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Environmental Condition

Terms in this set (57)

Hyperthermia
elevated body temperature
Heat Stress
• Athletes who exercise in hot, humid environments are particularly vulnerable to heat stress
• Maintenance of normal temperature in a hot environment depends on body's ability to dissipate heat
Metabolic Heat Production
normal metabolic function causes production and radiation of heat; level of
increase in body heat depends on intensity of physical activity
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)
Convective heat exchange
heat loss or gain depending on temperature of circulating medium (cool breeze versus circulating air being hotter than body temperature)
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
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%
-Normal sweating rate: 1 quart/hour for 2 hours (some can lose as much as 2 quarts per hour)
-Variation in sweat rates:
• Athlete's height and weight
• Degree of acclimatization (well-acclimated athletes swear earlier and more)
• Fitness level (fit = sweat more)
• Hydration status
• Environmental conditions
• Clothing
• Intensity and duration of activity
• Hereditary
Monitoring Heat Loss
heat + humidity + bright sunshine = caution
Universal Wet Bulb Globe Temperature (WBGT)
o Dry bulb temperature (DBT): recorded from standard mercury thermometer
o Wet bulb temperature (WBT): uses wet wick or piece of gauze wrapped around end of thermometer that is swung around in the air
o Globe temperature (GT): measures the sun's radiation and has a black metal casing around the end of a thermometer
- WBGT: (0.1 x DBT) +( 0.7 x WBT) + (GT x 0.2)
- WBGT: (0.3 x DBT) + (0.7 x WBT)
o DBT & WBT can be measured with a psychrometer (consists of two thermometers - dry and wet - when
the cloth is soaked and thermometers are properly ventilated, WBT < DBT because of cooling due to evaporation; the drier the air is, the lower the WBT)
o Recording temperature takes about 90 seconds
Heat Category 1
-WBGT (°F) - 78-81.9
-Work/Rest (Easy)-no limit
-Water Per hour (Easy)-.5 qt
-Work/Rest (Moderate)-no limit
-Water Per hour (Moderate)-.75 qt
-Work/Rest (Hard)-40/20 min
-Water Per hour (Hard)-.75 qt
Heat Category 2
-WBGT (°F) - 82-84.9
-Work/Rest (Easy)- no limit
-Water Per hour (Easy)-.5 qt
-Work/Rest (Moderate)-50/10 min
-Water Per hour (Moderate)-.75 qt
-Work/Rest (Hard)-30/30 min
-Water Per hour (Hard)-1 qt
Heat Category 3
-WBGT (°F) - 85-87.9
-Work/Rest (Easy)- no limit
-Water Per hour (Easy)-.5 qt
-Work/Rest (Moderate)-40/20 min
-Water Per hour (Moderate)-.75 qt
-Work/Rest (Hard)-30/30 min
-Water Per hour (Hard)-1 qt
Heat Category 4
-WBGT (°F) - 88-89.9
-Work/Rest (Easy)- no limit
-Water Per hour (Easy)-.75 qt
-Work/Rest (Moderate)-30/30 min
-Water Per hour (Moderate)-.75 qt
-Work/Rest (Hard)-20/40 min
-Water Per hour (Hard)-1 qt
Heat Category 5
-WBGT (°F) ->90
-Work/Rest (Easy)-50/10 min
-Water Per hour (Easy)-1 qt
-Work/Rest (Moderate)-20/40 min
-Water Per hour (Moderate)-1 qt
-Work/Rest (Hard)-10/50 min
-Water Per hour (Hard)-1 qt
Activity Restriction for Outdoor Physical Conditioning in Hot Weather
1) WBGT (°F)
2) Flag Color
3) Guidance for nonacclimatized and fully acclimatized
-1) < 78.0°F
2) no flag
3)extreme exertion may precipitate heat illness (normal activity)
-1) 78.0 - 82.0°F
2) green
3)use discretion in planning intense exercise (normal activity)
-1) 82.1 - 86.0°F
2)yellow
3)limit intense exercise to 1 hour; limit total outdoor exercise to 2.5 hours (use discretion in planning intense physical activity)
-1)86.1 - 89.9°F
2)red
3)stop outdoor practice sessions & outdoor physical conditioning (limit intense exercise to 1 hour; limit total outdoor exercise to 4 hours)
-1)≥ 90°F
2)black
3)cancel all outdoor exercise requiring physical exertion (cancel all outdoor exercise requiring physical exertion)
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
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
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
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
Exertional Heat Stroke
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 101°F; call EMS
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
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
Exertional Hyponatremia
condition involving a fluid/electrolyte disorder that results in an abnormally low
concentration of sodium in the blood
-Often caused by hyperhydration; or lack of sodium in diet; or excessive replacement of water w/o sodium
-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
-Athlete should be transported directly to medical facility
