Environmental Considerations

Environmental Considerations


Your surroundings can have considerable influence on your fitness program and lifestyle. Weather conditions, pollution, and population factors need to be taken into consideration when carrying out your personalized activity program.

Environmental factors can often elevate people's stress levels. Background noise, weather extremes, overcrowded public transportation, and poor air quality are just a few of the everyday stressors we deal with. As a result, our eating and sleeping habits, interpersonal relationships, and attitudes may be negatively affected. It is often helpful to utilize stress management techniques to minimize negative consequences arising from such environmental influences.

In addition, we need to tailor our activity levels and clothing choices according to environment and climate. Urban areas are usually more densely populated with a concurrent increase of traffic and pollution. While participating in outdoor activities like walking, running, or biking, you should seek out routes less plagued by heavy traffic or choose private or indoor tracks if available.

If biking, ride with the traffic and pay close attention to the sounds and sights of the road. If walking or running outdoors, face the oncoming traffic. Remember to watch for cyclists and pedestrians as well as motor vehicles.

Avoid exercising in dangerous or high-crime areas. If you must venture into such areas, exercise with a partner and bring a whistle or personal alarm with you. Also try to exercise during daylight hours.

Rural and suburban areas can be dangerous as well. While pollution may not be as bad in rural surroundings, there is no guarantee that this will be the case.

When swimming in lakes, rivers or oceans, remain aware of your surroundings. Pay close attention to other water traffic, including canoes, motorboats, jet-skis, and other swimmers. Look out for posted warnings or signs and beware of adverse weather conditions. Be realistic concerning your swimming capabilities before attempting to swim greater than usual distances or in rough water conditions.

When exercising at night, make yourself more visible by wearing lightly-colored or reflective clothing and using a light. This is especially important for those who exercise along roads. Avoid staring into oncoming headlights when facing traffic to prevent temporary blindness. Keep to well-lit areas when possible and remain aware of what is going on around you. Avoid wearing headphones if you are walking, running or cycling on roadways.

Beating the Heat

Extreme weather conditions can seriously affect your exercise performance. The dangers related to high temperatures and humidity are quite serious.

Heat can sap your strength and endurance, causing decreased exercise performance. At the same time, your heart must work harder to send blood to the muscles and skin during exercise.

In addition, your muscles do not function as effectively as they normally would. Activity in hot and humid weather increases fluid loss while raising core body and muscle temperatures. With this temperature rise, the muscles do not extract oxygen as efficiently as they do at lower temperatures. Thus, energy production and force of muscular contraction are decreased. Your body has to work harder and expend more calories to exercise in heat and humidity. Increased heat production during exercise can also increase resting metabolic rate and the energy costs of food absorption, metabolism and storage.

The "benefits" of increased caloric expenditure for exercising in the heat are by far outweighed by the possible negative consequences. When the core temperature of the body is excessively high, the circulatory system suffers, limiting the heart's capacity to deliver oxygenated blood to the working muscles and skin fast enough.

The elevated temperature of the body results from the combined heat loads of the outside temperature and the heat produced by your own metabolic activity. As the intensity of exercise rises during such conditions, the body is subjected to increasingly greater stress while trying to shed the excessive heat. The increased sweating can eventually lead to dehydration. Progressive dehydration results from an inadequate sweat gland response to body heating during exercise.

Dehydration involves a decrease in blood volume to the point that there exists an inadequate amount of blood to supply the skin, muscles and internal organs like the brain and liver. Your body chooses to direct the blood flow to the organs and working muscles. The accompanying shutdown of blood transport to the skin causes body temperature to rise dramatically.

Dehydration can lead to a condition called heat exhaustion. As your body continues to dehydrate, you will grow progressively weaker. Other symptoms may include elevated body temperature, extreme sense of fatigue, weakened muscles, sudden weight loss and even changes in personality.

To counteract the effects of heat exhaustion or the heat cramps that might accompany this condition, stop exercising and consume large amounts of mineral-rich fluids such as fruit juice. By itself, heat exhaustion is normally not extremely serious. However, if you continue to exercise while suffering heat exhaustion, you grow more susceptible to the danger of heat stroke.

