Safety precautions for summer training. (Powerline).

THE SUMMER OF 2001 witnessed several devastating training and practice-related deaths at just about every level of play. Each incident had its own set of special circumstances, but the heat and/or humidity was at least partly culpable in each case.

As coaches, we were frustrated and haunted by questions and second-guessing. What, if anything, could have been done to prevent these tragedies? Even with all of the scientific information available, there were no clearcut answers. But we were obligated to continue our search for every piece of wisdom we could unearth for the safety of the athletes on our watch.

As we enter the summer of 2002, let us review the basic physiological stresses induced by a hot environment and how the body responds and adapts to them. And, more importantly, let us zero in on the safety precautions that coaches have to take.

Adapting to the Heat

Research has taught us that summer conditioning procedures are necessary for heat acclimatization and that the training must be gradual, progressive, and prudently executed, with detailed attention to the environmental conditions.

Acclimatization is a process involving both physical and psychological adaptations to a new or changing environment. It may be a move from a cooler to warmer climate, or simply an adjustment from the mild temperatures of spring to the hot and humid conditions of summer.

Following is an over-simplified explanation of the body's adjustment to external heat during exercise: The cardiovascular system (CVS) will compensate for the heat by shunting blood to the skin. This will improve the body's ability to cool itself by dissipating internal heat, but will diminish the blood supply to the working muscles.

If the air temperature is mildly warm, the body can release a portion of the internal heat overload through sweat evaporation. But when high humidity is coupled with warm air temperatures, it doubles the body's thermal stress and may stifle the body's ability to evaporate the sweat and cool itself.

This "Catch 22" happenstance will force the CVS to meet the competing demands of the thermoregulatory system and the requirements of muscle metabolism.

This physiological dilemma will be exacerbated whenever hydration is inadequate and/or the activity is prolonged, resulting in a convolution of heat-related problems.

Acclimatization can reduce the risks. The process encompasses approximately 10-14 short, less intense training sessions in the warmer environment. The initial duration of these workouts should be between 20-30 minutes at a low to moderate intensity level, with liberal fluid breaks.

There should also be a gradual build-up in the frequency of the sessions. Our football training, for example, starts with two days per week from mid-May through mid-June and progresses to 3-4 days per week from mid-June through July.

Areas that have extremely hot and humid climates would be wise to hold the initial workout sessions during a milder part of the day (early morning/early evening). This will produce a gradual acclimatization to the variable conditions throughout the day.

Heat acclimatization offers the following physiological benefits:

1. Reduction in heart rate.

2. Reduction in core temperature.

3. Increase in the cutaneous (skin) blood flow and perspiration rate that facilitate the cooling process.

4. Earlier beginning of perspiration, thus expediting the cooling process.

5. Decrease in the loss of vital electrolytes (minerals such as potassium and sodium).

To summarize: The gradual, systematic, and progressive steps in the acclimatization process will eventually produce well-conditioned athletes with a much higher heat tolerance than their sedentary counterparts or zealots who rush blindly into summer conditioning drills.

Wet Bulb Globe Temperature 

Our sports medicine staff uses a "sling psychrometer," a hand-held instrument that measures the heat stress index before every scheduled workout or practice. The heat stress index is calculated by a Wet Bulb Globe Temperature (WBGT), which takes into account the air temperature, relative humidity, and solar radiation.

It is very important to know the relative humidity, which is a measure of how much moisture the air contains, since it affects the amount of heat that can be lost through the evaporation of heat. A hot and humid day that is compounded with limited air movement severely hampers the body's ability to cool itself through convection.

The WBGT index is a practical measurement for assessing potentially harmful environmental conditions. The readings are gauged into low, moderate, high, and hazardous risk categories, providing the sports medicine and coaching staffs with solid information that will help them make prudent decisions on the duration and intensity of the workout/practice.

If the reading gauges a "high" or "hazardous" risk, the activity may be rescheduled for a safer time or day.

We recommend that at least two of your staff members learn how to take the WBGT by using the sling psychrometer prior to all summer workouts and practices.

Identifying Heat-Related Stresses

Two heat-related stresses of paramount concern are heat exhaustion and heat stroke. Coaches must be aware of the symptoms and immediate care procedures for each problem.

