Evidence based research that looks into factors that contribute to muscular fatigue. Answers the questions, does age, gender, or nervous system play a role in muscular fatigue.

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Evidence Based Practice Research
Presentation
Rumy Petkov ATS
Winona State University
Winona, Minnesota

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INTRODUCTION
 The diversity of measures, that have been used to quantify
fatigue, the specificity of the impairments that cause fatigue and
the lack of knowledge on the mechanism that limit performance
 Due to the specificity of the impairments that occur during fatiguing
contractions, there are no general answers to such questions as:
 Are older adults more fatigable than young adults?
 Are women less fatigable than men?
 Can the nervous system sustain an adequate activation of muscle
during fatiguing contractions?
 Are there differences between muscles?
 Dr. David Altchek from the Hospital for Special Surgery in New
York, “From an intuitive standpoint, the connection between tired
athletes and injuries appears obvious, however I see no
relationship between the two.”

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INTRODUCTION
 This topic is crucial because…
 It will produce better Athletic Training practice by understanding how
much is to much
 Muscle fatigue is not the point of task failure or the moment when the
muscles become exhausted
 Decline in a person's ability to exert force
 Muscle fatigue, it seems,
 can refer to a motor deficit
 a perception or a decline in mental function
 it can describe the gradual decrease in the force capacity of
muscle or the endpoint of a sustained activity
 it can be measured as a reduction in muscle force
 a change in electromyographic activity or an exhaustion of
contractile function

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CLINICAL QUESTION
 What factors contribute to muscular fatigue?

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SUMMARY OF FINDINGS
 Open chain methods (Functional
 Running
 Squatting
 Jumping
 Individual/Combination
 Closed chain methods
 Weight training machines
 Set number of repetitions at % of 1 rep max
 Isokinetic Dynamometry
 Experimental Design
 SPSS
 EMG testing
• Pearson product-moment
• Correlation Coefficient
 Repeated measures Anova

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SUMMARY OF FINDINGS
Differences in fatigability between young and old
adults
Differences in fatigability between young and old
adults

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SUMMARY OF FINDINGS
 Another example on the specificity of the impairments during
fatiguing contractions involves the sex difference that is often
observed during such tasks
 Women are usually able to sustain a contraction for a longer
duration, especially at lower contraction intensities but not
maximal contractions
 As the supply and demand of ATP is altered during the
occlusion of blood flow, the lower rate of fatigue development
observed in women during intermittent contractions may be
attributable to a sex difference in the relative contributions of
the metabolic pathways that supply ATP during fatiguing
contractions

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SUMMARY OF FINDINGS
Times to task failure for men and women Times to task failure for men and women

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SUMMARY OF FINDINGS
 The magnitude of the decline in voluntary activation during
fatiguing contractions ranges from minimal to substantial
 These studies suggest that some of the fatigue experienced
during repetitive maximal contractions and long-duration
submaximal contractions can be caused by an inadequate
activation of muscle by the nervous system
 Furthermore, the insufficiency of the activation can be
exacerbated by such conditions as a decline in the levels of
blood glucose and exercise in hot environments

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SUMMARY OF FINDINGS
Decreases in MVC torque and voluntary
activation during a fatiguing contraction
Decreases in MVC torque and voluntary
activation during a fatiguing contraction

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SUMMARY OF FINDINGS
 Eccentric hamstrings strength decreased as a function of time and
after the halftime interval. This finding indicates a greater risk of
injuries at these specific times, especially for explosive
movements, in accordance with epidemiologic observations.
 Fatigue can affect motor control with losses in proprioception
visualized by a significantly different arm path while throwing a
baseball. Like pain, fatigue is generally difficult to quantify because
it is a subjective measure that varies among persons.
Therefore, pitch counts, ball velocity, ball location, pitching
mechanics, and strength may be better guides in determining
fatigue.
 Fatigue-induced decrease in neuromuscular function with a
corresponding increase in Tibial Translation probably contributes
to the higher incidence of ACL injuries in women.

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CLINICAL BOTTOM LINE
 Task failure affords a strategy to identify the functional
significance of physiological adjustments that occur during
fatiguing contractions
 Higher injury risk in the fatigued player during explosive
movements such as sprinting is consistent with the increased
fatigue effect
 Fatigue should be considered in the rehabilitation process to
guide decisions on return to activities

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REFERENCES
 ABC 7 Health News (2010,). Year round sports lead to overuse injuries | Retrieved September 19, 2013
 Adlersberg J, Year round sports lead to overuse injuries.
http://abclocal.go.com/kabc/story?section=news/health&id=7525663. Assessed September 17,
2013
 Aoki , K., Nakao, A., Adachi, T., Matsui , Y., & Miyakawa, S. (2012). Pilot study: Effects of drinking
hydrogen-rich water on muscle fatigue caused by acute exercise in elite athletes. Med. Gas Res, 2(1), 12.
 Behrens M, Mau-Moeller A, Wassermann F, Bruhn S (2013) Effect of Fatigue on Hamstring Reflex
Responses and Posterior-Anterior Tibial Translation in Men and Women. PLoS ONE 8(2): e56988
 Demougeot L, Papaxanthis C. Muscle fatigue affects mental simulation of action. J Neurosci.
2011;31(29):10712-20.
 Dugan SA, Frontera WR. Muscle fatigue and muscle injury. Phys Med Rehabil Clin N Am. 2000;11(2):385-
403.
 Edouard P, Bankolé C, Calmels P, Beguin L, Degache F. Isokinetic rotator muscles fatigue in
glenohumeral joint instability before and after Latarjet surgery: a pilot prospective study. Scand J Med Sci
Sports. 2013;23(2):e74-80.

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REFERENCES
 Enoka R, Duchateau J, Muscle fatigue: what, why and how it influences muscle function. Journal of
Physiology. 586.1 (2008) pp 11–23
 Escamilla R, Barrentine S, Fleisig G, et al. Pitching Biomechanics as a Pitcher Approaches Muscular Fatigue
During a Simulated Baseball Game. The American Journal of Sports Medicine. January 2007; 35: 1
 Greig M, Siegler J, Soccer-Specific Fatigue and Eccentric Hamstrings Muscle Strength, National Athletic
Training Association, Mar-Apr 2009; Volume 44(2)
 Humphrey L, Arbuckle R, Mease P, Williams DA, Samsoe BD, Gilbert C. Fatigue in fibromyalgia: a conceptual
model informed by patient interviews. BMC Musculoskelet Disord. 2010;11(1):216.
 Pelton K, Pesca M, Fatigue and ACL Injuries.
http://www.basketballprospectus.com/article.php?articleid=2297, Assessed on September 17, 2013
 Rimmer P, Muscular Fatigue: Methods for Assessing fatigue and Implications for Anterior Cruciate Ligament
(ACL) Injury. [Powepoint]. Cardiff University.
 Woldstad J.C., Brace Tony, Musculoskeletal Disorders [Powerpoint]. Corvallis, Oregon: Oregon State
Engineering Program; 2007.
 University of Zurich (2011, December 5). How muscle fatigue originates in the head. ScienceDaily. Retrieved
September 17, 2013

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QUESTIONS?