wk1 heat and exercise performance

Question 1

what 4 regulators does heat stress cause conflict within

Answer 1

temperature regulation
blood pressure regulation
blood volume regulation/osmoregulation
respiratory regulation

Question 2

how does heat stress impair endurance performance

Answer 2

reduction in time to exhaustion
progressive decrease in work rates in self-paced exercise
reduced maximal aerobic power (lower vo2 max)

Question 3

what does heat stress lead to

Answer 3

hyPERthermia

Question 4

how does heat stress affect cardiovascular function

Answer 4

through redistribution and comp for blood flow - impacts o2 delivery and heat dissipation

Question 5

how does heat stress affect the central motor drive

Answer 5

influences muscle activation and force production capacity - makes normal work seem harder

Question 6

how does heat stress affect skeletal muscle function

Answer 6

metabolic demands increase, structural characteristics of the muscle
skeletal muscle autonomic responses

Question 7

what happens to HRmax under heat stress conditions

Answer 7

it is reached at a lower work rate - coupled with lower SV leads to less cardiac output

Question 8

what alterations happen in the central motor drive during heat stress

Answer 8

lower afferent input - less muscle activation and force, less voluntary activation and less excitability

lower motivation to exercise - increased total discomfit

Question 9

what happens when you reach your critical core temp

Answer 9

triggers premature fatigue by reducing your mental drive, acts as a safety break

Question 10

what problems occur in skeletal muscle functions during heat stress

Answer 10

increased muscle glyc utilization and anaerobic metabolism causing greater accumulation of ammonia and muscle lactate

Question 11

what is the order of priority of regulation during heat stress exercise

Answer 11

1.blood pressure
2.metabolism
3.body temperature

Question 12

what does dehydration cause

Answer 12

lower plasma volume
increased plasma osmolality (less diluted blood so more ions than water)

Question 13

what does plasma hyperosmolality do during exercise

Answer 13

this reduces the sweat rate at any gicen core temp, ultimately lowering evporative heat loss

Question 14

how does dehydration affect performance

Answer 14

heightens core temperature rapidly

Question 15

how can single-sprint performances be improved

Answer 15

passive local muscle heating - warm baths/heated blankets
active warm ups
passive heating - elevate core temp by 1c

Question 16

how can partial heat help anaerobic performances

Answer 16

faster rate of pcr utilisation
greater ATP turnover and adenine nucleotide degradation
accelerated muscle fiber conduction velocity

Question 17

what temp is best to improve repeated sprint performance

Answer 17

lower than 38.5c

Question 18

how can elevated core temp impair repeated sprints

Answer 18

impaired CNS
reduction in co2 and o2 transport

Question 19

how to optimise during heat stress

Answer 19

weeks - training, acclimatization
hours - hydration, pre-cooling
during - clothing, hydration, pacing, cooling

Question 20

what is the difference between acclimation and acclimatisation

Answer 20

acclimation = artificial exposure
acclimatisation = natural exposure

Question 21

how does acclimatizing help

Answer 21

larger reduction in body temp during exercise

increases onset threshold, sensitivity and max capacity of sweating and skin blood flow responses
increases total body water
reduces loss of ions through sweat

Question 22

how does acclimation increase total body water

Answer 22

rapid increase in plasma volume expansion
increase secretion or renal sensitivity to fluid regulation hormones (aldosterone, vasopressin and albumin)

Question 23

what adaptions occur when prepared for heat stress

Answer 23

higher blood volume
lower hr at rest and during exercise
increased stroke volume

all reduce cardiovascular strain during exercise

Question 24

what are heat shock proteins

Answer 24

heat acclimation increases HSP’S, these provide cytoprotection - protect and accelerate repair from heat stress

Question 25

how does heat adaption help the metabolism

Answer 25

glycogen sparing
increases lactate threshold
reduces lactate conc during exercise - improves economy

Question 26

what are the classic markers for heat acclimation

Answer 26

plasma volume expansion
lower core temp
lower hr
increased sweat
increased thermal comfort

Question 27

what is the difference between short and long term heat acclimation

Answer 27

short term has higher excitability in terms of mechanisms that help deal with heat tress however long term has higher efficiency

Question 28

what temps does performance decrement over a long period of time

Answer 28

anything over 10c for longer than 120mins will cause a decreased performance

Question 29

how else does heat acclimation help total body water

Answer 29

sweat losses less Na, Cl and K
increases renal retention of water and electrolytes
changes oncotic pressure and drawing fluid into the intravascular space

Question 30

when does acclimation set in

Answer 30

after 1 week of acclimation effects will be apparent, continous will obvs have more effect