Upgrade to remove ads
Only $35.99/year

Explosive Movement

Terms in this set (11)

What dictates how much force/power a person can produce?
-Muscle physiological cross sectional area
- Muscle fibre pennation angles
- Tendon insertions
- Limb mechanisms
- Technique
- Muscle Fibre types
Muscle Fibre Types
Type I- slow contracting,highly oxidative, highly fatigue resistant
Type II -
Type IIa (fast contracting, oxidative/glycolytic,relatively fatigue resistant)
Type IIx (Fat contracting glycolytic, rapidly fatiguable)
How many of each fibre
-muscle fibre types identified on the basis of the unique myosin protein types
- muscle fibres can be identified in individuals using biopsy and immunohistochemistry
- The number of each fibre type present in a muscle varies throughout the body and muscle groups
- the number of each fibre type differ within people according to: gene expression, blood hormone level , exercise history
Power capacity of each fibre type
Type I- Least amount of power produced
Type IIa - medium amount of power and contracting speed
Type IIx- high amount of power produced in relation to velocity
Motor units
a single motor neuron and all muscle fibers it innervates
3- Motor unit types
-Slow (S)
-Fast, fatigue resistant (FR)
-Fast, fatiguable (FF)
Contractile properties of motor units-can be identified by:
-size of motor neuron
-force produced by a single stimulus
-rate of force decay when stimulated repetivitely
Summation of force
force produced by motor units summates with rapid stimulation
- this is due to twitch duration and muscle viscosity
Motor unit recruitment
- Small (slow) motor units always recruited first
- Largest motor units recruited last
- Largest motor units de-recruited (turned off) first
- Firing rates increases with force in all motor units
Delay between muscle contraction and movement
- electromechanical delay (~35 ms)
-elastic elements of muscles and tendons must slow their lengthening before torque is applied around a joint
- Torque applied around a joint must overcome the inertia of the limb segment to be moved
Events leading to a movement
1. Motor neuron activation
2. Neurotransmitter release at NMJ
3. Calcium release by sarcoplasmic reticulum
4. Cross bridge cycle initiated
5. Muscle force produced
6. Elastic elements stretched
7. Torque applied about joint
8. Movement ensues after limb inertia is overcome