Although the Golgi tendon reflex may be intimidating in name, its actions can be explained in a simple manner. The actual physiological mechanisms through which this reflex acts are very complex; however, simply stated, if the body is carrying a heavier load than necessary, the Golgi tendon reflex jumps in to protect it. For example, if a weight lifter tries to bicep curl a heavy weight he or she cannot lift, rather than continuing to fight physics and risk muscular damage, the reflex causes this hypothetical person to drop the weight.
There are sensors associated with the tendons of the body that pick up on forces exerted to these cartilaginous structures. These are known as Golgi tendon organs. The Golgi tendon organ is connected to an afferent, or sensory, neuron, which is looped into the central nervous system. If a force becomes too heavy for a tendon, the central nervous system receives a signal from the Golgi tendon organ via the afferent neuron.
Once the central nervous system receives this signal, it is time to take action. The Golgi tendon reflex next acts by initiating efferent, or motor, neurons to complete a variety of tasks. These tasks include muscle relaxation, which is the same as with lengthening. This action prevents further contraction, therefore stopping the dangerous motion and eliminating the risk of future damage. Although this step-by-step analysis seems to take time, the process is rather ephemeral, usually taking place in a fraction of a second.
The Golgi tendon reflex is somewhat opposite another commonly studied action, known as the stretch reflex. The stretch reflex acts in an opposite manner, actually causing contraction and preventing muscular damage from the opposing viewpoint of overlengthening. An example of the stretch reflex in action would be an ankle bent in the wrong direction activated by the stretch reflex to return to its original position and prevent further damage.
There are a number of subconscious mechanisms, such as the Golgi tendon reflex, that act to keep the body away from harm. There are, of course, constraints with these reflexes as they are only capable of doing so much. If a person's arm, for example, is going to be contracted or extended in an extremely severe manner, there is little the any reflex can do to prevent such action.