The Evaluation of Exercise Using Electromyography

A special issue of Sports (ISSN 2075-4663).

Deadline for manuscript submissions: closed (31 March 2020) | Viewed by 18872

Special Issue Editor


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Guest Editor
Kinesiology and Physical Education, Northern Illinois University, DeKalb, IL 60115, USA
Interests: nutritional supplements; ergogenic aids; electromyography; muscle fatigue
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Special Issue Information

Dear Colleagues,

Electromyography is a diverse tool used to evaluate neuromuscular function through the analysis of the electrical activity of contracting skeletal muscle fibers. Specifically, the electromyographic signal provides global information related to the action potentials of the motor units within the pickup range of the recording electrodes. This technique is widely utilized across many fields, with therapeutic, clinical, and human performance applications.

The electromyographic technique is commonly used to examine changes in muscle activation during various forms of static (e.g., isometric muscle actions) and dynamic (e.g., cycling, running, isolated concentric and eccentric muscle actions) exercise. For example, electromyographic responses from active muscle reflect the motor control strategies (i.e., motor unit recruitment, motor unit firing rates, motor unit synchronization) associated with changes in force production and the development of fatigue specific to a given task.  

The aim of this Special Issue is to deliver new insight into the use of electromyography to assess neuromuscular function during exercise and promote novel applications. We hope that this knowledge will help provide coaches, clinicians, and other health and sport professionals with valuable information that can be used to establish new training methods, therapeutic strategies, and assessment techniques.

Prof. Clayton L. Camic, Ph.D.
Guest Editor

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Keywords

  • electromyography
  • neuromuscular function
  • neuromuscular fatigue
  • muscle activation
  • exercise
  • sports performance
  • motor control strategies
  • motor unit recruitment
  • motor unit firing rates

Published Papers (5 papers)

