{"doi":"10.14814/phy2.14826","title":"Bilateral NIRS measurements of muscle mitochondrial capacity: Feasibility and repeatability","abstract":"BACKGROUND: Non-invasive determination of mitochondrial capacity via near infrared spectroscopy (NIRS) typically involves voluntary exercise of a single muscle group followed by as many as 26 brief ischemic cuff occlusions to determine a single recovery rate constant (k). PURPOSE: To determine the within- and between-visit repeatability of a shortened bilateral NIRS protocol, and to establish the feasibility of hamstring k measurements. METHODS: Sixteen young (eight women, eight men; 22 ± 3 years) active adults underwent a bilateral electrical stimulation protocol in which multiple (n = 4) measurements of k for the vastus lateralis (VL) and medial hamstring (MH) muscles were determined on two visits. Repeatability (CV% and intraclass correlations, ICC) and equivalency across visits were assessed for both muscles. RESULTS: Mean k values in the VL were consistent with published values and within-visit ICCs were moderately high for both muscles in both sexes. In men, average k values on visit 2 were within 1% (VL muscle) and 5% (MH muscle) of the values on visit 1 (all p > 0.78). In women, average k values were 10%-15% lower on visit 2 (p = 0.01 and p = 0.15 for MH and VL) with the largest between-visit differences in a subset of participants with the most days between visits. CONCLUSIONS: This bilateral NIRS protocol is time efficient and provides valid estimates of k in both sexes and muscle groups with acceptable within-visit repeatability. Lower than expected between-visit repeatability in some participants reinforces the need for further investigation of this newly developed protocol to identify and control for experimental and behavioral sources of variation.","journal":"Physiological Reports","year":2021,"id":182667,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":14,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9592,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":735129,"name":"Jigar Gosalia","orcid":"0000-0002-1378-230X","position":1,"is_corresponding":false},{"id":735683,"name":"Alaina Demalis","orcid":null,"position":2,"is_corresponding":false},{"id":735684,"name":"Zachary Ryan Hobson","orcid":null,"position":3,"is_corresponding":false},{"id":490564,"name":"Kevin K. McCully","orcid":"0000-0001-9850-487X","position":4,"is_corresponding":false},{"id":514654,"name":"Brian A. Irving","orcid":"0000-0002-4131-9523","position":5,"is_corresponding":false},{"id":735685,"name":"Swapan Mookerjee","orcid":null,"position":6,"is_corresponding":false},{"id":735130,"name":"Giampietro L. Vairo","orcid":"0000-0002-7575-5016","position":7,"is_corresponding":false},{"id":535030,"name":"David N. Proctor","orcid":"0000-0002-4691-4575","position":8,"is_corresponding":false},{"id":735128,"name":"Rewais Hanna","orcid":"0000-0002-6227-087X","position":0,"is_corresponding":true}],"reference_count":35,"raw_metadata":null,"created_at":"2026-07-18T23:48:13.605421Z","pmid":"33945230","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":[]}