Muscle fascicle strains in human gastrocnemius during backward downhill walking

Hoffman, Ben W., Cresswell, Andrew G., Carroll, Timothy John and Lichtwark, Glen A. (2014) Muscle fascicle strains in human gastrocnemius during backward downhill walking. Journal of Applied Physiology, 116 11: 1455-1462. doi:10.1152/japplphysiol.01431.2012

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Author Hoffman, Ben W.
Cresswell, Andrew G.
Carroll, Timothy John
Lichtwark, Glen A.
Title Muscle fascicle strains in human gastrocnemius during backward downhill walking
Journal name Journal of Applied Physiology   Check publisher's open access policy
ISSN 8750-7587
1522-1601
Publication date 2014-06-01
Year available 2013
Sub-type Article (original research)
DOI 10.1152/japplphysiol.01431.2012
Open Access Status
Volume 116
Issue 11
Start page 1455
End page 1462
Total pages 8
Place of publication Bethesda, MD, United States
Publisher American Physiological Society
Collection year 2014
Language eng
Formatted abstract
Extensive muscle damage can be induced in isolated muscle preparations by performing a small number of stretches during muscle activation. While typically these fibre strains are large and occur over long lengths, the extent of exercise-induced muscle damage (EIMD) observed in humans is normally less even when multiple high-force lengthening actions are performed. This apparent discrepancy may be due to differences in muscle fibre and tendon dynamics in vivo; however muscle and tendon strains have not been quantified during muscle damaging exercise in humans. Ultrasound and an infrared motion analysis system were used to measure medial gastrocnemius (MG) fascicle length and lower limb kinematics while humans walked backwards downhill for 1-hr (inducing muscle damage), and while they walked briefly forward on the flat (inducing no damage). Supramaximal tibial nerve stimulation, ultrasound, and an isokinetic dynamometer were used to quantify the fascicle length-torque (L-T) relationship pre- and 2-hr post-exercise. Torque decreased ~23% and optimal fascicle length (Lo) shifted rightward ~10%, indicating that EIMD occurred during the damage protocol even though MG fascicle stretch amplitude was relatively small (~18% of Lo) and occurred predominately within the ascending limb and plateau region of the L-T curve. Furthermore, tendon contribution to overall muscle-tendon unit stretch was ~91%. The data suggest the compliant tendon plays a role in attenuating muscle fascicle strain during backwards walking in humans, thus minimising the extent of EIMD. As such, in situ or in vitro mechanisms of muscle damage may not be applicable to EIMD of the human gastrocnemius muscle.
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ
Additional Notes Published ahead of print April 4, 2013

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2014 Collection
School of Human Movement and Nutrition Sciences Publications
 
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Created: Sun, 17 Nov 2013, 11:35:11 EST by Deborah Noon on behalf of School of Human Movement and Nutrition Sciences