The time to complete the running leg of an Olympic distance triathlon is the strongest predictor of overall triathlon performance (r = 0.81-0.98 p < .01). Running economy (RE), which is thought to be heavily influenced by preceding cycling exercise, is an important determinant of running performance. Both the movement pattern interference and metabolic fatigue induced by cycling exercise may lead to changes in RE and possibly running mechanics. In fact, significant changes in running velocity, stride rate, knee and ankle angle at foot strike and trunk position, particularly within the first 5 min of running following cycle exercise, have been observed. However, within several studies, cycling has been shown to have little or no effect on RE and running mechanics. These findings are difficult to reconcile and are indicative of our lack of understanding of the effects of cycling exercise on RE and running mechanics. Detailed kinetic analyses of running following cycling, and specifically of the force transfer during the landing and take-off phases and their relationship with running kinematics and RE, have not been completed to our knowledge.
Therefore within the present study, RE and running mechanics will be measured before and after a simulated Olympic distance cycle bout. RE will be measured using a metabolic cart to measure expired gases whilst running on a treadmill. In a separate session, 3-dimentional motion analysis and force platforms will be used to measure running kinematics and kinetics, when running overground. This study will investigate force transfer and the landing-take-off symmetry (momentum lost during landing vs. momentum gained during push-off) and calculate mechanical work performed during the running stride.
The specific purposes of the proposed research are to: i) quantify RE, kinematic and kinetic patterns in running before and after a bout of cycling exercise, replicating that which might be done during a high-level Olympic distance triathlon; and ii) examine the relationships between the pre- and post-cycling changes in RE, kinematic and kinetic parameters. Additionally, this testing will allow us to describe the differences in kinematic and kinetic patterns between triathletes who do or do not show substantial changes in RE.
This research will enhance the understanding of physiological and biomechanical factors important in the cycle to run transition and thus will assist triathletes (and coaches) in their preparation for competition.
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