An arm exercise apparatus is disclosed which includes a substantially rigid framework having a stand supporting a first, a second and a third frame member, a rod flexibly coupled to the first frame member at a vicinity of a first end of the rod, the rod having a second end opposite to the first end for being held by a user's hand during an exercise, a first elastic band coupling the rod at a predetermined location to the second frame member, the predetermined location being between the first end and the second end and having a predetermined distance to the first end, the first elastic band exerting a first force at the rod, and a second elastic band coupling the rod to the third frame member, the second elastic band exerting a second force at the rod countering the first force, wherein the rod is statically suspended in a space between the second and the third frame member.

A system that includes a portable basketball goal assembly and a rebound assembly that can be used together as a single piece of equipment or split and used as separate pieces of equipment. The rebound assembly has a rebound frame that is supported on a base frame. The angle of inclination of the rebound frame relative to the base frame can be selectively adjusted. The rebound frame defines a first central opening. The base frame defines a second central opening. A flexible rebound surface spans the first central opening. The rebound assembly selectively connects to, and detaches from, the portable basketball goal assembly. When the rebound assembly is attached to the portable goal assembly, the rebound surface redirects basketballs that fall through the net. When the rebound assembly is detached from the portable basketball goal assembly, the rebound assembly is free standing.

A base assembly for a batting tee includes a base having a base guide path formed in an upper surface of the base, and a track plate positioned such that the track plate covers at least a portion of the upper surface of the base. The track plate includes a first segment and a second segment that surrounds at least a portion of the first segment. A position of the first segment relative to a position of the second segment defines a track plate guide path that extends between the first segment and the second segment such that the track plate guide path has a same shape as the base guide path and is positioned above the base guide path. Alignment of the track plate guide path and the base guide path form a non-linear track, such that the track is configured to slidably receive a portion of a tee.

An apparatus including an elongated foam piece first and second ends; and a suction cup attached to the elongated foam piece at the first end. The elongated foam piece may be a cylindrical foam piece. The suction cup is typically removably attached to the elongated foam piece. The apparatus may further include a plate to which the suction cup is removably attached. The plate typically has an outer diameter larger than an outer diameter of the suction cup. The apparatus may include a weight attached to the plate, underneath the plate, opposite from where the suction cup is removably attached to the plate. A plurality of such apparatuses, spaced apart from each other, may be attached to a surface by suction; and a plurality of exercises using each of the plurality of apparatuses may be performed, such as by contacting or weaving in and out of the apparatuses.

A portable water sports environment is provided. The environment includes a mat positioned on a liner. The front end of the liner may be positioned proximate to a body of water. The back end of the liner may be positioned distally to the body of water. A spray nozzle positioned along a front end of the liner may spray water from the body of water onto the mat and toward the back end of the liner. The environment may a ballast positioned on the top surface of the liner and spaced from the mat. The mat, the top surface of the liner, and the ballast may define a trench that extends away from the back end of the liner and toward the front end of the liner. The trench may guide water received from the spray nozzle toward the front end of the liner and into the body of water.

A swimming exercise device, comprising a restraint including an opening and a contact portion, the restraint configured to receive a head of a user through the opening and to restrain the user, via contact between shoulders of the user and the contact portion, such that the user is held substantially stationary during forward motion of the user against the restraint and an abutment structure configured to contact a pool surface and transmit forces associated with the forward motion of the user against the restraint to the pool surface.

A tackle training apparatus includes a padded body member and two padded elongate leg members in which each leg member has a first end for abutting the body member and a second end for contacting the ground. The two leg members are arranged in relation to the body member to extend from and to be resiliently movable relative to and/or separable from the body member, and in one configuration where the second end of each of the two leg members is placed on the ground, the two leg members can support the body member such that the apparatus is in a standing position, provides an effective training apparatus for improvements in collisions and especially tackles in rugby. Use of the apparatus facilitates improvement in point of contact, height of approach, grip technique and grip strength.

A practice device includes a base, a support tube, a post, an axle, a first ball rod, and a brake. The support tube extends upward from the base and has a support tube longitudinal axis. The post extends from the support tube and has a first portion and a second portion. The first portion is engaged with the support tube and the second portion includes a first arm. The axle is coupled to the first arm and has a rotation axis. The first ball rod is coupled to a first practice ball and extends between the first practice ball and the axle. The first ball rod is coupled to a first practice ball and extends between the first practice ball and the axle. The first ball rod is configured to rotate about the rotation axis of the axle and when the first ball rod rotates about the rotation axis of the axle, the first practice ball contacts the brake to slow rotation of the first ball rod.

A tennis training system may include a target mat including an intersection point and radial lines extending from the intersection point to visibly define sections. A target device may align with the target mat. The target device may include a body, a target assembly coupled to a first end of the body to define a target opening, and a base coupled to a second end of the body opposite the first end.

Methods and systems according to embodiments of the invention provide for a framework for privacy-preserving machine learning which can be used to obtain solutions for training linear regression, logistic regression and neural network models. Embodiments of the invention are in a three-server model, wherein data owners secret-share their data among three servers who train and evaluate models on the joint data using three-party computation (3PC). Embodiments of the invention provide for efficient conversions between arithmetic, binary, and Yao 3PC, as well as techniques for fixed-point multiplication and truncation of shared decimal values. Embodiments also provide customized protocols for evaluating polynomial piecewise functions and a three-party oblivious transfer protocol.