The barbell squat has been called the king of exercises, and unlike British royalty it has actually earned its crown. An absolute must for building thick, powerful quadriceps, hamstrings and glutes, the squat also promotes a growth response throughout the body as it calls on intensive stabilization from upper-body and core muscles during each rep. Here’s the problem, though: It’s effective, but it’s far from easy. The squat requires plenty of energy, strength and practice to master the technique, not to mention a bit of bravery as you drop into a below-parallel position with a challenging amount of weight draped across your upper back.To improve your performance, we’ve recruited an expert who knows the squat inside and out. Heather Farmer, a Tier 3 personal trainer at Equinox Fitness in midtown Manhattan, has competed in national-level Olympic lifting for the past four years while instructing clients in the intricacies of complex lifts such as the snatch, clean and jerk, deadlift, overhead press and squat. She recommends two squat-focused sessions a week, presented here- one is a squat-only workout and the other is an array of variations and assistance exercises that help improve the muscles most responsible for leg power and explosiveness. They should be done at least one or two days apart for adequate recovery.And how do you know your efforts are bearing fruit? Well, by doing a max test, of course. “Do this program for five weeks, then test your max squat at the end of the sixth week, allowing at least four to five days of recovery before the test,” Farmer says. “A max could be tested as often as every three weeks or as infrequently as 12 weeks, but six weeks is pretty common.”Maxes can vary: You can test a three-rep max, five-rep max or traditional one-rep max,” she adds. “Testing different sets can be helpful, but I’d recommend doing the one-rep more often than the others. Otherwise, if you do a one-rep max to start and then in six-week increments do a five-rep max, three-rep max and then circle back to a one-rep, it’ll have been 18 weeks since you did it last.”Warm-Up For Both WorkoutsThese are both bodyweight-only moves that are meant to loosen the legs and hips, “gradually getting the hips to sit under the shoulders with an upright torso and tight, upright lower back,” as Farmer explains. Start with lateral squats for two sets of 10 reps per side. For these, take a wide stance and sit down into a deep squat on alternating legs. Follow that with pole squats for two sets of 10 reps: Grasp a pole or stationary object (like a power rack) and descend into a deep squat, keeping your heels down, lower back tight and chest upright, allowing the hips to sit in toward the ankles.