The sudden, uncontrollable rise in body temperature and the body's failure to regulate core temperature and dissipate heat can eventually lead to heat stroke. Heat stroke is the most dangerous condition that can result from exercising in unfavorable heat and humidity conditions. A potentially fatal disorder, heat stroke is characterized by short, labored breathing, parched feelings in the mouth, blurred vision, sensations of "burning" muscles and lungs, dizziness, nausea and possible sequences of irrational thought and action.

If you ignore these signs and continue to exercise, your skin will grow dry and sweating will completely stop. You will then lose conciousness. Without proper treatment, death will result. The abnormally high level of core body temperature will literally cook your brain cells. The elevated blood temperature also prevents clotting. As a result, blood can leak from the blood vessels into the brain, heart, liver and kidneys, causing even greater damage. In addition, the continuing drop in blood volume may eventually shut down your circulatory system due to inadequate blood supply. The end result is shock.

If someone you know collapses from heat stroke, seek medical help immediately. The longer the person goes without proper medical attention, the greater the chance of death. While awaiting the ambulance or emergency medical services, take the following steps:

  • Place the victim in shock position with head down and feet elevated.
  • Pour large amounts of liquid of any type all over the victim's body. The evaporation will help cool body temperature.
  • Rub ice on the skin to open the victim's blood vessels while cooling the body temperature.
  • If the victim awakens, stop treatment and observe to make sure he or she is alert and out of pain. Keep close watch over the victim for at least an hour.

    People who have suffered heat stroke should refrain from vigorous exercise and activity for a minimum of a month following their recovery.

    Also, avoid taking salt tablets at any time. Too large a concentration of salt in your blood can be lethal. In fact, salt excesses can lead to blood clotting, which may result in stroke, heart attack or kidney failure. You should never consume salt tablets unless under the supervision of a physician.

    The majority of people who experience heat illnesses are novice runners and cyclists, pre-season football players, the elderly, and people who suffer from circulatory and respiratory disorders. These groups, along with those with high blood pressure, coronary artery disease, or history of previous stroke should avoid outdoor exercise during periods of high temperature or high humidity.

    The most demanding climate for exercise involves a combination of high heat and humidity. When there is a large quantity of water vapor in the air, as their is during periods of high humidity, sweat doesn't evaporate as readily. Since evaporation is an important method of cooling the body, body temperature is likely to continue to rise. If such climate conditions occur in early spring, when fitness enthusiasts and athletes have not had adequate time to acclimate themselves to exercise in the heat and humidity, the incidence of heat stroke can be quite high.

    Fitness Facts recommends that you pay close attention to the climate conditions when exercising outdoors. A dry-bulb/wet-bulb thermometer which measures temperature and humidity could prove quite useful during the spring and summer months. You can usually find one reasonably priced at your local hardware store. Also, local radio and TV news programs usually provide information about the weather throughout the day.

    When the temperature is over 95 degrees Fahrenheit and the humidity is over 97%, the chances for heat stroke can be extremely high. Only highly-conditioned, heat-acclimated individuals should attempt to exercise under such conditions.

    When the temperature is between 85 and 95 degrees Fahrenheit and the humidity is between 92% and 98%, there is a moderate chance of heat stroke for most people. Those groups which were previously described at risk should avoid exercise under these conditions.

    At 85 degrees Fahreheit and 92% humidity, there exists a low risk that heat stroke will occur. However, it is still important to pay attention to the warning signs of heat stress, heat exhaustion and heat stroke.

    To prevent heat illnesses, follow these tips when planning outdoor activities or exercise:

  • Try to exercise during the cooler parts of the day.
  • Drink plenty of water prior to, during, and after exercising in the heat.
  • Plan on regular fluid breaks. Fluid choices should be cold and relatively low in sugar.
  • Splash water onto the skin when you take your fluid breaks.
  • Be well-conditioned before engaging in vigorous exercise in the heat.
  • Avoid salt tablets (unless prescribed by a medical doctor).
  • Modify your activity levels when heat and humidity are high. Exercise intensity and duration should decrease as humidity and outside temperatures increase.
  • Use a cool place for your rest periods if engaged in interval activity.

    Heat acclimatization is a progressive exercise program that is performed in the heat for one to two weeks. Successful heat acclimatization involves improved circulatory and sweating responses to exercise in the heat.

