Neuromuscular control and performance during the triathlon cycle-run transition

Jason Bonacci (2010). Neuromuscular control and performance during the triathlon cycle-run transition PhD Thesis, School of Health & Rehabilitation Sciences, The University of Queensland.

       
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Author Jason Bonacci
Thesis Title Neuromuscular control and performance during the triathlon cycle-run transition
School, Centre or Institute School of Health & Rehabilitation Sciences
Institution The University of Queensland
Publication date 2010-09
Thesis type PhD Thesis
Supervisor Professor Bill Vicenzino
Mr Peter Blanch
Total pages 235
Total colour pages 6
Total black and white pages 229
Subjects 11 Medical and Health Sciences
Abstract/Summary Triathlon is a multidiscipline endurance sport that involves sequential swimming, cycling and running. Success in triathlon is determined by the ability to excel at and link these three separate disciplines. In the standard triathlon format running is completed after cycling and is considered the most important discipline for overall race success. However running after cycling is very demanding and presents an immense challenge to the neuromuscular system’s ability to control movement and muscle recruitment patterns. Triathletes must switch from a predominantly concentric type of muscle activity used during cycling to a combined eccentric-concentric action during running, with time only to dismount the bike and change shoes. The ability of the neuromuscular system to function optimally during these conditions has not been fully investigated. The objective of this thesis was to investigate the influence of training on the neuromuscular system’s ability to function optimally during the triathlon cycle-run transition. A review of literature found that adaptations in skeletal muscle recruitment do occur with ongoing single discipline training but multidiscipline training may interfere with motor learning and impair adaptation of the neuromuscular system in highly trained triathletes. Cycling also has a direct negative effect on some highly trained triathletes’ ability to execute muscle recruitment strategies specific to running. Links between optimal muscle recruitment and running economy have been established during isolated running, however the implications of altered muscle recruitment or kinematics on run performance after cycling are largely unknown. Improvements in running economy after strength and plyometric training have been hypothesised to be due to enhanced neuromuscular function which suggests training can influence neuromuscular control and run performance. Neuromuscular control during the cycle-run transition was investigated by measuring muscle recruitment and kinematics during control (no preceding cycle) and transition (preceded by cycling) runs in moderately trained and elite international triathletes. Run performance was investigated by measuring submaximal oxygen consumption; herein referred to as running economy. Five of 15 (33%) moderately trained triathletes had difficulty reproducing their pre-cycling running kinematics immediately after a short period of submaximal cycling, but cycling had little influence on their running muscle recruitment. Alterations in kinematics and muscle recruitment were evident in seven of 15 (46%) moderately trained triathletes after a 45 minute high intensity cycle, with changes in ankle kinematics explaining 67% of the variance in running economy. Elite international triathletes show no change in neuromuscular control or running economy after a 20 minute low intensity and a 50 minute high intensity cycle. An eight week randomised controlled trial investigated the efficacy of plyometric training as an intervention to correct altered muscle recruitment in those triathletes in which it is aberrant during running after cycling. Plyometric training combined with endurance training was more effective than endurance training alone in correcting muscle recruitment waveform shape (p = 0.03, standardized mean difference = 2.1) and amplitude (p = 0.01, standardized mean difference = 2.9) offsets in those triathletes in which it was previously aberrant during running after cycling. Aberrant muscle recruitment was corrected at eight weeks in three of three (100%) triathletes in the plyometric group, compared to two of five (40%) triathletes in the control group (relative risk = 2.5). The correction in muscle recruitment was not associated with an improvement or impairment in running economy. Together these studies improve our understanding of the influence of training on neuromuscular control and performance during the cycle-run transition. The findings suggest that triathletes respond differently to cycling depending on their experience and training in the sport. Elite international triathletes’ ability to preserve neuromuscular control and run performance after cycling may be a reason for their success. At the moderately trained level, changes in ankle kinematics after cycling are related to alterations in running economy, and the implementation of plyometric training into a triathlete’s training program may be beneficial for enhancing motor control and injury prevention and/or management.
Keyword Electromyography
Kinematics
Triathlon
Running economy
biomechanics
transition
Run performance
Additional Notes Colour page numbers are page 50, 58, 63, 64, 65, 207 Landscape page numbers are 37, 71, 105, 130, 131 (total of 5)

 
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Created: Wed, 09 Feb 2011, 15:43:35 EST by Mr Jason Bonacci on behalf of Library - Information Access Service