Rising on the %22correct%22 diagonal on a circle or curve helps counterbalance the horse's movement asymmetry created by the curve itself. And if the horse is lame, the wrong diagonal could enhance that lameness and the right diagonal could mask it. | Photo: iStock

You’ve heard it since your first posting trot: “Rise and fall with the leg on the wall.” Being on the correct diagonal is all but a time-honored tradition of proper equestrianism on any curve or circle—you lift your body out of the saddle when your horse’s outside shoulder is forward and you sit through the second half of the stride, when his inside shoulder is forward.

But why?

“We don’t know,” said Marie Rhodin, PhD, Dipl. ACVSMR, associate professor at the Swedish University of Agricultural Sciences, in Uppsala. “We can’t find any history of where this ‘correct diagonal’ concept comes from, or when it began