An apparatus (20, 900) for performing isometric exercises comprising: a frame (22, 902) having a base (24, 904) and a sidewall (26, 906) joined to the base (24, 904), the base (24, 904) having an exercise platform for supporting a user's body; a restraint arm assembly (330, 1060) connected to the frame (22, 902), the restraint arm assembly (330, 1060) including: a swing arm pivotally connected to the base (24, 904) and disposed opposite the sidewall; a restraint arm carried by the swing arm and positionable above the exercise platform to inhibit movement of a portion of the user's body so as to allow the user to perform isometric exercises; the restraint arm being positionable to extend across an exercise area between the swing arm and the sidewall; the restraint arm having a first portion attached to the swing arm and a second portion releasably connected to the sidewall (26, 906); an indexing assembly for fixing the swing arm in a predetermined angular position (θ a - θ k) selectable from a set of discrete angular positions relative to the base (24, 904); and at least one limb restraint accessory (152, 540) positionable at predetermined locations along the base (24, 904) for inhibiting movement of the user's limb so as to allow the user to perform isometric exercises; wherein the sidewall (26, 906) has defined therein a plurality of indexing bores (310a - 310k); each indexing bore corresponds to one of the predetermined angular positions (θa - θk) and is configured to receive the second portion of the restraint arm, and wherein the plurality of indexing bores (310a - 310k) is disposed along a length of the sidewall (26, 906) that corresponds to a majority of the length of the base (24, 904); and wherein the sidewall is usable as a restraint for performing isometric exercises. a frame (22, 902) having a base (24, 904) and a sidewall (26, 906) joined to the base (24, 904), the base (24, 904) having an exercise platform for supporting a user's body; a restraint arm assembly (330, 1060) connected to the frame (22, 902), the restraint arm assembly (330, 1060) including: a swing arm pivotally connected to the base (24, 904) and disposed opposite the sidewall; a restraint arm carried by the swing arm and positionable above the exercise platform to inhibit movement of a portion of the user's body so as to allow the user to perform isometric exercises; the restraint arm being positionable to extend across an exercise area between the swing arm and the sidewall; the restraint arm having a first portion attached to the swing arm and a second portion releasably connected to the sidewall (26, 906); an indexing assembly for fixing the swing arm in a predetermined angular position (θ a - θ k) selectable from a set of discrete angular positions relative to the base (24, 904); and a swing arm pivotally connected to the base (24, 904) and disposed opposite the sidewall; a restraint arm carried by the swing arm and positionable above the exercise platform to inhibit movement of a portion of the user's body so as to allow the user to perform isometric exercises; the restraint arm being positionable to extend across an exercise area between the swing arm and the sidewall; the restraint arm having a first portion attached to the swing arm and a second portion releasably connected to the sidewall (26, 906); an indexing assembly for fixing the swing arm in a predetermined angular position (θ a - θ k) selectable from a set of discrete angular positions relative to the base (24, 904); and at least one limb restraint accessory (152, 540) positionable at predetermined locations along the base (24, 904) for inhibiting movement of the user's limb so as to allow the user to perform isometric exercises; wherein the sidewall (26, 906) has defined therein a plurality of indexing bores (310a - 310k); each indexing bore corresponds to one of the predetermined angular positions (θa - θk) and is configured to receive the second portion of the restraint arm, and wherein the plurality of indexing bores (310a - 310k) is disposed along a length of the sidewall (26, 906) that corresponds to a majority of the length of the base (24, 904); and wherein the sidewall is usable as a restraint for performing isometric exercises.