The class of “reasonable exceptions” for not wearing clerical garb, while I would say it is most certainly ingrained in most modern Catholic minds, makes me wonder about its history and development. Nowadays we seem to consider a very wide array of activities too strenuous or dirty for clericals; off the top of my head I’ve heard sports, biking, jogging, yard work, house work, and car repair. There are probably more.
From that list, however, I think back to my college roomate’s yearly editions of the “Nuns Having Fun” calendar, which had pictures of nuns from I would guess about the 1950s participating in all sorts of activities: bowling, skeet shooting, sailing, bumper cars, etc. - all in full habit. I then thought of contemporary pictures of FSSP priests and seminarians running their summer camp, which includes hiking and sports, in cassocks. In the case of religious the arguments seems stronger that they shouldn’t put aside their habit, but knowing that priests even today are willing to keept their cassocks on for more physical activity makes me curious as to what might historically have been considered reasonable exceptions to the mandate for clericals and, if these were historically different, when the standards began to shift.
I think the bike riding mentioned above is a great example of what I would consider a non-issue turned into an exception. As to riding 20+ miles, well yes riding around in a black suit might pose a health risk. But as for looking silly, who cares? For riding a bike to the store or a leisurely bike through the neighborhood clerical garb poses no real difficulty, it’s just slightly less comfortable, which I think traditional symbolism would find quite fitting.