Chapter 6 - Environmental Considerations

Acute mountain sickness

33% chance for individuals who go to altitudes of 7,000-8,000 feet o Headache, nausea, vomiting, sleep disturbance, and dyspnea (unpleasant breathing) for up to 3 days o Caused by tissue disruption in brain that affects sodium/potassium balance - can cause excess fluid retention within cells and subsequent occurrence of abnormal pressure

• Sickle-cell trait reaction

8-10% of AAs have sickle-cell trait - abnormality of structure of RBCs & Hb content o When abnormal Hb molecules become deoxygenated as a result of high altitude, cells tend to clump (this process causes an abnormal sickle shape to RBC, which can be destroyed easily) o Can cause an enlarged spleen, which in some cases has ruptured at high altitudes

Heat syncope

associated with rapid physical fatigue during overexposure to heat o Caused by peripheral vasodilation of superficial vessels, hypotension, or a pooling of blood in extremities, which results in dizziness, fainting, and nausea o Lay athlete down in cool environment and replace fluids

AIR POLLUTION

Two types: photochemical haze and smog

• Pulmonary edema

at altitudes of 9000-10,000 feet. Lungs accumulate a small amount of fluid w/i alveolar walls o Most individuals: fluid is absorbed in a few days (for some, continues to collect & forms pulmonary edema) o S/S: dyspnea, cough, headache, weakness, sometimes unconsciousness o Treatment: move to lower altitude ASAP and give oxygen (rapidly resolves)

Identifying susceptible individuals

athletes with large muscle mass o overweight individuals (18% greater heat production than underweight, heat illness rate increases at a ratio of 4:1as body weight increases) o women are more physiologically efficient in body temperature regulation (sweat less and maintain a higher heart rate when working in heat) o other susceptible individuals: those with poor fitness levels, history of heat illness, febrile condition

Fluid & electrolyte replacement

average adult doing minimal physical activity requires at least 2.5L of water o Normal sweat loss during 1 hour exercise: 0.8-3L/hr (average of 1.5 L/hr) o When body weight drops by 1-2%, individual beings to feel thirsty o Prevention: replace lost fluid (do not rely on thirst as an indicator) • Most people only replace 50% of lost fluid through sweating o Hypohydration: reduced muscular strength and endurance, decreased blood and plasma volume, altered cardiac function, d thermoregulation decreased kidney function, reduced glycogen stores, and loss of electrolytes o Using sports drinks: better than water (athletes more likely to drink it, replace electrolytes lost in sweat, and provide energy to working muscles) • Water is not a good rehydrator because it "turns off" thirst before body is completely rehydrated (also "turns on" kidneys prematurely, fluid loss in urine is quicker than when drinking sports drink) • Optimal CHO level: 14g CHO/8 oz. water for quickest fluid absorption • Too much CHO = absorbed more slowly

Gradual acclimatization

becoming accustomed to heat and also getting used to exercising in hot temperatures o Progressive exposure over 7-10 day period: • First 5-6 days: 80% acclimatization (2 hour px in morning, 2 hour px in afternoon) • Each px should be broken down into 20/20 work/rest ration

Exertional heatstroke

characterized by CNS abnormalities and potential tissue damage resulting from significantly elevated body temperature (as body temp rises, extreme circulatory and metabolic stresses can produce damage and severe physiological dysfunction that can ultimately result in death) o Breakdown of thermoregulatory mechanism due to excessively high body temperature and inability of the body to dissipate heat through sweating o Sudden collapse with CNS dysfunction (altered consciousness, seizures, confusion, emotional instability, irrational behavior, or decreased mental acuity) o Rectal temperature > 104°F, flushed and hot skin with sweating about 75% of the time, shallow & fast breathing, rapid & strong pulse, nausea, vomiting, diarrhea, headache, dizziness, weakness, decreased BP and dehydration o Tx: aggressive and immediate whole-body cooling - cool environment, strip of clothing, immerse athlete in cool water bath (35-58°F); try to lower rectal temperature to 102°F; call EMS

