I mean they weren't bred or trained as sled dogs, but of course they love(d) running and pulling stuff, and I have had them pull me along on a sled before - but mostly what they've done is canicross (long distance running with me and my partner, training for half- and full marathons, attached to us with specialised harnesses and bungie cords) and bikejoring (me cycling, dogs attached to bike with special arm and harness).

Although with them turning 14 in a few weeks, and one now being blind, they're not really into that sort of thing anymore - long, sniffy walks with a bit of bouncing around are fine, otherwise it's snoozing on their favourite cushions.