The goal of this observational study is to learn about physiological transitions around the limit of moderate exercise intensity on cardiac, respiratory and motor modalities, in healthy population.

The main questions it aims to answer is:

• is it possible to define criteria on cardiac, respiratory and motor modalities to identify transitions?
• are those transitions visible on embedded and non-intrusive monitoring equipment?
• are those identified transitions somehow connected to first ventilatory threshold (VT1)?

Participants will do a sub-maximal effort test on cycloergometer calibrated to make them cross their first ventilatory threshold.

Cycling is a commonly prescribed activity when it comes to physical activities for rehabilitation. Because it is soft and progressive effort, cycling suits well for patients with chronic conditions (diabete, cancer, fibromyalgia, ...) For safety and effectiveness of the activity, it is necessary to prescribe activity at a regular and moderate intensity. This can be achieved by personalizing intensities to match specifically the patient health condition in order to build an efficient and progressive rehabilitation program.

Physical activity prescription rely on four pillars: frequency, duration, volume and intensity. While first three pillars are quite easy to regulate,effort intensity is harder to handle on training planning. It is harder to measure, and defining personalized guideline for practice is more complex.

It is known that first ventilatory threshold (VT1) is a individualized marker representing the higher limit of moderate intensity effort zone. It makes it an interesting tool for the prescription of intensity for retraining purposes: it guaranties a safe practice, intense enough to make beneficial physiological adaptations for the patient.

In this retraining context and with this study, we aim to identify markers of this transition on cardiac, respiratory and motor modalities, with embedded and non intrusive equipment, during a sub-maximal effort test in laboratory.

Inclusion Criteria:

• Capability to cycle during 20min
• No contraindication to cycling at a moderate pace
• No acute pathology (less than 2 years old)
• No cardiac or respiratory chronic pathology
• No locomotive problem on the spine or the lower limbs
• No recent injuries (less than 2 months)
• Stature compatible with the use of the plethysmography t-shirt

Exclusion Criteria:

• Pregnant (urine strip test) or breastfeeding women
• Persons referred to in articles L1121-5 to L1121-8 of the CSP (protected persons) person deprived of liberty by judicial or administrative decision, person subject to a legal protection measure
• Subject being excluded from another study
• Subject who reached the ceiling of 4500 euros due to their participation in other studies involving human in the past 12 months

Heathy volunteers with various physical conditions