Matthew S Tenan1, Yi-Ling Peng, Anthony C Hackney, Lisa Griffin. 1. 1Department of Kinesiology, University of Texas at Austin, Austin, TX; 2Human Research and Engineering Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, MD; and 3Department of Exercise and Sport Science, University of North Carolina at Chapel Hill, Chapel Hill, NC.
Abstract
PURPOSE: Sports medicine professionals commonly describe two functionally different units of the vastus medialis (VM), the VM, and the vastus medialis oblique (VMO), but the anatomical support is equivocal. The functional difference of the VMO is principle to rehabilitation programs designed to alleviate anterior knee pain, a pathology that is known to have a greater occurrence in women. The purpose of this study was to determine whether the motor units of the VM and VMO are differentially recruited and if this recruitment pattern has an effect of sex or menstrual cycle phase. METHODS: Single motor unit recordings from the VM and VMO were obtained for men and women during an isometric ramp knee extension. Eleven men were tested once. Seven women were tested during five different phases of the menstrual cycle, determined by basal body temperature mapping. The recruitment threshold and the initial firing rate at recruitment were determined from 510 motor unit recordings. RESULTS: The initial firing rate was lower in the VMO than that in the VM in women (P < 0.001) but not in men. There was no difference in recruitment thresholds for the VM and VMO in either sex or across the menstrual cycle. There was a main effect of menstrual phase on initial firing rate, showing increases from the early follicular to late luteal phase (P = 0.003). The initial firing rate in the VMO was lower than that in the VM during ovulatory (P = 0.009) and midluteal (P = 0.009) phases. CONCLUSION: The relative control of the VM and VMO changes across the menstrual cycle. This could influence patellar pathologies that have a higher incidence in women.
PURPOSE: Sports medicine professionals commonly describe two functionally different units of the vastus medialis (VM), the VM, and the vastus medialis oblique (VMO), but the anatomical support is equivocal. The functional difference of the VMO is principle to rehabilitation programs designed to alleviate anterior knee pain, a pathology that is known to have a greater occurrence in women. The purpose of this study was to determine whether the motor units of the VM and VMO are differentially recruited and if this recruitment pattern has an effect of sex or menstrual cycle phase. METHODS: Single motor unit recordings from the VM and VMO were obtained for men and women during an isometric ramp knee extension. Eleven men were tested once. Seven women were tested during five different phases of the menstrual cycle, determined by basal body temperature mapping. The recruitment threshold and the initial firing rate at recruitment were determined from 510 motor unit recordings. RESULTS: The initial firing rate was lower in the VMO than that in the VM in women (P < 0.001) but not in men. There was no difference in recruitment thresholds for the VM and VMO in either sex or across the menstrual cycle. There was a main effect of menstrual phase on initial firing rate, showing increases from the early follicular to late luteal phase (P = 0.003). The initial firing rate in the VMO was lower than that in the VM during ovulatory (P = 0.009) and midluteal (P = 0.009) phases. CONCLUSION: The relative control of the VM and VMO changes across the menstrual cycle. This could influence patellar pathologies that have a higher incidence in women.
Authors: Jonathan D Miller; C J Lund; Marissa D Gingrich; Kyle L Schtul; Mandy E Wray; Trent J Herda Journal: Exp Brain Res Date: 2019-08-08 Impact factor: 1.972
Authors: Ellen Casey; Maria Reese; Ezi Okafor; Danielle Chun; Christine Gagnon; Franz Nigl; Yasin Y Dhaher Journal: PM R Date: 2016-02-10 Impact factor: 2.298
Authors: Mikaeli Anne Carmichael; Rebecca Louise Thomson; Lisa Jane Moran; Thomas Philip Wycherley Journal: Int J Environ Res Public Health Date: 2021-02-09 Impact factor: 4.614
Authors: Katja M Schmalenberger; Hafsah A Tauseef; Jordan C Barone; Sarah A Owens; Lynne Lieberman; Marc N Jarczok; Susan S Girdler; Jeff Kiesner; Beate Ditzen; Tory A Eisenlohr-Moul Journal: Psychoneuroendocrinology Date: 2020-10-13 Impact factor: 4.905