The reel mechanism includes a case and a flexible line (webbing, etc.) retractably coiled therein. The line passes over a ramp and doubles back around a pin to exit the case. A pivoting chock has a toggle end raised by the line, depending on the line's departure path from the case, and an opposite grip end clamping the line against itself and the ramp when the toggle end is raised. Control of line payout, retraction, or locking is determined by the departure path of the line from the case. This mechanism provides sufficient clamping force on the line to support the weight of person therefrom while performing arm strengthening exercises. The case may include various handle configurations for different exercise routines, and the distal end of the line permits attachment to a variety of structures. The device may also be used as a pet leash or for other purposes.