Question:

During aerobic exercising, people often suffer injuries to knees and other joints due to HIGH ACCELERATIONS. When do these high accelerations occur?

Responses:
1. These injuries occur when a runner increases his/her speed and is running faster than 'normal.' People need to slowly build up to a quicker speed instead of diving right into it.

2. These high accelerations occur when you start and stop the excersices because the initial and final speed is zero. While exercising the speed of bending joints is pretty much constant; therefore, the acceleration is zero.

3. Injuries to the knee occur when the foot makes contact with the floor. The acceleration swiftly goes to zero and then back up again in the opposite direction that it was just going. This causes great stress on the knee and is when most of the injuries occur.

4. The high accelerations will occur when high velocity is achieved over a short period of time like in a leg kick. The injury probably occurs when the motion comes to an almost instant stop and the acceleration is a large negative value.

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