Exoskeleton for physical activity, specially snow skiing, for preventing knee, leg and hip injuries by preventing the excessive torsion of the knee and other movements that could be dangerous for the person wearing it. The exoskeleton diverts the potential dangerous forces to the strong parts of the body and resists the generated forces when it reaches dangerous anatomical positions. The exoskeleton includes at least one first support member configured to couple above the knee; at least one second support member configured to couple below the knee; both of them linked together by a linkage assembly that limits that the coupling to the body of the support members reach dangerous positions; and at least one angle limitation mechanism that limits the relative rotation between the first support member and the second support member.