chapter 6: environmental considerations © 2011 mcgraw-hill higher education. all rights reserved

Chapter 6: Environmental Considerations

© 2011 McGraw-Hill Higher Education. All rights reserved.

• Environmental stress can adversely impact performance and pose serious health threats

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


Hyperthermia

• Hyperthermia: elevated body temperature

• Has caused a number of deaths over the years

• Must manage heat stress appropriately and plan accordingly with coaching staffs


Heat Stress• Extreme caution should be used when training in

the heat (overexposure could result in heat illness) and is risky

• It is preventable• Physiologically the body will continue to function

if body temperature is maintained• Body must be able to dissipate (get rid of) heat to

maintain homeostasis• Youth and elderly most susceptible


Heat can be gained or lost through:• 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 (standing on turf)

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

circulation of medium (water or air)

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

temperature


• Evaporative Heat Loss– Evaporation of water takes heat with it– Sweat glands allow water transport to

surface– 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 (2 pounds)

– Air must be relative water free for evaporation to occur

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


QUESTIONS

• Name the five ways heat is gained or lost through.

• T/F: The heavier athlete sweats more.

• T/F: A “fit” athlete sweats more.

• T/F: A well hydrated athlete sweats earlier.

Preventing Heat Illness

• Common sense and precaution– Consume fluids and stay cool

• Hydration– Should begin activity well hydrated

• Involves hydrating during the 24 hours prior to activity

• Urine should be a light yellow in color• Dark urine is an indication of dehydration• Recommended is to drink small quantities at

regular intervals vs. huge volume all at once


– Should consume fluid at regular intervals

• 17-20 fl oz of water or sports drink 2-3 hours prior to activity

and an additional 7-10 fl oz 10-20 minutes before exercise

• Dehydration– Mild dehydration occurs when 2% of body weight is

lost in fluid

– Will impair cardiovascular and thermoregulatory responses

– Signs & symptoms

• Thirst, dizziness, dry mouth, irritability, excessive fatigue, and possible cramps

– Must move individual to cool environment and begin rehydration

• Return to normal weight and absence of symptoms


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

in minimal activity– Adult will typically lose ~1.5L per hour during

exercise– 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


• 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 or

6%– More CHO results in slower absorption– Effective for both short term and endurance

activities© 2011 McGraw-Hill Higher Education. All rights reserved.

• Gradual Acclimatization– Most effective method of avoiding heat stress– Involves becoming accustomed to heat and exercising in

heat over a period of time– 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

– Equipment restrictions may help athlete gradually acclimate


• Identifying Susceptible Individuals– Athletes with 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, the young and the elderly


• 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 >2% loss of BW could be a health threat and should be

removed from practice until normal weight is achieved


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- humidity)

• 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


Mesa Public Schools

• http://www.mesasports.org/heat_index/

Figure 6-3


QUESTIONS

• What are some ways to prevent heat illnesses?

• What type (identity) of athletes are more susceptible to heat illnesses?

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


– Profuse sweating results in loss of water and electrolytes (sodium, potassium, magnesium, and calcium)

– Prevent by consuming extra fluids and maintaining electrolyte balance

– Treat with fluid ingestion and light stretching with ice massage

– Return to play unlikely due to continued cramping


• Exertional Heat Exhaustion– Result of inadequate fluid replacement– Unable to sustain adequate cardiac output– Will exhibit signs of profuse sweating, pale skin,

mildly elevated temperature, dizziness, nausea, vomiting or diarrhea, hyperventilation, persistent muscle cramps, and loss of coordination

– May develop heat cramps or become faint/dizzy– Core temperature will be <104o

– Performance may decrease


– Immediate treatment includes fluid ingestion (intravenous replacement, ultimately), place in cool environment, remove excess clothing

– Must continue to monitor vital signs– Return to play – must be fully hydrated and

be cleared by a physician– If not appropriately treated it could

progress to exertional heat stroke


• Exertional Heatstroke– Serious life-threatening condition, with

unknown specific cause– Characterized by sudden onset - sudden

collapse, LOC, CNS dysfunction, flushed hot skin, minimal sweating, shallow breathing, strong rapid pulse, and core temperature of > 104o F

– Breakdown of thermoregulatory mechanism


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

– Athlete should avoid exercise for a minimum of one week and gradually return to full practice

• Must be asymptomatic and cleared by physician

– Death may result if not treated appropriately


QUESTION

• What is the difference between heat exhaustion and heat stroke?

