Lots of people ask me about ideal posture for buggy running so I have some advice on that coming from Ed, The Run Doctor (a running coach). But in the meantime check out this speedy dad. You may be bored before the end but I think its interesting to observe a few things.
1) For stability at speed you must have a locked front wheel.
2) He is really upright. No hunched shoulders, no bum sticking out!
3) He manages the buggy well with one hand and uses the other to swing to help the natural bio-mechanics.
4) He doesn't run off to the side, the buggy hasn't inhibited his stride length.
I'm not saying its perfect form but its certainly interesting to look at!
Now over to you to beat the time....!