Physiology of the endurance athlete Flashcards
What is the definition of endurance performance?
Continuous activity beyond 5 minutes but less than 4 hours in duration
Exercise that predominantly requires aerobic energy systems
What are the other aspects of endurance performance?
Intensity variation
Significant team component to winning performance
Equipment choices
Nutritional considerations; fuel utilisation - very high % CHO, endogenous CHO are limiting 2 hrs, CHO absorption during exercise (>60g)
Dehydration
Environmental considerations; hot environments. cold environments, altitude
What are the physiological components of elite endurance performance?
Lactate threshold
Maximal oxygen consumption
Gross mechanical efficiency
What is VO2max and what factors affect it?
“maximum rate at which oxygen is used by the skeletal muscle”
Size of the athlete
Active skeletal musculature
Gender comparison - females lower due to lower oxygen carrying capacity of the blood
How does VO2 max correlated with performance?
It is not the strongest predictor of performance
BUT it represents the maxima rate of ATP generation aerobically and therefore provides an upper ceiling for endurance performance
Describe the Fick equation
VO2 = Qmax x a-v(o2)max
What affects Q = SV x HR
Blood volume lower in untrained than cycling professionals
End diastolic volume is higher in endurance athletes by 33%
What affects stroke volume?
Myocardial mass is higher in endurance athletes (and higher on the left side) by 33%
LV Stroke volume is higher by 33%
High stroke volume due to more blood (total and filling heart) and muscle mass
What affects VO2max?
Improved vascular network
Higher number of capillaries in skeletal muscle so more per muscle fibre which slows down the transit time of O2 and therefore more O2 diffusion
Higher % of type 1 muscle fibres
Increased mitochondrial volume - to utilise O2
What happens when lactic acid is produced?
It is the end product of anaerobic glycolysis - it is a fuel and allows glycolysis to continue
An increase in lactate means an increase in H+ which means a decrease in pH which;
Inhibits Ca2+ release disrupting muscular contraction
Inhibits PFK decreased rate of glycolysis
Describe the three lactate thresholds
Baseline = 1mmol/L
LT1 = increase in BLa above baseline levels
LT2 (OBLA) = exercise intensity at which BLa increases exponentially (4mmol/L)
How does blood lactate correlate with performance?
Right shift for endurance athlete - BLa at a given workload is lower in endurance athletes
LT is crucial in determining how much power an athlete can produce
90% of variance in performance explained by LT
Explain how reduced appearance of BLa improves endurance athletes performance
The absolute workloads at which anaerobic energy contribution significantly increases is higher because of improved aerobic system
Explain how improved clearance of BLa improves endurance athletes performance
Improved buffering of H+ ions via increased monocarboxylate transporters
Define gross efficiency and describe the equation
“the ratio of power output to energy expenditure”
( Work accomplished / energy expended ) * 100
