Final answer:
When a high jumper takes off, the quadriceps muscles contract eccentrically to generate power and height.
Step-by-step explanation:
When a high jumper takes off, the quadriceps muscles are contracting eccentrically. Eccentric contraction occurs when the muscle lengthens while contracting, acting as a brake or shock absorber for movements. In the case of a high jumper, the quadriceps muscles are responsible for extending the knee joint when they contract eccentrically, allowing the jumper to generate power and height.
Learn more about Muscle contractions in high jumping