Differentiating whether a muscle is stiff or short

In a client assessment it is important to observe if a muscle is short or if it is stiff. This helps in developing a corrective plan strategy.

Treating each case in a cookie cutter approach will only give you a 50% success rate. A short muscle lacks length. It may be that the muscle is positioned in a shortened position frequently (due to an injury) and the muscle fibers have atrophied and discarded sarcomeres in series or the connective tissues have adaptively shortened due to muscle creep in daily activities.

If you actively and/or passively stabilize the proximal attachment of the muscle and move the joint into a position to stretch the muscle, the proximal attachment will move well before reaching the end range of motion of the joint i.e. You will feel a sudden stop and the joint will start moving.

A stiff muscle has greater resistance to stretch. This may be due to muscular hypertrophy or a greater quantity of connective tissues. In the case of a stiff muscle, if you actively and/or passively stabilize the proximal attachment and move the joint into a position to stretch the muscle, The joint will move through it’s full range of motion (ROM) without movement at the proximal attachment assuming enough force is applied to stretch the muscle. You will just feel a constant resistance to stretch through full ROM.

Short muscles require repetitive, prolonged stretching (up to 10min) to encourage creep of connective tissues and the addition of sarcomeres in series to add length.

Stiff muscles can be corrected by balancing the stiffness across a joint by strengthening their antagonists and by holding the antagonists in a shortened position as they may have been adaptively lengthened over time. Stretching techniques like Active Isolated Stretching, Contract Relax Antagonist contract aids in stretching stiff muscles. Core work has also been shown to influence extensibility of stiff muscles.