Effects of neuromuscular fatigue on electromechanical delay of the leg extensors and flexors in young men and women

Conchola, Eric C.; Thiele, Ryan M.; Palmer, Ty B.; Smith, Doug B.; Thompson, Brennan J.

doi:10.1002/mus.24598

Cited by 18 publications

(15 citation statements)

References 42 publications

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“…In this regard, short EMD reflects fast force transmission from the musculotendinous unit to the bone (Ricci Hannah et al, 2012). In general, longer EMD of hamstring muscles suggests impaired neuromuscular control which again affects knee joint stability (Hannah et al, 2014; Conchola et al, 2015). More specifically, there is evidence that short EMD of the hamstring muscles is crucial to protect the ACL from any excessive mechanical overload by providing stability to the tibia and by mitigating anterior tibia translation (Yanagawa et al, 2002; Hannah et al, 2014).…”

Section: Discussionmentioning

confidence: 99%

“…Given the above, this study aimed at examining the effects of neuromuscular fatigue on knee flexor EMD during the performance of eccentric muscle actions in healthy young adults according to their training status (i.e., athletes vs. physically active vs. sedentary). Based on previous literature (Conchola et al, 2015; De Ste Croix et al, 2015b; Bachasson et al, 2016), we hypothesized that neuromuscular fatigue induces longer knee flexor EMDs, particularly in individuals with low training status (Mitchell et al, 2011). Findings from this study could be clinically relevant for monitoring injury risk and for the implementation of injury preventive programs (Ristanis et al, 2009; Hannah et al, 2014; Flevas et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

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Effects of Neuromuscular Fatigue on Eccentric Strength and Electromechanical Delay of the Knee Flexors: The Role of Training Status

et al. 2019

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Purpose: To examine the effects of fatiguing isometric contractions on maximal eccentric strength and electromechanical delay (EMD) of the knee flexors in healthy young adults of different training status. Methods : Seventy-five male participants (27.7 ± 5.0 years) were enrolled in this study and allocated to three experimental groups according to their training status: athletes (ATH, n = 25), physically active adults (ACT, n = 25), and sedentary participants (SED, n = 25). The fatigue protocol comprised intermittent isometric knee flexions (6-s contraction, 4-s rest) at 60% of the maximum voluntary contraction until failure. Pre- and post-fatigue, maximal eccentric knee flexor strength and EMDs of the biceps femoris, semimembranosus, and semitendinosus muscles were assessed during maximal eccentric knee flexor actions at 60, 180, and 300°/s angular velocity. An analysis of covariance was computed with baseline (unfatigued) data included as a covariate. Results: Significant and large-sized main effects of group ( p ≤ 0.017, 0.87 ≤ d ≤ 3.69) and/or angular velocity ( p < 0.001, d = 1.81) were observed. Post hoc tests indicated that regardless of angular velocity, maximal eccentric knee flexor strength was lower and EMD was longer in SED compared with ATH and ACT ( p ≤ 0.025, 0.76 ≤ d ≤ 1.82) and in ACT compared with ATH ( p = ≤0.025, 0.76 ≤ d ≤ 1.82). Additionally, EMD at post-test was significantly longer at 300°/s compared with 60 and 180°/s ( p < 0.001, 2.95 ≤ d ≤ 4.64) and at 180°/s compared with 60°/s ( p < 0.001, d = 2.56), irrespective of training status. Conclusion: The main outcomes revealed significantly higher maximal eccentric strength and shorter eccentric EMDs of knee flexors in individuals with higher training status (i.e., athletes) following fatiguing exercises. Therefore, higher training status is associated with better neuromuscular functioning (i.e., strength, EMD) of the hamstring muscles in fatigued condition. Future longitudinal studies are needed to substantiate the clinical relevance of these findings.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Neuromuscular Fatigue on Eccentric Strength and Electromechanical Delay of the Knee Flexors: The Role of Training Status

et al. 2019

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“…The knee‐extensors and knee‐flexors MVC was used to individually tailor the fatiguing protocol. This consisted of a duty‐cycle of 6 s isometric knee extension or flexion and 4 s of recovery until exhaustion (Conchola, Thiele, Palmer, Smith, & Thompson, 2015). During the isometric exercise, the participants were required to hold a horizontal line corresponding to 70% of the knee‐extensors or knee‐flexors MVC on a monitor displaying the force exerted in real time, as previously used (Boccia, Coratella, et al., 2016; Boccia, Dardanello, et al., 2016; Boccia, Dardanello, Coratella, et al., 2015; Boccia, Dardanello, Rinaldo, et al., 2015).…”

