, the temperature of a subject wearing a scrub suit stayed level for a few minutes after he stopped exercising and then slowly dropped to normal—but the temperature of the same subject in a football uniform continued to rise after he stopped exercising. It dropped back to normal much more slowly. One of the team's conclusions was that the microclimate created inside the uniform prevents effective dissipation of heat. "Naturally," comments Dr. Ashe, "the longer the heat load must be carried, the more danger there is to the player."
To explore the heat-hoarding qualities of the uniform, Dr. Mathews sent one to the U.S. Army Research Institute of Environmental Medicine at Natick, Mass., where Dr. Ralph F. Goldman tested it on the so-called "copper man." This is actually a calorimeter (measurer of heat) in the shape of a human being. Patterned in size after an average taken of 5,000 Air Force cadets, the copper figure is 5 feet 8 inches tall and has the physique of a 175-pound man. It is heated electrically by a network of wires under its "skin" to the desired number of degrees, in the manner of an electric blanket.
Dressed in the uniform for these tests, the copper man's skin temperature was maintained at 92�, the average skin temperature of a man at rest. The room was kept between 40� and 50�. Twenty thermocouples—electrical devices for measuring temperatures at specific areas on a surface—were attached at various points on the copper man, some under the jersey, some under padded areas of the pants, some under the stockings and so on. Then various currents were turned on, and individual thermocouple readings were taken.
When the readings were translated into calories (units of heat), it was found that, while the nonpadded areas of the uniform allowed heat to dissipate, the padded areas did not. Says Dr. Goldman, "To maintain temperature at normal levels, the average player must produce and efficiently evaporate about 1? pounds of sweat an hour. It is well within a person's ability to produce this much sweat. Evaporating this much on a hot, humid day or through this uniform is another story. Inability to evaporate this sweat will, of course, result in increasing body temperatures. A 185-pound player will have a body temperature rise of 1� for each two to three ounces of sweat he is unable to eliminate. Thus, if the humidity is 100%, body temperatures could rise 10� or 11� in an hour, which is intolerable. Heat exhaustion, sheer physical exhaustion or, at worst, heatstroke would occur first. The uniform, with all the plastic or plasticized pads, obviously blocks evaporative heat transfer over 40% to 50% of the body surface." When adhesive tape is worn in addition to the uniform—on the ankles, wrists, thighs or ribs—the percentage of skin available to cool the body through evaporation of sweat is further lowered.
With the padding in the uniform thus identified as a major factor in heatstroke and heat exhaustion, two solutions to the problem suggested themselves to the OSU research team. The first was to see if it was possible to increase the ventilation of the pads. The second—regardless of the success of the first—was to devise a program of acclimatization for players so that they could develop resistance to great heat loads.
Preliminary inquiries by SPORTS ILLUSTRATED indicate that, at the moment at least, manufacturers are reluctant to add perforations to uniform padding, the most obvious way of allowing air to penetrate. Perforations, it is pointed out, inevitably weaken the material, reducing its protective qualities. It is a question of which presents the greater risk—injury to a limb, organ, joint or muscle or the less likely possibility of suffering heat exhaustion or heatstroke. Says Howard Wilkins of the Brunswick Sports Co., a prominent uniform (MacGregor) manufacturer, "The prime purpose of the padding is to protect the player from injury. We haven't been working on this part [the heat factor] of the problem. It has only come to my attention in the last year or so. But I think it can be accomplished without perforating the padding."
The padding is not the only problem. Because the head functions somewhat like a chimney flue in drawing heat upward and allowing it to dissipate, covering the head and part of the face with a helmet likewise interferes with the body's efforts to cast off heat. Some helmets have small holes at the top and some do not; most have shock-absorbent features that provide protection for the player's head. None of them, however, provides good ventilation. Further research by equipment manufacturers obviously is called for. In the meantime, Dr. Mathews recommends that players be allowed to remove their helmets when opportunities arise—in lulls during practice or time-outs during a scrimmage or a game.
Despite the attention they are now receiving, it is not likely that the pads or the helmet will be changed drastically in the near future. Dr. Mathews therefore advocates a program of acclimatization whereby a player can become "90% accustomed, after five or six days, to the heat load he must carry." During this period there should be about two hours' practice in the morning and two in the afternoon. On the first day players should wear shorts and tennis shoes. In morning and afternoon they should alternate 20 minutes of workout with 20 minutes of rest in the shade. On the second day, still in shorts and tennis shoes, they should work out for 23 minutes, then take 20 minutes of rest in the shade. On the morning of the third day, 26 minutes of workout in football uniform, 20 minutes of rest in the shade; in the afternoon, the same schedule of workout and rest, in shorts and tennis shoes. On the fourth day, morning and afternoon, 30 minutes of workout in uniform, 20 minutes of rest in the shade. On the fifth day, morning and afternoon, 50 minutes of workout in uniform, 15 minutes of rest in the shade. "The healthy human body readily adapts itself to withstanding heat stress," Dr. Mathews says, "but the adaptation must be gradual. If a team can't fit this program into existing schedules, it should start practice a week early."