Chapter 6: Environmental Conditions

• Environmental stress can adversely impact an athlete’s performance and pose serious health threats

• Areas of concern– Hyperthermia– Hypothermia– Altitude– Exposure to the sun– Lightening storms– Air pollution– Circadian dysrhythmia

Hyperthermia

• Athletic trainers require knowledge and information concerning temperature, humidity and weather to adequately make decisions regarding environmental dangers

• Has caused a number of deaths over the years

• Must manage heat stress appropriately

Heat Stress• Extreme caution should be used when training in

the heat (overexposure could result heat stress)

• It is preventable

• Athletes that train under these extreme conditions are at risk

• Physiologically the body will continue to function if body temperature is maintained

• Body must be dissipate heat to maintain homeostasis

• Metabolic Heat Production – Normal metabolic function results in production of heat (will

increase with intensity of exercise)

• Conductive Heat Exchange– Physical contact with objects resulting in heat loss or gain

• Convective Heat Exchange– Body heat can be lost or gained depending on circulation of

medium

• Radiant Heat Exchange– Comes from sunshine and will cause increase in temperature

• Evaporative Heat Loss– Sweat glands allow water transported to surface– Evaporation of water takes heat with it– When radiant heat and environment temperature are

higher than body temperature, loss of heat through evaporation is key

– Lose 1 quart of water per hour for up to 2 hours– Air must be relative water free for evaporation to occur

• relative humidity of 65% impairs evaporation• relative humidity of 75% stops evaporation

Monitoring Heat Index• Heat, sunshine and humidity must be monitored

closely• Wet bulb globe temperature index (WBGT) provides

objective measure for determining precautions concerning participation in hot– WGBT incorporates different thermometer readings

• Dry bulb (standard mercury temperature)

• Wet bulb (thermometer with wet gauze that is swung around in air)

• Black bulb (black casing that measures radiant heat)

• Formula yields WBGT index

– DBT and WBT can be measured with psychrometer (combines both thermometers)

• Wet bulb will be lower due to evaporation of water

• Drier air = greater depression of wet bulb temperature due to evaporation

– Ventilation is provided by whirling thermometer (sling psychrometer) or suction fan (aspiration psychrometer

– Newer models utilize digital sensors

Heat Illnesses

• Heat rash (prickly heat)– Benign condition associated with red, raised

rash, combined with prickling with sweat– Result of continuously wet un-evaporated sweat– Continually toweling the body will prevent– Generally localized to areas covered with

clothing

• Heat Syncope (heat collapse)– Associated with rapid fatigue and overexposure, standing in

heat for long periods of time– Caused by peripheral vasodilation, or pooling of blood in

extremities resulting in dizziness and fainting– Treat by placing athlete in cool environment, consuming fluids

and laying down

• Heat Cramps– Painful muscle spasms (calf, abdominal) due to excessive

water loss and electrolyte imbalance– Occurs in individual in good shape that overexert themselves

– Prevent by consuming extra fluids and maintaining electrolyte balance

– Treat with fluid ingestion, light stretching with ice massage– Return to play unlikely due to continued cramping

• Heat Exhaustion– Result of inadequate fluid replacement– Will exhibit signs of profuse sweating, pale skin, mildly

elevated temperature, dizziness, hyperventilation and rapid pulse

– May develop heat cramps or become faint/dizzy– Core temperature will be ~102o

– Performance may decrease– Immediate treatment includes fluid ingestion (intravenous

replacement, ultimately), place in cool environment

• Heatstroke– Serious life-threatening condition, with unknown specific

cause– Characterized by sudden onset - sudden collapse, LOC,

flushed hot skin, minimal sweating, shallow breathing, strong rapid pulse, and core temperature of > 106o F

– Temperature must be lowered within 45 minutes

– Drastic measures must be taken to cool athlete• Strip clothing• Sponge with cool water• Do not immerse in water• Transport to hospital immediately

– Malignant hyperthermia• muscle disorder causing hypersensitivity to anesthesia and

heat• Similar S&S to heatstroke - muscle biopsy is needed to detect• Athlete with condition should be disqualified from

competition in hot, humid environments

• Acute Exertional Rhabdomyolysis– Sudden catabolic destruction and degeneration of skeletal

muscle (myoglobin and enzyme leakage into vascular system)– Occurs during intense exercise in heat and humidity resulting

in:• gradual muscle weakness, swelling, pain, dark urine, renal

dysfunction• severe case = sudden collapse, renal failure and death

– Associated with individuals that have sickle cell trait– Should be referred to a physician immediately