    Additional improvements include lower skin temperature during exercise, decreased heart rate, decreased core body temperature, decreased salt loss in sweat and earlier onset of sweating. These improved responses all help facilitate heat loss and reduce the risk of heat illnesses.

    To properly acclimate yourself to exercise in the heat, you should begin gradually. For experienced, well-conditioned athletes try the following: On your first day in the hotter climate, do about half of your normal exercise volume. On the second day, attempt to accomplish 60% of your normal workload. The third day should involve approximately 70% of your normal amount of exercise. The fourth day should be 80%, the fifth day should be 90% and the sixth day should be 100%.

    Less-conditioned individuals should exercise for three to five days at each level before progressing. This will allow for a slower, but safer, acclimatization rate. They should also start at a lower percentage of normal workload. Thus, a novice exerciser might spend the first three days in the hotter environment doing only 40% to 45% of his normal amount of exercise before progressing.

    Individuals at higher risk for heat illnesses should seek medical consultation before attempting any heat acclimatization program.

    The Cold Truth

    Cold weather also influences exercise performance and body temperature. In fact, exposure to temperatures cold enough to reduce the body's core temperature can negatively affect endurance exercise performance by decreasing VO2 Max, or maximal aerobic power.

    In addition, when the temperature is lower than your core body temperature, you lose heat to the environment. To replace that loss, your body increases its resting metabolic rate. The involuntary muscular act of shivering serves to produce additional heat.

    The degree to which cold affects you during exercise is dependent upon two primary factors: your present fitness level and skinfold thickness. The greater your level of fitness and conditioning, the easier time you should have adapting to activity in cold weather.

    In addition, since subcutaneous fat is such an effective insulator, the thicker the skinfold, the greater one's resistance to heat loss. However, the benefits of thicker skinfolds in relation to tolerating cold weather do not offset the negative health consequences of being overweight.

    Wind exposure will intensify the effects of cold weather. Be sure to take the wind force and direction into consideration when exercising outdoors in cold weather.

    It is important to engage in extensive warm-up procedures before starting any activity in cold weather. Generally, you should plan to exercise more intensely and longer than usual during the warm-up phase immediately prior to the activity itself. Some people find it beneficial to warm-up and engage in stretching while indoors, then warm-up again outdoors right before the event or exercise begins.

    Appropriate clothing should be worn in a layered fashion, so that you can remove garments as your body temperature rises during exercise. For more specific information regarding clothing and climate considerations, please refer to the clothing discussion at the end of this section.

    There are some serious risks associated with exercising in cold weather. Some of the factors that influence cold weather-related injuries are:

  • Prolonged exposure
  • Subfreezing temperatures
  • Inadequate clothing
  • Dehydration
  • Wind chill
  • Wet clothes
  • Poor nutrition
  • Injury
  • Fatigue
  • Consumption of large quantities of alcohol

    As just described, dehydration can occur during cold-weather activities. Well-meaning enthusiasts often make the mistake of bundling up head to toe with unlayered clothing before beginning their activity session. Unfortunately, as they exercise and their body temperatures begin to rise, the heavy clothing prevents the effective removal of heat by way of sweat and evaporation. This is the primary reason for layering clothes. The harder and longer you exercise, the more heat your body produces. As body temperature rises and sweat production increases, clothing can be removed so heat can be effectively transferred away from the body.

    Many people believe that since it is not hot outside, they don't require as much water as they do during warmer conditions. On the contrary, you should drink as much water exercising in the cold as you do in the heat. In addition to the sweat loss, you also lose water when you breathe in cold weather. Your pulmonary system moistens and warms the cold air that you inhale. Cold weather also increases urine production, contributing to even greater levels of fluid loss.

    One of the most dangerous cold weather-related conditions is frostbite. This extremely painful condition involves the destruction of bodily tissue by freezing. People most at risk for frostbite are those who are stuck outdoors in the cold without shelter. Such people include back packers, mountain climbers, hikers, and cross-country skiers.

    If you experience frostbite, seek immediate medical attention. The physician will attempt rapid thawing of the affected body part at temperatures of 100 to 108 degrees Fahrenheit. In addition to symptoms of pain and numbness, there is a high chance of nerve and blood cell damage. In fact, loss of the affected body part is also a possibility depending on the severity and duration of the frostbite. If rewarming is successful, avoid exposing the affected body part to cold until your physician advises you that it is safe.

