Common Exercise Form Mistakes (And How to Actually Fix Them)

Bad form rarely comes from not knowing the "right" technique. It comes from compensating for something, a weak point, a mobility restriction, or a weight that's too heavy for your current position.

Here are the most common breakdowns on the lifts that matter most, and what actually fixes them.

Squat: knees caving in

What it looks like: Your knees track inward as you stand up, especially near the top of a hard rep.

Why it happens: Usually weak glutes (specifically the glute medius, which controls hip rotation) or a weight that's heavier than your current hip stability can control.

The fix: Actively think "push your knees out" throughout the rep, not just at the bottom. Add single-leg work (Bulgarian split squats, step-ups) to build the stabilising strength that a bilateral squat doesn't directly train. If it happens consistently at a specific weight, that weight is currently too heavy to control safely, drop it and rebuild.

Squat: heels rising off the floor

What it looks like: Your weight shifts onto your toes, heels lift slightly, especially at the bottom of the squat.

Why it happens: Limited ankle mobility. Your shin can't travel far enough forward to keep your heel down while reaching depth.

The fix: Work on ankle dorsiflexion mobility directly (weighted ankle stretches against a wall). In the short term, a small heel lift, either dedicated squat shoes or a pair of small plates under your heels, reduces the ankle mobility demand.

Deadlift: rounding the lower back

What it looks like: Your lower back rounds as you pull the bar off the floor, particularly with heavier loads.

Why it happens: The weight is too heavy for your current ability to maintain a braced spine, or you're not engaging your lats to keep the bar close to your body.

The fix: Before every rep, actively pull your shoulders down and back, and think "bend the bar around your shins" to engage your lats. If rounding happens consistently, it's a clear signal to reduce the weight and rebuild your setup position before adding load back. Never train through a rounded lower back under load, this is one of the few gym mistakes with genuine injury risk.

Bench press: bar path drifting toward your face

What it looks like: Instead of a slight J-curve (down toward your chest, up and slightly back toward your face), the bar moves in a straight vertical line or drifts too far forward.

Why it happens: Often a lack of shoulder retraction (not pinning your shoulder blades back and down) or pressing with the shoulders instead of driving through the chest and triceps.

The fix: Set your shoulder blades back and down before unracking, and keep them pinned throughout the set. Lower the bar to your mid-to-lower chest, not your neck, and drive it up and slightly back toward your face.

Overhead press: excessive lower back arch

What it looks like: Your lower back arches significantly as you press the weight overhead.

Why it happens: Compensating for limited shoulder mobility or a weak core by using your lower back to help "throw" the weight up.

The fix: Brace your core hard before each rep, as if you're about to be punched in the stomach. Squeeze your glutes throughout the lift, this limits your ability to over-arch. If mobility is the limiter, work on thoracic spine extension and shoulder flexion drills.

Barbell row: using momentum instead of your back

What it looks like: A jerking motion where your torso swings to help heave the bar up, rather than a controlled pull driven by your back muscles.

Why it happens: The weight is heavier than your back can currently pull with strict form, so your body recruits momentum to move it anyway.

The fix: Reduce the weight until you can perform the movement with a fixed torso angle and control both the lifting and lowering phase. A small amount of momentum on the final rep or two of a hard set is fine (this is sometimes deliberate), but if every rep looks like a heave, the weight is too heavy for the exercise's purpose.

The pattern behind almost every form breakdown

Look back through the list above and you'll notice the same two root causes repeating:

1. The weight exceeds what your stabilising muscles or mobility can currently control.
2. You're not consciously cueing the position you need before the rep starts, you're relying on it happening automatically.

Fixing form is rarely about learning a completely new technique. It's about reducing the weight to a level your current form can actually control, then rebuilding the load back up while keeping that form intact.

How to actually check your own form

Most people can't feel their own form breakdowns in real time, the body compensates automatically, and it feels normal because it's the pattern you've reinforced.

Three practical options:

Record yourself. A side-angle video of your working sets, reviewed after the session, catches almost everything listed above.

Watch the demo, then compare. Before you attempt an unfamiliar exercise, watch a proper demonstration and note the 2–3 key positions (where your knees should track, where the bar should travel). Check your own video against those specific points rather than trying to judge "does this look right" generally.

Reduce weight until you can self-correct. If you can't tell whether your form broke down, that's usually a sign the weight is above the threshold where you have enough control and attention left to monitor yourself.

Using RepEight's exercise library to fix form

Every exercise in RepEight's 1,400+ exercise library includes an animated demo GIF and written form cues, viewable in the same screen where you log your sets. Instead of guessing at a movement or trusting memory from a video you watched weeks ago, you can check the correct positioning immediately before you load the bar.

Bad form is rarely a knowledge problem. It's a load problem. Fix the weight first, and the form usually follows.

Browse the full exercise library to check your form on any movement before your next session.