Environmental influences on_performance,_exercise_in_hypobaric,_hyperbaric_and_microgravity_environment

ENVIRONMENTAL INFLUENCES ENVIRONMENTAL INFLUENCES ON PERFORMANCEON PERFORMANCE

Thermal Regulation And Exercise Mechanisms Thermal Regulation And Exercise Mechanisms

of Body Temperature Regulationof Body Temperature Regulation

The heat from deep of body (core) is moved The heat from deep of body (core) is moved

by blood to the skin (the shell). by blood to the skin (the shell).

From there transferred to the From there transferred to the

environment by: conduction, convection, environment by: conduction, convection,

radiation, evaporation radiation, evaporation

Conduction, convection - heat loss 10 - 20 Conduction, convection - heat loss 10 - 20

percentpercent

Radiation - 60 percent during rest (infrared, Radiation - 60 percent during rest (infrared, electromagnetic waves)electromagnetic waves)

Evaporation - 80 percent of heat loss Evaporation - 80 percent of heat loss during exerciseduring exercise

Heat production at rest - 1,5 kcal of Heat production at rest - 1,5 kcal of heat/min. at exercise - 15 kcal/min.heat/min. at exercise - 15 kcal/min.

Humidity Humidity

– high - limits sweat evaporation and heat losshigh - limits sweat evaporation and heat loss

– low - ideal for sweat evaporation and heat loss. low - ideal for sweat evaporation and heat loss.

Control of Heat ExchangeControl of Heat Exchange

Hypothalamus Hypothalamus - Body´s Thermostat - Body´s Thermostat

Thermoregulatory center - Thermoregulatory center -

hypothalamushypothalamus Two sets of Two sets of

thermoreceptors: central -hypoth. thermoreceptors: central -hypoth.

peripheral - in skin (temperature peripheral - in skin (temperature

around the body) impulses to hypoth. around the body) impulses to hypoth.

and cerebral cortex - consciously and cerebral cortex - consciously

perceive temperature - voluntary perceive temperature - voluntary

control exposure to heat or cold.control exposure to heat or cold.

Effectors Altering Body Effectors Altering Body

TemperatureTemperature

Sweat glands, smooth muscles Sweat glands, smooth muscles

around arterioles, skeletal muscles, around arterioles, skeletal muscles,

endocrine glands (thyroxin, endocrine glands (thyroxin,

epinephrine)epinephrine)

Physiologic Responses Physiologic Responses to Exercise in the to Exercise in the HeatHeat

Exercise in Hot EnviromentExercise in Hot Enviroment

Competition between active muscles Competition between active muscles and skin for limited blood supply and skin for limited blood supply muscles - blood and oxygen for muscles - blood and oxygen for sustain activity, sustain activity,

skin - blood to facilitate heat loss to skin - blood to facilitate heat loss to keep the body cool.keep the body cool.

Cardiovascular ResponseCardiovascular Response

Adjustement - Adjustement - blood volume returning blood volume returning to the heart - to the heart - end. diastolic end. diastolic volume - volume - ↓↓SV - compensation - SV - compensation - gradual upward drift in HR gradual upward drift in HR cardiovascular driftcardiovascular drift..

Energy ProductionEnergy Production

Exercise in hot enviroment - Exercise in hot enviroment - O O22 uptake, uptake, use of more glycogen, produce more use of more glycogen, produce more lactate - earlier fatigue and exhaustionlactate - earlier fatigue and exhaustion

Body Fluid Balance - SweatingBody Fluid Balance - Sweating

Sweat - filtration of plasma. Reabsorption of Na and Sweat - filtration of plasma. Reabsorption of Na and Cl´ in passing through the duct. Cl´ in passing through the duct.

Increased sweat rates - quick movement, less time Increased sweat rates - quick movement, less time for reabsorption - loss of natrium and chloride - with for reabsorption - loss of natrium and chloride - with training - aldosterone stimulates for more training - aldosterone stimulates for more reabsorption of Na´, Cl´ . Sweat production in hot - reabsorption of Na´, Cl´ . Sweat production in hot - 1l/HR/m2 - 2 - 4 percent of body weight 1l/HR/m2 - 2 - 4 percent of body weight blood volume - dehydration. Triggering aldosterone, blood volume - dehydration. Triggering aldosterone, ADH ADH Na´ excretion in kidneys ADH - water Na´ excretion in kidneys ADH - water reabsorption in kidneys reabsorption in kidneys fluid retention. fluid retention.

