Recently (here) I looked at a Daily Express health based comic strip. This is the only other strip I know of but there may be others! This is by the same writer (Ridwan Aitken) but a different Modesty Blaise artist - this time it's Romero.
The whole point of Isometrics seems to be that you can exercise without moving. You just don't move for six seconds (!!!) and that's your exercise. Can't believe this stuff isn't still very popular unless, just maybe, it doesn't work.
All other mentions of Romero on the blog are here
For newspaper strips click here