You can try pinching when the plant leafs out in Spring. It usually helps make shrubs more bushy.

Just wondering about the legginess... how much sun do they get?

Full morning sun for a few hours then filtered sun from the large Alder tree that is twenty feet away the rest of the day.

Someone posted a question about another leggy Limelight months ago. That shrub also had a few hours of sun only and the person was asking for suggestions of what shrubs could be added in front of Limelight to hide the leggy-ness.

In preparation for some outdoor construction I pruned one of my Limelights severely the first of June- and I mean down to five or so stems no more than a foot high each.
It is blooming right now.

Limelights bloom on new wood so can be pruned anytime early in the season- I usually do mine the week after I do the roses. I don't do it in the fall as pruning encourages growth and the last thing you want is new leaves during the first freeze.

I don't take them down that drastically every year but do it every 2nd or 3rd year to keep them from getting leggy and to foster the type shape I want.