How do you maintain impulsion through lateral work in dressage?

Maintaining impulsion through lateral work is one of the most common challenges for developing dressage riders, because the concentration required to coordinate the lateral aids often causes the leg to become passive and the forward energy to decrease, producing lateral movements that are technically in the correct position but lacking the active, flowing quality that genuinely correct lateral work requires. The most important principle is that forward always comes before sideways: the horse must be genuinely forward and active in the gait before any lateral movement is asked for, and the first sign that impulsion is being lost in a lateral movement is the signal to straighten and ride forward to restore the energy before returning to the lateral work. The leg's role during lateral work requires particular attention: in lateral movements, the legs have specific tasks — one leg maintains forward energy while the other creates the sideways movement or the bend — and the leg responsible for forward energy must not be neglected in the process of coordinating the lateral aids. The calf must remain active enough to maintain the horse's impulsion even while coordinating with the other leg for the lateral request. Transitions into and out of lateral work are valuable for maintaining impulsion: riding a few strides of leg yield or shoulder-in, then straightening and riding forward, then returning to the lateral work keeps the horse honest about the forward expectation and prevents it from gradually slowing as the lateral work continues. A horse that loses impulsion in lateral work typically needs more forward work between lateral exercises and a clearer leg aid that maintains the energy during the lateral movement rather than only providing the sideways request.