Kinetic Chain Interactions

Length–tension Relationship

Muscles can create maximal tension or force at an ideal length. Shortening or lengthening of a muscle reduces the ability for it to produce maximal force.

Hence, If a muscle is too short or too long, it will not be able to produce maximal force, A muscle at ideal length can produce the most force.

Force-couple Relationships

The action of muscles working synergistically to produce movement at a joint is known as a force-couple relationship.

Due to an individual’s deconditioned state if muscles are lengthened or shortened, force-couple relationships can be altered, changing the overall movement and therefore potentially putting too much stress on the synergists.

Reciprocal Inhibition

Reciprocal inhibition is a natural process that occurs when the muscles on one side of a joint relax to allow the muscles on the other side to contract. It is functional in all ideal human movement. For example: as the biceps brachii contract in an elbow flexion, the triceps brachii relax. 
Altered reciprocal inhibition can however also occur, which contributes to muscular imbalances and potential injury. This occurs when a muscle becomes overactive, reducing neural drive from the muscle that should be its functional antagonist in the force-couple relationship.