Physiology wk9 Flashcards
what factors affect performance
- the type of exercise itself
- strength and skill acquired – practise and genetics
- energy demands
- environment
- diet
- psychological component – motivation and reward
what is the definition of fatigue
inability to maintain power output or force during repeated muscular contraction
what is central fatigue
fatigue of the central nervous system
what is peripheral fatigue
fatigue of:
* neural factors
* mechanical factors
* energetics of contraction
how do you characterize cns fatigue
reduction in motor unit activation and firing frequency
what neural factors influence peripheral fatigue
Sarcolemma and t-tubules –
* altered muscle membrane to conduction and action potentials, inability of Na/K pump to maintain
* an action potential block in t-tubules, reduced sarcoplasmic reticulum Ca release
what mechanical factors affect peripheral fatigue
cross bridge cycling and tension depend on:
* arrangement of actin and myosin
* Ca binding to troponin
* Atp availability
High h+ conc contributes to fatigue:
* Reduce force per cross bridge
* Inhibit Ca release from SR
how do energetics of contraction influence peripheral fatigue
Imbalance between ATP supply and demand, causes accumulation of Pi leading to:
* Inhibits maximal force
* Reduced cross-bridge binding to actin
* Inhibits Ca release from SR
what are free radicals
molecules with an unpaired outer orbital electron, capable of damaging proteins and lipids in muscle
how do radicals hurt the body
- Damage contractile proteins (myosin/troponin)
- Depress Na/K pump activity
what two things should we consider when performing
source of energy and fibers used for production
what are the principles of training
overload
specificity
reversibility
what is the formula for o2 consumption
cardiac output x A-V o2 diff
what does heritbility mean
genetics, determines vo2 max and training response
formula for vo2 max
maximal cardiac output x a-v02 difference
how does endurance training increase sv
- Increases preload (edv)
- Increases plasma volume
- Increases venous return
- Increases ventricular volume
how else does endurance training help the athlete
lowers afterload
increases contractility
why is resting hr lower after training
- Vagal tone increase
- Greater filling time (edv)
how does training increase a-vo2 difference
- Less sns vasoconstriction
- Increases diameter and compliance of arteries
- Increased capillary density
- Increases mitochondrial number
what is the ability to perform prolonged submaximal exercise dependent upon
ability to maintain homeostasis
what adaptions occur in muscles after endurance training
- Shift in muscle fiber type (fast-to-slow) and increased number of capillaries.
- Increased mitochondrial volume.
- Training-induced changes in fuel utilization.
- Increased antioxidant capacity.
- Improved acid-base regulation.
what is mitophagy
breakdown of damaged mitochondria
what is the significance of increased subsarcolemmal and intermyofibrillar mitochondria
greater capacity of etc
decreased cytostolic adp due to increased ADP transporters, results in less lactate/H+ and less PC depletion
how does endurance training change fuel utilization
Increased utilization of fat and sparing of plasma glucose and muscle glycogen
