Abstract: A muscle training apparatus comprising a force arm (1) which is rotatably mounted in a carrier (2) and which cooperates with a simple acting or double acting force applying means, especially a gas spring (8) which with one end is rotatably mounted in a bracket (7) of a lever arm (4) included in the force arm, and which with the opposite end is adapted for being mounted in an optional position in the carrier (2) on different distances from the axis of rotation (5) of said lever arm. The force arm (1) is adapted to quickly and easily be rotated from traction operation to pressure operation and vice versa and in an optional position on a support (3). Two or more force arms (1) can be mounted on one and the same support (3) for combined traction or pressure actuation in many different alternative embodiments.