Section: Methodsmentioning

confidence: 99%

“…The present study comes with some acknowledged limitations. Firstly, only two muscles (biceps 347 femoris and vastus lateralis) were selected to represent the knee-flexors and knee-extensors EMG 348 activity respectively (Conchola et al, 2015). Since the complex morphology in knee-flexors and 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 In conclusion, a standardized intermittent sub-maximal isometric fatiguing protocol induced similar 361 decreases in isometric MVC in both knee-flexors and knee-extensors.…”

mentioning

confidence: 99%

Greater fatigability in knee‐flexors vs. knee‐extensors after a standardized fatiguing protocol

Coratella

Grosprêtre²,

Gimenez³

et al. 2018

European Journal of Sport Science

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The present study aimed to investigate the effects of a standardized fatiguing protocol on central and peripheral fatigue in knee-flexors and knee-extensors. Thirteen healthy men (age: 23 ± 3 years; height: 1.78 ± 0.09 m; body-mass: 73.6 ± 9.2 kg) volunteered for the present study. Maximal voluntary contraction (MVC), Electromyography (EMG) activity, voluntary activation level (VAL) as an index of central fatigue and twitch potentiation as an index of peripheral fatigue were measured before and after the fatiguing protocol. The fatiguing protocol consisted of a 0.6 duty-cycle to exhaustion (6 s isometric contraction, 4 s recovery) at 70% MVC. After the fatiguing protocol, MVC decreased in both (Effect-size (ES) = 1.14) and knee-extensors (ES = 1.14), and EMG activity increased in both knee-flexors (ES = 2.33) and knee-extensors (ES = 1.54). Decreases in VAL occurred in knee-flexors (ES = 0.92) but not in knee-extensors (ES = 0.04). Decreases in potentiation occurred in both knee-flexors (ES = 0.84) and knee-extensors (ES = 0.58). The greater central occurrence of fatigue in knee-flexors than in knee-extensors may depend on the different muscle morphology and coupled with a greater tolerance to fatigue in knee-extensors. The present data add further insight to the complicated knee-flexors-to-knee-extensors strength relationship and the mechanisms behind the different occurrence of fatigue.

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“…For the current study to have 90% statistical power with an alpha level of 0.05, it would require at least 22 (same-sex) volunteers, according to data from a previous investigation on how neuromuscular fatigue impacts electromechanical delay (EMD) values. The power calculations were based on an effect size of 1.47 when investigating the impact of fatigue on EMD values for hip flexor muscles 33 . The inclusion criteria for athletes with CLBP and non-CLBP were: players ranging from 20 to 35 years old who have at least four years' history of playing in the Iranian super-league and first division league.…”

Section: Methodsmentioning

confidence: 99%

The effect of fatigue on electromechanical response times in basketball players with and without persistent low back pain

Abdollahi

Sheikhhoseini

Roostayi

et al. 2022

Sci Rep

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Typically, athletes alter movement mechanics in the presence of back pain, but the effect of these changes on lower extremity injury risk is not well understood. This study aimed to compare the effect of fatigue on electromechanical response times during a choice reaction task in basketball players with and without persistent low back pain. Twenty-four male basketball players participated. Total reaction time (TRT), premotor time (PMT), and electromechanical delay (EMD data were recorded before and after fatigue. The chronic low back pain (CLBP) group had significantly longer EMD in Med gastrocnemius (p = 0.001) and Tibialis anterior (p = 0.001), and shorter EMD in Vastus Lateralis (p = 0.001), Vastus Medialis Oblique (p = 0.003), and Semitendinosus (p = 0.025) muscles after fatigue. PMT in the CLBP group had longer than the Non-CLBP in Vastus Lateralis (p = 0.010), Vastus Medialis Oblique (p = 0.017), Semitendinosus (p = 0.002). Also, TRT was longer in knee flexion (p = 0.001) and ankle plantarflexion (p = 0.001) muscle groups. The different effects of fatigue on electromechanical response times of the knee and ankle in people with CLBP may represent the effect of an axial injury on lower extremity injury risk factors in situations of higher cognitive load, similar to competitive play.

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Effects of neuromuscular fatigue on electromechanical delay of the leg extensors and flexors in young men and women

Abstract: No differential gender-related fatigue effects on EMD were shown. There were different fatigue-induced responses between leg extensors and flexors, with leg extensors exhibiting higher EMD immediately post-fatigue.

Cited by 18 publications

References 42 publications

Effects of Neuromuscular Fatigue on Eccentric Strength and Electromechanical Delay of the Knee Flexors: The Role of Training Status

Effects of Neuromuscular Fatigue on Eccentric Strength and Electromechanical Delay of the Knee Flexors: The Role of Training Status

Greater fatigability in knee‐flexors vs. knee‐extensors after a standardized fatiguing protocol

The effect of fatigue on electromechanical response times in basketball players with and without persistent low back pain

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