The present study examined the magnitude of performance fatigability as well as the associated limb- and intensity-specific neuromuscular patterns of responses during sustained, bilateral, isometric, leg extensions above and below critical force (CF).
Twelve women completed three sustained leg extensions (1 below and 2 above CF) anchored to forces corresponding to RPE = 1, 5, and 8 (10-point scale). During each sustained leg extension, electromyographic (EMG) and mechanomyographic (MMG) amplitude (AMP) and mean power frequency (MPF) were assessed from each vastus lateralis in 5% of time-to-exhaustion (TTE) segments. Before and after each sustained leg extension, the subjects completed maximal voluntary isometric contractions (MVIC), and the percent decline was defined as performance fatigability. Polynomial regression was used to define the individual and composite neuromuscular and force values versus time relationships. Repeated-measures ANOVAs assessed differences in performance fatigability and TTE.
The grand mean for performance fatigability was 10.1 ± 7.6%. For TTE, the repeated-measures ANOVA indicated that there was a significant (p < 0.05) effect for Intensity, such that RPE = 1 > 5 > 8. There were similar neuromuscular patterns of response between limbs as well as above and below CF. EMG MPF, however, exhibited decreases only above CF.
Performance fatigability was unvarying above and below CF as well as between limbs. In addition, there were similar fatigue-induced motor unit activation strategies above and below CF, but peripheral fatigue likely contributed to a greater extent above CF.
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Ratings of perceived exertion
Time to exhaustion
Anders JPV, Smith CM, Keller JL et al (2019) Inter- and intra-individual differences in EMG and MMG during maximal, bilateral, dynamic leg extensions. Sports 7:175. https://doi.org/10.3390/sports7070175
Anders JPV, Keller JL, Smith CM et al (2020) Performance fatigability and neuromuscular responses for bilateral versus unilateral leg extensions in women. J Electromyogr Kinesiol 50:102367. https://doi.org/10.1016/j.jelekin.2019.102367
Ansdell P, Brownstein CG, Škarabot J et al (2019) Sex differences in fatigability and recovery relative to the intensity–duration relationship. J Physiol 597:5577–5595. https://doi.org/10.1113/JP278699
Barbero M, Merletti R, Rainoldi A (2012) Atlas of muscle innervation zones: understanding surface electromyography and its applications. Springer, Mailand
Beck TW, Housh TJ, Cramer JT et al (2005) Mechanomyographic amplitude and frequency responses during dynamic muscle actions: a comprehensive review. Biomed Eng Online 4:67. https://doi.org/10.1186/1475-925X-4-67
Burnley M, Vanhatalo A, Jones AM (2012) Distinct profiles of neuromuscular fatigue during muscle contractions below and above the critical torque in humans. J Appl Physiol 113:215–223. https://doi.org/10.1152/japplphysiol.00022.2012
De Luca CJ, Contessa P (2015) Biomechanical benefits of the onion-skin motor unit control scheme. J Biomech 48:195–203. https://doi.org/10.1016/j.jbiomech.2014.12.003
Duchateau J (2018) Muscle fatigability: what, why and how it constrains motor performance. In: Masia L, Micera S, Akay M, Pons JL (eds) Converging clinical and engineering research on neurorehabilitation III. Springer International Publishing, Italy, pp 999–1002
Enoka RM, Duchateau J (2016) Translating fatigue to human performance. Med Sci Sports Exerc 48:2228–2238. https://doi.org/10.1249/MSS.0000000000000929
Farina D, Merletti R, Enoka RM (2014) The extraction of neural strategies from the surface EMG: an update. J Appl Physiol 117:1215–1230. https://doi.org/10.1152/japplphysiol.00162.2014
Gandevia SC (2001) Spinal and supraspinal factors in human muscle fatigue. Physiol Review 81:1725–1789. https://doi.org/10.1152/physrev.2001.81.4.1725
Gearhart R, Goss FL, Lagally KM et al (2001) Standardized scaling procedures for rating perceived exertion during resistance exercise. J Strength Cond Res 15:320–325
Hendrix CR, Housh TJ, Johnson GO et al (2009a) A comparison of critical force and electromyographic fatigue threshold for isometric muscle actions of the forearm flexors. Eur J Appl Physiol 105:333–342. https://doi.org/10.1007/s00421-008-0895-3
Hendrix CR, Housh TJ, Johnson GO et al (2009b) Comparison of critical force to EMG fatigue thresholds during isometric leg extension. Med Sci Sports Exerc 41:956–964. https://doi.org/10.1249/MSS.0b013e318190bdf7
Hermens HJ, Freriks B, Merletti R, Stegeman D, Blok J, Rau G, Disselhorst-Klug C, Hägg G (1999) European recommendations for surface electromyography. Roessingh research and development 8(2):13-54.
