W7 - Heat_Performance Flashcards
W7 - Heat_Performance
What is the relationship b/w heat & match play performance?
Decrease in overall performance, but particularly in HSR (even in self paced HSR). Body will prioritise dissipation of heat over movement.
What is the relationship b/w core body temperature & endurance performance?
Those who’s core temperature increased quickly as a → of the warm up had > core temp at the end than those that didn’t. However, finish times were similar irrespective of core temp
Are long distance athletes quicker or slower if it’s hot?
Slower. The hotter we get the worse our performance
Are single sprint athletes quicker or slower if it’s hot?
Quicker
Are middle distance athletes quicker or slower if it’s hot?
F affected more (slower) than M with limited affect on M performance
Name 4 ways that athletes can try to manage their response to heat eg pre cooling
Accimatisation; Pre Cooling; Fluid Consumption Strategy; Recovery Strategies
How does wind speed affect performance?
Wind helps evaporation of sweat, but doesn’t need to be fast (16km/h) just moving
What happens to our Cardiovascular system in hot conditions?
• Increased HR • Decreased SV
• Decreased CO • ↓ BP. Can even get CV drift, where HR ↑ to a lvl where can no longer continue
What temperature is Thermo Neutral?
Approx 20-25 °
How does cerebral blood flow change with heat and how can this affect performance?
↓ - Some evidence that prolonged high-intensity exercise in the heat can:
• < attentional focus
• < mental readiness
• < wakefulness
• < mental readiness
• < arousal
How does heat affect maximal O2 uptake?
↓ - but doesn’t happy immediately and relise on ↑ in ‘mean body temperature’ (weighted average of core and skin i.e. whole body temp)
How does heat affect skeletal muscle blood flow?
• > blood flow perfusion
• > oxygen delivery
• > contractile function (velocity/force) • > nerve conduction velocity
Improved jump and sprint performance. Heat can be skin and/ or core temp - i.e. just standing in sun can → in these
How does heat affect metabolism?
Prolongedexerciseintheheat:
• > muscle glycogen utilisation
• > anaerobic metabolism
• > lactate accumulation • > Central limitation of muscle activation (fatigue) • < Force production
How does heat affect fatigue?
↓ VO2 Max; ↑ O2 demand but ↓ O2 delivery; ↓ endurance time and time to anaerobic threshold; overall ↓ in time to volitional exhaustion or ↑ fatigue
The way heat affects volitional exhaustion is multifactorial. What are the 5 factors?
- Psychological factors (experience and expectations eg if lived in Darwin all life, will power, motivation, mood, pain tolerance. 2. CNS requirements eg cerebralblood temp and neurotransmitter depletion 3. CV requirements ↓ SV, ↓ CO, ↑ HR 4. Peripheral Recepttors - altered muscle fn 5. Respiration ↑ ventilation, ↓ O2 tfr
Whats the difference b/w acclimation and acclimatisation?
Acclimation:
• Physiological changes elicited from experimentally induced adaptations to certain climatic conditions (e.g. heat chamber, warm baths).
Acclimatisation:
• Physiological and behavioural changes which occur due to a lifetime or extended exposure to a stressful natural environment (e.g. seasonal or geographical).
Improved cutaneous blood flow is an acclimatisation response, what’s the effect?
Transports metabolic heat from deep tissues to skin
Effective distribution of cardiac output is an acclimatisation response, what’s the effect?
Appropriate circulation to skin and muscles to meet demands of metabolism and thermoregulation; greater blood pressure stability during exercise
Lowered threshold for sweating is an acclimatisation response, what’s the effect?
Evaporative cooling begins early during exercise
More effective distribution of sweat over skin surface is an acclimatisation response, what’s the effect?
Optimum use of effective body surface for evaporative cooling
Increased sweat output is an acclimatisation response, what’s the effect?
Optimum use of effective body surface for evaporative cooling
Lowered salt concentration of sweat is an acclimatisation response, what’s the effect?
Diluted sweat preserves electrolytes in extracellular fluid
Lower skin, core temperature, and heart rate for standard exercise is an acclimatisation response, what’s the effect?
Frees greater proportion of cardiac output to the active muscles
Less reliance on carbohydrate catabolism during exercise is an acclimatisation response, what’s the effect?
Carbohydrate sparing
