I keep fit and wear my system whilst doing so. I play soccer once a week and I run a lot, as well as doing some weights at home. It puts some stress on the bond, but only in the sense that you need to clean and reattach more often (in the same way that sweat makes your clothes gross!). I don't have any issues while exercising, and have run full marathons in my system. The bond will loosen the more you sweat, but once you cool down, it sorts itself out.
I assume you're asking as a prospective wearer, rather than a current. If so, the take home messages are:
- You can work out as much as you want in your system. Wearing it won't hinder your workout at all
- Working out 7 days a week will mean that you will spend more time than most on things like hairline lifts. This is really not a problem. I have to fix my hairline every day, but it takes less than 5 minutes to do
- You will want to do a complete clean/reattach every week. Don't buy into any salon's sales pitch that tells you that you can leave it on between monthly visits. That will be awful for your scalp. In fact, don't even try to push it. Even if one week you think you can get away with it, don't try. I'm guessing since you work out a lot that you're the sort of guy who takes care of himself. Make this clean up part of that routine.
All in all you're good though! A year and a half a go, I didn't hair hair or a gym body. Now I have both!
N.B On the scalp thing, I spoke to my stylist about this and she said that she's had to excuse herself from her clients in the past because of the smell. It's awful how some guys allow that stuff to fester on their heads!