Lecture 17 - Physiological determinants of exercise performance Flashcards
What are the potential sites of fatigue?
Excitatory input to motor cortex
excitatory drive to lower motoneuron
motoneuron excitabililty
NM junction
sarcolemma excitability
excitation- contraction coupling
contractile mechanism
metabolic energy supply
Feedback from the muscle to the brain can modify the central motor drive
when the feedback is inhibited, what happens?
the muscle initially has a larger power output, but will fatigue quicker and reduce power output below that of subjects without the inhibition
There’s normally a balance between how much the CNS wants to drive the muscle and how much the muscle is actually coping
What are the potential factors or fatigue?
Central fatigue
Ionic disturbances
Impaired excitation- contraction coupling
Substrate depletion (ATP, PCr, CHO)
Metabolite accumulation (Pi, H+, ROS)
Fluid and electrolyte loss
Hyperthermia
Muscle damage
What are the essential factors for sprint success?
Muscle mass to geerate force and pwoer
Fast twitch fibres
Neuromusclar recruitment
fatigue resistance
Ability to generate and tolerate lactic acid (buffer capacity)
Fast reaction time
What are the essential factors for sprint success?
Muscle mass to generate force and power
Fast twitch fibres
Neuromuscular recruitment
fatigue resistance
Ability to generate and tolerate lactic acid (buffer capacity)
Fast reaction time
intermittent activity that involve high intensity efforts and periods of rest will be influenced by ____ availability
When more ___ is available, the output for each bout of exercise will decrease to a lesser extent
glycogen
What is the rationale for increasing extra-celullar pH?
A decrese in the msucle pH is associated with fatigue
What are the essential elements for endurance success?
High VO2 max - a big engine, and this is how it’s defined
Ability to maintain high % of VO2 max (fractional utilisation)
High power output at lactate threshold - muscle oxidative capacity
fatigue resistance
efficient/economical technique
Ability to oxidise fat at high power outputs
As cyclists get better what happens to the way muscles are used in the lower limb
the load is spread around so it’s not just the quadriceps providing the power output.
elite cyclists will have a steadily high VO2 max but the muscle oxidative capacity will…
vary depending on whether it’s off-season, will go down a bit
The increase is muscle oxidative capacity means that you don’t use as much ___
glycogen
in other words for the same level of glycogen use, you can exercise at a higher intensity
It is not only the amount of muscle glycogen, but also…
where exactly it is which is relevant
some needed around the sacroplasmic reticulum for Ca2+ channels for instance (checkthat)
Glycogen loading works well for events longer than…
90 mins
Carbohydrate ingestion improves…
exercise capacity
How does Carbohydrate ingestion improve performace?
Prevents fall in glucose
maintain mscle CHO oxidation and brain glucose supply
reduces perception of fatigue
Increases exercise time to fatigue and power output
