All or none principle and muscle tension factors
relaxation phase
follows contraction phase, lasts about 50 milliseconds
maximal stimuli
stimuli strong enough to produce action potentials in all motor units of a particular muscle
submaximal stimuli
stimuli that are strong enough to produce action potentials in additional motor units
threshold stimulus
stimulus is strong enough to produce action potential
What are the phases of a muscle fiber contraction/twitch
stimulus, latent period, contraction phase, relaxation phase
When would the number of muscle fibers being recruited increase
Activate neurons containing greater number of fibers, activate more motor neurons, or increase the frequency of motor unit activation
What is the all or none principle?
All of the muscle fibers in a motor neuron or none at all
sub threshold stimulus
Not strong enough to cause an action potential so it does not result in a contraction
Summation
Successive stimuli are provided before relaxation phase
latent period
brief period of a few milliseconds following a stimulus
contraction phase
muscle fiber begins shortening, lasts about 40 milliseconds
Treppe
occurs when multiple maximal stimuli are provided to rested muscle at a low frequency to allow complete relaxation between contractions (dead lift). Second is contraction provides more tension than the first, third provides more tension than the second, then every contraction afterwards produces same amount of tension
Tetanus
occurs when stimuli are provided at a high frequency so that no relaxation can occur between contractions
Characteristics of the consecutive stimulus in treppe
slight increase between first 3. After 3, equal tension is produced