For athletes, there are many difficulties that go along with exercising in hot temperatures. Whether you are a football player, track athletic or a year-round swimmer, it is extremely important to consider the environment in which you train. This post will explain your body’s adaptations to training in the heat and provide you with some tips on how to beat the heat this summer and keep you on target to reach your athletic goals.
Physiological Responses to Heat
- You sweat more. Your body has several mechanisms for heat loss, however during intense exercise your body’s sweating response is the primary way to dissipate heat. This response becomes even more important when exercising in hot environmental temperatures. Heat released from your body evaporates sweat off your skin contributing to this significant heat loss. (.58kcal of heat is lost for every gram of water evaporated). Acclimation can help with this.
- Your blood plasma volume decreases. The increase in sweating contributes to a more drastic decrease in plasma volume when exercising in the heat. This decrease in blood volume decreases the hearts stroke volume (amount of blood pumped out in one heart beat), which is likely to impair athletic performance.
- A rise in heart beat. Cardiac output = heart rate • stroke volume. Because stroke volume has decreased due to excessive sweating, heart rate must increase to maintain cardiac output. The heart is now working harder to provide the required oxygen to working muscles.
Dangers of the Exercising in the Heat
- Dehydration is the loss of fluid from the body. Review this post on hydration to recall the negative impact dehydration has on performance.
- Heat Exhaustion is a condition caused by a loss in plasma volume and the circulatory systems’ inability to effectively release heat and supply muscles with oxygen concurrently. Symptoms of heat exhaustion include an elevated heart rate, heavy sweating, faintness, and psychological disorientation. Treatment for heat exhaustion includes having the person lie down in a cool environment and consume cool fluids.
- Heat Stroke is the failure of the body’s thermoregulatory centers resulting in a body temperature of 105˚. Heat stroke is extremely serious and can cause permanent brain damage or death. Symptoms include headache, dizziness, nausea, disorientation, seizures and sometimes a loss in consciousness. If you suspect someone is suffering of heat stroke, immediately call 911 for professional medical treatment and monitoring. Treatment involves mechanical cooling of the body through the combined use of ice packs and fanning and rehydration of the patient.
Beat the Heat tips
- Prepare ahead of time. Begin hydrating the night before a hot practice. Don’t start your workout already dehydrated.
- Be aware of your sweat rate. Know your body. If you are a heavy sweater to make sure you are replenishing your lost fluids.
- Avoid the hottest times of the day. If you have the option to choose when you exercise avoid the early afternoon (2pm-4pm), which tends to be the hottest time of the day.
- Wear appropriate clothing. Avoid cotton t-shirts that can trap heat close to your body and opt for lightweight moisture-wicking clothing designed to help promote sweat evaporation. Also, wear a hat if possible to keep the hot sun off your face.
- Listen to your body. Be aware of your body throughout your practice. Take note if you begin to feel any heat exhaustion symptoms and don’t be afraid to take a break. Successful training is safe training.
- Brooks, George et al. Exercise Physiology: Human Bioenergetics and Its Applications. Exercise in Heat pages 526-530. McGraw-Hill: 2005