Let’s take a look at what occurs within a skeletal muscle, from excitation to contraction to relaxation:

An electrical signal (action potential) travels down a nerve cell, causing it to release a chemical message (neurotransmitter) into a small gap between the nerve cell and muscle cell. This gap is called the synapse.

The neurotransmitter crosses the gap, binds to a protein (receptor) on the muscle-cell membrane and causes an action potential in the muscle cell.

The action potential rapidly spreads along the muscle cell and enters the cell through the T-tubule.

The action potential opens gates in the muscle’s calcium store (sarcoplasmic reticulum).

Calcium ions flow into the cytoplasm, which is where the actin and myosin filaments are.

Calcium ions bind to troponin-tropomyosin molecules located in the grooves of the actin filaments. Normally, the rod-like tropomyosin molecule covers the sites on actin where myosin can form crossbridges.

Upon binding calcium ions, troponin changes shape and slides tropomyosin out of the groove, exposing the actin-myosin binding sites.

Myosin interacts with actin by cycling crossbridges, as described previously. The muscle thereby creates force, and shortens.

After the action potential has passed, the calcium gates close, and calcium pumps located on the sarcoplasmic reticulum remove calcium from the cytoplasm.

As the calcium gets pumped back into the sarcoplasmic reticulum, calcium ions come off the troponin.

The troponin returns to its normal shape and allows tropomyosin to cover the actin-myosin binding sites on the actin filament.

Because no binding sites are available now, no crossbridges can form, and the muscle relaxes.

RE:
How do muscles relax????? How does it occur???

i know that when you stretch that you are actually kinda tearing the muscle alittle bit so its not as compact..and aftera workout its deff teared and stressed..

during the relax period it shoudl repai itself im not sure how it doe sit, but when its relaxing it is bascially repairing itself from the strein put on it.. and after that it begins recuperating…