The competitive swimming and open water swimming events are scheduled for the 2024 Paris Olympic and Paralympian Games. Generally associated with a non-neglectable number of medals in the last Olympics, swimming performance depends on the swimmer's ability to manage his or her Stroke Length and Stroke Rate, where Velocity can be defined as the product of SR and SL. The optimisation of this management depends on the swimmer's ability to develop a large motor repertoire and to use the coordination mode (catch-up, opposition, superposition) best suited to the environmental constraints and opponents' adversity. These adaptations may contribute to 1) a modification of the energy expenditure or be dependent on the energy supply necessary for muscular contraction and 2) the preferential use of one or other of the metabolic pathways in the production of this chemical energy, moreover in an aquatic environment inducing particular thermal exchanges.

To swim fast, one need to be able to create great propelling forces in addition to minimizing resistance. Propulsion emerged from the appropriate spatial-temporal coordination of the four limbs. The purpose of this study is to determine the motor repertoire (coordination possibilities) of each swimmer and para-swimmer in order to monitor their swimming economy, as a function of their energy expenditure. Crawl coordination has been studied extensively, and recent technologies such as inertial units and machine learning methods may be combined to characterize it automatically. There is a strong need to extend this knowledge to the other three swimming strokes and adapt it to para-swimmers' disabilities to clearly measure the impacts of SR and V manipulations on swimming economy.

Swimming is performed in a complex aquatic environment serving both as a support for propulsion and as a resistance to progress forward. Therefore, to properly behave through water, swimmers coordinate their limbs to increase their velocity (V). Cyclic activities performance, such as swimming, corresponds to the reaching of high speed, defined by the product of stroke length (SL, in m.cycle-1) and stroke frequency (SR, cycles.min-1). Many authors have therefore focused on the behaviors of elite swimmers and they observed a change in arm coordination when values of 1.8 m.s-1 in V and/or 50 cycles.min-1 in SR were reached. Such results are related to the high degree of flexibility in the swimmer's motor behavior , that should not imply an additional energy expenditure that may become detrimental to performance. Studies showed that changes in V and/or SR would influence the value of the energy cost of swimming. These studies, mainly performed in front crawl would be of valuable interest to develop for all other strokes (i.e. breaststroke, butterfly and backstroke) and for multiple group of participants (i.e. para-swimmers).

Two intermittent swimming tests of progressive velocity will be performed in the swimmers' and para-swimmers' specialty with or without prescription of the SR. Coordination and physiological variables will be collected to investigate if changes in motor behaviors are linked to changes in energy expenditure.

The study will be performed in two main centers, with a duration of the inclusion period equals to 3 years. Moreover, the duration of participation of each participant is also fixed to 3 years . One of the objectives is obtaining a landscape of possible motor behaviors for each participant according to the manipulation of swimming frequency and speed. This 'landscape' will show whether, for all participants, the behavioral adaptations are efficient (in reference to their energy expenditure).

Inclusion Criteria:

• High-level swimmers and para-swimmers on ministerial lists
• Current license to participate in national and international competitions
• Over 12 and under 50 years old
• Signed consent form
• Willingness to participate / cooperate

Exclusion Criteria:

• Absence of authorization from legal guardians for the minor athlete at the time of inclusion in the study.
• For disabled athletes: non-union fracture, pressure sore stage 2 or more, infection (CRP > 5, body temperature > 38°C), non-union musculo-tendinous lesion at the time of inclusion.
• Hemophilia, coagulation disorders
• Regular medication intake that may influence the data
• Any metabolic or hormonal disorder. Contraindications to competitive swimming
• Any other condition that the investigating physician considers may pose an individual risk or interfere with the evaluation of the data.