• Malignant hyperthermia– Muscle disorder causing hypersensitivity to

anesthesia and heat– Similar S&S to heatstroke - muscle biopsy is

needed to detect– Athlete will complain of muscle pain after exercise– Temperature will remain elevated 10-15 minutes

following exercise– 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


• Exertional Hyponatremia– Fluid/electrolyte disorder resulting in abnormally low

concentration of sodium in blood– Caused by ingesting too much fluid before, during and

after exercise– May be result of too little sodium in diet or to much

ingested fluids over a period of prolonged exercise– Athletes that ingest large quantities of water and sweat

over several hours are at risk (marathon, triathlon)– Preventable – must maintain balance


– Signs and Symptoms• Progressively worsening headache, nausea, vomiting• Swelling of hands and feet, lethargy, apathy or agitation• Low blood sodium• Could compromise CNS and create a life-threatening

situation

– If levels can not be determined on-site, measures to rehydrate should be delayed and the athlete should be transported to a medical facility

• Delivery of sodium, diuretics, or intravenous solutions may be necessary


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 in wrestling


QUESTION

• Go to page 160, read 6-1 clinical application exercise.

• On a half sheet of paper answer:– What type of heat illness does the athlete

have?– What should the athletic trainer do?

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

generated by metabolism– Results in impairment of neuromuscular function

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

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


Figure 6-4


• 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 inactivity)– Be aware of 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


QUESTION

• What is the difference between frost nip, superficial frost bite and deep frost bite?

Altitude• Most events do not occur at extreme heights

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

• Body compensates through tachycardia and hyperventilation

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


• Adaptations– Increased height = reduced barometric pressure =

decreased pressure of O2 = less saturation of red blood cells– Individual adaptations dependent on whether the person is a

native, resident or visitor• Native: larger chest capacity, more alveoli, capillaries and red

blood cells• Resident: partial adaptations (increased mitochondria and

hemoglobin, glycogen conservation)• Visitor: 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 dyspnea

• Caused by brain disruption associated with sodium potassium imbalance resulting in fluid retention and cellular pressure changes


– Altitude Pulmonary Edema• Occurs at 9000-10,000 feet.• Lungs accumulate fluid in alveolar walls forming

pulmonary edema• Signs and symptoms: dyspnea, cough,

headache, weakness and occasionally unconsciousness.

• Treat by moving athlete to lower altitude and providing oxygen


– High Altitude Cerebral Edema (HACE)• Usually occurs in conjunction with other life threatening conditions

that can lead to coma or death• Occurs in ~1% of people adjusting to altitudes above 9,000 feet• Result of increased cerebral edema due to increased cerebral

blood flow, which is caused by increased permeability of cerebral endothelium when exposed to hypoxia

• The increased cerebral blood flow results in increased intracranial pressure

• Signs & symptoms– Severe, persistent headache which may precede mental

dysfunction, neurologic abnormalities

• Decent to lower altitudes may save those with HACE


– Sickle Cell Trait Reaction• 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


SCENARIO- ALTITUDE

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


Lightning Safety

• #2 cause of death by weather phenomena

• 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 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– Lightning 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 lightning 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 lightning strike

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

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


• Lightning detector– Hand-held instrument– Able to detect storm

occurring within 40 miles– Allows you to know level

of activity and direction– When it detects a

lightning stroke it emits an audible warning tone

– Inexpensive alternative to setting up contract with weather service


Figure 6-6

SCENARIO- LIGHTNING

Air Pollution

• Significant problem throughout the United States

• Two types– Photochemical haze: nitrogen dioxide and

stagnant air acted on by sunlight to produce ozone

– Smog: combination of carbon monoxide, sulfur dioxide, and particulate matter


• Ozone• Formed by the action of sunlight on carbon based chemicals

(hydrocarbons) in combination with nitrogen dioxides

– 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 become desensitized 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


• Nitrogen Dioxide– Produced through combustion

(automobiles, power plants, home heaters and gas stoves)

– Factor in atmospheric reaction to generate ozone and acid rain

– Can irritate the lungs, lower resistance to respiratory infection and may increase incidence of respiratory disease in children


• 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


• Particulate Matter– Solids found in atmosphere (dust, pollen, molds,

ashes, soot, aerosol)– Generated through wood burning, factory

smokestacks, mining construction– Small enough to be inhaled and absorbed into the

bloodstream or remain imbedded– Exposure to this matter may trigger asthma attacks,

cause whizzing or coughing, respiratory irritation in people with chronic obstructive pulmonary lung disease (COPD) including emphysema and bronchitis


• 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)

• 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 negatively 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 traveling 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 obtained on 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)


chapter 6: environmental considerations © 2011 mcgraw-hill higher education. all rights reserved

Documents

loss of heat

production of heat

mcgrawhill higher education

rid of heat

heat overexposure

ways heat

air radiant heat exchange

heat stress extreme