Acute exertional rhabdomyolysis

characterized by sudden catabolic destruction and degeneration of skeletal muscle accompanied by leakage of myoglobin and muscle enzymes into the vascular system o Often occurs in healthy individuals during intense exercise in extremely hot & humid conditions o Gradual onset of muscle weakness, swelling, and pain; presence of darkened urine and renal dysfunction; severe cases: sudden collapse, renal failure, and death

• Frost nip

commonly occurs when there is a high wind, severe cold, or both; most often affects ears, nose, cheeks, chin, fingers and toes. Skin appears very firm with cold, painless areas that may peel/blister in 24-72 hrs o tx: affected areas can be treated early with sustained pressure of hand (without rubbing), by blowing hot breath on the spot, or by placing (fingers) in armpits

Exertional hyponatremia

condition involving a fluid/electrolyte disorder that results in an abnormally low concentration of sodium in the blood o Often caused by hyperhydration; or lack of sodium in diet; or excessive replacement of water w/o sodium o S/S: progressively worsening headache; nausea and vomiting; swelling of hands and feet; lethargy, apathy or agitation; low blood sodium (<130mmol/L) - can compromise CNS o Athlete should be transported directly to medical facility

• Hyperthermia

elevated body temperature

o Radiant heat exchange

from sunshine (effect greater in sunlight than in shade); on a cloudy day, the body also emits radiant heat energy (thus radiation may result in decreased body temperature) • During exercise, body attempts to dissipate heat production by metabolism by dilating superficial arterial and venous vessels, thus channeling blood to superficial capillaries of skin

Malignant hyperthermia

genetically inherited muscular disorder that causes hypersensitivity to anesthesia and extreme exercise in hot environments - causes muscle temperature to increase faster than core temperatures and causes symptoms similar to heatstroke o Complaining of muscle pain after exercise, rectal temp remains elevated for 10-15 minutes after exercise (during this period, muscle tissue is destroyed and breakdown products may damage kidneys) o Should be disqualified from exercising in hot, humid environments

o Convective heat exchange

heat loss or gain depending on temperature of circulating medium (cool breeze versus circulating air being hotter than body temperature)

Dehydration

mild hydration is defined as loss of <2% of body weight o S/S: thirst, dry mouth, headache, dizziness, irritability, lethargy, excessive fatigue, & possibly cramps o Replace fluids and move to cool environment (sports drink that contains CHO & electrolytes) o Should not return to activity until normal body weight (fluid replacement should not exceed fluid loss)

Heat cramps

muscle spasms (calf & abdomen) related to excessive loss of water and several electrolytes (sodium, chloride, potassium, magnesium, and calcium) but especially sodium o Profuse sweating may cause large losses of water and small losses of electrolytes, which destroys the balance in the concentration of these elements within the body o Most likely victim: fairly fit athlete who is not acclimatized to the heat o Prevent by adequate replacement of electrolytes and fluids o Immediate tx: ingestion of large quantities of fluids, mild prolonged stretching with ice massage

• Photochemical haze

nitrogen dioxide and stagnant air that are acted on by sunlight to produce ozone o Ozone: form of oxygen (O3) - produced by reaction of oxygen (O2), nitrogen oxides, & hydrocarbon plus sunlight. Usually does not reduce function capacity in normal work output • Increased work output affected by ozone: shortness of breath, coughing, chest tightness, pain during deep breathing, nausea, eye irritation, fatigue, lung irritation, and lowered resistance to lung infection (asthmatics are at greater risk when ozone levels increase) • Over a period of time, can become desensitized to ozone

o Metabolic heat production

normal metabolic function causes production and radiation of heat; level of increase in body heat depends on intensity of physical activity

o Evaporative heat loss

water is transported to surface via sweat glands, where it evaporates, taking large quantities of heat with it (body highly dependent on sweat if air temperature > body temperature) • Heat loss via evaporation is severely impaired when relative humidity reaches 65%, and is virtually impossible when humidity reaches 75%