Heat exhaustion, while rarely a life-threatening condition, can lead to more serious problems if left unattended. The symptoms of heat exhaustion can include headache, nausea, dizziness, light-headedness, rapid pulse, and muscle cramps.

An athlete with any of these symptoms should be required to stop the activity, be taken to a cool, shady area, and told to sit or lie down in a supine (with slightly elevated feet) position. Cool liquids (water or a sports drink) can then be given to sip on. Activity should not be resumed until all of the symptoms have passed and qualified medical clearance has been granted.

Coaches must understand that heat exhaustion, when left untreated, can lead to heat stroke -- a significantly more dangerous condition.

The symptoms of heat stroke can vary, but may include any or all of the following: disorientation, an extremely high body temperature (above 103 degrees Fahrenheit orally), red, hot, dry skin, rapid, strong pulse, nausea and/or vomiting, throbbing headache, and unconsciousness.

If any of these warning signs are detected, you must understand that you are dealing with a potentially life-threatening emergency requiring medical assistance.

Do the following immediately:

* Call 911 for emergency assistance, or the closest, most readily available medical staff in your situation.

* Get the victim to an air-conditioned or cool, shady area.

* Cool the victim with any available means; water hose, shower, wet towels, farming, etc.

* If severe nausea and vomiting are apparent, do not administer fluids. Make sure that the airway is clear if the individual is unconscious.

* If possible, monitor body temperature until it drops below 101 degrees Fahrenheit.

Hydration

It is vitally important to incorporate and maintain a sound hydration strategy for workouts, practices, and games. Unfortunately, an athlete's thirst mechanism is a poor indicator of actual fluid needs.

During exercise, athletes should start drinking cool (50-59 degrees F.) fluids at a rate of at least 8 ounces every 15-20 minutes. Water is fine, but for intense activities lasting longer than one hour, the sports carbohydrate/electrolyte drinks may be a better choice. Reason: They provide needed energy and mineral replacement, as well as fluid replacement. The palatability of these drinks also encourages a higher usage, which helps in meeting the objectives.

Fruit juices and soft drinks that have a 12% or higher carbohydrate concentration are not good choices during exercise, as they may cause gastrointestinal distress. Fruit juices are fine for post-exercise recovery, and it might be a good idea to avoid all carbonated, caffeinated soft drinks.

Pre-hydration is a critical component in this strategy Athletes should drink the appropriate beverages liberally throughout the day and evening, and should be encouraged to take a plastic water bottle to meetings, class, etc., and to drink from them regularly.

Approximately two hours prior to an intense workout or competition, the athlete should gradually ingest at least 17-18 ounces of fluid.

Post-exercise/competition hydration calls for at least 20-24 ounces of fluid for every pound of body weight lost (which is primarily fluid loss).

Athletes should be taught to monitor their urine for signs of dehydration. Dark yellow urine and little or no urine over the course of several hours can be indicators of dehydration. Ideally, athletes should urinate every couple of hours and it should be relatively clear in color.

Final Rep

Further suggestions for preventing heat-related problems:

* Perform warm-up activities in the shade whenever possible to prevent sudden excessive rises in body temperature.

* Wear loose-fitting, light-colored clothing when possible.

* Adjust the intensity and/or the duration of the workout session in accordance with the environmental conditions and the conditioning level of the athletics.

* Be aware of the "perceived exertion" or the outward distress indicators that the athletes may be telegraphing via their body language. Their inability to produce the desired effort can be a precursor to heat stress.

Exercise-Induced Asthma

Exercise-induced asthma (ETA) affects approximately 15% of the general population. Its symptoms range from coughing, wheezing, chest tightness, shortness of breath, and fatigue to prolonged recovery times after exercise.

Asthma is an obstructive disease of the airways that is categorized by inflammation, bronchial wall edema (swelling), and mucus production. ETA is airway obstruction brought on by the combination of exercise and numerous environmental conditions (e.g., temperature, allergens, pollutants, etc.)

It is important to recognize the potential symptoms of this condition for medical referral. With proper treatment and precautionary measures in place, EIA can be effectively controlled and managed.

SEND YOUR QUESTIONS TO: Ken Mannie, Michigan State University, Duffy Daugherty Building, East Lansing, Ml 48824

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