High-bar squats are your big-ticket move for leg size, but you have to get them right to really emphasize the quads.
Place a barbell on your upper traps while squeezing your upper back muscles together to form a shelf. If you aren't used to a bar on your upper traps it can feel uncomfortable at first. Get used to it. Just make sure the bar isn't sitting on the bony ridges of your spine or your neck.
Find your best foot position, allowing maximum hip mobility at the bottom of the squat and preventing rounding of your spine or knee discomfort. Start with heels around hip width and toes angled outward. Then adjust and use what feels best. We're often taught to use a narrow stance for better quad recruitment. This may produce more quad tension but isn't essential. If you can't set up narrow you'll still get excellent quad recruitment with good range of motion, loading, and reps.
Form a strong arch by squeezing the ball of your foot toward your heel. Externally rotate your hips to get your knees vertically stacked with your toes. The stress and tension of the load should be directed through stacked bones, joints, and muscles.
Protect your lower back by flexing the abs and locking your sternum down into your pelvis. Though the high-bar position keeps your torso more upright than the mechanics of low-bar squatting, this doesn't mean your torso must be perpendicular to the ground. Too often, lifters create a vertical position by aggressively arching their lower backs. This can lead to potential injury.
Maintain a neutral lumbar spine (natural arch) to protect your lower back. With abs locked down, elevate your chest and extend at the thoracic spine to maintain a slight but not excessive upright posture. If you're tall with long femurs, no amount of exaggerated arch will allow you to sit vertically in a squat.
Exaggerating a vertical torso also pushes the knees forward to maintain center of gravity – producing even more stress in the knee and possibly causing patella-femoral pain. This usually restricts the ability to squat deeper, which can lead to overloading a shorter range of motion squat and further aggravating joint stress. Most lifters subsequently abandon squats and knee-wrap their leg press because "they hurt my knees."
High-bar squats are more upright and quad dominant than low-bar squats. More emphasis on quads, and therefore knees, doesn't mean your knees can't handle the stress. Our joints aren't fragile structures ready to explode if loaded.
Creating strong muscles around your knees by using correct form will encase the knee with muscle to protect and stabilize it, while applying controlled stress to strengthen your connective tissue and bones over time.
Just don't be careless. Loading through the ball of the foot can cause knee pain. This may happen when your knees dive too far forward past your toes at the bottom of the squat. Your knees can and should go past your toes on a good squat.
Often lifters let their heels rise at the bottom of a squat as the focus is in the front of the foot. Maintain your weight evenly through the entire foot and push firmly through your heel as you squat. If you can't squat deeply without your heels rising, this means you have poor ankle mobility. So restrict your depth while working to improve your ankle dorsiflexion. Healthy, mobile ankles are crucial for good squatting.
Warm up with an empty bar or bodyweight set to mobilize hips, knees, and ankles and to sense any major joint discomfort early. Do 2-3 warm-up sets of 10-12 reps before moving up to working weight.
Then, use 3-4 working sets of 8-12 reps. Adjust the weight so that you get within two reps of failure to optimize muscle growth. This will produce enough mechanical tension and metabolic stress to trigger a growth response. Occasionally jumping to 15-20 reps to near failure is an unpleasant yet effective way to break plateaus.
High-bar squats are tough. Even sets of 8-12 will leave you winded while taxing your central nervous system. The goal is to do enough training volume to grow. Focus on developing the stamina to do more reps, sets, and weight.
Hitting absolute failure is fine for curls and cable rows, but it increases the chance of getting hurt on heavy compounds and accumulates fatigue more rapidly than training effect.
Excess fatigue cuts into training volume of subsequent sets and later exercises. As you progress through weeks of training, apply progressive overload with added weight, reps, and carefully timed sets.
Rest as long as needed to recover to start the next set with excellent form for the 8-12 reps. Taking only 60 seconds of rest means you aren't lifting heavy enough or giving yourself enough time to recover. Working quickly doesn't burn more body fat. Instead it cuts into training volume and overall results. Taking 2-3 minutes of rest between your working sets should be adequate.