Limitation of activity is one of the main item used by composites scores designed to assess the level of asthma control. Since this item is systematically subjectively assessed by the patient, the investigators would like to know if these subjective data are correlated with objective data.

Aims of this study are: 1) To describe what means "limitation of activity" for asthma patients and how they deal with; 2) To describe the objective exercise capacity and characteristics of daily activity in two situations (on exacerbation, out of an exacerbation).

Inclusion Criteria:

• Diagnosis of asthma made by a pulmonologist.
• Age ≥ 18 yrs-old, < 65 yrs-old.
• Moderate or severe exacerbation of asthma (as defined by Reddel et al in 2009) at the time of inclusion.

Exclusion Criteria:

• All other diseases than asthma that can affect the physical activity (e.g. orthopaedic or neuromuscular disease, cardiac or vascular disease).
• Pregnancy or suspicion of pregnancy at the time of inclusion. The women who become pregnant during the study period will be excluded.

Exacerbated asthma patients coming to the outpatient clinic of pulmonology.