Responses of group III and IV muscle afferents to dynamic exercise

Christine M. Adreani, Janeen M. Hill, Marc P Kaufman

Research output: Contribution to journalArticle

154 Scopus citations

Abstract

Tetanic contraction of hindlimb skeletal muscle, induced by electrical stimulation of either ventral roots or peripheral nerves, is well known to activate group III and IV afferents. Nevertheless, the effect of dynamic exercise on the discharge of these thin fiber afferents is unknown. To shed some light on this question, we recorded in decerebrate cats the discharge of 24 group III and 10 group IV afferents while the mesencephalic locomotor region (MLR) was stimulated electrically. Each of the 34 afferents had their receptive fields in the triceps surae muscles. Stimulation of the MLR for 1 min caused the triceps surae muscles to contract rhythmically, an effect induced by an α-motoneuron discharge pattern and recruitment order almost identical to that occurring during dynamic exercise. Eighteen of the 24 group III and 8 of the 10 group IV muscle afferents were stimulated by MLR stimulation. The oxygen consumption of the dynamically exercising triceps surae muscles was increased by 2.5-fold over their resting levels. We conclude that low levels of dynamic exercise stimulate group III and IV muscle afferents.

Original languageEnglish (US)
Pages (from-to)1811-1817
Number of pages7
JournalJournal of Applied Physiology
Volume82
Issue number6
StatePublished - Jun 1997

Keywords

  • Aδ fibers
  • Autonomic nervous system
  • C fibers
  • Mesencephalic locomotor region
  • Reflex control of the circulation

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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