The main objective of this work is to validate the dynamometer LABIN in comparison with the technique of gold-standard reference JAMAR, in a healthy population.

The infringement of the prehension is frequent and impacts on the social and professional quality of life of the patients. There are numerous instruments measuring the strength of prehension. The JAMAR is a mechanical, hydraulic dynamometer, exploring in kilograms the maximal strength of the prehension. It is at present Gold Standard for the measure of the strength of prehension. There is for the moment no electronic known instrument exploring the endurance of the strength of prehension during an effort of tightening. This parameter would indeed be interesting for the exploration in geriatrics and in the neuromuscular pathologies.

This study justifies itself by the fact that the dynamometer LABIN should allow the evaluation of the muscular endurance of the strength of hand as complement of the peak of strength

Measure of the strength of prehension with JAMAR and LABIN according to the following protocol:

• Position: the subject sits comfortably on a chair without armrests, feet put on the ground, the pond at the bottom of the seat, the hips and the knees in 90 ° of flexion, shoulder in adduction and neutral rotation, the elbow bent in 90 °, forearm in neutral position, the wrist between 0 and 30 ° of extension and between 0 and 15 ° of slope ulnaire. The dynamometer is vertically presented and in front of the forearm to maintain the standardized positions.
• Test: regulation of the zero by making a vacuous acquisition during 5 seconds. The order "Jamar then Labin" or Labin then Jamar is chosen by randomization. The operator encourages the subject to every test. The subject does not see the curve displaying.
• Test: 3 clampings of a handle of a dynamometer LABIN by the right hand during 5 seconds, with a break of 30 seconds between the tests. After 2 minutes of break the subjects make 3 clampings with a left hand. After that , the same session is realized with the dynamometer JAMAR

The order "Jamar then Labin" or Labin then Jamar is chosen by randomization. The operator encourages the subject to every test. The subject does not see the curve displaying.

Total duration of participation in the study for the patient: 30 minutes

Main analysis: the calculation of the coefficient of correlation (Pearson or Spearman with regard to the statistical distribution), coefficient of linen concordance and the coefficient of intra-classy correlation.

Inclusion Criteria:

• Age : > 20 years and <60 years
• Professionally active
• Right-handed(right-wing) or left-handed person
• Volunteer
• Subjects have given its consent in writing to participate in the study

Exclusion Criteria:

• Subjects with a trauma or surgery of the upper limb
• Subjects with a diabetes
• Subjects with a dysthyroïdie
• Subjects with a neurological disease
• Subjects with a syndrome canalaire of the upper limb
• Subjects with a cutaneous disorders(confusions) of the cognitive upper