there are gyms in both avignon and arles.

the best is a place called essentiel in arles, and you can buy 11 day-passes for 110 euros.

avignon has a couple of gyms a bit out of town,

near les angles and villeneuve (over the bridge from the old town), and these will be fine if you just want the basics (i.e. a stairmaster and weights). do not expect nice showers, modern equipment, etc. -- it hasn't hit this part of provence yet! if you expect a u.s.-style gym, your best bet will be essentiel.