Kinesiology 2230A/B Lecture Notes - Sarcolemma, Myoglobin, Basal Lamina

• School: Western University
• Department: Kinesiology
• Course: Kinesiology 2230A/B
• Professor: Glen Belfry

Document Summary

The muscles are maximally activated and are approaching their maximum length. There is extension of leg over a relatively short angle of hip: during sprinting, the hamstring muscles work eccentrically to decelerate the tibia as it swings out. The hamstrings are going from complete shortening to a lengthening situation very quickly the leg is at full extension, the hip is starting to extend. At the last stage, the hamstrings are at their greatest length as well as instantly maximally activated. This is a huge lengthening contraction (lengthening = actin myosin bridges broken). It is in this phase just before the foot strikes the ground that the hamstrings, most commonly the biceps femoris muscle, are injured. It usually occurs past 30 meters down the course because metabolically you are switching from atp-pcr to a slower glycolysis, meaning energy will be produced at a slower rate.