A method of manufacturing a string 10 for use in a racket includes: (A) preparing an untreated string; and (B) irradiating the untreated string with radioactive rays. Preferably, the untreated string is irradiated with gamma rays. A preferable irradiation amount of the radioactive rays is greater than or equal to 250 kGy but less than or equal to 2000 kGy. Preferably, a material of the untreated string is polyester. Alternatively, the material of the untreated string may be nylon.

A pulling string apparatus of a stringing machine comprising a string gripper, a sensor, a drive element, a transmission mechanism and a control circuit; the sensor is connected with the string gripper to detect the pull force of the string gripper; the control circuit compares the detected pull force value with a pre-set value, and control the rotation of the drive element; the transmission mechanism comprises a mounting base, a sliding block, a transmission rack and a drive gear; wherein the drive gear is connected to the drive element and is engaged with the transmission rack, the sliding block arranged on the transmission rack is connected with the sensor; when the sensor and the string gripper are driven forward or backward by the sliding block under the act of the transmission rack engaged with the drive gear, the racket string will be tensioned or loosened.

Described herein are devices and systems relating to sports training equipment, for example, for baseball. These devices and systems can comprise a mat with markers identifying a plurality of positions on the mat. In some embodiments, the system can comprise removably attachable footpads to identify ideal foot positions for an athletic performance. In some embodiments, the footpads comprise one or more pressure sensors. The system can comprise one or more position sensors on a ball, and one or more position sensors removably attachable to a hand-held sports instrument. In some embodiments, the system can comprise a memory, communicatively coupled to a processor and a camera, with executable instructions to implement a set-up component, a user recognition component, a practice component, and instructional component, and a play component.

An artificial shuttlecock, a feather and a preparation method thereof are provided. The feather includes a connecting portion, a first portion, a second portion and a concave. The first portion and the second portion are disposed on the opposite sides of the connecting portion. The concave is located at an outer edge of the second portion. The concave is formed by the following steps of: defining an overlapped outline, which is the outline of the adjacent feather overlapping on the second portion; defining a reference point, which is a point where the overlapped outline is closest to the connecting portion; defining a shifting reference line, which passes through the reference point and is parallel to the connecting portion; defining a reference outline, which is located outside the shifting reference line; and cutting the reference outline to form the concave.

A composite material body (10) includes a first material layer (20) and a second material layer (30) overlapping the first material layer (20). The first material layer (20) and the second material layer (30) are wound to form a flexible and circular rod. Impact absorption is effectively improved and impact resisting strength is enhanced because energy-absorber or damping material or its composition is attached into the composite material body (10). Technical characteristics, effects and objects of this invention are achieved thereby.

A composite material body (10) includes a first material layer (20) and a second material layer (30) overlapping the first material layer (20). The first material layer (20) and the second material layer (30) are wound to form a flexible and circular rod. Impact absorption is effectively improved and impact resisting strength is enhanced because energy-absorber or damping material or its composition is attached into the composite material body (10). Technical characteristics, effects and objects of this invention are achieved thereby.

A composite material body (10) includes a first material layer (20) and a second material layer (30) overlapping the first material layer (20). The first material layer (20) and the second material layer (30) are wound to form a flexible and circular rod. Impact absorption is effectively improved and impact resisting strength is enhanced because energy-absorber or damping material or its composition is attached into the composite material body (10). Technical characteristics, effects and objects of this invention are achieved thereby.

Training equipment includes a hollow shaft having a sidewall defining an internal cavity and at least one polymer material filling at least a portion of the internal cavity. The polymer material may fill the entire internal cavity of the hollow shaft. The polymer material may be a visco-elastic polymer material or polyurethane. A spacer or a filler may fill at least a portion of the internal cavity. A method of making weighted training equipment with a hollow shaft having a sidewall defining an internal cavity may include injecting a curable composition into at least a portion of the internal cavity. The method may further include curing the curable composition into a polymer material.

A portable ball net post includes an adjustable base, and ball net lacing bars mounted on the base and adjustable in angle and height, wherein the base includes telescopic lacing bars and two support receptacles, both ends of each telescopic lacing bar are respectively connected to the support receptacles, a number of snap-fit fixing bases are installed surrounding the telescopic lacing bars by connection sleeves, and on each connection sleeve is provided a telescopic positioning assembly for controlling the stretching length of corresponding telescopic lacing bar; on the upper end surface of each snap-fit fixing base is provided net lacing bar clamping grooves for clamping the ball net lacing bars when retracted, on the lower end surface of each snap-fit fixing base are provided several racket clamping grooves, the ball net lacing bars are mounted on the support receptacles by a rotation positioning and angle adjusting structure and inside the support receptacle is provided a storage cavity.

A composite material body (10) includes a first material layer (20) and a second material layer (30) overlapping the first material layer (20). The first material layer (20) and the second material layer (30) are wound to form a flexible and circular rod. Impact absorption is effectively improved and impact resisting strength is enhanced because energy-absorber or damping material or its composition is attached into the composite material body (10). Technical characteristics, effects and objects of this invention are achieved thereby.