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Schmitz DG, Thelen DG, Cone SG. A Single-Sensor Approach for Noninvasively Tracking Phase Velocity in Tendons during Dynamic Movement. MICROMACHINES 2023; 15:32. [PMID: 38258151 PMCID: PMC10821348 DOI: 10.3390/mi15010032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 12/16/2023] [Accepted: 12/21/2023] [Indexed: 01/24/2024]
Abstract
Shear wave tensiometry is a noninvasive method for directly measuring wave speed as a proxy for force in tendons during dynamic activities. Traditionally, tensiometry has used broadband excitation pulses and measured the wave travel time between two sensors. In this work, we demonstrate a new method for tracking phase velocity using shaped excitations and measurements from a single sensor. We observed modulation of phase velocity in the Achilles tendon that was generally consistent with wave speed measures obtained via broadband excitation. We also noted a frequency dependence of phase velocity, which is expected for dispersive soft tissues. The implementation of this method could enhance the use of noninvasive wave speed measures to characterize tendon forces. Further, the approach allows for the design of smaller shear wave tensiometers usable for a broader range of tendons and applications.
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Affiliation(s)
- Dylan G. Schmitz
- Department of Mechanical Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Darryl G. Thelen
- Department of Mechanical Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA
- Department of Biomedical Engineering, University of Wisconsin–Madison, Madison, WI 53706, USA
| | - Stephanie G. Cone
- Department of Biomedical Engineering, University of Delaware, Newark, DE 19713, USA;
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Horslen BC, Milburn GN, Blum KP, Simha SN, Campbell KS, Ting LH. History-dependent muscle resistance to stretch remains high after small, posturally relevant pre-movements. J Exp Biol 2023; 226:jeb245456. [PMID: 37661732 PMCID: PMC10560558 DOI: 10.1242/jeb.245456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 08/17/2023] [Indexed: 09/05/2023]
Abstract
The contributions of intrinsic muscle fiber resistance during mechanical perturbations to standing and other postural behaviors are unclear. Muscle short-range stiffness is known to vary depending on the current level and history of the muscle's activation, as well as the muscle's recent movement history; this property has been referred to as history dependence or muscle thixotropy. However, we currently lack sufficient data about the degree to which muscle stiffness is modulated across posturally relevant characteristics of muscle stretch and activation. We characterized the history dependence of muscle's resistance to stretch in single, permeabilized, activated, muscle fibers in posturally relevant stretch conditions and activation levels. We used a classic paired muscle stretch paradigm, varying the amplitude of a 'conditioning' triangular stretch-shorten cycle followed by a 'test' ramp-and-hold imposed after a variable inter-stretch interval. We tested low (<15%), intermediate (15-50%) and high (>50%) muscle fiber activation levels, evaluating short-range stiffness and total impulse in the test stretch. Muscle fiber resistance to stretch remained high at conditioning amplitudes of <1% optimal fiber length, L0, and inter-stretch intervals of >1 s, characteristic of healthy standing postural sway. An ∼70% attenuation of muscle resistance to stretch was reached at conditioning amplitudes of >3% L0 and inter-stretch intervals of <0.1 s, characteristic of larger, faster postural sway in balance-impaired individuals. The thixotropic changes cannot be predicted solely on muscle force at the time of stretch. Consistent with the disruption of muscle cross-bridges, muscle resistance to stretch during behavior can be substantially attenuated if the prior motion is large enough and/or frequent enough.
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Affiliation(s)
- Brian C. Horslen
- Department of Kinesiology and Health Sciences, University of Waterloo, Waterloo, ON, Canada, N2L 3G1
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and The Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Gregory N. Milburn
- Department of Physiology, University of Kentucky, Lexington, KY 40536, USA
| | - Kyle P. Blum
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and The Georgia Institute of Technology, Atlanta, GA 30332, USA
- Department of Physiology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Surabhi N. Simha
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and The Georgia Institute of Technology, Atlanta, GA 30332, USA
| | | | - Lena H. Ting
- Wallace H. Coulter Department of Biomedical Engineering, Emory University and The Georgia Institute of Technology, Atlanta, GA 30332, USA
- Department of Rehabilitation Medicine, Division of Physical Therapy, Emory University, Atlanta, GA 30322, USA
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