Human Sport Performance (Environmental Conditions)

Training Strategies for Competing at Altitude

- Arrive at site 24 h of scheduled performance - Arrive at competition site >2 weeks prior to competition to enhance acclimatization. Ideally, arrive 4-6 weeks prior to competition. - Training should occur between 4900 ft and 9800 ft. - Training intensity should be reduced to 60-70% of sea-level intensity first and gradually increased within 10-14 days.

Hypobaric environment

- As an individual ascends above sea level, barometric pressure is reduced relative to the magnitude of the elevation. - Because the weight of the upper atmosphere compresses the air of the lower atmosphere, barometric pressure decreases rapidly as one ascends from sea level.

Acute Hypothermia

- Body temperature dropping between 90-95 degrees. - Exposure to the cold is of relatively short duration but the cold stress exceeds the ability of the body to maintain core temperature despite maximum heat production.

Exertional Heatstroke Tx Gold Standards

- Cold tub immersion - rectal thermometer insertion = 4-6 in. - Patient is removed from cold tub when core temperature is 101.8 or 102 degrees. - Fluid replenishment via IV.

Example of Convection

- Cool breeze cools the body by removing heat from the body. - If the circulating air is higher than the temperature of the skin, then body heat increases.

What physiological responses occur in the cold regarding exercise?

- Core body temperature - Blood volume - Thermogenesis - Role of shivering - O2 consumption

training at altitude for sea level competition

- Erythropoietin response increases as altitude increases. - Altitude >6600 ft appears necessary to elicit increases in red cell volume. - Training should be performed at an altitude as close to sea-level as possible. 4100 ft is low enough to provide a training stimulus sufficient to improve endurance performance while athletes are residing at higher altitudes.

Warning Signs of Exertional Heatstroke

- Headache - Unconsciousness, coma - Loss of mental clarity - Bizarre behavior - Rapid, strong pulse - Hot, red, dry skin - Pupils constricted - Convulsions - High body temperature (105 degrees)

Heat Exhaustion Warning Signs

- Headache, irritability - Tingling or numbness in head, neck, back, limbs - Chills or shivering - Great fatigue - Weak and rapid pulse - Cool, clammy skin - dizziness - vomiting, nausea - dehydration - low BP - excess sweating - in and out of consciousness - shallow, rapid breathing

Preventative measures for Immersion Foot

- Heavy socks in well-fitting boots or shoes. - Keep the feet out of water or snow. - Numbness and tingling is a sign to warm the foot immediately.

What factors can athletic trainers use to improve heat acclimatization?

- Hydration process should be sooner rather than later (could be days or even a week where the hydration process begins) - No practice during the middle of the day - Increase rest and hydration breaks - Lower the intensity level

Simulated Altitude and Ethical Issues

- Potential for an increased propensity to illness as a result of a suppressed immune function associated with altitude and exercise. - Hypoxic tents may disturb the sleep of some athletes. - Facilities that simulate altitudes at 5000 m may increase the athlete's risk of thromboembolism. - Using simulated environments instead of blood doping and erythropoietin use.

What is Evaporation? What is the % of heat dissipation with evaporation?

- Rate of sweating. Loss of body heat becomes dependent on sweat evaporation. - 85-90%

Hypothermia Tx

- Remove person from cold environment - Remove wet clothing - Cover the person with blankets or have the person go inside a sleeping bag for insulation. - Warm fluids either oral or IV.

What are some factors that contribute to heat loss?

- Temperature = ambient temperatures drop below core body temp.; this results in loss of body heat. - Moisture - Windchill - conduction and convection

How we treat heat cramps?

- Water and electrolytes. IV solutions are effective and result in rapid relief. - Oral NaCl solutions --> two 10-grain salt tablets dissolved in 1 L of water. - Preventative measures such as consuming salt in the diet or isotonic electrolyte solutions. - Ice massage - Light Stretching --> no overstretching because you will tear the ends of the muscles.

What are ways to combat the cold?

- multiple thin layers - gloves - ski goggles and facemask if breathing in cold air is distressful

Heat Exhaustion Sx

- nausea - vomiting - irritability - headache - anxiety - diarrhea - chills - piloerection - hyperventilation - tachycardia - hypotension - heat sensations in the head and upper torso. - Orthostatic intolerance (dizziness) and syncope (fainting) may also occur.

Heat Exhaustion Tx

- thin layer of clothing - water and sodium replenishment (IV or oral depending on state)

Sx of Immersion foot

- tingling pain - swelling - blister formation - ulceration - gangrene - desquamation - Raynaud's disease

What do we want to avoid when acclimatizing to the heat?

