Battery Charging Question

I have a MAHA C401FS AA charger that has two settings, Rapid Charge and Slow Charge for charging NiMH batteries. When I use the rapid charge feature the batteries get extremely hot due to the 1000mA current being applied (slow charges at 300mA). I've heard that heat harms the batteries during charging so I put a power supply fan over the charger while it was charging on the rapid setting and the batteries never got above 97deg (externally). I am charging with the cover off. I am thinking that if I was only cooling only the surface of the battery, then as soon as the battery says it's done and I remove it from the charger the battery would start to warm at least a little bit. When I remove them (as soon as they are done) they are cool and stay that way as apposed to when I don't use the fan they are very hot. So back to my original question. If I am cooling them sufficiently then is the fast charging damaging to the battery? Is this helping me save the life of my batteries or am I wasting my time? Anyone a battery guru?