Measuring Behavior 2005: Hofmijster

Identification of determinants of performance in sports: A case study in rowing

M. Hofmijster

IFKB, Vrije Universiteit, Amsterdam, The Netherlands

Feedback on biomechanical and physiological parameters is of paramount importance to athletes. Apart from helping athletes to improve performance, feedback also enhances motivation, irrespective of the skill level. Traditionally, feedback is provided by a trainer or coach, relying on visual observation. In recent years, electronics and sensor technology have developed to the extent that it is now feasible to develop portable measurement and feedback devices that can provide athlete (and coach) with objective information on biophysical parameters (motion, forces, heart rate).

However, electronic feedback is useless when it does not contain meaningful information for the athlete in question. In this perspective experienced coaches provide a valuable source of information. To capture their implicit knowledge in explicit biophysical terms is not straightforward. A well defined theoretical framework is necessary. Rowing was chosen as a case study since performance is easy to quantify (namely average velocity over the race distance) and technique plays an important role. The approach described may also be applicable in other types of (endurance) sports however.

The analysis of rowing is based on the mechanical power equation. Averaged over a rowing cycle, the rower delivers a certain amount of mechanical power. Part of this power is lost at the oar blades during the push-off, because water is set in motion. The remainder of the power is dissipated by the drag force on the hull. Conceptually, the power loss due to hull drag can be separated into an effective part that is related to average boat velocity, and an ineffective part that is related to substantial intracycle fluctuations in boat velocity. From the perspective of the power equation, the rower with the better technique has less power loss at the blades and/or less power loss due to intracycle boat velocity fluctuations, resulting in a higher average velocity.

Feedback on these power losses or feedback on forces or motions that lead to these losses may help the rower in achieving better performance. Ongoing cooperation between industry, science and sports is necessary to ensure new technologies will be used in the most advantageous way.

Paper presented at Measuring Behavior 2005 , 5^th International Conference on Methods and Techniques in Behavioral Research, 30 August - 2 September 2005, Wageningen, The Netherlands.