Saddle height effects on pedal forces, joint mechanical work and kinematics of cyclists and triathletes

Abstract

The effects of saddle height on pedal forces and joint kinetics (e.g. mechanical work) are unclear. Therefore, we assessed the effects of saddle height on pedal forces, joint mechanical work and kinematics in 12 cyclists and 12 triathletes. Four sub-maximal 2-min cycling trials (3.4 W/kg and 90 rpm) were conducted using preferred, low and high saddle heights (±10° knee flexion at 6 o'clock crank position from the individual preferred height) and an advocated optimal saddle height (25° knee flexion at 6 o'clock crank position). Right pedal forces and lower limb kinematics were compared using effect sizes (ES). Increases in saddle height (5% of preferred height, ES=4.6) resulted in large increases in index of effectiveness (7%, ES=1.2) at the optimal compared to the preferred saddle height for cyclists. Greater knee (11-15%, ES=1.6) and smaller hip (6-8%, ES=1.7) angles were observed at the low (cyclists and triathletes) and preferred (triathletes only) saddle heights compared to high and optimal saddle heights. Smaller hip angle (5%, ES=1.0) and greater hip range of motion (9%, ES=1.0) were observed at the preferred saddle height for triathletes compared to cyclists. Changes in saddle height up to 5% of preferred saddle height for cyclists and 7% for triathletes affected hip and knee angles but not joint mechanical work. Cyclists and triathletes would opt for saddle heights <5 and <7%, respectively, within a range of their existing saddle height.

The Influence of Extrinsic Factors on Knee Biomechanics During Cycling: A Systematic Review of the Literature

“…In contrast, cyclists with anterior cruciate ligament injury or reconstruction may benefit from a lower saddle height and lower cadences. 30,34,37 However, force effectiveness, a measure of force output in relation to angle of force application, may be decreased with these settings, 29 and thus the effects of combining these conditions is unknown. The effect of crank length due to loading is more difficult to interpret as a shorter crank length at a higher cadence increases power output, 25 yet increased crank lengths may shift more of the power production from the knee extensors to the hip extensors.…”

“…34 In competitive cyclists, they found increased force effectiveness for road cyclists at optimal saddle height, and increased mean knee flexion angles at low and preferred compared to high and optimal saddle heights for road cyclists and triathletes. 29 Interestingly, Farrell et al 31 reported that while saddle height was set in the optimal position statically, knee flexion seen while cycling was greater due to lateral movement of the pelvis in recreational cyclists, which may decrease risk of ITB impingement. 31 Finally, Tamborindeguy and Bini 33 set saddle height based on cyclists' anthropometrics and found no differences in peak tibiofemoral compressive/anterior shear components across three slightly different saddle heights based on percentages of floor-greater trochanter heights of 97%, 100%, and 103%.…”

“…27 In contrast, Ferrer-Roca et al 32 reported increased crank length led to increased torque around joints; however the range of crank lengths used was much smaller (10 mm) 32 and tibiofemoral compressive forces. 28 Three studies examined various saddle heights, 29,33,34 one of which being a height considered optimal, which was defined as the position that achieved 25-30° of knee flexion at bottom dead center. 29 Bini et al 34 examined four different saddle heights and found increased tibiofemoral anterior shear forces at high and optimal compared to low saddle height 34 and large differences in knee angle across conditions in recreational cyclists.…”

“…28 Three studies examined various saddle heights, 29,33,34 one of which being a height considered optimal, which was defined as the position that achieved 25-30° of knee flexion at bottom dead center. 29 Bini et al 34 examined four different saddle heights and found increased tibiofemoral anterior shear forces at high and optimal compared to low saddle height 34 and large differences in knee angle across conditions in recreational cyclists. There were no differences for patellofemoral or tibiofemoral compressive forces across seat heights and no differences seen between cyclists with and without knee pain.…”

Electromyographic analysis of riding posture during the bicycling start moment

“…Many factors are known to affect cycling performance: (i) the geometry of the bike, such as crank length 1 and saddle position 2,3 ; (ii) various aerodynamic variables such as proper aero position and (iii) pedaling frequency, which determines maximal power output during cycling 3,4 . Alterations in posture, such as changing from a seated to a standing posture, also result in changes in performance 5,6 .…”