What is Reflexive Antagonism?

Reflexive Antagonism is the phenomenon by which muscles with opposing functions tend to antagonistically inhibit each other. When one muscle is activated, its opposite muscle or muscle group or is reflexively inhibited or deactivated.

The phenomenon is now known to be fleeting, incomplete, and weak. By example, when the triceps brachii is stimulated, the biceps is reflexively inhibited. The incompleteness of the effect is related to postural and functional tone. Also, reflexes in vivo are polysynaptic, with entire muscle groups responding to noxius stimuli (Nociceptive Withdrawal Reflex).

Reflexive antagonism is the basic original notion behind indirect muscle energy techniques. While this notion is now understood to be incomplete, the clinical mechanism of Reflexive Antagonism continues to be useful in widespread Osteopathic and OMT-derived practice. Reciprocal Inhibition is a synonym. (See Entry under Muscle Energy Techniques)

Techiques that utilize reflexive antagonism, (such as Rapid De-Afferentation Techniques) are manual medicine techniques and protocols that utilize reflexive pathways and the phenomenon of reciprocal inhibition as a means of switching off inflammation, pain, and protective spasm for entire synergistic muscle groups or singular muscles and soft tissue structures.

Reciprocal inhibition describes muscles on one side of a joint relaxing to accommodate contraction on the other side of that joint.

Reciprocal Inhibition, however, can backfire by both muscles attempting to contract at the same time. Thus a common tear can occur at muscle level. The body handles this pretty well during physical activities like running, where muscles that oppose each other are engaged and disengaged sequentially to produce coordinated movement. This facilitates ease of movement and is a safeguard against injury. Sometimes, for example, a footballer running back can experience a "misfiring" of motor units and end up simultaneously contracting the quads and hamstrings during a hard sprint. If these muscles, which act opposite to each other are fired at the same time, at a high intensity, a tear can result. The stronger muscle, usually the quadriceps in this case, overpowers the hamstrings. This sometimes results in a common injury known as a pulled hamstring.