- weakness - dizziness - flushed skin - other signs of heat stress

Examples of conduction

1. A football player competing on artificial turf on a sunny August afternoon experiences an increase in body temperature simply by standing on synthetic turf. 2. Person camping out during the winter months. When the camper sleeps on snow-covered ground, significant heat exchange occurs between the person's body and the ground.

Factors of the Cardiovascular System in response to heat

1. Blood volume 2. Skin temperature 3. Core temperature 4. Venous return 5. Cardiac Output 6. Sweat rate

List the factors of the cardiovascular system in response to heat as either increasing or decreasing when exercising in the heat.

1. Blood volume -> increases 2. Skin Temperature -> increases 3. Core body temperature -> increases 4. Venous return -> decreases due to blood volume increasing 5. Cardiac Output -> decreases due to the decrease in stroke volume. 6. Sweat rate -> increases to enhance evaporative cooling.

What are the 4 ways the body dissipates heat?

1. Conduction (nonevaporating) 2. Convection (nonevaporating) 3. Radiation (nonevaporating) 4. Evaporation

List what increases or decreases regarding physiological responses to exercise in cold.

1. Core body temperature -> Decreases due to the rapid transfer of heat from the core to the periphery. 2. Blood volume -> decreases 3. Thermogenesis -> metabolic process during which body burns calories to produce heat. increases! 4. Role of Shivering -> Increase since metabolic rate is increasing 5. O2 consumption -> increases since shivering increases

List the 3 physiological stresses that is experienced with the thermoregulatory system?

1. Heat Acclimatization 2. Level of physical fitness 3. Hydration status *All of these factors affect the athlete's ability to perform.

What are some Recommendations for Exercise in a cold environment?

1. No tight clothing -> restrict circulation 2. Avoid exercising in the snow or in wet areas. 3. maintain proper water balance 4. Avoid wetting clothing, shoes, and socks and be prepared to change wet clothing with dry socks, shoes, undergarments. 5. Cover exposed areas of the body with mittens, scarves, wool hat, high-top shoes or boots. 6. Use proper judgement in deciding to exercise outside.

Effect of Sudden Exposure to Various Altitudes

1500 m = Night vision becomes impaired 2000 m = RHR increases 3000 m = Performance of novel tasks may be affected 3000-4500 m = Ability to perform skilled tasks is impaired and physical work capacities are reduced. 4500-6000 m = Signs and symptoms of hypoxia become apparent, including tingling sensations in fingers and mouth. NM impairment and decreases in judgement ability are evident. 6000 m and above = rapid onset of severe signs and symptoms of hypoxia. Comprehension and mental performance rapidly decline.

How much will the metabolic rate increase during exercise compared to being at rest in order to provide energy for a muscle contraction?

5-15x higher

Physiological adaptations to the environment takes over _________ days.

7-14 days

How long does it take to acclimatize to heat?

7-14 days (more so 14 days).

What is the exposure time needed to develop trench foot?

>12 hours to 3-4 days in cold, wet environments.

Exertional Heatstroke

A life-threatening illness characterized by high body temperature and central nervous system dysfunction.

Chilblain

Affects more women than men. It is an inflammatory condition that develops as a result of cold exposure. This injury appears to be more frequent in cold, humid conditions than in cold, dry conditions.

Immersion Foot

Also known as trench foot. It is a cold injury associated with feet that are cold or wet for a prolonged period of time. It frequently occurs when the feet are in water or snow and may take from several hours to repeated exposures over several days to manifest.

What is referred to when we use the term acclimation?

Artificial environment

Frostbite

As ambient temperature drops toward the freezing point, the skin becomes numb and loses its sense of touch and pain at about 50 °F.

Living low and training high

Athlete lives at sea level but trains at a moderate altitude.

What does Living high/training high refer to?

Athlete resides and trains at moderate altitude.

Training at Altitude vs Sea Level --> What does Living High/training Low refer to?

Athlete resides at a moderate altitude but trains at a lower altitude.

Where do most of the chilblain lesions occur?

Back of the extremities and between the joints.

What are the 2 cold stressors?

Cold air and water.

Windchill

Combined effects of cold ambient temperature and air movement.

Chronic Hypothermia

During a mild cold stress over a prolonged period of time (days or weeks), the thermoregulatory response is not overwhelmed but is unable to maintain sufficient body heat.

