Heat Kills. Stay Cool!

Heat-related illness continues to be a significant threat to athletic performance and overall health. Among high school athletes heat-related illness is the third most common cause of death. In order for the body to function normally, its core temperature must remain within a narrow range around 98.6°F (37.0°C). Acclimating to warm outdoor temperatures means that the body makes adjustments so that you do not feel the adverse effects of heat. The primary way the body acclimates is by sweating. The process of sweating helps cool the body, but it also results in the loss of water and electrolytes (e.g. sodium, chloride). Electrolytes are substances that help the body maintain fluid balance. Dehydration is the excessive loss of fluid and electrolytes from the body, and it leads to heat-related illness. Replacing lost water and electrolytes by drinking fluids is essential to maintaining normal core temperature and bodily functions. Therefore, athletes need to drink fluids to avoid heat-related illness.

The point at which the body starts to sweat in response to heat is higher in children than adults. Children also sweat at a slower rate than adults. Both of these factors place children at higher risk for developing heat-related illness. Other risk factors for heat-related illness include under-hydration, obesity, poor fitness, sleep deprivation, and illness that impairs the body’s ability to sweat. Athletes with heat-related illness may experience profuse sweating, muscle cramps, dry mouth, low urine output, fatigue, headache, nausea, and a change in mental status (dizziness, fainting). Overall, the basic treatment for athletes experiencing these symptoms is to stop playing, move to a cooler area, drink fluids, and seek evaluation by a doctor.

The key steps to prevent heat-related illness are drinking fluid to replenish water and electrolytes and avoiding overexertion in warm climates. By the time an athlete is thirsty, dehydration may already be developing. Therefore, thirst is not a reliable indicator of fluid replacement needs during athletic activity. Ideally, replacement of fluid should be equal to the amount of sweat an athlete produces per hour during activity (hourly sweat rate).

Athletes should be encouraged to drink before, during, and after activity to replenish fluids and electrolytes and to prevent dehydration before it starts to develop. However, drinking an excessive amount of fluid can be harmful to the body and is not recommended. Overall, fluids (water, sports drinks) should be consumed at levels approximately equivalent to sweat lost during activity as determined by the hourly sweat rate. The guidelines for fluid replacement established by American College of Sports Medicine should be reviewed by all athletes, coaches, and parents. Heat-related illness is largely preventable with careful attention to the temperature, hydration, and activity level.

Resources for more information on heat-illness see the position statements developed by the American College of Sports Medicine:

  1. Exertional Heat-Illness During Training & Competition www.acsm.org
  2. Exercise & Fluid Replacement www.acsm.org




Young athletes are not smaller versions of adult athletes and should not be trained in the same manner.  There are specific differences in the body structure of a child that increase the risk of sports injuries in the younger population. Some primary differences include the following:

  1. Children have head to body proportions that create imbalance.
  2. Children are smaller in size and protective gear may not fit properly.
  3. Children have open growth plates. Damage to the growth plate can lead to early closure and abnormal growth of the bone. For example, injury to a growth plate around the knee joint may lead to a leg length discrepancy or a change in the alignment of the bone.
  4. Children lack mature motor skills, which usually do not develop until 10-12 years-old. During puberty, as children experience their growth spurt, a temporary decline in coordination and balance places them at greater risk for falling and sustaining an injury. Overall, they may not have the motor skills required for certain sports until after puberty.
  5. Children have softer bones and growing cartilage is more sensitive to the force across joints during activity. Both of these factors increase the risk of fracture and injury to the growth plate.

Some tendons attach to a special part of the growth plate in immature bone called the apophysis. In children the apophysis is separated from the main part of the bone. When a muscle contracts tension develops in the muscle-tendon unit and is transmitted to the apophysis. Repetitive pulling at the site of the apophysis creates inflammation, swelling, and pain. This condition is referred to as apophysitis and commonly develops in the elbow (Little League Elbow), the knee (Osgood-Schlatter Disease and Sinding-Larsen-Johansson Disease), and the heel bone, which is also referred to as the calcaneus (Sever disease). When the apophysis fuses to the main bone at the time of skeletal maturity (adulthood), these conditions no longer develop.

Peak height velocity (PHV) is the point in puberty when the tempo of growth is greatest. During this time, children and teenagers experience “growing pains” including conditions such as apophysitis. In general, PHV begins around age 9 in girls and age 11 in boys. As children grow they gain weight and are able to move faster. Their movements become associated with more force, which increases the risk of injury. Overall, the stages of development in each age group influence the capacity to adapt to the stress of athletic activity. Being aware of the differences in development between children, teenagers and adults is an important step in preventing sports injuries.

The Problem of Sports Injuries

During the past several decades athletic activity has become a more common cause of injury among children, teenagers, and adults. In fact, millions of sports and recreational-related injuries occur each year. More than half of them occur between the ages of 5 and 24 years-old and require treatment by a doctor. These statistics most likely underestimate the problem because many athletes avoid medical attention or the injuries go unreported. Athletes may not seek medical care until an injury causes significant pain or in some way limits their ability to play. Sports with high injury rates include football, wrestling, gymnastics, basketball, volleyball, baseball, and track.

Sports injuries have increased due to the rise in the number of young athletes playing sports, the development of overaggressive training programs, year-round game schedules, and participation in multiple sports in one season. The cost of medical care for injured athletes has risen with the number of sports injuries. Billions of dollars are required to treat sports injuries each year. More importantly, an injury in a young athlete can potentially end an athletic career early and become a source of life-long disability.

More information:



athlete schematic