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Research

10 pages, 877 KiB  
Article
Military-Type Workload and Footwear Alter Lower Extremity Muscle Activity during Unilateral Static Balance: Implications for Tactical Athletic Footwear Design
by Christopher M. Hill, Hunter DeBusk, Adam C. Knight and Harish Chander
Sports 2020, 8(5), 58; https://doi.org/10.3390/sports8050058 - 28 Apr 2020
Cited by 3 | Viewed by 2325
Abstract
Maintaining upright standing balance is critical for military personal. The impact of military footwear and occupation-related fatigue on muscle activity during balance performance has been previously documented. However, the current literature has not provided a muscle activation profile of the lower extremity during [...] Read more.
Maintaining upright standing balance is critical for military personal. The impact of military footwear and occupation-related fatigue on muscle activity during balance performance has been previously documented. However, the current literature has not provided a muscle activation profile of the lower extremity during challenging conditions such as unilateral balance trials. Twenty-two recreationally active male participants (age: 22.2 ± 2.7 years; height: 177 ± 6.8 cm; mass: 79.8 ± 9.7 kg) donned two styles of military footwear (minimalist and standard) and performed a military style workload. Unilateral static balance was accessed before (PRE) and after (POST) the workload as surface electromyography was recorded on the right lower extremity. This study found that the minimalist footwear increased muscle activation prior to the workload compared to the standard footwear (co-contraction index mean difference: 0.149), whereas the standard footwear increased muscle activity after the workload (co-contraction index mean difference: 0.097). These findings suggest that footwear design characteristics affect lower extremity muscle activity differently depending on the workload condition. These findings intend to aid in the design of military footwear to maximize balance performance in a military population. Full article
(This article belongs to the Special Issue The Evaluation of Exercise Using Electromyography)
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15 pages, 4770 KiB  
Article
Inter- and Intra-Individual Differences in EMG and MMG during Maximal, Bilateral, Dynamic Leg Extensions
by John Paul V. Anders, Cory M. Smith, Joshua L. Keller, Ethan C. Hill, Terry J. Housh, Richard J. Schmidt and Glen O. Johnson
Sports 2019, 7(7), 175; https://doi.org/10.3390/sports7070175 - 18 Jul 2019
Cited by 17 | Viewed by 5552
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 [...] Read more.
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 180°·s−1 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. Full article
(This article belongs to the Special Issue The Evaluation of Exercise Using Electromyography)
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11 pages, 1157 KiB  
Article
Fatigue-Mediated Loss of Complexity is Contraction-Type Dependent in Vastus Lateralis Electromyographic Signals
by Luis R. Hernandez and Clayton L. Camic
Sports 2019, 7(4), 78; https://doi.org/10.3390/sports7040078 - 2 Apr 2019
Cited by 10 | Viewed by 3144
Abstract
The purpose of this study was to investigate the effect of fatigue status and contraction type on complexity of the surface electromyographic (sEMG) signal. Twelve females (mean age ± SD = 21.1 ± 1.4 years) performed three fatigue-inducing protocols that involved maximal concentric, [...] Read more.
The purpose of this study was to investigate the effect of fatigue status and contraction type on complexity of the surface electromyographic (sEMG) signal. Twelve females (mean age ± SD = 21.1 ± 1.4 years) performed three fatigue-inducing protocols that involved maximal concentric, eccentric, or isometric knee-extensor contractions over three non-consecutive sessions. Pre- and post-fatigue assessments were also completed each session and consisted of three maximal efforts for each type of contraction. Complexity of sEMG signals from the vastus lateralis was assessed using Sample Entropy (SampEn) and Detrended Fluctuation Analysis (DFA) as expressed using the scaling exponent α. The results showed that fatigue decreased (p < 0.05) sEMG complexity as indicated by decreased SampEn (non-fatigued: 1.57 ± 0.22 > fatigued: 1.46 ± 0.25) and increased DFA α (non-fatigued: 1.27 ± 0.26 < fatigued: 1.32 ± 0.23). In addition, sEMG complexity was different among contraction types as indicated by SampEn (concentric: 1.58 ± 0.22 > eccentric: 1.47 ± 0.27 and isometric: 1.50 ± 0.21) and DFA α (concentric: 1.27 ± 0.18 < isometric: 1.32 ± 0.18). Thus, these findings suggested sEMG complexity is affected by fatigue status and contraction type, with the degree of fatigue-mediated loss of complexity dependent on the type of contraction used to elicit fatigue. Full article
(This article belongs to the Special Issue The Evaluation of Exercise Using Electromyography)
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10 pages, 881 KiB  
Article
Thinking Outside the Block: External Focus of Attention Improves Reaction Times and Movement Preparation Times in Collegiate Track Sprinters
by Attila J. Kovacs, Garrett F. Miles and Harsimran S. Baweja
Sports 2018, 6(4), 120; https://doi.org/10.3390/sports6040120 - 19 Oct 2018
Cited by 12 | Viewed by 4149
Abstract
While focusing attention on external cues (EF) has been shown to enhance performance track and field coaches tend to provide instructions that promote internal focus of attention (IF) during block starts. The aims of this study were to determine: (1) whether promoting EF [...] Read more.
While focusing attention on external cues (EF) has been shown to enhance performance track and field coaches tend to provide instructions that promote internal focus of attention (IF) during block starts. The aims of this study were to determine: (1) whether promoting EF versus IF would improve reaction time (RT) of sprinters, and (2) if changes occur at the level of central processes during movement preparation (premotor RT) or peripheral processes during movement execution (motor RT). Twelve collegiate track sprinters (age 20.8 ± 1.7) completed three testing sessions under EF, IF, and no focus instruction (NF) conditions. RT was recorded from the left and right blocks. Muscle activation time (EMG) was recorded from the vastus lateralis and gastrocnemius muscles. Mean rear foot RT was significantly shorter (p < 0.0001) under the EF (212.11 ms) compared with the IF (234.21 ms) and NF conditions (236.87 ms). Front foot RT was significantly shorter (p < 0.05) during EF (250.24 ms), compared to IF (266.98 ms) but not shorter than the NF (268.73 ms) condition. Mean premotor RT under the EF condition (157.75 ms) was significantly shorter (p < 0.001) compared with the IF (181.90 ms) and NF (173.60 ms) conditions. No differences were found in motor RT across conditions (p > 0.05). Adopting an EF improves RT during sprint starts. This improvement likely originates from a shortening in movement preparation time, as opposed to a faster excitation contraction coupling of the muscle fibers. These findings could potentially contribute to the development of new coaching methods aimed at improving the starting technique of athletes. Full article
(This article belongs to the Special Issue The Evaluation of Exercise Using Electromyography)
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13 pages, 1609 KiB  
Article
Co-Activation, Estimated Anterior and Posterior Cruciate Ligament Forces, and Motor Unit Activation Strategies during the Time Course of Fatigue
by Cory M. Smith, Terry J. Housh, Ethan C. Hill, Joshua L. Keller, Glen O. Johnson and Richard J. Schmidt
Sports 2018, 6(4), 104; https://doi.org/10.3390/sports6040104 - 21 Sep 2018
Cited by 8 | Viewed by 2898
Abstract
This study aimed to combine co-activation as well as anterior and posterior cruciate ligament force estimations with the motor unit activation strategies employed by the primary muscles that are involved in the movement at the knee joint. Fourteen male subject performed 25 maximal [...] Read more.
This study aimed to combine co-activation as well as anterior and posterior cruciate ligament force estimations with the motor unit activation strategies employed by the primary muscles that are involved in the movement at the knee joint. Fourteen male subject performed 25 maximal concentric isokinetic leg extension muscle actions at 120 s−1. Electromyographic and mechanomyographic signals from the vastus lateralis and bicep femoris, as well as force, were used to measure co-activation, and estimated anterior and posterior ligament forces during the time course of fatigue. There were decreases in quadriceps force and increases in hamstring force during the 25 leg extensions. The posterior cruciate ligament force was greater than the anterior cruciate ligament force during each leg extension. Both the posterior and anterior cruciate ligament forces decreased during the 25 leg extensions. Each muscle indicated unique neuromuscular responses, which may explain the decreases in quadriceps force and increases in the hamstring force. The combination of anterior and posterior cruciate ligament force estimation and motor unit activation strategies helped to provide a better understanding of the fatigue-related mechanism that was utilized to avoid injury and increase or maintain joint stability during the time course of fatigue. Full article
(This article belongs to the Special Issue The Evaluation of Exercise Using Electromyography)
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