exercise physiology

what are the avenues of dry heat exchange?

convenction , radiation, conduction , evaporation

convection

heat transfer by movement of air or water (through physical touch)

radiation

infrared heat emitted to enviroment / infrared rays

conduction

heat transfer by movement of air or water

wet heat exchange

evaporation

evaporation

sweat changing from liquid to vapor

primary mechanism of heat loss during exercise:

evaporation

critical temperature theory

states the brain shuts down around 40-41 degrees C

what is the body’s thermostat

prepptic : anterior hypothalamus (POAH)

3 WAYS TO INCREASE HEAT PRODUCTION IN RESPONSE TO COLD

shivering , non shivering , exercise

involuntary ways to increase heat production in response to cold

• shivering

• non- shivering

voluntary ways to increase heat production in response to cold

• exercise ( muscular contraction)

what is the wet bulb globe thermometer

enviormental heat stress index

• dry temperature

• wet bulb temperature (humidity)

• globe temperature ( radiation)

how helpful is it for athletic events

• when is it safe to practice

• hydration breaks

• when to cancel events

• prevent heat illness

how will dehydration affect the components of q

• cardiovascular drift occurs

• skin blood flow

• core temperature

• performance

heat & illnesses symptoms

• heat cramps

• heatstroke (medical emergency)

• heat exhaustion

heat cramps

• sodium loss + dehydration

• painful spasms ( calves, abdomen)

heat exhaustion

• severe dehydration

• weak rapid pulse

• dizziness

• nausea

• fainting

• low plasma volume

heatstroke (medical emergency)

• core temperature >40 c

• hot , dry skin

• confusion / altered mental state

• possible unconsciousness

• immediate cold-water immerssion needed

why is it more difficult to deliver o2 when we are at altitude

• less oxygen loaded into blood

• hypoxia in tissues

• lower Vo2 max

dehydration risk increase , why ?

• dry air increases respiratory water loss

• cold induced diuresus

• increased ventilation

• blunted thirst

how to counteract dehydration

• drink more water than thirst signals

• warm fluids

• electrolytes

• avoid acohol / caffeine early on

caloric increases , why ?

• higher metabolic rate

• increased carbohydrate rate

• shivering

• harder breathing

how to counteract caloric increase

• increase calorie intake

• high-carb diet

• snacks between meals

• iron-rich food ( for rbc production)

altitude sickness

• acute mountain sickness

• HAPE

• HACE

actue mountain sickness

• headache

• nausea

• fatigue

• dizziness

• shortness of breath

timeline: begins 6-48hrs after arrival : last 2-4 days

HAPE ( pulmonary edma)

• fluid in lungs

• extreme shortness of breath

• frothy sputum

• fatigue

• life- threatening

timeline: 2-4 days

HACE ( cerebral edma)

• severe headache

• confusion

• loss of coordination

• possible coma

• life - threatening

timeline : 2-5 days

Acute effects on VO2 max, HR, Q, Ventilation, Hematocrit

• vo2 max decrease (8-11% per 1000m above 1500m)

• HR increases

• Q intially increases (due to HR rise)

• stroke volume decrease (plasma volume drops)

• ventilation increases immediately (hyperventilation)

• hematocrit increases (due to plasma volume loss , no RBC rise yet

Long term effects on hematocrit, why does it happen ?

chronic hypoxia → kidneys release epo→ increase RBC production

• higher hematocrit

• higher hemoglobin

• more o2 - carry capacity

takes two weeks to fully occur

what is blood doping ?

artifically increasing RBC count by blood transfussion

advantages of blood doping

• increase hemoglobin

• increase o2 carrying capacity

• vo2 max increase

• delayed fatigue

Live High , Train low benefits to competition at sea level

• live at high altitude → stimulate EPO→ more RBCs

• train at low altitude → maintaining high- intensity workouts

benefits of live high, train low

• increase vo2 max

• improved endurance at sea level

• enhance RBC mass

• better performance 3-4 weeks after returing

coldness illness

• hypothermia

• frostbite

hypothermia

• <35 c core temp

• mild : shivering / numbness

• moderate: confusion

• severe: no shivering , no HR

frostbite

• skin tissue freezing

• pale/ white skin

• numbness

• most common: fingers, toes , ears , nose