Chicken legs are the inevitable result of working out extensively the upper body while ignoring the lower body.
Any gym is filled with these guys that think that in order to achieve the magazine adonis look, they need to just work chest and biceps, and the rest will be covered with shorts or pants.
What they probably ignore is that after a certain point, even with shorts and pants covering the legs, it will be noticeable. Another negative aspect is that it will destabilize the whole body, making it more difficult to engage in full body workouts and general movements, staying in balance becomes harder and injuries because of cramps are more frequent.
I know this will surprise nobody, but the solution for the chicken leg phenomenon is to work the legs out. Squats, lunges and kettle-bell lifting with a resistance band attached to it are excellent exercises for increasing leg strength and definition.
The frequency must equal to that of upper body. If the upper body is exerted three times a week, then the lower body should also be worked out three times a week.
That aspect of full body workout that I keep mentioning: all in one, time efficiency; is another way to avoid the lower body lag. When the full body is exercised, the concentrated exercises can be left for another day.