Preventing Heat Illness• Common sense and precaution

– Consume fluids and stay cool

• Fluid and Electrolyte Replacement– Body requires 2.5L of water daily when engaged in

minimal activity– 1-2% drop in body weight (due to dehydration) results

in thirst– If thirst is ignored, dehydration results in:

• nausea, vomiting, fainting and increased risk for heat illness

– More likely to occur when exercising outdoors sweating heavily and engaging in strenuous exercise

– Prevent through hydration, don’t ignore thirst, and don’t rely on it being your indicator

– Generally only 50% of fluid is ever replaced and should therefore be replaced before, during and after exercise

– Athletes should have unlimited access to water to prevent decrements in performance and hypohydration

• Using Sports Drinks– More effective than just replacing fluids with water

– Flavoring results in increased desire to consume

– Replaces fluids and electrolytes

– Water alone can prematurely stop thirst response and initiate fluid removal by kidneys

– Small amounts of sodium help in retention of water

– Different drinks have different nutrient levels

– Optimal CHO level is 14g per 8 ounces of water

– More CHO results in slower absorption

– Effective for both short term and endurance activities

• Gradual Acclimatization– Most effective method of avoiding heat stress

– Involves becoming accustomed to heat and exercising in heat

– Early pre-season training and graded intensity changes are recommended with progressive exposure over 7-10 day period

– 80% of acclimatization can be achieved during first 5-6 days with 2 hour morning and afternoon practice sessions

• Identifying Susceptible Individuals– Athletes was large muscle mass– Overweight athletes (due to increased metabolic rate)– Death from heat stroke increase 4:1 as body weight

increases– Women are physiologically more efficient with

regard body temp. regulation– Others that are susceptible include, those with poor

fitness, history of heat illness, or febrile condition

• Uniform Selection– Base on temperature and humidity

– Dress for the weather and temperature

– Avoid rubberized suits

• Weight Records– Keep track of before and after measures for first two weeks

– If increase in temperature and humidity occurs during the season, weights should again be recorded

– A loss of 3-5% reduce blood volume and could be a health threat

• Temperature and Humidity Reading– Dry and wet bulb readings should be taken on

the field prior to practice to monitor heat index– Modify practice according to severity of

environmental conditions

Guidelines for Athletes Who Intentionally Lose Weight

• Predispose themselves to heat related injuries and could create life-threatening situations

• Weight loss should not be accomplished through dehydration

• Gradual process over weeks and months and should be a result of body fat lost

• NCAA and high school federations have established guidelines for weight loss for wrestling

Hypothermia

• Cold weather vs. nature of particular sport

• Most activity allows for adequate heat production (increased metabolism) and dissipation, allowing for sufficient functioning

• Impact on warm-up and “down time”

• Temperature in conjunction with wind chill and dampness or wetness can increase chances of hypothermia

• 65% of body heat is lost through radiation (head and neck 50%)

• 20% through evaporation

• 2/3 through skin and 1/3 through respiration

• Problems arise when heat lost exceeds heat production via metabolism– Results in impairment of neuromuscular function (which can also be

impaired by shivering)

• Drop in core stimulates shivering but stops after temp. drops below 85-90oF

• Death is imminent when temp falls below 77-85oF.

• Prevention– Apparel geared for weather to provide semitropical

microclimate for body and prevent chilling– Waterproof and windproof fabrics that allow passage of heat

and sweat and allow movement– Layers and adjusting them are key to maintaining body

temperature (during period of (in)activity)– Inadequate clothing, improper warm-up and chill factor can lead

to injury, frostbite, chilblains, and/or minor respiratory problems– Be aware of hydration levels as well to enhance blood volume

and heat maintenance

• Common Cold Injuries– Localized cooling can result in tissue damage

• Formation of ice crystals between cells, destroys cells, disrupts blood flow, clotting may occur

– Frost nip• Involves, ears, nose, chin, fingers, and toes• Occurs with high wind and/or severe cold• Skin appears firm with cold painless areas that may peel and blister

