Exam 1 Flashcards
3 components of neuromuscular control
volitional contractions
reflex reactions
complex functional movements
definition of AMI
compromised ability to contract a muscle due to injury
what affects volitional muscle contractions (what can cause AMI)
swelling
pain
altered mechanoreceptor input
how does swelling impact muscle contractions
-may stimulate stretch receptors and trigger reflex inhibition
how does pain impact muscle contractions
-contributes to deficits in neuromuscular control
-painful exercise may slow recovery
pain -> inhibits muscle groups -> altered motor control -> change in movement pattern -> delayed recovery/increased risk of re-injury
how does altered input impact muscle contractions
-altered patterns may affect function
-ex: ankle: decreased position and balance sense, postural control; treatment: progressive balance/coordination exercises
what is used to address AMI after injury or surgery
neuromuscular electrical stimulation (NMES)
how does NMES work against AMI
developed to increase muscle strength
a nerve’s response to electrical stimulation is based on 3 factors
1) diameter of the nerve
2) depth of the nerve in relation to the electrode
3) phase duration of the current
which nerves are stimulated first
sensory nerves
which nerves are depolarized first
large-diameter nerves
exogenous contration
-NMES elicited
-entire motor unit stimulated to fatigue
-synchronous firing
-fatigues quickly (PC energy system)
-large diameter, fast-twitch fibers recruited first (low capacitance), slow twitch recruited once stimulation is increased
-GTO is excited
endogenous contraction
-physiological
-slow twitch fiber recruitment first
-asynchronous firing
-slow to fatigue
-slow twitch fibers excited first, fast-twitch are recruited if enough force is given (preserves energy)
-GTO causes inhibition = relax muscles from strong contraction
duty cycle for NMES
1:5 on to off time (10 seconds on, 50 seconds off)
-progress to 10:30
phase duration of NMES
250-300 us
pulse rate of NMES
35-50 pps
amplitude of NMES
produce strong, yet tolerable contractions
types of neuromuscular stimulation
russian
PENS
russian stimulation
-used for muscle reeducation
-patient contracts with the current, then relaxes
-preset parameters
-can produce a strong tetanus contraction
PENS
-patterned electrical neuromuscular stimulation: timed stimulation based on typical firing patterns (walking, running, jumping, etc)
-asymmetrical low-voltage pulsed current
-50 Hz pulse rate
-70 us phase duration
electrode placement of russian
bipolar: proximal and distal ends of the muscle
treatment duration of russian
10 cycles or until they are fatigued
ramp time of russian
2 seconds; time to reach full current
treatment of AMI with inhibited muscle
-apply NMES
-recruit motor neurons being reflexively inhibited