title: A mechanomyographic fatigue threshold test for cycling.
abstract: The purposes of this study were twofold: 1) to derive the mechanomyographic mean power frequency fatigue threshold (MMG MPFFT) for submaximal cycle ergometry; and 2) to compare the power outputs associated to the MMG MPFFT to other neuromuscular and gas exchange fatigue thresholds. 9 adults (5 men and 4 women; mean+/-SD age=23.7+/-3.7 years; body weight=66.3+/-8.2 kg) performed an incremental cycle ergometry test to exhaustion while expired gas samples, electromyographic (EMG), and MMG signals were measured from the vastus lateralis muscle. The non-significant correlations (r=0.17 to 0.66; p>0.05) among the physical working capacity at the fatigue threshold (PWCFT), MMG MPFFT, and gas exchange threshold (GET) suggested that different physiological mechanisms may underlie these 3 fatigue thresholds. A significant correlation (r=0.83) for the MPFFT vs. respiratory compensation point (RCP) suggested that these fatigue thresholds may be mediated by a common physiological mechanism. In addition, the significantly lower mean values found for the PWCFT (mean+/-SD=163+/-43 W), MMG MPFFT (132+/-33 W), and GET (144+/-28 W) than MPFFT (196+/-53 W) and RCP (202+/-41 W) suggested that these gas exchange and neuromuscular fatigue thresholds may demarcate different exercise intensity domains.
authors.affiliation: University of Nebraska-Lincoln, Nutrition and Health Sciences, Lincoln, Nebraska 68583-0806, United States. jzuniga2@unlserve.unl.edu
authors.forename: J M
authors.initials: JM
authors.lastname: Zuniga
authors.forename: T J
authors.initials: TJ
authors.lastname: Housh
authors.forename: C L
authors.initials: CL
authors.lastname: Camic
authors.forename: C R
authors.initials: CR
authors.lastname: Hendrix
authors.forename: R J
authors.initials: RJ
authors.lastname: Schmidt
authors.forename: M
authors.initials: M
authors.lastname: Mielke
authors.forename: G O
authors.initials: GO
authors.lastname: Johnson
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D016552:Ergometry; D005080:Exercise Test / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology; D009213:Myography / Q000379:methods; D011659:Pulmonary Gas Exchange / Q000502:physiology; D055815:Young Adult