OCaPE: MMB #5
Muscle Physiology Weight Lifting Competition
Ibrahim is training for a weight lifting competition. He constantly works out, but one day he couldn’t go to training complaining of stiffness in his back and pain down his leg.
5 minutes
Q1)
What type of muscle fibre is used in weightlifting and how does it generate bursts of force?
Type 2(x/d)/Fast Twitch
Anaerobic glycolysis of large glycogen stores (2)
Name and describe the type of contraction occurring as he lifts the weight.
Concentric = load greater than force; muscle shortens (2)
Distinguish between Muscle Strength, Power and Torque.
Strength = Maximum force/tension generated by muscle.
Power = Force * Velocity
Torque = Angular motion of muscle (3)
Explain how muscle strength can be increased (during a contraction).
Increases recruitment of motor units
Starting with smaller units first (size recruitment principle)
Summation; increasing motor unit firing rate (3)
Describe and Explain what this graph is showing.
Muscle Length-Tension Relationship (during contraction)
Force proportional to extent of overlap between actin and myosin
(Upon contraction) Sarcomere shortens; length of thick and thin filaments does NOT change
c/b = maximal actin-myosin cross-bridges formed; maximum force
( e = ‘too much’ overlap; ineffective cross bridge formation )
(4)
To investigate his back stiffness, you order an X-ray.
Describe the findings.
Spondilolysthesis (due to degeneration of articular cartilage) at L4-L5
NOT SLIPPED DISC (2)
You test his lower limb reflexes.
His knee jerk is normal but his ankle reflex is absent.
Identify the nerve roots involved in both these reflexes.
knee = L3/L4
Ankle = S1/S2 (2)
What nerve is likely to be damaged?
Sciatic Nerve (1)
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