3 types of Frostbite

o Chillblains: result from prolonged and constant exposure to cold for many hours. Skin redness, tingling, swelling, and pain in toes and fingers. Caused by problems of peripheral circulation o Superficial frostbite: involves only the skin and subcutaneous tissue. Skin appears pale, hard, cold, and waxy; palpating will reveal a sense of hardness but with yielding of underlying deeper tissue structures • When rewarming: area will feel numb, then will sting and burn; may later produce blisters/pain o Deep frostbite: deep tissues are also frozen; medical emergency requiring prompt hospitalization • Tissue is initially cold, hard, pale or white, and numb • Rapid rewarming (hot drinks, heating pads, or hot water bottles at 100-110°F) • During process, tissue will become blotchy red, swollen, and very painful (later injury may become gangrenous, causing a loss of tissue)

Exertional heat exhaustion

occurs from environmental heat stress and strenuous physical exercise o Athlete becomes dehydrated to the point that he/she is unable to sustain adequate cardiac output o Mild hyperthermia (rectal temp < 104°F), no evidence of CNS dysfunction o Signs/symptoms of dehydration/electrolyte depletion: pale skin, profuse sweating, stomach cramps with nausea, vomiting, diarrhea, headache, persistent muscle cramps, dizziness, loss of coordination o Tx: remove from activity, remove clothing, lie down with legs elevated, cooling efforts, rehydration or IV fluids; AT should monitor heart rate, BP, and core temperature

o Conductive heat exchange

physical contact with other objects can result in a heat gain or loss (i.e. a football player standing on synthetic turf will experience an increase in body temperature)

• Smog

produced by combination of carbon monoxide and sulphur dioxide (emanates from combustion of a fossil fuel such as coal) • Sulfur dioxide (SO2): colorless gas that is a component of burning coal or petroleum o Air contaminant: causes increased resistance to air movement in and out of lungs, decreased ability of lungs to rid themselves of foreign matter, shortness of breath, coughing, fatigue, and increased susceptibility to lung diseases o Adverse effect mostly on asthmatics and other sensitive individuals o Nose breathing lessens effects of sulfur dioxide (nasal mucosa acts as SO2 scrubber) • Carbon monoxide (CO): colorless, odorless gas; reduced Hb ability to transport oxygen and restricts release of oxygen to the tissues; interferes with performance in exercise and also various psychomotor, behavioral, and attention-related activities

Heat rash

red, raised rash with sensations of prickling and tingling during sweating; usually occurs when skin is continuously wet with unevaporated sweat; generally localized to areas covered by clothing; continually toweling body can help prevent rash from developing

• Jet lag

refers to physical and mental effects caused by traveling rapidly across several time zones o Disruption of both circadian rhythms and the sleep-wake cycle o Fatigue, headache, problems with digestion, changes in BP, heart rate, hormonal release, endocrine secretions and bowel habits o Younger individuals adjust more quickly than older people o 30-50% faster adaptation in persons flying westerward (rather than eastward) o Traveling north-to-south has no effect on body o Minimizing effects of jet lag: • Preadjust by getting up and going to bed 1 hour later for each time zone crossed • Drink plenty of fluids to avoid dehydration • Traveling west: light meals early, heavy meals late; consume caffeine; exercise/train later in day • Traveling east: heavy meal earlier; avoid caffeine; exercise/train earlier in day

Prevention

• Athlete must stop or significantly decrease physical activity during periods of high pollution • Perform activity when commuter traffic has lessened and when ambient temperature has lowered • Ozone levels rise during dawn, peak at midday, and are much reduced after late-afternoon rush hour • Running should be avoided on roads containing a concentration of auto emissions & carbon monoxide

Prevention of Hypothermia

• Clothing should not restrict movement, should be as lightweight as possible, and should permit free passage of sweat and body heat (athlete should dress in thin layers that can be easily added or removed) o Continuous adjustment will reduce sweating and likelihood that clothing will become damp/wet • Wear warm-up suits before exercising, during activity breaks or rest periods, and at termination of exercise o Runners should use lightweight insulating clothing and possibly ski goggles/face mask • For sport in temperatures below 32°F, a layer of protective clothing should be added for every 5mph of wind • Need to replace fluids (dehydration → reduced blood volume → less fluid available to warm tissues)

