Chapter 5 - Muscle Structure and Function

Tendons

located at each end of the muscle

• during muscle contraction, functions to move various parts of skeleton

biomechanics of human movement

assessment of movement and sequential pattern of muscle activation acting through joints to move body segments

troponin and tropomyosin

proteins that play an important role in regulating muscle contractions

• contained in thin actin filaments

Cross Bridge formation

process when a signal comes from the motor nerve activating the fibre, heads of the myosin filaments temporarily attach themselves to the actin filaments

muscle biopsy

determines muscle fibre type

• done by a small incision to the skin and fascia of the muscle

  • tiny piece of tissue is cut and removed from muscle and then analyzed under a microscope

Motor end plate

delivers impulses to activate each fibre

Activation Threshold

threshold a motor unit must reach for activation to occur

Muscle Force Deficit

difference between assisted and voluntarily generated maximal force

• deficit is larger in untrained individuals (approx. 20-35%)

Why is training specific muscle groups for specific sports beneficial?

• an athlete whose muscles have been trained and developed in isolation using specific exercises should train muscles that are relevant to the movement in their specific sport

  • ex. a weightlifter who uses exercises that increase strength only in arm and leg extensors (and not trunk muscles) might experience major disturbance of intermuscle coordination

How does an individual’s performance improve?

through biological adaptation (increase in strength)

Trainable and non-trainable factors in human muscle (due to strength exercise)

Trainable factors

• fibre diameter

• intramuscle coordination

• nerve impulse frequency

• intermuscle coordination

• elasticity of muscle and its tendons

• energy stores of muscle and liver

• capillary density of muscle

Non-trainable factors

• number of fibres

• fibre structure (ST or FT fibres)

Why is Skeletal Muscle Striated and voluntary control?

• striated because of the alternating light and dark bands (from organization of muscle fibres) that appear when viewed under a light microscope

• voluntary because we can contract skeletal muscle when we want to

How to muscles and tendons work together to create movement

• muscles supply energy to contract and create movement

• tendons act as the bridge that transmits the force from muscles onto the bones in order to move them