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Title: Time-course of kinetic and kinematic changes in cyclists' pedalling technique with fatigue
Author: Kelly, Jon
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 2007
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The limited research to date that has examined the biomechanical responses that occur with fatigue has been restricted to examining limited discrete time points. Whilst this indicates that changes occur, it does not elucidate their time course. This research therefore seeks to redress this by using continuous collection of kinetic and multiple time windows of kinematic data in the context of cycling. To this end, a unique design of force instrumented pedals were developed and validated against a criterion measures (SRM Power Measuring Crankset) and two methodologies that attempt to increase the accuracy of kinematic data were investigated. Adaptations with fatigue were investigated utilising these equipment and methodologies using a high and a low -fatigue trial both with identical initial stages ending in a ramp up to 95% of maximal minute power (MMP). In the high fatigue trial, the subjects then maintained this power output till failure whilst in the low fatigue trial, power output was returned to 50% MMP and maintained at this level. Results showed significant (p < 0.05) trial and time interactions indicating fatigue related changes in the mean Instantaneous Index of Effectiveness (IIE), the crank angle at which positive work started and at which maximum foot angle occurred, as well as minimum knee and maximum hip angular velocities. Within trial analysis of the complete 95% MMP section of the high fatigue trial showed significant effects for the magnitude of peak resultant and ineffective forces and for the crank angle at which peak effective and ineffective forces occurred. Significant changes were also shown for mean IIE, mean power, total work and the crank angle at which positive work started. In the kinematic data, significant effects were also shown in foot minimum and maximum angles, angle of peak knee extension, the crank angle at which maximum hip extension occurred and the maximum hip and knee and minimum knee angular velocities. Post -hoc analyses of these data indicated that the changes in some of the kinetic variables appeared to occur in stages (Instantaneous Index of Effectiveness and the crank angles at the start of positive work and at peak effective force) with similar staged responses also being apparent in the performance measure (power output), with some evidence of possible temporal alignment in the changes in the different parameters. However, stages in the changes observed in the kinematic variables could not be established. It is concluded that changes do occur with fatigue in cyclist's pedalling techniques and that the time course of these may not be linear or uniform across biomechanical parameters.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available