THE USE OF FORCE PEDALS FOR ANALYSIS OF CYCLING SPRINT PERFORMANCE

Abstract

INTRODUCTION: Force application patterns in cycling have been studied using cadences between 60-100 rpm, but not during sprint cycling. The aim of this study was to investigate the force application patterns during sprint cycling (above 135 rpm), and to compare these with those obtained for constant velocity exercise in other studies. METHODS AND PROCEDURES: Two piezoelectric force transducers (Kistler 8067) were incorporated into two specially-designed pedals, and statically calibrated for vertical loads of 0 to 2000N and antero-posterior and medio-lateral loads of -2000 to 2000N. Crank and pedal angles were measured with continuous turn potentiometers. 9 national and international sprint cyclists (mean age 26.5 ñ 2.7yr, height 1.80 ñ 0.06m, mass 82.0 ñ 6.6kg) performed a 10s sprint on a Monark 864 ergometer against a load of 9% body mass (to simulate a track 200m sprint). Data were sampled at 100Hz. Specially-written software calculated Effective and Ineffective crank forces, and computed the Index of Effectiveness (Sanderson, 1991) RESULTS AND DISCUSSION: Two distinct pedalling styles emerged. Two subjects demonstrated smooth application of pedal forces throughout the whole pedal cycle; whereas, others applied very large forces (up to 1100N) only in a small range of crank angles (90 to 135ø past TDC). ‘Smooth’ pedallers had a greater Index of Effectiveness, suggesting more mechanically efficient cycling. No subjects showed an upward ‘pull’ on the pedals during recovery (BDC to TDC), in contrast to earlier studies examining steady state cycling. CONCLUSIONS: The force pedals realised interesting aspects of force application during sprint cycling. Further study should be carried on actual bicycles and, if possible, in track situations. Previous research on steady-state cycling cannot be generalised to sprinting at high cadences. REFERENCES: Sanderson, D. J. (1991). The Influence of Cadence and Power Output in the Biomechanics of Force Application During Steady-Rate Cycling in Competitive and Recreational Cyclists. Journal of Sports Sciences 9, 191-203.