Influence of respiratory afferents upon the proprioceptive reflex of skeletal muscles in healthy humans.
Relationships between respiratory afferents and the motor drive to skeletal muscles are well documented in animals, but human data are scarce. Tonic vibratory response (TVR) elicited by mechanical tendon vibrations were explored in an arm (extensor digitorum, ED) and a leg (vastus lateralis, VL) muscle, in healthy subjects. Tendon vibrations were delivered during unloaded breathing and after 10 breathing cycles while the subject breathed through an inspiratory or expiratory resistive load in order to activate respiratory afferents. Inspiratory loaded breathing significantly enhanced TVR in ED and VL muscles whereas the effects of expiratory loading depended on the vibrated muscle (increased TVR in ED; decreased TVR in VL). These results suggest that inspiratory muscle afferents activated during inspiratory loading facilitate the gamma motor drive to arm and leg muscles whereas the activation of pulmonary vagal afferents during expiratory loading can exert a facilitating or suppressive influence on the gamma motor drive, depending on the limb muscle group.
Balzamo
E
E
Laboratoire de Physiopathologie Respiratoire Cellulaire et Intégrée ER-CNRS 6095/UPRES-EA 2201, Institut Jean Roche, Faculté de Médecine Nord, Marseille, France.
Vuillon-Cacciuttolo
G
G
Burnet
H
H
Jammes
Y
Y
D000328:Adult; D001132:Arm; D004576:Electromyography; D006801:Humans; D008168:Lung / Q000294:innervation* / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009046:Motor Neurons / Q000502:physiology; D018482:Muscle, Skeletal / Q000294:innervation* / Q000502:physiology; D009475:Neurons, Afferent / Q000502:physiology*; D011434:Proprioception / Q000502:physiology*; D012018:Reflex / Q000502:physiology; D012119:Respiration / Q000502:physiology; D013710:Tendons / Q000294:innervation / Q000502:physiology; D014732:Vibration