NM III Flashcards
Mastery
is central and peripheral fatigue fall under performance or perceived fatigue or performance fatigue
where are they compared to NM junction
describe central
describe peripheral
Central and peripheral are performance fatigue
central is before NM junction and peripheral is after
central is physiological not the feeling
central means there is less motor drive to the muscle
what are some mechanisms of peripheral fatigue
IN THE NM JUNCTION
Anything that inhibits pre and post synaptic areas
too much K+ in extra cellular space
Not enough ATP, for Na+K+ ATPase, or SERCA
Less Ca2+ release of Uptake, SERCA and SR
too MANY or too FEW Ach
Interpolated Twitch technique
how does it work
what does it study
put electrodes on muscle and nerve and stimulate the nerve to see muscle force produced
mechanisms of central fatigue, is it harder to study
factors
yes it is harder to study
the brain sends motor drive down to muscles to contract them, the muscle contracts and Metabolites buildup, like K+ or Lactic Acid
Afferent feedback senses too much and to negative feedback it tells the brain to lower the intensity or stop altogether
cortical drive is affected
motorneurons are affected
and afferent feedback on buildup of metabolites
USE a MVC and use ITT for a resting twitch,
what is happening what is it reading
how to know what is being activated or not
perform a MVC and hold for 5 seconds
send additional stimulus during MVC and see Super imposed twitch, the muscles your brain couldn’t activate
resting twitch is only stimulation for ITT, peripheral fatigue
from graph, what is small jump and what does it measure
how to calculate Central fatigue
Resting twitch is only peripheral fatigue, as it happens at the neuromuscular junction and can’t produce as much force, the buildup of metabolites
to calculate central fatigue from the graph, you need to put superimposed over resting twitch. see what the muscles didn’t produce, and look at peripheral fatigue
VA(central fatigue) = 1- SIT/RT
break down the two graphs and describe what is happening
Top one:
Central fatigue, low intensity for a long time
Large SIT means CNS isn’t producing as large of a motor drive and activates less muscles,
Bottom:
Peripheral fatigue, high intensity over short time, resting twitch goes down as muscles can’t produce as much force
what does MVC force consist of
what does a large SIT mean
lowering of VA meaning
small RT meaning
lower RT means
MVC is the capacity of the nervous system plus muscles
measures central and peripheral. combined of both
large SIT means that the CNS is producing less of a motor drive
Lower VA means central fatigue is increasing
SMALL RT means muscles can’t produce as much force
LOWER resting twitch means peripheral fatigue is increasing
Exercise intensity and duration
high intensity shorts time and low intensity long time
Twitch
MVC
and VA
MVC, doesn’t change much
Twitch, large change in high intensity, small in low intensity, more peripheral, muscles can’t produce force
VA, large change in low intensity but tiny in high,more central, CNS can’t send a large enough more drive
when is Central fatigue more prevelant
when is peripheral fatigue more prevelant
central- lower intensity, long time
jogging
brain doesn’t send motor drive because of buildup of metabolite OVER TIME
Peripheral- high intensity, short time
sprinting
muscles can’t produce as much force because of inhibits in post synaptic areas, not enough ATP or Ach
muscle fatigue