    The threat of hypothermia is also a very real risk when exercising in cold climates. Hypothermia occurs when your body temperature drops below 98.6 degrees Fahrenheit. This decrease in body temperature can cause paralysis of the arms and legs. Some of the signs and symptoms of hypothermia at various levels below normal body temperature include the following:

  • Drop of one degree: slurred speech
  • Drop of two degrees: fingers grow numb and weak, feel clumsy, body shivers
  • Drop of three degrees: lose strength and feeling in feet, cannot stand up
  • Drop of four degrees: difficulty with clear thought
  • Drop of nine degrees: muscles become rigid
  • Drop of 14 degrees: heart beat becomes irregular, loss of consciousness
  • Drop of 23 degrees: heart failure, death

    When experiencing or observing any of the above symptoms, it is important to take immediate action. The best treatment is rapid rewarming of the entire body. If the subject is wearing wet clothes, take them off and wrap him/her up in blankets with warming instruments like hot water bottles. Other people's body heat may also be used. If available, place the person in a warm bath. The water should be heated to approximately average body temperature, or 98.6 degrees Fahrenheit.

    Hypothermia can strike quickly. People who are immersed in water that is 50 degrees Fahrenheit or less are likely to succumb to the paralyzing effects of hypothermia within seconds. Unless outside aid is available, death is almost always certain in such cases.

    A helpful hint to cold-weather enthusiasts­since your body consumes a greater amount of calories in cold climates in order to warm the body, be sure to "stoke the furnace" properly. Adequate amounts of carbohydrates and fat can help provide the body with the necessary fuel sources for endurance activity and play in cold weather.

    Try to avoid large quantities of alcohol prior to or during activity in cold temperature. In addition to contributing to dehydration, alcohol dilates your blood vessels and thus facilitates further heat loss from the body. Moreover, it may cloud your senses, preventing you from noticing sensations of cold, numbness or pain.


    High altitude can also have a large effect on one's exercise capabilities and performance. In fact, at levels above 3,000 feet, exercisers are likely to experience a marked decrease in their ability to deliver sufficient oxygen to working muscles.

    Fitness enthusiasts who visit such areas often complain of major discomfort or hyperventilation during their first exercise sessions at these new altitudes. Moreover, at heights over 5,000 feet above sea level, an individual's VO2 Max exhibits a drop of 3% per every 1,000 feet over the 5,000 foot elevation mark. The reason behind the blood's reduced oxygen carrying capacity at moderate to high altitudes involves the reduced partial pressure of oxygen in the air itself at such elevations.

    Upon arrival at areas of high altitude (7,200 feet or more), it is not uncommon for people to experience breathlessness, headaches, nausea, weakness, dizziness and even sleeping difficulties. In addition, respiratory distress often occurs during exercise. It also takes the body longer to recover from activity conducted at high elevations in comparison to exercise done at sea-level.

    Due to the above considerations and decreased oxygen transport capability, newcomers to high altitudes should adjust their fitness and activity programs accordingly. The major change in your activity program should involve intensity. By reducing intensity, you may be able to avoid some of the problems associated with exercise at high elevations.

    For those wishing to continue their exercise plan, simply reduce the exercise intensity to a more comfortable level while maintaining the same duration or distance involved. It is also recommended that the warm-up and cool-down sessions should be conducted at a more gradual pace.

    Your body will eventually adapt to regular exercise at the new elevations. Altitude acclimatization takes approximately 1-4 weeks. As your body becomes accustomed to the air and pressure differences at the higher elevation, your breathing rate increases to compensate for the differences. Furthermore, muscle capillary density and hemoglobin also increase. There is even an improvement in the percentage of myoglobin in the muscle itself.

    The end result of these physiological adaptations is that an increased amount of oxygen is carried by blood to the working muscles. Moreover, there is greater retention of oxygen in the muscle cells themselves. As you become acclimated to the new altitude, you can continue to gradually work up to your previous exercise intensity levels and eventually improve even further. Serious athletes have engaged in high altitude training in an effort to improve their performance when they return to normal altitudes.

    The Quality of Air vs. the Quality of Exercise

    Air pollution, both indoor and outdoor, can hamper your activity program and cause serious health problems. Whether you reside in urban or suburban areas, chances are you have been exposed to pollution in one form or another.

