title: Fatigue and soft tissue vibration during prolonged running.
abstract: Muscle tuning paradigm proposes that the mechanical properties of soft tissues are tuned in such a way that its vibration amplitude become minimized. Therefore, the vibrations of soft tissue are heavily damped. However, it has been hypothesized that the ability of muscle tuning decreases with fatigue. This study investigated the changes in vibration characteristics of soft tissue with fatigue. Vibrations of the gastrocnemius muscle of 8 runners during a prolonged run protocol on a treadmill at constant velocity (4 ms(-1)) were measured using a tri-axial accelerometer. The vibration amplitude is calculated using the Fourier transform and a wavelet-based method was used to calculate the damping coefficient. The results showed that: (1) the vibration amplitude in longitudinal direction increased with fatigue, which may be interpreted as the decreased muscle function with fatigue. (2) The amplitude increase percent strongly depended on the vibration frequency. (3) The damping coefficient of the gastrocnemius increased with fatigue. A 1-DOF mass-spring-damper model was used in order to validate the wavelet based method and simulate the observed phenomena.
authors.affiliation: Department of Mechanical Engineering, University of Tabriz, Tabriz, Iran.
authors.forename: Arash
authors.initials: A
authors.lastname: Khassetarash
authors.affiliation: Department of Mechanical Engineering, University of Tabriz, Tabriz, Iran. Electronic address: hassannejhad@tabrizu.ac.ir.
authors.forename: Reza
authors.initials: R
authors.lastname: Hassannejad
authors.affiliation: Department of Mechanical Engineering, University of Tabriz, Tabriz, Iran.
authors.forename: Mir Mohammad
authors.initials: MM
authors.lastname: Ettefagh
authors.affiliation: Department of Exercise Physiology, Faculty of Physical Education and Sport Sciences, University of Tabriz, Tabriz, Iran.
authors.forename: Vahid
authors.initials: V
authors.lastname: Sari-Sarraf
mesh_terms: D061725:Accelerometry; D000328:Adult; D003238:Connective Tissue / Q000502:physiology*; D005080:Exercise Test; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D012420:Running / Q000502:physiology*
keywords: Damping; Fatigue; Gastrocnemius; Running; Wavelet