skeletal muscle energy systems Flashcards
anaerobic metabolism
short term fast energy production no O2 required ATP (2-4s contraction), CP (20s contraction and stored in muscle) and glycolysis generates energy required quickly
aerobic metabolism
long term and steady slower energy production O2 required oxidative phosphorylation if O2 runs out it will shut off
energy for relaxation
Ca2+ re-uptake into the SR - stored in here for the nest contraction. uncoupling of the cross bridges - unlinking of the myosin and the actin uses ATP, energised myosin cant make a connection if there is no ATP
what happens if we run out of ATP?
Rigor mortis
the cross-bridges don’t unlink so the muscles are permanently stiff and the muscles go rigid.
our proteins start to break down and our metabolism stops
Red muscle fibre
high myoglobin high aerobic enzymes slow rate of interaction with actin slow force produced slow energy consumption sustained by aerobic metabolism long term posture
White muscle fibre
low myoglobin low aerobic enzymes fast rate of interaction with actin fast force production fast energy consumption use of anaerobic metabolism short bursts of lots of power
Intermediate muscle fibres
has a use for anaerobic and aerobic
has a mix of fast and slow, will be recruited for jobs and movements that require a mixture of lots of power for a medium amount of time
ratios of fibers
depending on the muscle function, muscles are dominated by one fibre type or a mixture of fibre types.
different types have different ratios of white to red to intermediate
sprinters muscles
need explosive power short duration anaerobic metabolism need relatively less O2 leg muscles develop higher proportions of fast/ white and intermediate fibres
endurance athletes
need fatigue resistance
pace slower for endurance
uses aerobic metabolism
leg muscles develop higher proportion of red/ slow and intermediate fibres
Twitch
a twitch is a mechanical event
to build up a decline a tension in a muscle takes longer than the underlying biomechanical processes
a single twitch can occur spontaneously but usually do not
electrically evoked twitches are usually used to study muscle functions
most of the movements we make last seconds, minutes or hours not usually milliseconds
twitches
repeated stimuli causing increasing levels of tension due to
sustained levels of sarcoplasmic Ca2+
actin- myosin interaction becoming more sensitive to Ca2+
heat (higher temp it can produce more tension
more tension is produced each time
tetanus
series of closely spaces twitches
in a muscle we don’t have oscillations of twitches it is a sustained contraction as the stimulus is firing so fast that there is little to no time for any relaxation
rapidly repeated stimuli cause even higher levels of tension; summation
“incomplete tetanus” - fluctuations from individual twitches visible
what happens in real life is that we don’t feel the relaxing part as it is so fast.
when activated tetanus is the contractile state reached most of the time and most of the skeletal muscle fibres.
Ca2+ is fluctuating slightly even though it is going down ti is still enough to keep the troponin on the myosin actin binding sites as long as the stimulus is coming in unless you fatigue
strength training
increase in number of contractile filaments (hypertrophy)
more power
improved anaerobic metabolism
disuse
loss in number of contractile filaments (atrophy)
less power - muscles waste away
