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EMG Activation in the Forelimb Musculature of Three-toed Sloths (Bradypus variegatus)

Gorvet, Marissa A.
http://rave.ohiolink.edu/etdc/view?acc_num=ysu1547111569993329

Abstract Details

2018, Master of Science in Biological Sciences, Youngstown State University, Department of Biological Sciences and Chemistry.
Suspensory behaviors require both strength and fatigue resistance of the limb flexors; however, the muscle mass of sloths is reduced compared to other arboreal mammals. Although suspensory locomotion demands that muscles are active to counteract the pull of gravity, it is possible that sloths minimize muscle activation and/or selectively recruit slow motor units, thus indicating neuromuscular specializations to conserve energy. Electromyography (EMG) was evaluated in a sample of three-toed sloths (B. variegatus: N=6) to test this hypothesis. EMG was recorded at 2000 Hz via fire-wire electrodes implanted into eight muscles of the left forelimb while sloths performed trails of suspensory hanging (SH), suspensory walking (SW), and vertical climbing (VC). All muscles were minimally active when performing SH. During SW and VC, sloths moved slowly (Duty Factor: 0.83–0.86) and activation patterns were consistent between behaviors; the flexors were activated early and for a large percentage of limb contact, while the extensors were activated later in the stride and showed biphasic (contact and swing) activity. EMG burst intensities were maximal for the elbow flexors and smallest for the carpal/digital flexors, and overall activation intensity was significantly greater for SW and VC compared with SH. Wavelet analysis indicated high frequency motor unit (MU) recruitment at low intensities for SH, whereas the opposite patterns of MU recruitment were similarly demonstrated for SW and VC, with the shoulder flexors and elbow flexor m. brachioradialis having the extremely low activation frequencies. Collectively, these findings support the hypothesis and suggest that sloths may selectively recruit smaller, fast-contracting MU for suspensory postures but have the ability to offset the cost of force production by recruitment of large, slow MU during locomotion.
Michael Butcher, PhD (Advisor)
Mark Womble, PhD (Committee Member)
Kenneth Learman, PhD (Committee Member)
98 p.
Animals; Biology; Morphology; Physiology
Sloth; Electromyography; Neuromuscular recruitment; Wavelet analysis

Recommended Citations

Citations

  • Gorvet, M. A. (2018). EMG Activation in the Forelimb Musculature of Three-toed Sloths (Bradypus variegatus) [Master's thesis, Youngstown State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1547111569993329

    APA Style (7th edition)

  • Gorvet, Marissa. EMG Activation in the Forelimb Musculature of Three-toed Sloths (Bradypus variegatus). 2018. Youngstown State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ysu1547111569993329.

    MLA Style (8th edition)

  • Gorvet, Marissa. "EMG Activation in the Forelimb Musculature of Three-toed Sloths (Bradypus variegatus)." Master's thesis, Youngstown State University, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ysu1547111569993329

    Chicago Manual of Style (17th edition)

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This open access ETD is published by Youngstown State University and OhioLINK.