environment and exercise Flashcards
heat related injuries
hyperthermia: body temp inc too high
heat syncope: fainting and strength loss
heat cramps: serious when multiple muscles
heat exhaustion: may need med attention, dizzy, nausea
heat stroke: med emergency, body temp too high and cause organ damage…confusion, seizure, high core temp
treatment of heat injuries
cold water immersion is best, most rapid dec in body temp
drink cold fluid, cold compress
w cramps, mult cramps = sign of heat stroke, treat as heat exhaustion
factors related to heat injury
- fitness: more fit = dec risk
- tolerate inc work in heat, acclimatize faster, inc sweat - acclimatization: best protection against heat stroke
- exercise in heat 10-14 days
- low intensity, long duration i.e. less than 50% vo2max, 60-100mins
- mod intensity, short i.e. 75% vo2, 30-35 mins
- adaptations: inc plasma vol, vo2max, sweat, qmax…dec body temp and HR resp, dec sodium loss - hydration
- environ temp: convection and radiation dependent on gradient b/w skin and air temp
- high temp = heat not lost, can even gain some - clothing: exposure as uch skin as possible, materials that wick sweat i.e. cotton, polyester
- humidity: water vapor pressure
- evaporation dependent on grad b/w skin and air - metabolic rate: core temp is proportional to work rate
- high work rate inc metabolic heat production - wind: inc heat loss by evaporaton and convection
implications of heat on fitness
- know signs of heat illness i.e. lightheaded
- exercise cooler times
- gradual inc to acclimatize
- light clothes
- monitor HR and alter exercise intensity…stay w/in target HR
- water always
WBGT
wet bulb globe temperature
quantifies overall heat stress
dry bulb temp
block globe temp
wet bulb temp
dry bulb temp: Tdb, ordinary measure of air temp in SHADE
block globe temp: Tg, measure of radiant heat taken in by DIRECT SUNLIGHT
wet bulb temp: Twb, uses mercury bulb thermometer
- sensitive to relative humidity
- index of ability to evaporate sweat
- MOST IMP in determining overall heat stress
environ heat stress
risk of heat stress depends on WBGT
hypothermia when WGBT less than 10degC
hyperthermia when WGBT greater than 27.9deg
hypothermia
core temp below 35deg
- 2deg drop assoc w max shivering
- 4dec = ataxia/clumsiness and apathy
- 6deg = unconscious
- further drop = arrhythmia, dec brain BF, asystole, death
conduction
from body thru phys contact
convection
from body thru air or water
radiation
no phys contact i.e. infrared rays
evaporation
body to water on surface or skin i.e. sweat
what to prioritize in hypothermia
core temperature over limbs
peripheral vasoconstriction occurs, dec skin BF
environmental factors of hypothermia
- temp: gradient for convective heat loss
- vapour pressure: low pressure inc evap
- wind: loss is impacted by wind speed, windchill index
- water immersion: 25x heat loss than air of same temp
insulating factors of hypothermia
- subcutaneous fat: esp effective in cold water
- clothing: clo units…1 clo = insulation needed to maintain core temp at rest 21degC
inc clohtes in windy, cold, wet conditions
dry > wet
amount of insulation needed dec w exercise
heat production in cold
heat production inc upon cold exposure
- inc vo2, dec body fat
- earlier onset of shivering in lean men
inc cold water: resting vo2 and core temp maintained in fat men
- vo2 and core temp dec w thin ppl
fuel use: fat is used for shivering, similar to MICT
- can lead to muscle glycogen depletion bcs inc number of bursts
the cold and personal characteristics
bio sex: at rest, women have faster dec in body temp despite more fat
- inc cold water, similar heat loss among sexes
- body composition is explanation i.e. muscle produces heat
age: 60+ less tolerant, kids have fast loss
treating hypothermia
symptoms: slurred speech, impaired judgment, dec coordination
treating from mild to severe:
- remove from cold, wind, rain
- remove wet clothes
- warm drink and dry clothes
- sleeping bag w other person
- find heat source
- prep for emergency and evac
altitutde
is atmospheric pressure, dec at higher altitude
dec partial pressure of gases
altitude impact on performance
dec PO2 has NO EFFECT on short term anaerobic performance
- o2 transport to muscle isn’t limitation
- dec air resistance may inc performance
long term aerobic performance: dec PO2 will dec performance bcs dependent on o2 delivery to muscles
max aerobic power at altitude
high alt = dec vo2max bcs dec o2 extraction
up to moderate altitudes, dec vo2 max because of dec arterial po2
at high alt, dec vo2max because decrease in Qmax
- max HR dec at altitude
heart rate and altitude
at altitude, inc HR bcs dec o2 in arterial blood
altitude requires inc ventilation, bcs fewer o2 molecules in air
acclimatization to high altitude
inc RBC production, inc hemoglobin concentration because of HIF-1 and erythropoietin (hormone stim RBC prod)
- more hemo, fewer o2
attempts to counter desaturation by lower po2
inc o2 saturation bcs in BF to lungs
- inc nitric oxide
- 1deg adaptation in himalayan sherpas
lifetime altitude residents: complete adaptations in arterial o2 content and vo2max
high altitude climbling
successful climbers have high capacity for hyperventilation
- drives down PCO2 and H in blood
- allows more o2 bind to hemo w same low PO2
climbers contend w appetite loss
- weight loss causes dec type 1 and type 2 muscle diameter
