ReviewGroup III and IV muscle afferents: Role on central motor drive and clinical implications

- The group III and IV muscle afferents are determinant for motor unit control.
- Such afferents could partially explain the motor/autonomic deficits after traumas.
- Recent evidence on metabosensitive fiber functions needs to be clarified.
- Understanding these afferent actions may help therapists for choosing exercises.

The present review is focused on neural mechanisms responsible of group III and IV muscle afferent actions on central motor drive during physical exercise in both healthy and pathological populations. It seems that these mechanisms contribute to improve muscle performance by regulating the peripheral fatigue development and by avoiding excessive muscle impairments. Therefore, a great deal of attention is paid to their influences on motor unit activation during fatiguing exercise both in human and animal models. Recent evidence indicated that these afferents from a given active muscle could contribute to regulate the motor activity of the homonymous as well as surrounding skeletal muscles by acting at both spinal and supraspinal levels. In addition, given that the recovery of the sensory feedback plays a key role in the improvement of motor function following numerous neuromuscular traumas, the role of these afferents in preclinical and clinical situations is also explored in animal and human models. It is supposed that studying the motor and autonomic functions of group III and IV afferents might help healthcare professionals in the future to find appropriate treatments and rehabilitation programs.