A training aid for use with a suspended and tensioned line, a dynamic suspended line, one or more ropes or a slackline for improving the human proprioceptive system, athletic performance, athletic speed, athletic agility, athletic vertical leap, athletic eye/hand coordination, spatial awareness, left/right brain organization and increasing the muscular development of a user. The training aid includes a board member. The user places all or part of their body weight on a top surface of the board member and attempts to balance. A latch member may be provided for securing the board member to the line. One or more engagement members may be provided for providing a reduction to the oscillation of the line when the training aid is mounted thereto. Optionally, the board member may be placed atop a flexible and/or deformable support member to provide for balance training.