title: Two protocols to measure mitochondrial capacity in women and adolescent girls: a 31P-MRS preliminary study.
abstract: The phosphocreatine (PCr) recovery time constant (τ) following exercise provides a measure of mitochondrial oxidative capacity. The purpose of this investigation was to use 2 different protocols to determine τ in adolescent females. 31P-MR spectra were collected during 2 exercise tests in 6 adolescent girls (13.8 ± 0.3 y) and 7 women (23.2 ± 3.4 y). The first test consisted of 23 repeated 4 seconds maximal isometric calf contractions separated by 12-second recovery; PCr recovery between the final 18 contractions was used to calculate τ. The second test was a sustained 20-second maximal contraction; recovery was fitted with an exponential function to measure τ. PCr τ did not significantly differ between groups: (gated exercise: 4 girls: 16 ± 5 s, 7 women: 17 ± 5 s, p; sustained exercise: 6 girls: 19 ± 6 s, 7 women: 19 ± 4 s). Bland-Altman analysis demonstrated a close agreement between sustained and gated exercise. Both gated and sustained exercise appear feasible in a pediatric population, and offer a noninvasive evaluation of mitochondrial oxidative capacity.
authors.affiliation: Children's Health and Exercise Research Center, University of Exeter, Exeter, UK.
authors.forename: Rebecca Jane
authors.initials: RJ
authors.lastname: Willcocks
authors.forename: Jon
authors.initials: J
authors.lastname: Fulford
authors.forename: Alan Robert
authors.initials: AR
authors.lastname: Barker
authors.forename: Neil
authors.initials: N
authors.lastname: Armstrong
authors.forename: Craig Anthony
authors.initials: CA
authors.lastname: Williams
mesh_terms: D000293:Adolescent; D000328:Adult; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology*; D009682:Magnetic Resonance Spectroscopy; D008928:Mitochondria / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010084:Oxidation-Reduction; D013997:Time Factors; D055815:Young Adult