The other weekend I decided to take my sailing dinghy out for a race - not used it for ages and good forecast, decent race, etc. Wind turned out to be a bit stronger than expected and I ended-up having to hike out a lot of the time. My dinghy (a Laser https://en.wikipedia.org/wiki/Laser_(dinghy)) to keep it powered-up (fast) many points of sailing you hike- put your feet under a strap in the middle of the boat, thighs rest on the side decks and bum and body hang out over the side and to get max. performance (it was a race) you should keep your body horizontal. Illustrated (from Improper course http://www.impropercourse.com/2013/03/everything-i-know-about-hiking-benches.html)
.It gets hard on your stomach muscles and as I had not been out for ages I expected to really suffer and end-up sitting up most of the time. But I found I was managing exceptionally well. My stomach muscles should have been pretty weak but were not.
So, does cycling develop your stomach muscles ?
Ian