HEALTH RISKS DURING EXERCISE HEALTH RISKS DURING EXERCISE IN THE HEATIN THE HEAT

Heat StressHeat Stress - reflected not only by air temperature, - reflected not only by air temperature, further variables take into account: humidity, air velocity, further variables take into account: humidity, air velocity, amount of radiation.amount of radiation.

Heat-related DisordersHeat-related Disorders1) 1) Heat CrampsHeat Cramps

Involving muscles heavily used during exercise, brought Involving muscles heavily used during exercise, brought on by mineral losses and dehydration accompanying high on by mineral losses and dehydration accompanying high rates of sweating.rates of sweating.

2) 2) Heat ExhaustionHeat ExhaustionSymptoms: fatigue, dyspnea, dizzines, vomiting, fainting, Symptoms: fatigue, dyspnea, dizzines, vomiting, fainting, clammy, or hot dry skin, hypotension, weak, rapid pulse - clammy, or hot dry skin, hypotension, weak, rapid pulse - cause:CV system´s inability to adequately meet the bodycause:CV system´s inability to adequately meet the body´s needs. Treatment - rest in cooler enviroments, feet ´s needs. Treatment - rest in cooler enviroments, feet elevated, salt water.elevated, salt water.

3) 3) Heat Stroke - Life - Threatening DisorderHeat Stroke - Life - Threatening Disorder

CHARACTERISTICS: CHARACTERISTICS: internal body temperature internal body temperature

4040ooC, cessation of sweating, hot, dry skin, rapid C, cessation of sweating, hot, dry skin, rapid

pulse and respiration, hypertension, confusion, pulse and respiration, hypertension, confusion,

unconsciousness. unconsciousness.

CAUSE: failure of thermoregulatory mechanism CAUSE: failure of thermoregulatory mechanism

Treatment - cooling body in a bath of cold water or Treatment - cooling body in a bath of cold water or

ice, or wrapping the body in wet sheets and fanning.ice, or wrapping the body in wet sheets and fanning.

Prevention of HyperthermiaPrevention of Hyperthermia

Cancel training or competition if the Cancel training or competition if the environmental heat stress to high, wearing environmental heat stress to high, wearing proper clothing, being alert to signs of proper clothing, being alert to signs of hyperthermia, ensuring adequate fluid intake.hyperthermia, ensuring adequate fluid intake.

Heat AcclimatizationHeat Acclimatization

Exercise in the heat for up to an hour each Exercise in the heat for up to an hour each day for 5 to 10 days. CV changes occur in the day for 5 to 10 days. CV changes occur in the first 3 - 5 days, sweating mechanisms first 3 - 5 days, sweating mechanisms take longer, up to 10 days. Heat take longer, up to 10 days. Heat acclimatization - acclimatization - the rate of muscles the rate of muscles glycogen use, delaing fatigue.glycogen use, delaing fatigue.

EXERCISE IN THE COLDEXERCISE IN THE COLD

Cold StressCold Stress - environmental condition causing loss - environmental condition causing loss of body heat threatening homeostasis, two of body heat threatening homeostasis, two major cold stressors: air and water. Primary means major cold stressors: air and water. Primary means CONSERVING BODY HEATCONSERVING BODY HEAT activated by activated by hypothalamus: hypothalamus:

SHIVERINGSHIVERING - - 4 - 5 fold increase resting heat 4 - 5 fold increase resting heat productionproduction

NONSHIVERING THERMOGENESISNONSHIVERING THERMOGENESIS - - metabolism metabolism by sympathetic nervous s. - by sympathetic nervous s. - internal heat internal heat productionproduction

PERIPHERAL VASOCONSTRICTIONPERIPHERAL VASOCONSTRICTION - sympathetic - sympathetic stimulation smooth muscles in arterioles - stimulation smooth muscles in arterioles - heat loss heat loss metabolism of skin cells - metabolism of skin cells - less O less O22 requirement requirement

FACTORS AFFECTION FACTORS AFFECTION BODY HEAT LOSSBODY HEAT LOSSa) a) Body Size And CompositionBody Size And Composition- subcutaneous fat - more fat mass - - subcutaneous fat - more fat mass -

conservation heat more efficientlyconservation heat more efficiently- ratio of body surface area to body mass. - ratio of body surface area to body mass.

ratio - lower susceptibility to hypothermiaratio - lower susceptibility to hypothermia- gender - defferences minimal- gender - defferences minimal

b) b) WindchillWindchillWind - increase the rate of heat loss via Wind - increase the rate of heat loss via convection and conductionconvection and conduction

Heat Loss in Cold WaterHeat Loss in Cold Water Water - thermal conductivity 26 times greater Water - thermal conductivity 26 times greater

than air. The body loses heat 4 x faster in water than air. The body loses heat 4 x faster in water than in air of the same temperature.than in air of the same temperature.

