Muscle Physiology

Yesterday I discussed muscles unique ability to change its required action in a joint movement depending on its angle to the main orientation of force. Another unique ability of muscle is its ability to lengthen or shorten depending on the amount of constant force on the protein filaments of the contractile units. Each unit has a normal overlap length, and with all units connected in series over the entire length of the muscle fiber, the fiber will add or remove units in that chain depending on the force distributed over the connection points of these overlapping filaments.

In simple terms this means that if a muscle is physically stretched that it will in time lengthen by adding additional contractile units in that series chain to keep that normal overlap length over all units in the fiber. This also means that if a muscle is kept in a shortened state (sitting for a prolonged period with the knees bent is a great example) resulting in greater filament overlap, then contractile units will be removed (broken down into proteins) to return the remaining units to their normal overlap length.


I feel have just given you one of the greatest reasons to add a stretching program to your daily fitness routine.