Hermens HJ, Freriks B, Disselhorst-Klug C, Rau G (2000) Development of recommendations for SEMG sensors and sensor placement procedures. J Electromyogr Kinesiol 10:361–374. https://doi.org/10.1016/S1050-6411(00)00027-4
Hu X, Rymer WZ, Suresh NL (2013) Reliability of spike triggered averaging of the surface electromyogram for motor unit action potential estimation. Muscle Nerve 48:557–570. https://doi.org/10.1002/mus.23819
Hunter SK (2016) The Relevance of sex differences in performance fatigability. Med Sci Sports Exerc 48:2247–2256. https://doi.org/10.1249/MSS.0000000000000928
Hureau TJ, Romer LM, Amann M (2018) The ‘sensory tolerance limit’: a hypothetical construct determining exercise performance? Eur J Sport Sci 18:13–24. https://doi.org/10.1080/17461391.2016.1252428
Jones AM, Wilkerson DP, DiMenna F et al (2008) Muscle metabolic responses to exercise above and below the “critical power” assessed using 31P-MRS. Am J Physiol Regul Integr Comp Physiol 294:R585–R593. https://doi.org/10.1152/ajpregu.00731.2007
Keller JL, Housh TJ, Smith CM et al (2018) Sex-related differences in the accuracy of estimating target force using percentages of maximal voluntary isometric contractions vs. ratings of perceived exertion during isometric muscle actions. J Strength Cond Res 32:3294–3300. https://doi.org/10.1519/JSC.0000000000002210
Kluger BM, Krupp LB, Enoka RM (2013) Fatigue and fatigability in neurologic illnesses. Neurology 80:409–416. https://doi.org/10.1212/WNL.0b013e31827f07be
Koral J, Oranchuk DJ, Wrightson JG et al (2020) Mechanisms of neuromuscular fatigue and recovery in unilateral versus bilateral maximal voluntary contractions. J Appl Physiol. https://doi.org/10.1152/japplphysiol.00651.2019
Lindstrom L (1970) Muscular fatigue and action potential conduction velocity changes studied with frequency analysis of EMG signals. Electromyography 10:341–356
Macefield VG, Gandevia SC, Bigland-Ritchie B et al (1993) The firing rates of human motoneurones voluntarily activated in the absence of muscle afferent feedback. J Physiol 471:429–443
Matkowski B, Place N, Martin A, Lepers R (2011) Neuromuscular fatigue differs following unilateral vs bilateral sustained submaximal contractions. Scand J Med Sci Sports 21:268–276. https://doi.org/10.1111/j.1600-0838.2009.01040.x
Miller JD, Lippman JD, Trevino MA, Herda TJ (2020) Neural drive is greater for a high-intensity contraction than for moderate-intensity contractions performed to fatigue. J Strength Condition Res 34:3013–3021. https://doi.org/10.1519/JSC.0000000000003694
Monod H, Scherrer J (1965) The work capacity of a synergic muscular group. Ergonomics 8:329–338. https://doi.org/10.1080/00140136508930810
Neyroud D, Kayser B, Place N (2016) Are there critical fatigue thresholds? Aggregated vs individual data. Front Physiol 7:1–6. https://doi.org/10.3389/fphys.2016.00376
Oda S, Moritani T (1995) Movement-related cortical potentials during handgrip contractions with special reference to force and electromyogram bilateral deficit. Eur J Appl Physiol Occup Physiol 72:1–5. https://doi.org/10.1007/bf00964106
Pescatello LS, Arena R, Riebe D, Thompson PD (2013) American College of Sports Medicine’s Guidelines for Exercise Testing and Prescription. Lippincott Williams & Wilkins.