Heat Cramps

During prolonged exercise or repetitive exercise, the athlete may experience painful contractions within the exercising muscles.

Frostnip

Exposure resulting in freezing of only the superficial layers of the skin.

Deep Frostbite

Exposure to cold that involves muscle, bone, and tendons.

What is referred to when we use the term acclimatization?

External natural environment

Heat Syncope

Fainting due to heat. It occurs when individuals stand for a prolonged period of time in the heat or exercise for a prolonged period of time in an upright position. *Lightheadedness

How do you treat heat syncope?

Fluids and electrolytes and have the patient lie in a horizontal position with the feel elevated.

Frostbite Tx

Gradual warming (i.e., hands put in warm water, warm shower).

Hyperthermia

High body temperature. If it is not controlled, body temperature levels can rise to where the person is in danger.

What places a burden on the thermoregulatory system?

Higher metabolic rate that creates a large heat production that needs to be dissipated in order to maintain heat balance within the body.

Cardiovascular physiological response to altitude

Increase in CO and HR and decrease in plasma volume

During exercise in the heat, what happens to the core body temperature?

Increases rapidly which correlates to increased metabolic heat that is generated during exercise in hot conditions.

Where are heat cramps usually observed?

Large muscles of the extremities and abdomen. If happens at 2 or more spots, we can rule it in.

How do heat cramps occur?

Loss of sodium and chloride ions in sweat and the replacement of sweat loss with dilute fluid, pure water, or both.

Hypothermia

Lowering of the core body temperature below 95 degrees.

Thermal Homeostasis in terms of cold

Maintaining a steady body temperature.

Heat Exhaustion

Most common heat illness. Considered a volume depletion problem and primarily occurs when Cardiac Output is reduced, resulting in an inability of the CV system to meet the demands of both the exercising muscle and peripheral tissues.

Convection

Occurs when a mass of either air or water moves around an individual. Body heat is lost or gained depending on the temperature of the circulating medium.

Respiratory physiological response to altitude

Oxygen will be reduced which results in an increase in breathing rate and blood pH elevation.

______ is a more severe form of chilblain and is associated with a greater burning and pain sensation in the affected area.

Pernio

Conduction

Physical contact between 2 objects. Can result in heat gain or loss (High to low concentration of heat).

How is Heat Syncope caused?

Pooling of blood in the vasculature of the limbs and skin because of excessive ambient temperatures.

What is the goal of the thermoregulatory system during exercise in the heat?

Remove heat from the body.

Example of radiation

Sun radiating heat to the athlete and from the ground.

What is the defense mechanism of the body when there is an increase in core temperature?

Sweat glands are stimulated to increase sweat production and the smooth muscle of the arterioles of the skin relaxes to allow for vasodilation and an increase in blood flow to the periphery.

Hypoxia

Tissues have a lack of oxygen.

Radiation

Transfer of energy waves that are emitted by one object and absorbed by another.

Boyle's Law

relationship between pressure and volume. It states that the pressure of a given gas at a constant temperature is inversely proportional to its volume.

Charles' Law

relationship between volume and temperature. It states that at constant pressure, the volume of a gas is proportional to its absolute temperature.

Superficial Frostbite

result of freezing of the skin and subcutaneous tissues. During this injury, the skin becomes white and frozen, but the deep underlying tissues remain pliable.

Subacute Hypothermia

When prolonged activity in the cold is accompanied by exhaustion and depletion of energy reserves and the ability to maintain core temperature is diminished.

Acute Mountain Sickness

caused by reduced air pressure and lower oxygen levels at high altitudes.

What are the effects of exercise on thermal balance?

• Increased heat transfer from the core to the periphery because of increased blood flow. • Increased heat production in the extremities vs the trunk compared with that in non-exercise conditions • Reduced insulator benefit of the boundary layer of the skin-water interface if movement of the upper and lower extremities increases • Increased effective surface area for heat transfer provided by the redistribution of blood from the trunk core to extremity

Dalton's Law

each gas in a mixture exerts a pressure according to its own concentration, independently of the other gases present.

What controls body temperature?

hypothalamus

Metabolic physiological response to altitude

lactic acid production increases, increase in anaerobic metabolism, and decrease in glycolytic efficiency.

What does Chilblain cause?

vasodilation, itchiness, and edema.

Individual is at a greater risk of cold injury when cold _____ is added. ______ times greater risk when ______ is added compared to ________.

water; 25x; water is added compared to air. *Fall through ice and into cold water, you can die within 45 minutes.