An isometric exercise apparatus adaptable to an existing treadmill or similarly shaped platform provides a height-adjustable bar assembly and rigid supporting pole portions. The horizontal bar is vertically adjustable by selectively unclamping and sliding the bar along the vertical bars. The apparatus may be adjusted and secured in various positions for singular or combined use with the treadmill. The mounting means of the apparatus to frame portions of the treadmill allows for easy disassembly and storage of the apparatus in a closet or under a bed.