A training bat assembly for improving a user's swing of a baseball bat is provided. In one embodiment, the assembly includes a bat portion and a plug or cap portion, where the plug or cap portion is configured to mate with a distal end of the bat portion. For example, the bat may include a circular opening, and the plug may include a circular rod that is configured to fit within the opening. Alternatively, a cap with a circular opening can be used, where the cap is configured to fit over a distal end of the bat. By mating the plug or cap with the bat, and swinging the bat from a first position to a second position, the plug or cap is propelled from the bat, where the resulting location of the plug or cap can be used to determine the correctness of the user's swing was.

A position estimation method according to the present disclosure includes a step of extracting an image of a moving object from a captured image obtained by imaging a predetermined imaging range including the moving object from a first direction, a step of estimating a direction of the moving object by matching a plurality of images viewed from the first direction with the extracted image of the moving object, the moving object having different inclinations in a second direction orthogonal to the first direction and in a third direction orthogonal to the first direction and the second direction, and a step of estimating a position of the moving object in the second direction and the third direction from the captured image, and estimating a position of the moving object in the first direction based on the estimated positions in the second direction and the third direction and the estimated change in the direction of the moving object.

A tactile reference attachment for releasable attachment to a sports equipment handle providing a user with tactile biofeedback. The attachment includes a tactile reference feature that extends longitudinally along an exterior body surface and is formed with dimensions specifically tailored to harness the user's natural attributes of sensibility, proprioception, and neuromuscular memory to improve a user's accuracy. The tactile reference attachment includes a flexible primary substrate having a plurality of attachment perimeter edges, an exterior surface, an interior surface having an adhesive, a thickness, and at least a first tactile reference projection having a plurality of perimeter edges, a projection width of no greater than 5.0 millimeters, a projection height of at least 0.5 millimeters, and an indentation length.

The disclosure discloses a thermal expansion compound for handles, a preparation method, and applications thereof. The thermal expansion compound for handles is prepared by 20-80 wt of thermosetting resin, 5-50 wt of foaming agent, 5-50 wt of stuffing, and 0-60 wt of diluent. The thermal expansion compound for handles applies to the preparation of various sports instruments such as tennis rackets, badminton rackets, squash rackets, PK rackets, beach rackets, flexible rackets, ball bats and clubs. Handles prepared from the thermal expansion compound have an elegant appearance and a good hand feel, avoid secondary expansion during 100-160 C. post-heating treatment, and have a hardness of SHORE D 60-95.

An object is to provide a badminton racket capable of easily achieving different performance properties on both sides of the hitting surface easily. A racket includes a frame which extends annularly, a grip, and a string which is stretched across the frame to form a hitting surface on both sides of the frame. The frame is formed to make the front surface portion and the back surface portion thereof asymmetrical in shape in a cross sectional view taken along a plane orthogonal to the extension direction of the frame. The formation of the frame into such an asymmetrical shape makes it possible to change performance properties on shuttlecock hitting between the front and back sides of the hitting surface at the time of hitting the shuttlecock, thus making it possible for the player to obtain two difference capabilities with the single racket simply by changing his or her grip.

An object is to make it possible for a single racket to present different design appearances easily. A racket includes a frame which extends annularly, a grip, and a string which is stretched across the frame to form a hitting surface on both sides of the frame. The frame and the shaft is provided with a first colored portion and a second colored portion. As the racket is viewed from a certain angle in a direction nonparallel and non-orthogonal to the hitting surface, the first colored portion appears visible while the second colored portion is hidden from view, and flipping the hitting surface from this state causes the second colored portion to appear visible and causes the first colored portion to be hidden from view.

A handle for sport equipment comprises a tubular body (7) which extends along a longitudinal axis (L) and has an outer peripheral surface (8) adapted to be grasped by a user and shaped with a plurality of longitudinal faces (9) placed side by side in correspondence of edges (10) adapted to facilitate the positioning of the finger joints of the gripping hand by the user. The edges (10) are arranged along at least one pair of helical or spiral paths that develop around said longitudinal axis (L) with mutually opposite sign to subdivide each of said longitudinal faces (9) into a plurality of areas or flat surfaces (11) sized to accommodate a corresponding phalanx of the gripping hand of the user, each of said areas or flat surfaces (11) being perimetrically delimited by at least one pair of edges (10, 10) of each of the helical or spiral paths.

A tactile reference attachment for releasable attachment to a sports equipment handle to provides a user with tactile biofeedback. includes a tactile reference feature that extends longitudinally along an exterior body surface and is formed with dimensions specifically tailored to harness the user's natural attributes of sensibility, proprioception, and neuromuscular memory to improve a user's accuracy. The tactile reference attachment includes a flexible primary substrate having a plurality of attachment perimeter edges, an exterior surface, an interior surface having an adhesive, a thickness of no more than 4 mm, and at least a first tactile reference indentation having a plurality of perimeter edges, an indentation width of at least 2.0 millimeters and no greater than 5.0 millimeters, an indentation depth of at least 0.5 millimeters and no greater than the indentation width, and an indentation length that is at least five times the indentation width.

A tactile reference attachment for releasable attachment to a sports equipment handle to provides a user with tactile biofeedback. includes a tactile reference feature that extends longitudinally along an exterior body surface and is formed with dimensions specifically tailored to harness the user's natural attributes of sensibility, proprioception, and neuromuscular memory to improve a user's accuracy. The tactile reference attachment includes a flexible primary substrate having a plurality of attachment perimeter edges, an exterior surface, an interior surface having an adhesive, a thickness of no more than 4 mm, and at least a first tactile reference indentation having a plurality of perimeter edges, an indentation width of at least 2.0 millimeters and no greater than 5.0 millimeters, an indentation depth of at least 0.5 millimeters and no greater than the indentation width, and an indentation length that is at least five times the indentation width.

Methods, apparatus and kits for modifying natural feathers that are used in sporting goods that result in long lasting feathers with increased mechanical stability, reliability and durability as well as improved flight consistency is disclosed. Some of the sporting goods that use natural feathers are badminton shuttlecocks, arrow fletchings, and darts. The disclosed methods consist of controlled treatment of feather shuttlecocks with crosslinking agents to crosslink the keratin protein present on the natural feathers of the shuttlecock.