Year

1996

Degree Name

Doctor of Philosophy

Department

Department of Biomedical Science

Abstract

The assessment of mechanical energy expenditure (MEE) during human movement is an essential step in the determination of the proficiency of the movement. Dynamics methods of estimating MEE have their derivation in the sources of MEE , the joint forces and moments, and are less arbitrary about the rules governing energy compensation when compared with instantaneous segment energy methods. Further, dynamics methods enable the exercise scientist to attribute energy costs and savings to particular body segments, sources and mechanisms. This thesis describes the application of a dynamics method (Aleshinsky, 1986a-e) to the mechanical energy analysis of maximal ergometer rowing.

A two-dimensional, nine-segment mathematical model of the rower was constructed and implemented in a computer program which allowed the estimation of MEE and associated energy transfers within and between segments. Ten female rowers (national, n= 5; club, n=5) performed a six minute maximal rowing test while the position of the joints, the handle and foot stretcher forces and the activation of eight major muscle groups were measured. Total MEE , moment MEE , and all energy fractions were quantified for each minute of the test. Repeated measures analysis of variance was used to assess differences between the groups and over time.

National level rowers used significantly less moment MEE per joule of external work than the club level rowers. Both groups of rowers demonstrated a significant trend over time of an increasing moment MEE per joule of external work. The origin of these differences was distributed among a number of factors such as the amount of energy dissipation due to the joint moments and degree of useful energy transfers. The muscle activation patterns supported the view that the two joint muscle action is timed to produce further economies in the motion.

The analysis of energy transfers revealed mechanisms by which the two groups of rowers achieved their particular economies and thus had practical usefulness to rowers. However, the magnitudes of the compensation coefficients and the quantities of energy transfers may not be accurate indicators of energy economy when considered in isolation.

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