Flashcards in Physiology of an Endurance Athlete Deck (10):
Define endurance and ultra endurance exercise
Endurance is a continuous exercise bout lasting between 5 minutes and 4 hours, or it is exercise that predominantly requires the aerobic energy system, ultra endurance is a continuous exercise bout lasting longer than 4 hours or longer than a marathon (running)
What are the exercise management considerations for ultra endurance performance?
Long term preparation (periodisation of training, injury management, suitable goal setting), optimal rate of movement (race pace, training pace, efficiency of effort/economy), overtraining, prevention of injury, sufficient nutrition (pre and during event), psychological toughness
What are the physiological factors affecting endurance performance?
VO2max, running economy, lactate threshold, performance vo2, fuel supply
What are the central and peripheral limiting factors of VO2max?
Pulmonary diffusing capacity (central), maximal cardiac output (central), oxygen carrying capacity of blood (central), skeletal muscle characteristics (peripheral)
Explain how the body controls blood lactate
Lactate regulated at rest so that production and removal keep resting levels between 0.5-1.5 mmol/L, when rate of appearance (RA) matches rate of disappearance (RD) blood lactate remains in a steady state, when rate of glycolysis increases, RA increases, causing RA > RD and an accumulation of blood lactate
What causes fatigue during high intensity exercise?
As lactate increases so does the production of H+ ions which decrease pH of the blood causing acidosis, acidosis inhibits PFK (rate limiting enzyme) and calcium release which has a detremental effect on muscular contraction, lactate does not cause fatigue but it is the accompanying acidosis that affects enzymes of energy metabolism and muscle contraction
Explain why muscle capillary density, stroke volume and aerobic enzyme activity impacts VO2max
Increased muscle capillary density increases mean transit time at the muscle allowing more oxygen into the muscle and waste removal, increased stroke volume means higher cardiac output (a major determinant of VO2max) increasing blood flow and oxygen supply to working muscles, increased aerobic enzyme activity increases ATP production capacity allowing athletes to work at a higher % of VO2max
Why would an athlete with an improved running economy have a better lactate have a better lactate threshold velocity?
Increased running economy leads to lower oxygen consumption and a lower rate of fuel consumption, this alllows an athlete to run at a faster pace without working any harder or run at the same pace for longer without fatiguing
Explain why a greater % of slow twitch skeletal muscle fibres is associated with a greater running economy
More slow twitch muscle fibres results in more mitochondria, this means less oxygen is being used to maintain a given output, there is an increased capacity for aerobic resynthesis of ATP so athletes can maintain a higher VO2max during exercise or perform the same workload at a lower % of VO2max, lower rate of oxygen consumption associated with an improved running economy