The Sexes Do Not Differ for Neural Responses to Submaximal Elbow Extensor Fatigue
| Autor: | Chris J. McNeil, Alexandra F. Yacyshyn |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Adult
Male Contraction (grammar) medicine.medical_treatment Elbow Physical Therapy Sports Therapy and Rehabilitation Stimulation Isometric exercise Young Adult 03 medical and health sciences 0302 clinical medicine Isometric Contraction Afferent medicine Humans Orthopedics and Sports Medicine Evoked potential Muscle Skeletal Motor Neurons Afferent Pathways Sex Characteristics Electromyography business.industry Motor Cortex 030229 sport sciences Evoked Potentials Motor Transcranial Magnetic Stimulation Transcranial magnetic stimulation medicine.anatomical_structure Torque Anesthesia Muscle Fatigue Female Muscle group business |
| Zdroj: | Medicine & Science in Sports & Exercise. 52:1992-2001 |
| ISSN: | 1530-0315 0195-9131 |
| DOI: | 10.1249/mss.0000000000002342 |
| Popis: | PURPOSE To investigate possible sex-related differences in group III/IV muscle afferent feedback with isometric fatigue, we aimed to assess the effect of a sustained submaximal elbow extensor contraction on motoneuronal excitability (cervicomedullary motor evoked potential [CMEP]) and voluntary activation (VA). METHODS Twenty-four participants (12 females) performed a 15-min contraction at the level of EMG activity recorded at 15% of maximal torque. Each minute, CMEP were elicited by cervicomedullary stimulation with and without conditioning transcranial magnetic stimulation (TMS) delivered 100 ms earlier. Unconditioned and conditioned motor evoked potentials (MEP) in response to TMS were also recorded to assess motor cortical excitability. CMEP and MEP were normalized for changes in downstream excitability and expressed as percentage of their prefatigue (control) values. Postfatigue, VA was calculated from superimposed and resting tetani evoked by stimulation over triceps brachii. RESULTS Males were twice as strong as females, but the sexes did not differ for any variable during the fatigue protocol. On a 0-10 scale, RPE increased from ~2.5 to 9. The unconditioned CMEP did not change, whereas the conditioned CMEP was reduced by ~50%. By contrast, the unconditioned and conditioned MEP increased to ~200% and ~320% of the control values, respectively. At task termination, maximal torque was reduced ~40%, and VA was ~80%, down from a prefatigue value of ~96%. CONCLUSIONS Results support the scant published data on the elbow extensors and indicate no sex-related differences for isometric fatigue of this muscle group. The motoneuronal and VA data suggest that metabolite buildup and group III/IV muscle afferent activity were similar for females and males. |
| Databáze: | OpenAIRE |
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