KINE 2P97 Lecture Notes - Lecture 15: Hypertrophy, Joint Stability, High Force
8 May 2018
School
Department
Course
Professor
KINE 2P97
Muscle Physiology & Exercise Metabolism
Motor Unit
- number of fibres per motor unit varies so does the number of motor units
- innervation ratio
o represents how many fibres are activated per unit
Recruitment
- orderly
- all or none response
- small, slow, low
- large, fast, high
- sizes allow for graded contractions
- Heeas size priciple: recruited i order of sallest to largest otor euro
o Additive
o Waterfall – drinking game
- Fatigability, activate fatigue last
Twitch
- Type of muscle and which twitch is activated
- Fibre type and twitch shape
o Rate of contraction: myosin heavy chain isoform (myosin ATPase activity)
o Rate of relaxation: SERCA1 or SERCA2 – calcium ATPase activity
- Fast twitch, fast pumps
- activity determined by isoforms
Myosin Heavy Chain Isoforms
- Calcium oscillations alter gene expression
- Its the calciu release ad how ofte it takes place that helps to deterie the
characteristics of the fibre
- Chronic patterns of MU firing determine muscle form and function
Development of muscular force affected by
- Number of motor units recruited
o Size/type
- Frequency of stimulation
- Length of muscle
- Contraction type
Rate Coding
- Hz, pulses per time
- Force-frequency relationship
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Number of fibres per motor unit varies so does the number of motor units innervation ratio: represents how many fibres are activated per unit. He(cid:374)(cid:374)e(cid:373)a(cid:374)(cid:859)s size pri(cid:374)ciple: recruited i(cid:374) order of s(cid:373)allest to largest (cid:373)otor (cid:374)euro(cid:374) small, slow, low large, fast, high sizes allow for graded contractions: additive, waterfall drinking game. Type of muscle and which twitch is activated. Fibre type and twitch shape: rate of contraction: myosin heavy chain isoform (myosin atpase activity, rate of relaxation: serca1 or serca2 calcium atpase activity. It(cid:859)s the calciu(cid:373) release a(cid:374)d how ofte(cid:374) it takes place that helps to deter(cid:373)i(cid:374)e the characteristics of the fibre. Chronic patterns of mu firing determine muscle form and function. Number of motor units recruited: size/type. Same frequency, changing in the force compared to fully fused, the summation changes depending on the type of unit. Twitches close together are additive, they summate. Length and work force applied over distance (work)
