ARTICULAR EFFORTS QUANTIFICATION AT THE L4/L5 LEVEL FOR THE ROWER

Abstract

INTRODUCTION Most rowers have complained at some time of lumbar pain (lumbago, back pain). The purpose of this paper was to present the first results of the computation of the articular efforts at the L4L5 level, from experiments carried out on a male rower competing at French regional level and for 6 stroke rates. METHODS The first stage consisted of developing an experimental device. The device was made up of a Model C Concept 11 fully instrumented ergometer (Pudlo 1996) and opto-electronic system (SAGA-3, Biogesta). The device allows the measurement of the 3D coordinates of the anatomic points, the measurement of the external efforts, as well as their application point. The second stage was the 3-dimensional modeling of the body : anthropometric characteristics such as mass and position of the centre of gravity (Dempster 1955) and inertial characteristics (Hanavan 1964). RESULTS The modulus of articular efforts (force (F) and torque (T)) presented, are the average of x rowing cycle (x changing 2 to 8 according to stroke rate), the X axis shows 100% of the cycle. The curves morphology for the force and the torque being identical for the 6 studied stroke rates, only the curves of the force and the torque for 32.67 stroke rate at L4L5 level are presented (figure 1 and 2). Figure 1 : Force at LAL5 level (32.67) Figure 2 : Torque at IAIL5 level (32,67) CONCLUSION The results show, for this rower, that : (1) the articular force was maximal at L4IL5 level during the push of the lower limbs, it increases at the end of propulsion, presents a flat shape for recovery for the 6 stroke rates (less than the body mass above LALS), and still increases for the back bending (figure 1). (2) 3 peaks for the torque : the first corresponds to the back resistknce for the push of the lower limbs, the second is the action of the 1 back and the upper limbs, the third is the back recovery (figure 2). I REFERENCES Dempster W.T. (1955). Space requirement of the seated operator, Wright Patterson Air Force Base, WASC-TR, pp 55-159. Hanavan I.A. (1964), A mathematical model of the human body, A.M.R.L.-TR, pp 64-102, Aero Medical Research Laboratories, Wright Patterson, A.F. Base OHIO. Pudlo P., Barbier F., AnguC J.C., (1996). Instrumentation of the Concept II ergometer for optimization of the gesture, The Engineering of Sport, Editor : Steve Haake, ISBN: 90-5410-822-3, pp 137-140.