Aging affects almost all the tissues and physiological functions, and skeletal muscle is the most affected organ. The progressive decline of the weight and the muscular function linked to the aging contributes to the lack of autonomy and dependence, but also to an increase of the mortality risks. Sarcopenia is also a prevalent condition, because it is detected in 13-24% of 60 years old, and 50% of 80 years old and more.

However, strong inter-individual variations of this prevalence of sarcopenia exists. The key issue is to understand why the biological aging of the skeletal muscle is so different between people.

In this study, mechanisms involved in biological aging of the skeletal muscle in aging people (same chronological age) will be specified.

Aging affects almost all the tissues and physiological functions, and skeletal muscle is the most affected organ. The progressive decline of the weight and the muscular function linked to the aging contributes to the lack of autonomy and dependence, but also to an increase of the mortality risks. Sarcopenia is also a prevalent condition, because it is detected in 13-24% of 60 years old, and 50% of 80 years old and more.

However, strong inter-individual variations of this prevalence of sarcopenia exists. Some elderly (60 years old) reveal a biological aging of 80 years old, whereas 60 years old people reveal a biological aging of 60 years old. The key issue is to understand why the biological aging of the skeletal muscle is so different between people.

Previous sarcopenia studies in Humans did not really focus on chronological aging, they were all based on a comparison between young and old people. No study considered inter-individual modifications (biological aging) in sarcopenia. Furthermore, few studies were associated in the same study to "omic", histological, and epigenetic data, to obtain integrated point of view of Human Sarcopenia.

In this study, mechanisms involved in biological aging of the skeletal muscle in aging people (same chronological age) will be specified.

Inclusion Criteria:

• Belonging to the Proof cohort
• Between 80 and 83 years old
• Informed consent signed
• Genetic analyses consent signed
• Subject affiliated or entitled to a social security scheme

Exclusion Criteria:

• Anti coagulative treatment
• Severe obesity (>35)
• All chronic pathology requiring a treatment
• Severe renal insufficiency (discovery less than 6 months)
• Abnormal coagulation appraisal
• Allergy to local anesthetics
• Installation of a prosthetic hip and / or knee in the last six months
• Senile dementia
• Refusal of genetic study

Patients are recruited in the Proof cohort (Barthélemy et al., 2007).