Differences among motor units in a muscle, motor unit properties, skeletal muscle structure, muscle force

3 Pages
Unlock Document

Colorado State University
Health + Exercise Science
HES 319
Brian Tracy

26 March Things That Are Very Different Among/Between Motor Units Within A Muscle Innervation number/ratio Speed of contraction (contraction time) Time from 0 force to peak force Peak twitch force Tetanic force Fatigability, fatigue resistance Muscle fiber type Recruitment threshold Motor neuron properties Size of soma of motor neuron Axon diameter Fast fatigable motor unit has rapid decline in force Produces highest force Fatigue-resistant: oxidative metabolism Fatigable: glycolytic Motor unit properties Motor units with long contraction times (S) exert low tetanic forces. Motor units with fast contraction times (FR and FF) exert tetanic forces that range from low to high. Difference in tetanic force among motor units is mainly due to variation in innervation number A fast-twitch motor unit, therefore, does not necessarily correspond to a motor unit that can exert a large force. Low-intensity activities recruit slow motor units As intensity increases, FR motor units are recruited Maximal activities (e.g., vertical jump) recruit FF motor units Skeletal Muscle Structure Muscle fibers can be classified with several techniques Histochemical staining for myosin ATPase: types I (slow), IIa (intermediate), IIb (fast) (IIx or IId) Histochemical assays for oxidative and glycolytic enyzmes: types SO (slow oxidative), FOG (fast oxidative glycolytic), FG (fast glycolytic) Molecular measurable of myosin heavy chain content: types MHC-I, MHC-I
More Less

Related notes for HES 319

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.