Valentin Doguet1, Marc Jubeau. 1. Laboratory "Motricité, Interactions, Performance" (EA 4334), UFR STAPS Nantes, University of Nantes, 25 bis Boulevard Guy Mollet, BP 72206, 44322, Nantes Cedex 3, France.
Abstract
PURPOSE: This study aimed to evaluate the modulation and reliability of the vastus medialis (VM) and vastus lateralis (VL) H-reflexes in both passive and active conditions. METHODS: Recruitment curves of VM and VL H-reflexes and M-waves at rest and during muscle contraction (30% of maximal voluntary contraction) were performed for 12 healthy males and were then repeated after 1 h, 1 day and 1 week. The maximal H-reflexes of each muscle were normalized to their respective maximal M-waves (H/M ratio) and absolute (CV) and relative (ICC) reliability were calculated. RESULTS: The H-reflex was potentiated in active compared to passive condition and a higher H-reflex occurrence (12 vs. 10 subjects) and amplitude (≈+150%) was found for the VM compared to the VL in active condition. The intra- (ICChour = 0.97) and inter-day (ICCday = 0.92; ICCweek = 0.92) reliability was poor for the passive VM H/M ratio due to high within-subject variations (CVhour = 52.2%; CVday = 69.8%; CVweek = 60.9%) whereas for the active condition the reliability, especially intra-day, was good (ICChour = 0.93 and CVhour = 12%; ICCday = 0.86 and CVday = 14.5%; ICCweek = 0.79 and CVweek = 19.7%). CONCLUSIONS: This study showed differential modulation of the H-reflex between vasti muscles of the quadriceps and a higher occurrence and reliability for the active VM H-reflex. One can therefore conclude that it seems more appropriate to evoke quadriceps VM H-reflex (rather than VL) during an isometric muscle contraction.
PURPOSE: This study aimed to evaluate the modulation and reliability of the vastus medialis (VM) and vastus lateralis (VL) H-reflexes in both passive and active conditions. METHODS: Recruitment curves of VM and VL H-reflexes and M-waves at rest and during muscle contraction (30% of maximal voluntary contraction) were performed for 12 healthy males and were then repeated after 1 h, 1 day and 1 week. The maximal H-reflexes of each muscle were normalized to their respective maximal M-waves (H/M ratio) and absolute (CV) and relative (ICC) reliability were calculated. RESULTS: The H-reflex was potentiated in active compared to passive condition and a higher H-reflex occurrence (12 vs. 10 subjects) and amplitude (≈+150%) was found for the VM compared to the VL in active condition. The intra- (ICChour = 0.97) and inter-day (ICCday = 0.92; ICCweek = 0.92) reliability was poor for the passive VM H/M ratio due to high within-subject variations (CVhour = 52.2%; CVday = 69.8%; CVweek = 60.9%) whereas for the active condition the reliability, especially intra-day, was good (ICChour = 0.93 and CVhour = 12%; ICCday = 0.86 and CVday = 14.5%; ICCweek = 0.79 and CVweek = 19.7%). CONCLUSIONS: This study showed differential modulation of the H-reflex between vasti muscles of the quadriceps and a higher occurrence and reliability for the active VM H-reflex. One can therefore conclude that it seems more appropriate to evoke quadriceps VM H-reflex (rather than VL) during an isometric muscle contraction.
Authors: Paul W Marshall; Stine Brock Rasmussen; Malene Krogh; Samuel Halley; Jason C Siegler Journal: Eur J Appl Physiol Date: 2020-04-01 Impact factor: 3.078