What do people do wrt excessive when a bitch has just been mated. I always carry on with normal walks but tone down the ball throwing and tugging games. I stop agility training. I was surprised when discussing with an acquaintance that she just carries on as normal with agility classes even competing until her dogs are 5-6 weeks?

I don't treat my bitches any different exercise wise until if they are in whelp, I feel they are getting to big and heavy to cope with their normal walk and take them on a shorter route.

I let the bitches decide when enough is enough.

Our bitch was still working at 7 weeks albeit at a slower, steadier pace(in fact much better!!).  We stopped her from jumping fences and such but she still enjoyed outings and when we stopped her coming after 7 weeks, she was in such a strop with all the other dogs that still got to go.  She hated slowing down!.  Mine still swim and off-lead walk till they don't want too and infact it's only usually the last week or two that the walks are considerably slower and shorter.  I go with how my bitch feels.
One spaniel I had sat on the sofa from the minute she was mated and didn't move till the pups were 6 months.  Lazy dog!! But then, if that's how she felt, that was fine too.  Although she did have a longer, tougher labour than the bitch that worked and walked till the last week.

I wouldn't do agility with all the twisting and stretching if they're moving fast. But I do normal exercise, normal training, and I did once do an obedience weekend because I'd thought she'd missed. :-)

My BT was chasing Deer the day she started whelping, she was 4 days early!

lol kenya. My first bitch was eight weeks in whelp and heavy.  We went for a steady, short walk down near the canal when a bird shot out of a bush right under her nose.  She shot after it, down a grassy area about 50 - 75 yards wide, jumped into the canal, swam across to the other side and then swam back when she realised she couldn't climb out, ran back up the grassy area to me.  Sat panting and making a noise like a steam engine and I was panic-stricken :-(  One week later she whelped eight babies as easy as anything.  Raised them all without any fuss and went on to have another litter without any problem at all.  I let them tell me when they want to slow down.