When cyclists ride off the saddle, their center of mass (CoM) appears to go through a rhythmic vertical oscillation during each crank cycle. Just like in walking and running, the pattern of CoM movement may have a significant effect on the mechanical power that needs to be generated and dissipated by muscle. Purpose To date, neither the CoM movement strategies during nonseated cycling nor the limb mechanics that allow this phenomenon to occur have been quantified. Methods Here we estimate how much power can be contributed by a rider’s CoM at each instant during the crank cycle by combining a kinematic and kinetic approach to measure CoM movement and joint powers of 15 participants riding in a nonseated posture at three individualized power outputs (10%, 30%, and 50% of peak maximal power) and two different cadences (70 and 120 rpm). Results The peak-to-peak amplitude of vertical CoM displacement increased significantly with power output and with decreasing cadence. Accordingly, the greatest peak-to-peak amplitude of CoM displacement (0.06 ± 0.01 m) and change in total mechanical energy (0.54 ± 0.12 J·kg−1) occurred under the combination of high-power output and low cadence. At the same combination of high-power output and low cadence, we found that the peak rate of CoM energy loss (3.87 ± 0.93 W·kg−1) was equal to 18% of the peak crank power. Conclusion Consequently, it appears that for a given power output, changes in CoM energy contribute to peak instantaneous power output at the crank, thus reducing the required muscular contribution. These findings suggest that the rise and fall of a rider’s CoM acts as a mechanical amplifier during nonseated cycling, which has important implications for both rider and bicycle performance.

Mixed-effects models will improve data representation, promote superior experimental designs, and increase the validity and reproducibility of research findings.

Cyclists frequently use a nonseated posture when accelerating, climbing steep hills, and sprinting; yet, the biomechanical difference between seated and nonseated cycling remains unclear. Purpose This study aimed to test the effects of posture (seated and nonseated) and cadence (70 and 120 rpm) on joint power contributions, effective mechanical advantage, and muscle activations within the leg during very-high-power output cycling. Methods Fifteen male participants rode on an instrumented ergometer at 50% of their individualized instantaneous maximal power (10.74 ± 1.99 W·kg−1; above the reported threshold for seated to nonseated transition) in different postures (seated and nonseated) and at different cadences (70 and 120 rpm) while leg muscle activity, full-body motion capture, and crank radial and tangential forces were recorded. A scaled, full-body model was used to solve inverse kinematics and inverse dynamics to determine joint displacements and net joint moments. Statistical comparisons were made using a two-way repeated-measures ANOVA (posture–cadence). Results There were significant main effects of posture and cadence on joint power contributions. A key finding was that the nonseated posture increased negative power at the knee, with an associated significant decrease of net power at the knee. The contribution of knee power decreased by 15% at both 70 and 120 rpm (~0.8 W·kg−1) when nonseated compared with seated. Subsequently, hip power and ankle power contributions were significantly higher when nonseated compared with seated at both cadences. In both postures, knee power was 9% lower at 120 rpm compared with 70 rpm (~0.4 W·kg−1). Conclusion These results evidenced that the contribution of knee joint power to leg power was reduced by switching from a seated to nonseated posture during very-high-power output cycling; however, the size of the reduction is cadence dependent.

When riding off the saddle during climbing and sprinting, cyclists appear to coordinate the rhythmic, vertical oscillations of their centre of mass (CoM) with the side-to-side lean of the bicycle. Is the coordination of these two motions merely a stability requirement, or could it also be a strategy to more effectively generate crank power? Here we combined a kinematic and kinetic approach to understand how different constraints on bicycle lean influence CoM movement and limb mechanics during non-seated cycling. Ten participants cycled in a non-seated posture at a power output of 5 W·kg-1 and a cadence of 70 rpm under three bicycle lean conditions: unconstrained on rollers (Unconstrained), under instruction to self-restrict bicycle lean on rollers (Self-Restricted) and constrained in a bicycle trainer (Trainer). Bicycle lean angle in the Unconstrained condition was greater than Self-Restricted and in the Trainer. Vertical CoM displacement, peak vertical crank force, and peak instantaneous crank power in the Unconstrained condition were greater than Self-Restricted but similar to in the Trainer. The amount and rate of energy lost and gained by the rider’s CoM in the Unconstrained condition was greater than Self-restricted but similar to in the Trainer. The differences in joint power contributions to total joint power (hip, knee, ankle, and upper body) between conditions were inconclusive. We interpret these results as evidence bicycle lean plays an important role in facilitating the production of high crank force and power output during non-seated cycling by allowing a greater non-muscular contribution to crank power.