What exposures can I get away with when using a monopod and a 400mm f5.6 lens? (d700)

Dear All

I have never used a monopod, but I am thinking of getting one, to use primarily indoors, at a pool where my kids swim.  Right now I have an old Tokina 400 f5.6 manual focus lens, which I bought for $40, and is in really good condition, and also an older 70-210 mf lens.

What kind of exposure should I expect to get away with when using the monopod? For instance, could I get sharp pictures if I used 1/60 s with the 400? Or does the use of the monopod only helps in that I don't have to hand-hold a big heavy lens, and I still need to use 1/400 s or faster?

thanks

Christos