Author(s): BAHAR, M., WATIER ,B. SCHEINOWITZ,M., Institution: TEL AVIV UNIVERSITY, Country: ISRAEL, Abstract-ID: 1550

INTRODUCTION:
Peak instantaneous power during cycling occurs progressively later in the crank cycle as cadence increases. This cadence-dependent shift is commonly attributed to neuromuscular timing constraints related to force-development dynamics and electromechanical delay. Upper-limb forces play an important stabilizing role during high-intensity cycling and facilitate the attainment of maximal power output, yet their influence on the timing of peak power within the crank cycle remains unclear. The present study aimed to quantify the relationship between cadence and crank angle at peak power and to determine whether upper-body involvement modulates this relationship.
METHODS:
Forty cyclists spanning a wide performance range performed paired maximal seated efforts on an isokinetic ergometer under two conditions: intentional handlebar pulling and instructed avoidance of pulling. In the non-pulling condition, pulling was additionally constrained by an open-palm hand posture to minimize force application at the handlebar. Cadence was systematically varied from 60 to 120 rpm in 15-rpm increments. Peak crank angle was defined as the angle of maximal instantaneous power within each participant’s highest-power revolution. Linear mixed-effects models with random intercepts and slopes were used to characterize cadence-dependent timing and between-condition differences.
RESULTS:
Peak-power crank angle increased linearly with cadence in both conditions, with a 42 percent greater slope when pulling was allowed (0.356 vs 0.251 deg per rpm; difference = 0.105 deg per rpm, 95 percent CI 0.038 to 0.174, p = 0.002, Cohen's d = 0.85). Between-participant intercept variability was reduced by 58 percent when pulling was prevented (SD 4.5 vs 10.6 deg, p < 0.001), indicating that upper-body involvement accounts for a large proportion of inter-individual differences in peak-power timing. Within-participant residual variability increased by 34 percent without pulling (SD 8.1 vs 6.1 deg, p < 0.001), reflecting reduced timing consistency. The observed slopes, when expressed in temporal units by converting angular shift per rpm into milliseconds, correspond to 42 and 59 ms respectively, values that are physiologically plausible and that situate the mechanically derived cadence-timing relationship within neuromuscular time scales.
CONCLUSION:
Peak-power crank angle follows a robust linear cadence-dependent timing law during maximal seated cycling. Upper-body involvement significantly amplifies cadence sensitivity while reducing within-individual variability, suggesting a stabilizing role in timing control. These findings indicate that upper-body technique influences not only maximal power capacity but also the precision of power-phase timing during high-intensity cycling.