{"doi":"10.1152/jn.2000.84.1.358","title":"Motor-Unit Synchronization Is Not Responsible for Larger Motor-Unit Forces in Old Adults","abstract":null,"journal":"Journal of Neurophysiology","year":2000,"id":674002,"datarank":0.7104297672591745,"base_score":4.736198448394496,"endowment":4.736198448394496,"self_citation_contribution":0.7104297672591745,"citation_network_contribution":0.0,"self_endowment_contribution":0.7104297672591745,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":113,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":null,"is_data_producer":false,"deposit_databanks":null,"is_oa":false,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":null,"fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":1761002,"name":"Julie W. Steege","orcid":null,"position":1,"is_corresponding":false},{"id":1761003,"name":"Kurt W. Kornatz","orcid":null,"position":2,"is_corresponding":false},{"id":993320,"name":"Roger M. Enoka","orcid":"0000-0002-7881-2397","position":3,"is_corresponding":false},{"id":1761001,"name":"John G. Semmler","orcid":null,"position":0,"is_corresponding":false}],"reference_count":0,"raw_metadata":{"has_enrichment":true,"resolved":true,"title":"Motor-Unit Synchronization Is Not Responsible for Larger Motor-Unit Forces in Old Adults","abstract":"Motor-unit synchronization, which is a measure of the near simultaneous discharge of action potentials by motor units, has the potential to influence spike-triggered average force and the steadiness of a low-force isometric contraction. The purpose of the study was to estimate the contribution of motor-unit synchronization to the larger spike-triggered average forces and the decreased steadiness exhibited by old adults. Eleven young (age 19-30 yr) and 14 old (age 63-81 yr) adults participated in the study. Motor-unit activity was recorded with two fine-wire intramuscular electrodes in the first dorsal interosseus muscle during isometric contractions that caused the index finger to exert an abduction force. In a separate session, steadiness measurements were obtained during constant-force isometric contractions at target forces of 2.5, 5, 7. 5, and 10% of the maximum voluntary contraction (MVC) force. Mean (+/-SD) motor-unit forces measured by spike-triggered averaging were larger in old (15.5 +/- 12.1 mN) compared with young (7.3 +/- 5.7 mN) adults, and the differences were more pronounced between young (8.7 +/- 6.4 mN) and old (19.9 +/- 12.2 mN) men. Furthermore, the old adults had a reduced ability to maintain a steady force during an isometric contraction, particularly at low target forces (2.5 and 5% MVC). Mean (+/-SD) motor-unit synchronization, expressed as the frequency of extra synchronous discharges above chance in the cross-correlogram, was similar in young [0.66 +/- 0.4 impulses/s (imp/s); range, 0.35-1.51 imp/s; 53 pairs) and old adults (0.72 +/- 0.5 imp/s; range, 0.27-1.38 imp/s; 56 pairs). The duration of synchronous peaks in the cross-correlogram was similar for each group (approximately 16 ms). These data suggest that motor-unit synchronization is not responsible for larger spike-triggered average forces in old adults and that motor-unit synchronization does not contribute to the decreased steadiness of low-force isometric contractions observed in old adults.","is_dataset_classified":null,"base_score":4.736198448394496,"endowment":4.736198448394496,"datacite_reuse_total":0,"file_count":0,"downloads":0,"views":0,"has_version_chain":false,"is_dataset":false,"is_oa":false,"pmid":"10899210","pmcid":null,"openalex_id":"https://openalex.org/W2315607242","authors":[],"funders":[{"funder_name":"NIA NIH HHS","grant_id":"AG-090000","title":null}],"total_grants":1,"fwci":5.8675,"citation_percentile":0.96434454,"influential_citations":0,"citation_trend":[{"year":2012,"count":8},{"year":2013,"count":1},{"year":2014,"count":3},{"year":2015,"count":8},{"year":2016,"count":8},{"year":2017,"count":4},{"year":2018,"count":4},{"year":2019,"count":3},{"year":2020,"count":1},{"year":2022,"count":1},{"year":2023,"count":1},{"year":2024,"count":3},{"year":2025,"count":1}],"oa_status":"closed","license":null,"oa_locations":[{"url":"http://www.physiology.org/doi/pdf/10.1152/jn.2000.84.1.358","host_type":"publisher"},{"url":"https://doi.org/10.1152/jn.2000.84.1.358","host_type":"journal"},{"url":"https://pubmed.ncbi.nlm.nih.gov/10899210","host_type":"repository"}],"fields_of_study":["Muscle activation and electromyography studies","Transcranial Magnetic Stimulation Studies","Motor Control and Adaptation","Action Potentials","Adult","Aged","Aged, 80 and over","Aging","Female","Functional Laterality","Humans","Isometric Contraction","Male","Middle Aged","Motor Neurons","Muscle, Skeletal"],"mesh_terms":["Action Potentials","Adult","Aged","Aged, 80 and over","Aging","Female","Humans","Isometric Contraction","Functional Laterality","Male","Middle Aged","Motor Neurons","Muscle, Skeletal"],"keywords":["Isometric exercise","Motor unit","Electromyography","Synchronization (alternating current)","Physical medicine and rehabilitation","Dorsum","Muscle contraction","Chemistry","Anatomy","Medicine","Mathematics","Physical therapy"],"sdg_mappings":[],"linked_datasets":[],"clinical_trials":[],"software_tools":[],"database_accessions":[],"source":"live","citation_network_status":"fetched"},"created_at":"2026-08-16T15:12:34.088278Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}