Sport Science

There are several steps that take place when describing the process of muscle contraction in detail, these can be divided into five different sections.
At rest, Troponin and Tropomyosin cover theActin and Myosin filaments to prevent each other binding together. To allow this process to take place energy is necessary, and is generally obtained from the breakdown of ATP stores.
First of all, anervous impulse from the CNS (central nervous system) is sent to the working muscles to produce the desired movement through muscle contraction. This impulse arrives at the neuromuscular junction andcauses the release of a chemical called Acetylcholine. This chemical causes Calcium (Ca+) to be released into the sarcoplasm.
This presence of Calcium (Ca+) binds to Troponin, altering its shape andremoving it from the myosin binding area. This also moves the Tropomyosin molecule from the area of muscle contraction. This attachment leaves the area exposed allowing Myosin and Actin Filamentsto join forming a cross-bridge. This process takes place because the Myosin heads bind to the Actin filament and slide it across the Myosin filament, resulting in the shortening of the sarcomere.
ATPis broken down to release energy that enables the detachment of both Actin and Myosin filaments. These then reattach and pull the filaments inwards therefore a further shortening of the sarcomere.This happens along the entire length of every myofibril within the muscle. The cross-bridge is broken once the ATP molecule binds to the Myosin head, however as it repeats the breakdown of ATPreleasing energy results in the same attachment (power stroke).
This muscular contraction process lasts whilst there is energy provided from ATP breakdown and enough Calcium to remove Troponin andTropomyosin from the binding area. Once this stimulus ends, calcium ions are released that eliminate this calcium from the sarcoplasm causing Troponin and Tropomyosin to link to Myosin heads meaning they...