IMPLICATIONS ON FOOTWEAR AND FATIGUEThesis by Marie-Caroline Play

Supervisors: Marlène GIANDOLINI (ISS, Salomon SAS), Jérémy ROSSI & Guillaume MILLET (LIBM, Saint-Etienne)

Title: Interaction between soft tissue vibrations and morphological and functional characteristics of the runner: Implications on footwear and fatigue.

In running, each contact between the foot and the ground causes a strong deceleration of many parts of the body. This deceleration affects soft tissues including muscles, which start vibrating. According to the mechanism of 'muscle tuning', muscle activity is regulated to dampen soft tissue vibrations. Increasing muscle activity in order to reduce soft tissue vibrations and maintain comfort increases muscle demand. Therefore, this increase in muscle demand to minimize vibrations could induce an earlier neuromuscular fatigue. Improving the damping of muscle vibrations could be a relevant solution to preserve the neuromuscular system when running. Footwear has also the potential to influence both the amplitude and damping of soft tissue vibrations. However, this effect is highly subject-specific. It would be interesting to highlight the existence of different runner profiles and see the effects of midsole material properties on muscle vibrations. Being able to identify these different profiles thanks to simple anthropomorphic and functional variables would make it possible to orient the runner towards a footwear that minimizes the vibrations of the soft tissues and potentially the neuromuscular fatigue.

The main objectives of my thesis work are the following ones:

1 / Identify and characterize different runner profiles according to their biomechanical response to different footwear interventions.

2 / Propose a simple model for characterizing the different runner profiles.

3 / Evaluate the effects of better damping of muscle vibrations by the shoe on neuromuscular fatigue.

Contract duration: 3 years (November 2019 to October 2022)

Funding: Amer Sports Footwear Innovation and Sport Sciences Lab (ISS), Salomon SAS