Internal body´s temperature remain constant at Internal body´s temperature remain constant at temperature down to 32temperature down to 32ooC. Exposure to water at C. Exposure to water at 1515ooC - decrease of rectal t. at 2.1C - decrease of rectal t. at 2.1ooC/hour, at 4C/hour, at 4ooC - C - decrease at 3.2decrease at 3.2ooC/Hr. Heat loss further increased C/Hr. Heat loss further increased - water moving. Survival in cold water brief - - water moving. Survival in cold water brief - consciousness lose in minutes. Long - distance consciousness lose in minutes. Long - distance swimmers - subcutaneous fat important role - swimmers - subcutaneous fat important role - obese subjects swim for 6 h 50 min. in water obese subjects swim for 6 h 50 min. in water 11.811.8ooC with no change in rectal temp. Swimmers C with no change in rectal temp. Swimmers with low body fat - 30 min - discomfort, rectal t. with low body fat - 30 min - discomfort, rectal t. drop to 33.7drop to 33.7ooC. C.

FOR COMPETITION, water temp. between 23.9FOR COMPETITION, water temp. between 23.9ooC C - 27.8- 27.8ooC seem appropriate.C seem appropriate.

Physiological Responses Physiological Responses to exercise in cold to exercise in cold

When muscle is cooled, it is weakened When muscle is cooled, it is weakened

and fatigue occurs more rapidly. and fatigue occurs more rapidly.

Prolonged e. in cold, as energy Prolonged e. in cold, as energy

supplies diminish and e. intensity supplies diminish and e. intensity

declines, susceptibility to hypothermia declines, susceptibility to hypothermia

increaes. E. in cold - vasoconstriction increaes. E. in cold - vasoconstriction circulation to subcutaneous fat - circulation to subcutaneous fat -

decrease of FFA for fuel.decrease of FFA for fuel.

HEALTH RISKS DURING HEALTH RISKS DURING EXERCISE IN COLDEXERCISE IN COLD

HypothermiaHypothermia

Decrease of body t. down bellow 34.5Decrease of body t. down bellow 34.5ooC, C, hypothalamus lose ability to regulate t. hypothalamus lose ability to regulate t. Completely lost at 29Completely lost at 29ooC - drowsiness and C - drowsiness and coma. Heart´s SA-node - drop of HR - coma. Heart´s SA-node - drop of HR - CO. Breathing cold air does not freeze the CO. Breathing cold air does not freeze the respiratory passages of the lung. respiratory passages of the lung. Respiratory rateRespiratory rate , MV , MV ..

Frost BiteFrost Bite - vasoconstriction to the skin - - vasoconstriction to the skin - reduced blood flow, skin cooled. Lack of reduced blood flow, skin cooled. Lack of OO22 and nutrients - skin tissue death. and nutrients - skin tissue death.

TreatmentTreatment

Hypothermia - dry clothing, warm Hypothermia - dry clothing, warm beverages, slow rewarming, hospital beverages, slow rewarming, hospital treatment. Frostbite - left untreated until treatment. Frostbite - left untreated until can be thawed, best in a can be thawed, best in a hospital.hospital.

Cold AcclimatizationCold Acclimatization

Chronic daily exposure to cold water Chronic daily exposure to cold water increase subcutaneous fat. Repeated increase subcutaneous fat. Repeated exposure to cold - alter peripheral blood flow exposure to cold - alter peripheral blood flow and skin temperature - greater cold and skin temperature - greater cold tolerance.tolerance.

EXERCISE IN HYPOBARIC, EXERCISE IN HYPOBARIC, HYPERBARIC AND MICROGRAVITY HYPERBARIC AND MICROGRAVITY ENVIRONMENTENVIRONMENT

A A Hypobaric environmentHypobaric environment

Altitude presents a hypobaric Altitude presents a hypobaric environment. environment.

The ATMOSPHERIC PRESSURE is reduced, The ATMOSPHERIC PRESSURE is reduced, altitudes more than 1,500 m notable altitudes more than 1,500 m notable impact on human body. Reduced PO2 - impact on human body. Reduced PO2 - decreased performance at altitude (decreased performance at altitude ( pressure gradient - hinders oxygen pressure gradient - hinders oxygen transport to tissues).transport to tissues).

Air TemperatureAir Temperature

Drops as altitude increases, cold air - Drops as altitude increases, cold air - hold little water - dry air - hold little water - dry air - susceptibility to cold related susceptibility to cold related disorders and dehydration.disorders and dehydration.

