Date of Award

2014

Document Type

Thesis

Publisher

Edith Cowan University

Degree Name

Doctor of Philosophy

School

School of Exercise and Health Sciences

Faculty

Faculty of Health, Engineering and Science

First Supervisor

Dr Jeremy Sheppard

Second Supervisor

Professor Robert Newton

Abstract

Sprinting speed is a highly valued physical ability in rugby. There is little research examining sprinting biomechanics in rugby players and it is unclear the extent that sprinting speed and sprint momentum can even be improved in highly trained rugby players and how different speed and strength training methods might help improve it. This thesis consists of 6 studies that examine the sprinting biomechanics of elite rugby players, how strength and power training might improve sprinting speed and the potential for elite rugby players to make further improvement in their sprinting speed and sprint momentum.

Key biomechanical factors were that as a player transitions from a standing start to maximal velocity; they do so without an appreciable change in stride rate but with a substantial increase in stride length. Stride rate remains the same because ground contact time and flight time are inversely proportional with each other as they accelerate from a standing start to maximal velocity. Faster players were found to have lower ground contact times and longer stride lengths for both acceleration and maximal velocity. Sprinting with a rugby ball in one hand did not seem to negatively affect international players in either acceleration phases or maximal velocity phases.

Mass was found to have a negative relationship with acceleration and maximal sprinting velocity. Sprint momentum, on the other hand, was found to have a strong positive relationship with body mass. Body mass and height were found to be higher in successful teams at the 2007 and 2011 Rugby World Cups when compared with less successful teams. Senior international players were found to have much greater sprint momentum and body mass, but not sprinting speed, when compared to junior players. Collectively, all of these results point out that sprint momentum is a highly important physical quality. Sprinting speed is an important outcome of training programs but improving sprint momentum by increasing body mass is probably more important. The senior and junior athletes that were tracked for two years were able to effectively improve their sprinting speed and sprint momentum over a two year period which suggests that these are trainable qualities.

Strength and power were found to be important discriminators between fast and slow players. Faster players showed greater results in power clean, front squat, broad jump and triple broad jump. The relationships between these exercises and acceleration were similar for both the slow and fast groups but these exercises had much stronger correlations with maximal sprinting velocity in the slow group then with the fast group. The differences in these relationships seemed to be explained by ground contact time. The group of highly trained players that were tracked over a one year period did not show positive improvement in sprinting speed from increasing the different strength qualities. An 8 day hypergravity condition for international players was ineffective in producing profound changes in sprinting speed. These results suggest that sprinting speed is a trainable quality but there is a limited capacity for strength training to improve it once these qualities have been reasonably well developed in an elite population.

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