HYPOTHERMIA

• Dampness/wetness further increases risk of hypothermia • 65% of heat produced by body is lost through radiation (head and neck - 50% of heat loss) • 20% of heat loss is through evaporation (66% through skin, 33% through respiratory tract) • As muscular fatigue builds up, body heat loss may exceed metabolic heat production o Shivering ceases at < 85°-90°F o Death is imminent if core temperature is >107°F or drops to 77°-85°F

Preventing Heat Illness

• Dehydration • Fluid & electrolyte replacement • Gradual acclimatization • Identifying susceptible individuals • Selecting appropriate uniforms • Maintaining weight records: measure before/after px for first 2 weeks of px (loss of 3-5% BW=↓ blood volume) • Monitoring temperature and humidity readings: modify practice schedule depending on environment

CIRCADIAN DYSRHYTHMIA (JET LAG)

• Desynchronization of the athlete's biological and biophysical time clock • Body maintains many cyclical mechanisms (circadian rhythms) that follow a pattern and adapt at varying rates to time changes o Some adjust immediately (protein metabolism), whereas others take time (rise and fall of body temperature takes approximately 8 days to adjust) • Adrenal hormones (regulate metabolism & other functions) take as long as 3 weeks

Using Sunscreens

• Effectiveness in absorbing sunburn-inducing radiation is expressed as the sun protection factor (SPF) o SPF of 6 = person can be xexposed to UV light 6x longer than w/o sunscreen before skin will turn red o Those with family history may experience significant damage even when wearing SPF-15 • Should be worn particularly by individuals with fair complexion, light hair, blue eyes or skin that burns easily • Sun exposure causes premature aging of skin (wrinkling, freckling, prominent blood vessels, coarse texture) o Formation of precancerous growths & increased risk of developing skin cancer o 60-80% of lifetime sun exposure is obtained by age 20 • Needed most between March - November, between hours of 10am-4pm, should be applied 15-30 minutes before o White cotton t-shirt has an SPF of 5 o Reflected sunlight from water, sand, and snow may effectively increase sun exposure & risk of burning

Common Cold Injuries

• Frost nip • Frostbite o Chillblains o Superficial frostbite o Deep frostbite

Exertional Heat Illness

• Heat rash • Heat syncope • Heat cramps • Exertional heat exhaustion • Exertional heatstroke • Malignant hyperthermia • Acute exertional rhabdomyolysis • Exertional hyponatremia

LIGHTNING SAFETY

• Lightning always accompanied by thunder (20-40% of thunder cannot be heart due to atmospheric disturbances) o Flash to bang method: count # seconds from sighting of lightning to hearing thunder, ÷ by 5 • Flash-to-bang count of 30: lightning 6 miles away (inherent danger) • Count of 15: lightning is 3 miles away (everyone should leave and seek shelter) o 30 minutes must past since last lightning strike before resuming play

ALTITUDE

• Loss in maximum oxygen uptake represents a 4-8% deterioration in athlete's performance in endurance events (often body compensates for decrease in maximum oxygen uptake with corresponding tachycardia) o Hyperventilation may occur o Most responses result from athlete having fewer RBC than necessary to adequately capture available oxygen in the air

OVEREXPOSURE TO SKIN Long-Term Effects on Skin

• Premature aging of skin: dryness, cracking, and decrease in elasticity • Skin cancer: most common malignant tumor found in humans; associated with UV radiation exposure o Damage to DNA is suspected cause o Basal cell carcinoma, squamous cell carcinoma, and malignant melanoma o Rate of cure exceeds 95% with early detection and treatment

Adaptation to Altitude

• Problem of oxygen deficiency: ↓ barometric pressure = ↓ saturation of RBCs • Natives of areas with high altitude have a larger chest capacity, more alveoli, more capillaries that transport blood to tissue, and a higher RBC count • Resident (stays for months-years): makes a partial adaptation - conservation of glucose, increased # of mitochondria, and increased formation of hemoglobin • Visitor: physiological struggle - ↑ breathing, ↑ heart action, ↑ hemoglobin, ↑ blood alkalinity and ↑ myoglobin as well as change sin distribution of blood flow and cell enzyme activity; also possible dehydration