    Carbon monoxide gas, one of the most common pollutants, can reduce the amount of oxygen delivered to working muscles. In addition, it can impair normal vision as well as negatively affect subjectivity. Carbon monoxide gas is produced by the incomplete combustion of fuels by machines such as automobiles and gas ranges. Even small amounts of carbon monoxide can make you sick. Repeated exposure to substantial amounts of carbon monoxide can lead to constant headaches, chronic sleepiness and tiredness.

    Ozone gas is another widespread pollutant that causes problems. A combination of hydrocarbons and nitrogen oxide that reacts with the rays of the sun, ozone is one of the main substances that makes up smog. The bulk of ingredients comprising ozone are directly traceable to automobile emissions.

    High levels of ozone at ground level can cause serious problems for people with respiratory ailments like bronchitis and asthma. Ozone can cause damage to apparently healthy individuals as well. This harmful pollutant can scar your lungs, robbing them of elasticity and making breathing more difficult.

    If you live in an area with a lot of cars and frequent sunshine, use caution when exercising outdoors. High ozone levels can cause breathing difficulties during moderate exercise. Intense exercise in areas of high ozone can make it increasingly harder to breathe. Other symptoms associated with high levels of ozone include irritated eyes and fits of coughing.

    Sulfur dioxide gas is yet another threatening source of pollution. Emitted from refineries and smelters, sulfur dioxide is a precursor to acid rain. This substance will usually irritate the upper respiratory tract, causing additional breathing difficulty. Asthma sufferers are hardest hit by sulfur dioxide compounds.

    Other pollutants that have been found to cause problems are formaldehyde, radon, nitrogen oxides and passive cigarette smoke. These substances not only interfere with exercise, but also represent a serious danger to one's general health and well-being.

    In addition, substances like pollen, mold spores and dust mites may pose problems for allergy sufferers. For these individuals, an air conditioning system can prove most helpful. A word of caution: car air conditioners can cause difficulties for asthmatics and allergy sufferers due to fungus that grows deep in the machinery of the AC unit. Moisture, engine heat and darkness provide an attractive breeding ground for such molds. Fitness Facts recommends that you periodically open the car windows and air your automobile out for 10-15 minutes after switching on the air conditioner. Furthermore, if provided with a choice on the car AC unit, choose fresh air in place of recirculated air.

    If you live in a high-pollution area, you need to exercise caution before engaging in outdoor activity. Because you normally will breathe faster and deeper during periods of exercise, you take in larger quantities of harmful pollutants.

    To minimize potential damage to your health, Fitness Facts makes the following suggestions regarding air pollution:

  • If air pollution is a serious problem in your area, try to conduct exercise sessions indoors whenever possible.
  • If you must exercise outdoors, try to stay away from areas with heavy traffic or industry.
  • Try exercising early in the morning or later in the evening after rush hour. Pollution levels tend to be lower at these times of the day.
  • Avoid exercising in the early afternoon hours when ozone levels are at their highest.
  • If you begin to experience chest pain or discomfort,

    coughing, throat irritation or difficulty in taking deep breaths, cease activity immediately and go indoors, preferably in an air conditioned room.

    Cold Weather Clothing Considerations

    The most important clothing consideration for cold weather is to remain comfortable during activity. Wearing too much clothing or the wrong types of clothing can be just as bad as not wearing enough. In fact, many people make the mistake of overdressing for outdoor activity. This can lead to sweat accumulation in the clothing and possible cold-related injury.

    To prevent such an occurence, it is recommended that you dress in layers of clothing. This way, you can remove clothing as your body begins to produce greater amounts of heat during higher-intensity exercise. It is just as easy to replace the clothing during rest periods, cool-down sessions and periods of lower- intensity activity. An additional benefit of layering your clothes is that air is trapped between the different layers, thus providing a greater insulating effect.

    The amount of clothing worn during cold weather exercise is dependent on the type of activity itself. When participating in exercise of a continuous fashion, not as much clothing will be needed during the actual activity period. Frequently interrupted exercise such as alpine skiing, sledding or skating will naturally require greater insulation thickness from more clothing layers, especially during the non-activity rest periods.

