HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free Supplemental Video All Versions of this Article: 100/4/1311    most recent 01229.2005v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (3) Citing Articles via Google Scholar Google Scholar Articles by Loram, I. D. Articles by Lakie, M. Search for Related Content PubMed PubMed Citation Articles by Loram, I. D. Articles by Lakie, M.

INNOVATIVE METHODOLOGY

Use of ultrasound to make noninvasive in vivo measurement of continuous changes in human muscle contractile length

¹Applied Physiology Research Group, School of Sport and Exercise Sciences, University of Birmingham; and ²Institute for Biophysical and Clinical Research into Human Movement, Manchester Metropolitan University, Alsager, United Kingdom

Submitted 27 September 2005 ; accepted in final form 1 December 2005

Continuous measurement of contractile length has been traditionally achieved using animal preparations in which the muscle and tendon are exposed. More modern methods, e.g., sonomicroscopy, are still invasive. There is a widely perceived need for a noninvasive, in vivo method of measuring continuous changes of human muscle contractile length. Ultrasonography has been used for several years to measure relatively static, discrete changes in tendon, aponeurosis, and muscle fascicle length. We have recently developed this technique to continuously track changes in muscle contractile length during quiet standing. Here, we present the tracking algorithm and use externally applied perturbations to establish the spatial and temporal resolution of the technique. Subjects maintained a low level of ankle torque while a pneumatic actuator applied rapid, square-pulse ankle rotations of defined magnitude and 0.2-s duration. Tracked changes in gastrocnemius and soleus contractile length follow the temporal profile of the perturbations and scale progressively (5–400 µm) with the size of the ankle rotation (0.03–0.7°). In a second experiment, we tracked a wire oscillating in water with known peak to peak amplitudes of 1.5 µm to 8 mm. The ultrasound tracking procedure had near 100% accuracy at all amplitudes for frequencies up to 3 Hz and showed attenuation at higher frequencies consistent with an effective sampling frequency of 12 Hz and sampling time of 80 ms. This noninvasive technique is sensitive, without averaging, to changes as small as 1 µm and is suitable for observing neuromotor activity in posture and locomotion.

ultrasonography; muscle; contractile element

This article has been cited by other articles:

				F. Gao and L.-Q. Zhang Altered contractile properties of the gastrocnemius muscle poststroke J Appl Physiol, December 1, 2008; 105(6): 1802 - 1808. [Abstract] [Full Text] [PDF]

				K. Masani, A. H. Vette, N. Kawashima, and M. R. Popovic Neuromusculoskeletal Torque-Generation Process Has a Large Destabilizing Effect on the Control Mechanism of Quiet Standing J Neurophysiol, September 1, 2008; 100(3): 1465 - 1475. [Abstract] [Full Text] [PDF]

				I. D. Loram, C. N. Maganaris, and M. Lakie The passive, human calf muscles in relation to standing: the short range stiffness lies in the contractile component J. Physiol., October 15, 2007; 584(2): 677 - 692. [Abstract] [Full Text] [PDF]