Pedalling technique changes with force feedback training in competitive cyclists: Preliminary study 1
Rodrigo Bini, 2 Patria Hume and 3 James Croft Laboratório de Pesquisa do Exercício, UFRGS, Brazil 2 Sports Performance Research Institute New Zealand, AUT University, New Zealand 3 School of Physical Education, Otago University, New Zealand email:
[email protected] web: www.gepecbrasil.com 1
SUMMARY We compared training with different types of pedal force feedback on performance in cycling. Six cyclists performed eight technique-training sessions on a cycle ergometer with visual feedback of pedal forces from right then left pedals. Three cyclists in the “force effectiveness” group (FEG) received feedback during training of pedal force effectiveness and three cyclists in the “peak force” group (PFG) received feedback only for peak normal force. Normal, anterior-posterior forces and pedal-to-crank angles were measured using instrumented pedals. There were large increases in right normal force for FEG (4%) and PFG (5%). Effectiveness of right pedal force was largely increased for right FEG (7%) and right PFG (9%). Conversely effectiveness of left pedal force was largely reduced for FEG (10%) and PFG (9%). Preliminary results indicate that force effectiveness training can be translated into increased right pedal force effectiveness but not in better performance time during cycling time trials. INTRODUCTION Pedal force effectiveness has been computed as the percentage of the total force applied to the pedal that results in propulsive torque [1]. Efficiency has been related to performance in endurance cycling [2] and theoretically reducing resistive force on the pedal may lead to higher efficiency. However, improving pedal force effectiveness has resulted in higher [3, 4] and lower efficiency in cycling [5, 6]. Studies that reported lower efficiency when cyclists aimed to improve force effectiveness during pedalling suggested that greater activation of hamstrings [5] may result in additional energy expenditure compared to a “natural” pedalling action. Therefore, it is uncertain if cyclists should focus on improving pedal force effectiveness to reduce resistive force or if they should focus on producing high pushing force on the pedal when the crank is close to the 3 o’clock position due to the greatest moment arm. The latter would require greater force production from quadriceps muscle groups, which may be more efficient in trained cyclists [7]. Studies using pedal force feedback to improve pedal force effectiveness have been conducted using low exercise intensity (up to 80% of maximal oxygen uptake) and pedaling cadence (