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)
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
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
Using Sports Drinks for fluid & electrolyte replacement
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 ratio
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
Selecting Appropriate Uniforms
initial practices in short-sleeved Ts, shorts, and socks; athletes should be moved gradually into short-sleeved net jerseys, lightweight pants and socks as acclimatization proceeds
o Early season pxs/games: lightweight uniforms with short-sleeved net jerseys and socks
Maintaining Weight Records
measure before/after px for first 2 weeks of px (loss of 3-5% BW=↓ blood volume)
Monitoring Temperatures and Humidity Readings
Modify practice schedule depending on environment
Guidelines for Athletes who intentionally lose weight
• Wrestlers/other athletes - weight loss should NOT be accomplished by dehydration
o Gradual weight loss over several weeks/months, should result in a reduction in body fat percentage relative to lean body mass
Hypothermia
• Often, sports performed in cold weather do not require heavy protective clothing
• Usually, the activity itself enables athlete to increase the metabolic rate sufficiently to function physically in a normal manner and dissipate heat and perspiration through usual physiological mechanisms
• Dampness/wetness further increases risk of hypothermia
• 65% of heat produced by body is lost through radiation (heat 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 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)
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
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
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
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)
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
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
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
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)
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
Overexposure to Skin long term effects
• 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
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
Lightning Safety
• Lightning is #2 cause of death by weather phenomena (110 deaths/year)
• Each institution should develop an emergency action plan for inclement weather:
o Someone to monitor weather forecast & changing weather
o Someone to make the decision ot remove & return a team to practice field
• See/hear lightning: you are in immediate danger and should seek shelter
o Best=indoor facility; automobile is relatively safe
o Avoid standing near large trees, flagpoles, or light poles; choose area not on a hill; as a last alternative, find a ditch, ravine, or valley
o Hair standing on end/skin tingling: drop to ground and assume crouched position
o Avoid water, telephone lines, and metal
• 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
Lightning Detectors
• Hand-held instrument to detect lightning within 40 miles
• When it detects a lightning strike, emits an audible warning tone
Photochemical haze air pollution
nitrogen dioxide and stagnant air that are acted on by sunlight to produce ozone
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
Smog air pollution
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 SO 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
Prevention of Air Pollution
• 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
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
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
Synthetic Turf
• First: Astroturf (1966, Houston Astrodome)
o Claims: more durable, offers greater consistency, requires less maintenance, is more "playable" during inclement weather, and offers greater performance characteristics (increased speed & resiliency)
• "resilient infill turf" - claims to be more similar to natural grass and is considerably less expensive
o Made of polyethylene and polypropylene yarns that sit on a base of either sand, crumbled rubber pellets, or both
• Not enough conclusive evidence to suggest that more injuries occur on artificial surfaces than natural surfaces
o Empirical evidence shows that most athletic personnel believe injury is more likely & prefers grass
o Has been argued that synthetic surfaces lose their inherent shock absorption capability as they age
o Two more common injuries: abrasions and turf toe (get shoe with a stiff, firm sole)
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