The repeated bout effect can occur without mechanical and neuromuscular changes after a bout of eccentric exercise

Pincheira, P. A. and Hoffman, B. W. and Cresswell, A. G. and Carroll, T. J. and Brown, N. A. T. and Lichtwark, G. A. (2018) The repeated bout effect can occur without mechanical and neuromuscular changes after a bout of eccentric exercise. Scandinavian Journal of Medicine & Science in Sports, 28. pp. 2123-2134. ISSN 0905-7188

Abstract

Changes in muscle fascicle mechanics have been postulated to underpin the repeated bout effect (RBE) observed following exercise-induced muscle damage (EIMD). However, in the medial gastrocnemius (MG), mixed evidence exists on whether fascicle stretch amplitude influences the level of EIMD, thus questioning whether changes in fascicle mechanics underpin the RBE. An alternative hypothesis is that neural adaptations contribute to the RBE in this muscle. The aim of this study was to investigate the neuromechanical adaptations during and after repeated bouts of a highly controlled muscle lengthening exercise that aimed to maximize EIMD in MG. In all, 20 subjects performed two bouts of 500 active lengthening contractions (70% of maximal activation) of the triceps surae, separated by 7 days. Ultrasound constructed fascicle length-torque (L-T) curves of MG, surface electromyography (EMG), maximum torque production, and muscle soreness were assessed before, 2 hours and 2 days after each exercise bout. The drop in maximum torque (4%) and the increase in muscle soreness (24%) following the repeated bout were significantly less than following the initial bout (8% and 59%, respectively), indicating a RBE. However, neither shift in the L-T curve nor changes in EMG parameters were present. Furthermore, muscle properties during the exercise were not related to the EIMD or RBE. Our results show that there are no global changes in gastrocnemius mechanical behavior or neural activation that could explain the observed RBE in this muscle. We suggest that adaptations in the non-contractile elements of the muscle are likely to explain the RBE in the triceps surae.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Health and Wellbeing
Date Deposited: 24 Jan 2019 06:34
Last Modified: 04 Feb 2019 05:01
Uncontrolled Keywords: eccentric exercise; length-tension relationship; strain-induced muscle damage; ultrasound
Fields of Research : 11 Medical and Health Sciences > 1106 Human Movement and Sports Science > 110602 Exercise Physiology
11 Medical and Health Sciences > 1106 Human Movement and Sports Science > 110603 Motor Control
11 Medical and Health Sciences > 1106 Human Movement and Sports Science > 110601 Biomechanics
Socio-Economic Objective: E Expanding Knowledge > 97 Expanding Knowledge > 970111 Expanding Knowledge in the Medical and Health Sciences
Identification Number or DOI: 10.1111/sms.13222
URI: http://eprints.usq.edu.au/id/eprint/34419

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