(24-72 hours)• Treat with firm pressure, blowing warm air or hands in armpits (if

fingers involved)• Do not rub

– Frostbite• Chilblains result from prolonged exposure causing redness and

swelling, tingling pain in toes and fingers• Due to poor peripheral circulation• Superficial Frostbite involves only skin and subcutaneous tissue• Appears pale, hard, cold and waxy• When re-warming the area will feel numb, then sting and burn• It may blister and be painful for several weeks• Deep Frostbite indicates frozen skin requiring hospitalization• Rapid re-warming is necessary (100-110oF)• Tissue will become blotchy red, swollen, painful and may become

gangrenous

Altitude

• Most events do not occur at extreme heights

• As height decreases, maximum oxygen uptake decreases resulting in a decrease in performance

• Body compensates through tachycardia and hyperventilation

• Responses as a result of fewer red blood cells than necessary to adequately capture available oxygen

• Adaptations– Increased height = reduced barometric pressure resulting in

decreased partial pressure of oxygen = less saturation of red blood cells

– Individual adaptations dependent on whether an the person is a native, resident or visitor

• Resident has larger chest capacity, more alveoli, capillaries and red blood cells

• Resident makes partial adaptations (increased mitochondria and hemoglobin, glycogen conservation)

• Visitor responds with increased breathing heart action, hemoglobin, blood alkalinity, myoglobin and changes in blood flow and enzyme activity

– Other uncertainties with regards to training and competition• Time to adjust (2-3 weeks vs. 3 days)• Short adjustment allows acid-base balance to recover but does not

allow significant changes in blood volume and maximum cardiac output

• Altitude Illnesses– Acute Mountain Sickness

• 1 out of 3 will experience when making the jump 7000-8000 feet.• Experience headache, nausea, vomiting, sleep disturbance, and

dypsnea• Caused by brain disruption associated with sodium potassium

imbalance resulting in fluid retention and cellular pressure changes

– Pulmonary Edema• Occurs at 9000-10,000 feet.

• Lungs accumulate fluid in alveolar walls forming pulmonary edema

• Signs and symptoms: dypsnea, cough, headache, weakness and occasionally unconsciousness.

• Treat by moving athlete to lower altitude and providing oxygen

– Sickle Cell Trait• 8-10% of African Americans have sickle cell trait

• In most the trait is benign

• Abnormality in red blood cell hemoglobin structure

• When hemoglobin is deoxygenated, cells clump together causing blood cell to develop sickle shape making it easy to destroy

• Causes enlarged spleen and could rupture at high altitudes

Overexposure to Sun

• Precautions must be taken to protect athletes, coaches, athletic trainers and support staff

• Long Term Effects on Skin– Premature aging and skin cancer due to ultraviolet

exposure– Premature aging is characterized by dryness,

cracking and inelasticity of the skin– Skin cancer is the most common malignant tumor

found in humans

– Damage to DNA is suspected as the cause of cancer

– Major types include basal cell carcinoma, squamous cell carcinoma and malignant melanoma

– Rate of cure is 95% with early detection– Fair skinned individuals are more susceptible to

these maladies

• Using Sunscreen– Can help prevent damaging effects of UV radiation– Sunscreen effectiveness is expressed as SPF (sun

protection factor)• Indicates how many times longer an individual can be exposed

to the sun with vs. without sunscreen before skin turns red.• Greater the susceptibility the higher the SPF should be used

– Should be worn by athletes, coaches and athletic trainers who are outside a considerable amount, and/or have fair complexion, light hair, blue eyes or skin that burns easily

– Individuals with dark complexion should also apply

– 60-80% of sun exposure occurs before the age of 20

– Sunscreen use is at its highest March - November but should be used year round (particularly between the hours of 10am-4pm)

– It should be applied 15-30 minutes before exposure and re-applied after exposure to water, excess sweating, rubbing skin with clothing or a towel

Lightening Safety

• #2 cause of death by weather phenomena

• NATA has established position statement due to number of athletes and coaches potentially exposed to lightening scenarios

• Emergency action plans must be set for this type of event – Involving chain of command, monitoring of weather

service, decision making regarding removal and return to field

• In the event of a storm, shelter indoors must should be obtained

• Other guidelines– Avoid large trees, flag/light poles, standing water,

telephones, pools, showers, and metal objects (bleachers, equipment,umbrellas)

– Last resorts find car, ravine, ditch or valley for safety– If hair stands up on hand you are in imminent danger

and should get down on the ground but not flat as that increases surface area

• Additional Guidelines– Lightening is generally accompanied by thunder

(except 20-40% of the time due to atmospheric disturbances)

