Is there a label on your jogging suits? If the terrycloth is a natural fabric ie: 100 percent cotton, you would need a different type of dye, the kind you'd get at Dick Blick's or another artists supply store. If it is cotton/poly blend as I suspect it might be, the RIT should've worked.
But one thing that ruins the absorbency of dyes is fabric softener, so if you decide to re-dye them, wash them first without any fabric softener, and perhaps even with some vinegar or other astringent to strip any coating from the fabric as a preparation for dying. Fabric softener actually coats fabric, and that keeps dyes away, that is why if you ever do tie dying or other dying, you pre-wash the fabrics, the companies add starch & other goodies to make their products look their best in packaging and that prevents dye from reaching the materials.
A recent article I read in a quilting artist magazine said that RIT is actually good dye, particularly for synthetic fabrics, which aren't able to be easily died with artists' dyes. My son used to use it to dye his favorite t-shirts after they were stained. It worked great for that and lasted a while.
I hope all that helps you.
Good luck!
D.