Scientific Programme

Biomechanics & Motor control

IS-BM05 - Cyclic propulsion in sports

Date: 03.07.2025, Time: 10:00 - 11:15, Session Room: Castello 1

Description

Cyclic forms of human locomotion (such as cycling, running, swimming or kayaking) are characterized by cyclic force application. In the corresponding sports activities, this intermittent force is then utilized to sustain a target “average velocity” of motion which, ultimately, is the parameter to be maximized to improve athletic performance. When analyzing the dynamics of locomotion in these sports, the average force/velocity/power developed over a cycle are generally calculated. A deeper understanding of the intermittent application of the force and of the effects of this unsteady motion would, however, allow to better understand the determinants of performance in these sports.

Chair(s)

Paola Zamparo

Paola Zamparo

University of Verona, Department of Neurological, Biomedical and Movement Sciences
Italy
Christophe Clanet

Speaker A

Christophe Clanet

Ecole Polytechnique (Paris) , Department of Mechanics
France
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ECSS Rimini 2025: IS-BM05

Velocity and Power in cycling races

Velocity is usually easy to measure in sports, while measuring power is, in general, more delicate. However, in cycling, both measures are accessible, and this leads us to first focus on track cycling races. Knowing the instantaneous power injected by the cyclist on the pedals, what is the velocity of the bike? The usual way to answer this well-paused question is via energy conservation. But the system (cyclist+bike) is both open and deformable. To avoid the full complexity of the problem, we develop a phase average theory that “solidifies” artificially the system and allows us to predict the velocity of the centre of mass (and thus of the bike in this solid limit), provided the power is averaged over a pedal cycle. Thus, if the power is known the velocity can be calculated theoretically. However, the power developed by a cyclist is not known in advance and, moreover, it depends on the velocity! The second part of the presentation will thus be devoted to addressing the question of power production and the resolution of the Power-Velocity coupled system.

Remi Carmigniani

Speaker B

Remi Carmigniani

Hydraulic Saint Venant Laboratory , Ecole nationale des ponts et chaussée (Paris)
France
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ECSS Rimini 2025: IS-BM05

Velocity and frequency in cyclic sports

The principle of cyclic force application is a common thread across various forms of locomotion, be it on land, in water, or in air. This force application is essential to maintain a target average velocity of motion. In running, force is exclusively applied during ground contact. In cycling, force is consistently applied, but it exhibits a cyclic evolution during the rotation of the pedals. In kayaking, the force is applied when the paddles are in the water. In swimming, the force is similarly applied during the time the arm is in water, with the exception of certain strokes. Understanding the relationship between the velocity of motion of the center of mass and the frequency of gesture is crucial for studying locomotion. This understanding allows us to explore the link between speed and muscle contraction velocity, which is believed to be significant in building race control models to assist athletes in managing their pacing. In cycling, this relation is purely geometric and is fixed by the gear ratio. However, observations in running, swimming, and kayaking show linear, square root, and cubic root relations on an incremental test. To better understand these evolutions, a simplified model is proposed. This model enables us to identify the key parameters that can be monitored to track progress and characterize athletes. By doing so, we can gain a deeper understanding of the dynamics of locomotion and potentially improve athletic performance.

Paola Zamparo

Speaker C

Paola Zamparo

University of Verona, Department of Neurological, Biomedical and Movement Sciences
Italy
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ECSS Rimini 2025: IS-BM05

Active drag and added mass in water sports

Swimming is a racing sport similar to biking, running, rowing or kayaking, where the goal is to cover a given distance in the shortest possible time (e.g. at the fastest possible velocity). In these sports, the race starts with a standing start and the velocity gradually increases toward a maximum value that the athletes should try to maintain up to the end. This is not the case in swimming where, in pool races, a swimmer must accelerate after each turn. In addition, cyclic variations in speed could be observed, in swimming, even at “constant average speed” because of the fluctuations in resistive and propulsive forces that occur within each stroke. Only few studies attempted to quantify the hydrodynamic force that counteracts swimmers when the flow pattern changes with time. In this case, some of the water around the swimmer is set in motion and this can be thought of as an added mass the swimmer has to accelerate, in addition to body mass, during a change in velocity. These matters could be investigated using a novel method consisting of a series of tests (a standing start test, a full tethered test and semi-tethered tests) through which it is possible to gather the data required to compute the added mass and the active drag of a swimmer. The standing start test could also be utilized to assess these matters in boat locomotion (e.g. kayaking).