The objective of this trial is to constitute a cohort of sarcopenic versus non-sarcopenic patients to validate the most relevant biological, imaging, mobility and clinical markers considered individually or in association for the diagnosis of sarcopenic patients.

This trial is part of a Research Program partly funded by a grant from the Walloon region entitled "Development of Markers of Sarcopenia Using an Integrated Approach : From Cell to Human".

Consistent with the above-mentioned observation, there is not only one biological marker that perfectly matches the sarcopenia criteria but there is a range of complementary biomarkers - including but not limited to inflammation markers, products of oxidative damage, serum creatinine and urinary creatinine excretion, endocrine function, urine proteomics panel, N-terminal procollagen peptides, myostatin and agrin fragment - that will together constitute the ideal panel of markers (Fougère et al, 2015). These current biomarkers and the thresholds for correlation with clinical outcomes have to be deeply evaluated in clinical trials before being considered as good biomarkers.

In addition, one research priority is to investigate and define novel biomarkers allowing an improved assessment, characterization and follow-up of elderly people with sarcopenia. Biomarkers derived from blood can indeed easily be measured in a standardized and low-cost way and are therefore very attractive.

This clinical trial aims at confirming the relevance of new soluble markers and validating the most relevant biological (previously and newly identified), imaging, mobility and clinical markers for clinical research in sarcopenia.

Newly identified soluble markers of sarcopenia coming from DEMAIN Research program and using secretomic approach (to be identified in secretome of human myotubes during the program research) using immunoassays on biological fluids.

Inclusion Criteria:

Participants will have the following inclusion criteria:

• Male with age ≥ 65 years
• Body Mass Index: 20 < BMI < 35 kg/m2
• Able to understand and having signed an informed consent
• Able to follow the trial procedures

Sarcopenic population: diagnosed sarcopenia following definition of the EWGSOP2:

• Muscle strength assessed by the handgrip test <27 kg for male
• Skeletal muscle mass index (Appendicular lean muscle mass) assessed by DXA <7.0 kg/m2

Non-sarcopenic population: adapted from the EWGSOP2:

• Muscle strength assessed by the handgrip test ≥ 27 kg
• Skeletal muscle mass index (Appendicular lean muscle mass) assessed by DXA ≥ 7.0 kg/m2

Exclusion Criteria:

Participants will have the following exclusion criteria:

• Any clinically significant levels of the safety parameters (Creatine Kinase (CK), activated Partial Thromboplastin Time (aPTT), Prothrombin Time and International Normalized Ratio (PT/INR))
• Any severe, uncontrolled and limiting diseases (e.g. systemic inflammation, infectious diseases, active cancer, neurodegenerative disorders, diabetes) left to the investigator's discretion
• Bed resting for more than 10 days during the 3 months preceding the recruitment
• Immobilization of the lower limb, lasting more than one week during the 3 months preceding recruitment
• Medical treatment with anticoagulant, insulin, immunosuppressant, long-term corticosteroid (over 7.5 mg prednisone or its equivalent)
• Severe incapacity (class IV Steinbrocker Functional Classification - Appendix 2)
• Any treatment that may affect physical performance, muscle function, disrupts study measures or impairs the understanding of consent
• Known acute or severe renal insufficiency (glomerular filtration rate < 30 mL/min/1.73m2)
• Cushing' syndrome
• Known cachexia
• Currently participating or having participated in another therapeutic clinical trial in the three previous months
• Under guardianship or judicial protection