Inter- and Intra-Individual Differences in EMG and MMG during Maximal, Bilateral, Dynamic Leg Extensions

Authors

John Paul V. Anders, University of Nebraska-LincolnFollow
Cory M. Smith, University of Texas at El PasoFollow
Joshua L. Keller, University of Nebraska-LincolnFollow
Ethan C. Hill, University of Central FloridaFollow
Terry J. Housh, University of Nebraska-LincolnFollow
Richard Schmidt, University of Nebraska-LincolnFollow
Glen O. Johnson, University of Nebraska-Lincoln

ORCID IDs

https://orcid.org/0000-0003-0756-9358

Date of this Version

7-18-2019

Citation

2019 by the authors.

Comments

Sports 2019, 7, 175; doi:10.3390/sports7070175 www.mdpi.com/journal/sports

Abstract

The purpose of this study was to compare the composite, inter-individual, and intra-individual differences in the patterns of responses for electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF) during fatiguing, maximal, bilateral, and isokinetic leg extension muscle actions. Thirteen recreationally active men (age = 21.7 2.6 years; body mass = 79.8 11.5 kg; height = 174.2 12.7 cm) performed maximal, bilateral leg extensions at 1801 until the torque values dropped to 50% of peak torque for two consecutive repetitions. The EMG and MMG signals from the vastus lateralis (VL) muscles of both limbs were recorded. Four 2(Leg) 19(time) repeated measures ANOVAs were conducted to examine mean differences for EMG AMP, EMG MPF, MMG AMP, and MMG MPF between limbs, and polynomial regression analyses were performed to identify the patterns of neuromuscular responses. The results indicated no significant differences between limbs for EMG AMP (p = 0.44), EMG MPF (p = 0.33), MMG AMP (p = 0.89), or MMG MPF (p = 0.52). Polynomial regression analyses demonstrated substantial inter-individual variability. Inferences made regarding the patterns of neuromuscular responses to fatiguing and bilateral muscle actions should be considered on a subject-by-subject basis.