MPBandmom, that was the first run of the season for that team of dogs and was only a total of 1.25 miles. It's barely enough for them to get some adrenalin going and then use it up. The four-wheeler is used while their isn't enough snow to safely run a sled (some mushers do use snowmachines for early season work, though). The team is actually pulling against the resistance of the engine much of time. We give just enough power (or enough resistence) to maintain a relatively stead speed of about 10 MPH for my dogs. Using the machine allows us to control speed without wearing out brake pads.
The goal on the machine (or any other rig) is to try to duplicate the resistance of a heavily loaded sled, so they have to work harder going up hill. The only real advantage to a machine over a bike, scooter or cart is that we can safely run larger teams and/or we can bring along a helper in case we have to clear a tangle, as I had to do in the first part of the video.
Sled dogs will almost always take off as fast as the musher will allow them to go. During the first mile or it's our job to use the brakes to slow them so they don't use up all their energy in a mad dash. During that first mile or so I try to keep them down to a fast trot or slow lope. If I were working with sprint dogs rather than cruising dogs I'd do the whole run faster, and particularly I'd let them open up a bit more at the start - say 18 to 20 mph.
I'm sure that dryland mushers have to train a bit differently than those of us working with larger teams, but I don't really know the nuances. There is an active "Dryland Mushing" category on the Sled Dog Central dot Com forum you might want to check out. You can compare notes with others who are active in your particular discipline. http://www.sleddogcentral.com/forum/def ... ?CAT_ID=13
How does Sky behave at the end of your run? If she drinks her water and then lies down to rest you are working at the right distance to build endurance. If she is still interested in visiting, playing, etc. there is still a lot of "gas in the tank", and you can bump up the mileage. That's assuming her behavior is typical. For your discipline, I'd guess bumping up the mileage in 1 mile increments would be about right. With my guys I increase run distance by increments of 3 to 5 miles.
So, in the video most of our dogs were still on their feet after the run. The only dog who actually lied down to rest was Orion and that is just an individual behavioral quirk that he shares with his late father, Torus. Like Torus, Orion and his brother both instinctively take advantage of every rest break they can get. Orion's co-leader, Rose, was still up and about ready to run some more. Heck, most of the dogs weren't even panting hard. As I mentioned early, even going up hill that mile and quarter is just enough to warm their muscles and help them settle their brains. If trail conditions allowed I'd start them at 5 miles and be ready to bump up to 8 after just a couple of those. We still need another four or five inches of snow to be able to cross a muskeg without jolting the machine apart before we can do that (sigh). If this snow drought persists, I'll have to truck the team to access better, longer safe trails.
When sled dogs look back toward the musher, it can hint at many things. In a leader, the dog may be asking for direction or reassurance. A simple "good girl" or "straight ahead" cue usually resolves it. It may signal that the dog needs to pee or poop (we train ours to relive themselves while running), it may indicate s/he is nervous about the vehicle. In that case, reassurance and consistently safe experiences pulling the vehicle solves it. I'd suspect in Sky's case it was the latter and you handled it perfectly.
"Once infected with the mushing virus, there is no cure. There is only trail." - Sven Engholm