A physical training apparatus includes a housing, a flywheel mechanism accommodated in the housing, the flywheel mechanism including a spindle, at least one flywheel mounted on the spindle and bearings to support the spindle in the housing, a windable pull element, such as a pull cord or band, which is arranged to be wound up the spindle and unwound from the spindle, and a handgrip attached to the pull element. The spindle includes a spindle end portion. The flywheel is exchangeably mounted on the spindle end portion against a stop located on the spindle. A fastening knob is releasably coupled to the spindle end portion and adapted to engage the flywheel and force it against the stop located on the spindle.