In this study, the investigators will examine the effect of manual therapy on the thoracic spine and its impact on the muscular strength gain of the thoracic extensors. Treatment with manual therapy, as described by Maitland, consists of a specific mobilization of the thoracic spine in the postero-anterior direction on the transverse and spiny processes of the thoracic vertebrae. To ensure the relevance of the measures, and to better control the occurrence of biases inherent to the practice of manual therapy, the investigators constituted three distinct groups: an intervention group, a control group and a group without intervention. In short, this methodology will allow us to explore in detail the effects of specific spinal mobilization on motor control, while taking into account placebo response elements and natural variations in the results

Inclusion Criteria:

• Ages 18 to 65,
• healthy volunteer,
• membership in a social security scheme

Exclusion Criteria:

• Severe spinal trauma within the last 6 months
• history of low back pain, back pain, and/or neck pain within the last 6 months,
• history of spinal surgery,
• history of chronic systemic disease (cardiac, respiratory, diabetes, etc.),
• volunteer with Pacemaker, history of rheumatological pathology (rheumatoid arthritis, ankylosing spondylitis, Scheuermann's disease, etc.),
• patient under guardianship,curatorship, safeguard of justice, patient deprived of liberty, pregnant woman and patient without Red Flags Social Security described in literature.