Buoyant devices

A buoyant device for water-based aerobic exercises, comprising:

• a body configured to generate buoyancy in water, the body including a first portion, a second portion, and a third portion and having a material density of less than 0.3 kg/cm3, wherein
• a thickness of the body is measured by a distance difference between a first distance and a second distance from an axis around which the body is arranged, the first distance indicating an approximation value of an inner radius of the body and the second distance indicating an approximation value of an outer radius of the body, wherein the first distance is between 2.5 cm and 5.5 cm, and the distance difference between the second distance and the first distance is between 2.5 cm and 4.5 cm;
• the first portion and the second portion are arranged at two ends of the third portion, respectively, the first portion and the second portion having an overlapping portion, the second portion being located farther away from the axis relative to the first portion;
• the first portion and the second portion are configured to adjust a size of the buoyant device based on an overlapping size of the overlapping portion;
• a rotation angle is an angle defined by having the axis as a center and two positions on the body;
• a first rotation angle corresponds to a sub-portion of the first portion between an end position and a first position of the first portion, and a second rotation angle corresponds to a sub-portion of the first portion between the first position and a joint position of the first portion and the third portion, the first rotation angle being greater than the second rotation angle;
• a first distance difference indicates a thickness at different positions of the sub-portion corresponding to the first rotation angle, a second distance difference indicates a thickness at different positions of the sub-portion corresponding to the second rotation angle, a first difference group being composed of a plurality of first distance differences, a second difference group being composed of a plurality of second distance differences, and the first distance differences of the first difference group being less than the second distance differences of the second difference group;
• a third rotation angle corresponds to a sub-portion of the second portion between an end position and a second position of the second portion, and a fourth rotation angle corresponds to a sub-portion of the second portion between the second position and a joint position of the second portion and the third portion, the third rotation angle being greater than the fourth rotation angle;
• a third distance difference indicates a thickness at different positions of the sub-portion corresponding to the third rotation angle, and a fourth distance difference indicates a thickness at different positions of the sub-portion corresponding to the fourth rotation angle, a third difference group being composed of a plurality of third distance differences, a fourth difference group being composed of a plurality of fourth distance differences, and the third distance differences of the third difference group being less than the fourth distance differences of the fourth difference group;
• the third portion is configured to be applied to a body part of a user, the thickness of the first portion and the thickness of the second portion being less than a thickness of the third portion;
• a deformation determining member configured to fix a deformation of the body, wherein the body is configured to support the deformation determining member, and the deformation determining member includes one or more of a hook and loop tape, an elastic band, a hook, a buckle, and a reel;
• and
• a strap configured to connect the deformation determining member and the body.