Performing explosive exercises such as jump squats can help you build more power in your legs, which can equate to more leg strength. That means that you can squat more and therefore grow bigger legs due to the greater overload.
FLEX typically recommends that you do explosive exercises first in your workout. That’s because to maximize power development you want to perform these explosive moves when the fast-twitch muscle fibers are not fatigued and at their strongest. However, a recent study shows that to boost testosterone levels higher, which can help promote greater muscle growth, you might want to do the jump squats after your heavy squats.
New Zealand researchers had trained male athletes to perform four different workouts that consisted of jump squats and heavy squats using their 3-rep max weight. In one workout they did 3 sets of 3 jump squats followed by 3 sets of heavy squats. In another workout they first did the 3 sets of heavy squats followed by the 3 sets of jump squats. For the other two workouts they did either 6 total sets of heavy squats without any jump squats, or 6 sets of jump squats without heavy squats.
They discovered that when the athletes did the heavy squats first, followed by the jump squats, their testosterone levels were the highest. So to build more leg strength and power, as well as more leg mass, consider following squats with 3 sets of 3 jump squats. – FLEX