Solar RadiationSolar Radiation - more intense - more intense (thinner atmosphere, drier air)(thinner atmosphere, drier air)

Physiological response to altitudePhysiological response to altitude

Pulmonary ventilation both at rest, Pulmonary ventilation both at rest, exercise respiratory alkalosis (exercise respiratory alkalosis ( CO CO22 elimination, kidney excrete more elimination, kidney excrete more bicarbonates - more acids in blood - bicarbonates - more acids in blood - compensation for alkalosis) hemoglobin compensation for alkalosis) hemoglobin saturation drops from 98 percent to 92 saturation drops from 98 percent to 92 percent at height 2,439 m.percent at height 2,439 m.

POPO22 gradient arterial blood - tissue drops gradient arterial blood - tissue drops from 74 min Hj (94 - 20 from 74 min Hj (94 - 20 74) to 40 min 74) to 40 min (60 - 20 (60 - 20 40) at 2,439 m height. 40) at 2,439 m height.

VVO2O2 max decreases as altitude increases. max decreases as altitude increases.

Plasma Volume decrease - Plasma Volume decrease - red blood cells red blood cells

concentration - more O2 transportconcentration - more O2 transport

COINCREASECOINCREASE by increase of HR. by increase of HR.

During maximal work - SV, HR decrease – During maximal work - SV, HR decrease – CO DECREASECO DECREASE - - O O22 delivery and uptake. delivery and uptake.

Oxidative capacity decreased, anaerobic energy Oxidative capacity decreased, anaerobic energy production increase - production increase - blood lactate level. Hypoxic blood lactate level. Hypoxic vasoconstriction in pulmonary arteries vasoconstriction in pulmonary arteries PULMONARY HYPERTENSION PULMONARY HYPERTENSION

ENDURANCE ACTIVITY - most limited - oxidative ENDURANCE ACTIVITY - most limited - oxidative energy production decreased. energy production decreased.

Anaerobic SPRINT ACTIVITIES Anaerobic SPRINT ACTIVITIES 1 MIN - not limited. 1 MIN - not limited.

Thinner air - less resistance to movement (long Thinner air - less resistance to movement (long jump record 1968 at Olympic games in Mexico city)jump record 1968 at Olympic games in Mexico city)

Altitude TrainingAltitude Training Hypoxic conditions - Hypoxic conditions - release of release of

erythropoetin - INCREASED RED BLOOD erythropoetin - INCREASED RED BLOOD CELL PRODUCTION - increase blood oxygen CELL PRODUCTION - increase blood oxygen - carrying capacity. Advantage during first - carrying capacity. Advantage during first few days after returning to sea few days after returning to sea level. level.

Athletes who must perform at altitude - Athletes who must perform at altitude - train at altitude of 1,500 - 3,000 mtrain at altitude of 1,500 - 3,000 m

FOR AT LEAST 2 WEEKS prior to performing FOR AT LEAST 2 WEEKS prior to performing (adaptations to hypoxic and other (adaptations to hypoxic and other environmental conditions at altitude). environmental conditions at altitude).

CLINICAL PROBLEMS OF ACUTE CLINICAL PROBLEMS OF ACUTE EXPOSURE TO ALTITUDEEXPOSURE TO ALTITUDE

Altitude (Mountain) SicknessAltitude (Mountain) Sickness Symptoms: headache , nausea, vomiting, Symptoms: headache , nausea, vomiting,

dyspnea, insomniadyspnea, insomnia Appear - 6 - 96 HR after arrivalAppear - 6 - 96 HR after arrival Cause - probably accumulation of CO2 in Cause - probably accumulation of CO2 in

tissuestissues Prevention - gradual ascent, no more than Prevention - gradual ascent, no more than

300 m per day above 3,000 m300 m per day above 3,000 m Treatment - acetazol amide, Treatment - acetazol amide,

dexamethazone, retreat to lower altitudedexamethazone, retreat to lower altitude

High Altitude Pulmonary Edema High Altitude Pulmonary Edema (HAPE)(HAPE)

Symptoms: dyspneaSymptoms: dyspnea Treatment: Retreat, oxygenTreatment: Retreat, oxygen

High Altitude Cerebral Edema (HACE)High Altitude Cerebral Edema (HACE) Mental confusion, coma, death.Mental confusion, coma, death.

