 During the hypergravity initial part in of the parabola, the subject is standing with is two feet on each side of the platform. The traction system is loose 5 kg traction. During the injection, the traction system starts to progressively pull downwards on the subject. The traction force is tuned between 20 and 100 of body weight on Earth. The traction force is constant during each parabola. During the 20 second of weightlessness or partial gravity, the subject jumps several times. At the end of the parabola, the subject puts his feet at the side of the platform and the traction system stops to pull downwards before the pull out phase. 