OCCWMF - I'm old enough to remember (and have a copy in the loft) of the RCAF 5BX publication:
"The diversity of work assignments, combined with lack of adequate gymnasium facilities at many of our stations makes it difficult to schedule formal physical training periods for all our personnel. The 5BX Plan puts physical fitness within reach of every member of the RCAF."
You can down load the first edition (1960)
here and the 3rd (1975)
here.