Increase in the discharge of muscle spindles during diaphragm fatigue.
The discharge of 18 single unit spindles located in the right crural diaphragm was recorded during rhythmic diaphragmatic contractions before the onset of and during fatigue. Spindle discharge was significantly greater (P<0.05) during rhythmic exercise when the diaphragm was fatigued than spindle discharge during rhythmic exercise when the diaphragm was not fatigued. The increase in spindle discharge during diaphragmatic fatigue is inconsistent with the notion that spindles comprise the afferent arm of a fatigue-induced inhibitory reflex originating in the diaphragm.
Hill
J M
JM
Department of Kinesiology, Division of Natural and Applied Sciences, One University Drive, Chapman University, Orange, CA 92866, USA. jhill@chapman.edu
D000200:Action Potentials / Q000502:physiology*; D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D003964:Diaphragm / Q000294:innervation* / Q000502:physiology*; D004558:Electric Stimulation; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018763:Muscle Fatigue / Q000502:physiology*; D009470:Muscle Spindles / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology; D009433:Neural Inhibition / Q000502:physiology; D010507:Periodicity; D010791:Phrenic Nerve / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012018:Reflex / Q000502:physiology; D012143:Respiratory Physiological Phenomena