    When layering clothes, it is important to choose the correct type of material for the appropriate layer. Below are some helpful suggestions:

  • Inner layer: Thermal underwear should be made of materials that help draw sweat away from your skin. Such materials include Thermax®, Capilene, and polypropylene. Cotton also absorbs sweat rapidly and can be used next to the skin.
  • Middle layer: Concentrate on down materials or synthetics with similar properties, such as down vests and pile jackets. Use lycra tights or sweat pants to keep your legs warm.
  • Outer layer: Wool is one of the best materials available for cold weather activity. Even when wet, wool does not draw body heat away from you. Since it dries from the inside out, wool provides excellent insulation on the inside. Waterproof jackets made from such high-tech materials as Gore-tex® are also highly recommended. Their wind resistance and breathability help prevent moisture from becoming trapped in your clothes while keeping you warm.

    Other recommendations involving choice of clothing include:

  • Choose zippered garments for the outer and middle layers. They can be opened partially to let air in and can also be easily removed as your body temperature rises.
  • Mittens are preferable to gloves which are preferable to nothing. Mittens keep the fingers together, thus reducing the surface area vulnerable to wind exposure and allowing the fingers to warm one another.
  • Socks should be made of similar materials to those garments comprising the inner layer of clothing. Since cold is felt first in the toes, ears, and fingers, it is important to insulate each of these areas well.
  • Head protection should cover the ears. Wool or synthetic caps can help stop heat loss from the head while providing protection from the cold to normally exposed skin areas. Face masks and scarfs can also prove invaluable during cold weather activity.
  • Shoes should provide good traction as well as shock absorption for outdoor activity in cold weather. Wet, slippery surfaces are dangerous to runners and cyclists in particular. Try to find clear, dry surfaces on which to exercise. By choosing footwear with a bit of extra space, trapped air can be kept warm inside the sneaker or boot.
  • Bicyclists can reduce their risk of cold injury by starting their route against the wind and returning with the wind at their back. In this fashion, they do not expose sweaty, damp clothes to the added chill of a head wind on the return part of the route.
  • If the sun is strong, you may want to wear goggles or sunglasses to prevent vision impairment from sunlight reflected off snow. Skiers should choose a safe sunblock for the same reasons.

    Hot Weather Clothing Considerations

    Dressing for hot weather activity can get complicated. You need to wear enough clothing to protect you from the rays of the sun. However, you also need to take into consideration the fact that too much clothing can restrict evaporation and cooling. The best clothing choices should be solid enough to provide protection from the sun's rays, yet porous enough to allow sweat to evaporate.

    Recommendations favor light-colored, loose-fitting clothes that permit circulation of air and reflect the sunlight. Darker clothes tend to absorb more heat. Moreover, avoid impermeable and non-breathable clothing. Cotton tends to be cooler than many synthetic materials, which are known for their heat retention properties.

    It is a good idea to keep your head covered when exercising in the sun and heat. A light-colored cap or scarf can help block the sun's harmful rays while keeping you cool. Many runners and cyclists have adopted the practice of pouring water on their caps to help keep their head cool while simultaneously protecting themselves.

    To protect yourself from the sun, Fitness Facts suggests that you use a waterproof, non-allergenic sun block during extended periods of sun exposure. This holds true for exercise sessions as well as recreational activities.

    Overexposure to the sun can lead to sunburn, premature skin aging, and skin cancer. Sunburn results from the sun's ultraviolet radiation manifesting itself in the form of local inflammation, redness and swelling of the skin. Sunburn sufferers experience pain and burning sensations along with increased tenderness of the affected area. Serious instances of sunburn involve fever, headaches, feelings of nausea and possible vomiting.

    Repeated sun exposure increases the risk of skin cancer. If you frequently exercise or spend large amounts of time in the sun, be on the lookout for warts and moles that experience color changes or bleed. If you notice such developments, seek prompt medical attention from a dermatologist.

    As previously mentioned, prolonged exposure to the sun damages your skin, robbing it of its natural elasticity and oils. The end result is wrinkling of the skin. Aging can cause these developments by itself. There is no need to speed up this process with unnecessary overexposure to the sun.

    Always exercise caution when exposing yourself to the sun. Use sun-block and wear a hat or visor if you are going to be outside for long periods of time. If you choose to tan, do it gradually.

    For more information concerning the effects of the sun, contact your local chapter of the American Cancer Society or a dermatologist in your area.

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