It sounds more extreme than it is—“forced exercise” is simply tandem riding in which patients are required to pedal 80-90 rpm.
1906, initialism from revolutions per minute.
rpm or r.p.m.abbr. revolutions per minute
operating system, tool A Unix package-management system that helps installation of software packages; similar to an install program. [More details? Reference? Expansion?] (1996-03-07)