Piotrkiewicz M, Türker KS (2017) Onion skin or common drive? Front Cell Neurosci 11:2. https://doi.org/10.3389/fncel.2017.00002
Poole DC, Burnley M, Vanhatalo A et al (2016) Critical power: an important fatigue threshold in exercise physiology. Med Sci Sports Exerc 48:2320–2334. https://doi.org/10.1249/MSS.0000000000000939
Robertson RJ (2004) Perceived exertion for practitioners: rating effort with the OMNI picture system. Human Kinetics
Rossman MJ, Venturelli M, McDaniel J et al (2012) Muscle mass and peripheral fatigue: a potential role for afferent feedback? Acta Physiol 206:242–250. https://doi.org/10.1111/j.1748-1716.2012.02471.x
Rossman MJ, Garten RS, Venturelli M et al (2014) The role of active muscle mass in determining the magnitude of peripheral fatigue during dynamic exercise. Am J Physiol Regul Integr Comp Physiol 306:R934–R940. https://doi.org/10.1152/ajpregu.00043.2014
Ryan ED, Cramer JT, Housh TJ et al (2007) Inter-individual variability among the mechanomyographic and electromyographic amplitude and mean power frequency responses during isometric ramp muscle actions. Electromyogr Clin Neurophysiol 47:161–173
Škarabot J, Cronin N, Strojnik V, Avela J (2016) Bilateral deficit in maximal force production. Eur J Appl Physiol 116:2057–2084. https://doi.org/10.1007/s00421-016-3458-z
Smith JL, Martin PG, Gandevia SC, Taylor JL (2007) Sustained contraction at very low forces produces prominent supraspinal fatigue in human elbow flexor muscles. J Appl Physiol 103:560–568. https://doi.org/10.1152/japplphysiol.00220.2007
Søgaard K, Gandevia SC, Todd G et al (2006) The effect of sustained low-intensity contractions on supraspinal fatigue in human elbow flexor muscles. J Physiol 573:511–523. https://doi.org/10.1113/jphysiol.2005.103598
Thomas K, Goodall S, Howatson G (2018) Performance fatigability is not regulated to a peripheral critical threshold. Exerc Sport Sci Rev 46:240–246. https://doi.org/10.1249/JES.0000000000000162
Trevino MA, Sterczala AJ, Miller JD, Wray ME, Dimmick HL, Ciccone AB, Weir JP, Gallagher PM, Fry AC, Herda TJ (2018) Sex‐related differences in muscle size explained by amplitudes of higher‐threshold motor unit action potentials and muscle fibre typing. Acta Physiol 225(4): e13151.
Weir JP (2005) Quantifying test-retest reliability using the intraclass correlation coefficient and the SEM. J Strength Cond Res 19:231–240. https://doi.org/10.1519/15184.1
Yoon T, Delap BS, Griffith EE, Hunter SK (2007) Mechanisms of fatigue differ after low- and high-force fatiguing contractions in men and women. Muscle Nerve 36:515–524. https://doi.org/10.1002/mus.20844
We would like to thank all the participants for their time and for volunteering to comply with the protocol of the study. Also, we would like to thank the National Strength and Conditioning Association as well as the Northlands American College of Sports Medicine Chapter for funding this study.
This study was at least in part funded by the National Strength and Conditioning Association as well as the Northlands American College of Sports Medicine Chapter.
Conflict of interest
The authors have no conflicts of interest to report.
The University Institutional Review Board for Human Subjects approved the study (IRB#: 20190619436EP).
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During the familiarization visit, the subjects completed a health history questionnaire and gave written informed consent.
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Communicated by William J. Kraemer.
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Keller, J.L., Housh, T.J., Anders, J.P.V. et al. Similar performance fatigability and neuromuscular responses following sustained bilateral tasks above and below critical force. Eur J Appl Physiol (2021). https://doi.org/10.1007/s00421-020-04588-y
- Ratings of perceived exertion
- Critical force