– Flash-to-bang methods estimates distance away for the storm

• From time lightening is sighted to the clap of thunder count, divide by 5 to calculate the number of mile away

• Count of 30 indicates inherent danger• Count of 15 seconds everyone should leave the field

– NATA and National Weather Service recommend returning to the field 30 minutes following the last clap of thunder or lightening strike

– Major misconception is that lightening that is seen striking is coming down

• In actuality it is the return stroke of the lightening going back up after it has already hit the ground

Air Pollution

• Major problem in urban areas, particularly when considering large periods of exposure

• Two types– Photochemical haze: nitrogen dioxide and

stagnant air acted on by sunlight to produce ozone

– Smog: combination of carbon monoxide and sulfur dioxide

• Ozone– 3 atom molecule of oxygen

• reaction of oxygen, nitrogen oxides, hydrocarbons and sunlight

– Minimum activity levels - ozone will not impact– Higher intensity will have a negative effect on work output– May experience shortness of breath, coughing, chest

tightness, pain with deep breathing, nausea, eye irritation, fatigue, lung irritation, lowered resistance to lung infection

– Asthmatics are at greater risk– May desensitize to some degree over time

• Sulfur Dioxide– Colorless gas that is a component of burning coal or

petroleum– Causes increased resistance to air movement in and out

of the lungs, decreased ability of lungs to rid themselves of foreign matter, shortness of breath, coughing, fatigue and increased susceptibility to lung diseases

– Adverse effects mostly on asthmatics – Nose breathing lessens the effects due to filtering of

nasal mucosa

• Carbon Monoxide– Colorless, odorless gas.– Reduces hemoglobin’s ability to transport

oxygen and restricts release of oxygen to the tissue

– Interferes with performance, and various psychomotor, behavioral, and attention-related activities

• Prevention– To avoid problems, stop or decrease activity

during periods of high pollution– Perform when commuter traffic is less and

ambient temperature is lower– Avoid high times relative to ozone levels– Running should be avoided in areas of high

traffic due to auto emissions and carbon monoxide

Circadian Dysrhythmia (Jet Lag)

• Desynchronization of biological and biophysical time clock

• Body maintains cyclical mechanisms over 24 hour periods (circadian rhythms)– Changes in temperature, hormone levels)

• Body adapts over time to changes– Immediately (protein metabolism) – Over 8 days (body temperature)– Three weeks (adrenal hormones)

• Jet lag refers to physical and mental effects caused by traveling rapidly across time zones– Disrupts circadian rhythms and sleep-wake cycles

• May cause fatigue, headaches, digestive disorder, changes in blood pressure, heart rate, hormone and endocrine releases, and bowel habits

• Could negative impact performance and predispose athlete to injury

• May become ill, suffer short term anorexia, headaches, blurred vision, dizziness, insomnia and/or fatigue

– Younger individuals adjust more rapidly• 30-50% faster adaptation flying westward

• North-south travel has no impact unless time zones are crossed

• Changes in zones, illumination and environment can be disruptive (>5 time zones)

– To prevent• Depart well rested

• Pre-adjust– Eat according to time changes

– Avoid dehydration

– Training schedule

• Use caffeine when travelling west

• Adopt local time on arrival

• Avoid alcohol, before, during and after the trip

Synthetic Turf• Believed to be:

– durable, offer great consistency, usable with inclement weather, require less maintenance

– offer greater performance in areas of speed and resiliency

• Variety of surfaces have been created since 1960’s

• Most recent is “resilient infill turf”– Similar to grass, polyethylene and polypropylene yarn

on a base of sand, rubber pellets or combination

• Constant debate– Injury perspective- not conclusive evidence that synthetic

surface increases injury rates

– Empirically, athletes, coaches, and athletic trainers agree that injuries are more likely on turf

• Most would prefer to play and practice on natural surfaces

• Hybrid, more durable grasses are also available

– Synthetic surfaces• Lose shock absorbing capabilities

• Injuries are more likely to occur when training always occurs on turf

• Due to possibly of higher speeds as a result of turf, injuries involving collisions could be more severe due to increased force and impact

– Shoes that don’t “stick” will significantly reduce likelihood of injury

– Common injuries• Abrasions (reduce with padding)

• Turf toe (less likely to occur if shoes has stiff, firm sole)