Back to Search
Start Over
Fatigue-related firing of distal muscle nociceptors reduces voluntary activation of proximal muscles of the same limb.
- Source :
-
Journal of applied physiology (Bethesda, Md. : 1985) [J Appl Physiol (1985)] 2014 Feb 15; Vol. 116 (4), pp. 385-94. Date of Electronic Publication: 2013 Dec 19. - Publication Year :
- 2014
-
Abstract
- With fatiguing exercise, firing of group III/IV muscle afferents reduces voluntary activation and force of the exercised muscles. These afferents can also act across agonist/antagonist pairs, reducing voluntary activation and force in nonfatigued muscles. We hypothesized that maintained firing of group III/IV muscle afferents after a fatiguing adductor pollicis (AP) contraction would decrease voluntary activation and force of AP and ipsilateral elbow flexors. In two experiments (n = 10) we examined voluntary activation of AP and elbow flexors by measuring changes in superimposed twitches evoked by ulnar nerve stimulation and transcranial magnetic stimulation of the motor cortex, respectively. Inflation of a sphygmomanometer cuff after a 2-min AP maximal voluntary contraction (MVC) blocked circulation of the hand for 2 min and maintained firing of group III/IV muscle afferents. After a 2-min AP MVC, maximal AP voluntary activation was lower with than without ischemia (56.2 ± 17.7% vs. 76.3 ± 14.6%; mean ± SD; P < 0.05) as was force (40.3 ± 12.8% vs. 57.1 ± 13.8% peak MVC; P < 0.05). Likewise, after a 2-min AP MVC, elbow flexion voluntary activation was lower with than without ischemia (88.3 ± 7.5% vs. 93.6 ± 3.9%; P < 0.05) as was torque (80.2 ± 4.6% vs. 86.6 ± 1.0% peak MVC; P < 0.05). Pain during ischemia was reported as Moderate to Very Strong. Postfatigue firing of group III/IV muscle afferents from the hand decreased voluntary drive and force of AP. Moreover, this effect decreased voluntary drive and torque of proximal unfatigued muscles, the elbow flexors. Fatigue-sensitive group III/IV muscle nociceptors act to limit voluntary drive not only to fatigued muscles but also to unfatigued muscles within the same limb.
- Subjects :
- Adult
Biomechanical Phenomena
Brachial Plexus physiopathology
Electric Stimulation
Female
Humans
Ischemia metabolism
Male
Motor Cortex physiopathology
Muscle Strength
Muscle, Skeletal blood supply
Pain metabolism
Pain physiopathology
Regional Blood Flow
Time Factors
Transcranial Magnetic Stimulation
Ulnar Nerve physiopathology
Upper Extremity
Ischemia physiopathology
Muscle Contraction
Muscle Fatigue
Muscle, Skeletal innervation
Nociceptors metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 1522-1601
- Volume :
- 116
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- Journal of applied physiology (Bethesda, Md. : 1985)
- Publication Type :
- Academic Journal
- Accession number :
- 24356522
- Full Text :
- https://doi.org/10.1152/japplphysiol.01166.2013