B) HYPERBARIC CONDITIONS B) HYPERBARIC CONDITIONS - EXERCISING UNDERWATER- EXERCISING UNDERWATER

Submersion in WaterSubmersion in Water

Exposal to hyperbaric conditions -Exposal to hyperbaric conditions -volume decreases when pressure volume decreases when pressure increases.increases.

More molecules of gas are forced More molecules of gas are forced into solution, with rapid ascent, they into solution, with rapid ascent, they come out of solution and can form come out of solution and can form bubbles - emboli develop, block bubbles - emboli develop, block major vessels, extensive tissue major vessels, extensive tissue damage.damage.

Resting HEART RATE DECREASES by Resting HEART RATE DECREASES by 5 - 8 beats per minute (facilitation 5 - 8 beats per minute (facilitation blood return to the heart) diving in blood return to the heart) diving in cold water - greater bradycardia, cold water - greater bradycardia, higher incidence of arrhythmias higher incidence of arrhythmias

BRETH-HOLD DIVING. Hyper ventilation BRETH-HOLD DIVING. Hyper ventilation

used used

(( PaCO PaCO22), dangerous (), dangerous ( PaO PaO22 - lose - lose conscious ness under water). Volume of conscious ness under water). Volume of air can be reduced to RV, but no smaller.air can be reduced to RV, but no smaller.

TLV/RV - limit the possible diving depth TLV/RV - limit the possible diving depth large TLV/RV - deeper diving large TLV/RV - deeper diving

SCUBA DIVING - inhaled gas pressurized, SCUBA DIVING - inhaled gas pressurized, equal to that of water. Deeper dives equal to that of water. Deeper dives greater air flows, less time to exhaustion greater air flows, less time to exhaustion of the tank exhaustion.of the tank exhaustion.

Health Risks of Hyperbaric Health Risks of Hyperbaric ConditionsConditions1) 1) Oxygen PoisoningOxygen PoisoningVisual distortion, rapid, shallow Visual distortion, rapid, shallow

breathing - convulsion. PO2 breathing - convulsion. PO2 318 mm 318 mm Hg - constriction of cerebral vessels.Hg - constriction of cerebral vessels.

2) 2) Decompression SicknessDecompression SicknessNitrogen bubbles in circulation and Nitrogen bubbles in circulation and

tissues - attempt to rapid ascent. tissues - attempt to rapid ascent. Symptoms – pain in elbows, Symptoms – pain in elbows, shoulders, knees. Treatment - placing shoulders, knees. Treatment - placing in RECOMPRESSION CHAMBERin RECOMPRESSION CHAMBER

3) 3) Nitrogen NarcosisNitrogen Narcosis

Symptoms - impaired judgement, similar Symptoms - impaired judgement, similar to alcohol intoxication (for every 15 m to alcohol intoxication (for every 15 m increase in depth increase in depth 1 Martini on an empty 1 Martini on an empty stomach).stomach).

4) 4) Spontaneous PneumothoraxSpontaneous Pneumothorax

Expansion of air in lungs during ascent, Expansion of air in lungs during ascent, over distension - rupture of aveoli.over distension - rupture of aveoli.

5) 5) Ruptured EardrumRuptured Eardrum

Inability to equalize the pressure in the Inability to equalize the pressure in the middle ear - force against eardrum - pain, middle ear - force against eardrum - pain, rupture rupture

C) MICROGRAVITY ENVIRONMENTS, C) MICROGRAVITY ENVIRONMENTS, EXERCISE IN SPACEEXERCISE IN SPACE

Physiological changes during extended Physiological changes during extended periods exposure to microgravity similar to periods exposure to microgravity similar to those with detraining in athletes and in aging those with detraining in athletes and in aging population. Weight bearing bones, population. Weight bearing bones, antigravitational muscles are unloaded - antigravitational muscles are unloaded - reduced ability to function - similar effects in reduced ability to function - similar effects in CV system. Strength and cross-sectional area CV system. Strength and cross-sectional area of SA AND FA FIBERS DECREASE. BONE of SA AND FA FIBERS DECREASE. BONE MINERAL DENSITY DECREASES approximately MINERAL DENSITY DECREASES approximately 4% from the weight bearing bones. 4% from the weight bearing bones.

Microgravity results in body´s Microgravity results in body´s

dumping a large percentage dumping a large percentage

of plasma volume - ORTHOSTATIC of plasma volume - ORTHOSTATIC

HYPOTENSION ON RETURN to earthHYPOTENSION ON RETURN to earth

´s atmosphere. Exercise - most ´s atmosphere. Exercise - most

effective counter - measure during effective counter - measure during

space flight for successful adaptation space flight for successful adaptation

on return to earth.on return to earth.