A comparison of static and dynamic measures of lower limb joint angles in cycling: application to bicycle fitting

Abstract

Purpose. Configuration of bicycle components to the cyclist (bicycle fitting) commonly uses static poses of the cyclist on the bicycle at the 6 o'clock crank position to represent dynamic cycling positions. However, the validity of this approach and the potential use of the different crank position (e.g. 3 o'clock) have not been fully explored. Therefore, this study compared lower limb joint angles of cyclists in static poses (3 and 6 o'clock) compared to dynamic cycling. Methods. Using a digital camera, right sagittal plane images were taken of thirty cyclists seated on their own bicycles mounted on a stationary trainer with the crank at 3 o'clock and 6 o'clock positions. Video was then recorded during pedalling at a self-selected gear ratio and pedalling cadence. Sagittal plane hip, knee and ankle angles were digitised. Results. Differences between static and dynamic angles were large at the 6 o'clock crank position with greater mean hip angle (4.9 ± 3°), smaller knee angle (8.2 ± 5°) and smaller ankle angle (8.2 ± 5.3°) for static angles. Differences between static and dynamic angles (< 1.4°) were trivial to small for the 3 o'clock crank position. Conclusions. To perform bicycle fitting, joint angles should be measured dynamically or with the cyclist in a static pose at the 3 o'clock crank position.

Comparison of static and dynamic methods based on knee kinematics to determine optimal saddle height in cycling

“…We found a significant difference of around 8°b etween static and dynamic KA with pedal at BDC for the total population. This result is in the range with those reported in previous studies [6], [8], [11], [22], i.e., between 5 to 10°. Therefore, we can suggest a new range of 33-43° for KA during Dynamic BDC by adding 8° to the optimal range of 25-35° without pedalling [16].…”

“…The alterations of KA between static and dynamic conditions would be related to the larger HA and the smaller AA during pedalling. Thus, the transition from static position to active pedalling would affect joint angles [6], and particularly foot positioning [15]- [22]. Authors reported that these alterations would be required in dynamics to maintain a KA allowing for an effective pedalling [6]- [22].…”

“…Thus, the transition from static position to active pedalling would affect joint angles [6], and particularly foot positioning [15]- [22]. Authors reported that these alterations would be required in dynamics to maintain a KA allowing for an effective pedalling [6]- [22]. The hip and knee joint extensors may be longer and the ankle plantar flexors may be shorter while pedalling, which may affect the muscle tendon unit length and the force production.…”

“…On the other hand, kinematic methods based on knee angle (KA: angle between the thigh and the leg; 0° corresponds to full knee extension) have been developed for assessing the optimal saddle height to prevent injuries and to increase performance. They are considered accurate because they take the differences in thigh, shank and foot length between individuals into account [6]. Among them, the Holmes method recommends to use a saddle height that involves a KA of 25-35° when the pedal is at bottom dead centre (BDC), i.e., the lowest point of the crank cycle, without pedalling (static BDC) for injury prevention [16].…”

“…Optimisation of saddle height based on KA while pedalling (i.e., dynamic condition), which can be evaluated by two-dimensional video analysis [9], [11], [23], is more and more frequently used to respect usual practice conditions [10], [11]. KA measured at BDC in dynamic condition (Dynamic BDC) would be 5° to 10° higher than during static condition due to the lateral pelvic tilt [8], or the increase of ankle angle (angle between the leg and the foot) [6], [15], [22] and the decrease of hip angle (angle between the thigh and the horizontal) [6]. However, no specific angle range has been suggested in this condition of measurement.…”