Kinesiology 2230A/B Lecture 29: Lecture 29
Document Summary
During sprinting the hamstring muscles work eccentrically to decelerate the tibia as it swings out. Once the foot is on the ground the hamstrings function in extending the hip. It is in this phase just before the foot strikes the ground that the hamstrings, most commonly the biceps femoris muscle, are injured. The muscles are maximally activated and are approaching their maximum length. Muscle spindles are intrafusal fibres (embedded within muscle) As the muscle lengthens, frequency increases (greater tension on central portion) As the muscle shortens, contractile areas are going to be periodically activated to maintain tension on central portion. There needs to be tension in order to be able to observe change in tension. Spindles are activated by gamma motor neurons and can assist in rapid movement. Sensitive to tension: feed back information about force levels in the muscle to the central nervous system.