It can be easier to understand knee alignment if you don’t think of it as an exact position, but as a movement direction. In a squat and lunge, the knees generally should track in the same direction as the toes, not drop sharply inward, or wander aimlessly. This doesn’t mean every body’s look is the same. It means a pattern in which the knee, foot, hip, and core work in a connected, sensible way.
A good place to start is the feet. Before squats, stand on both feet, and assess whether your weight is mostly in the heels, mostly in the toes, or spread evenly on your whole foot. If your arches collapse, or you’re gripping the floor with your toes, the knees might mirror that. Try some shallow squats, with the big toes, small toes, and heels pressing down. That makes the feet more stable, so the knees can find a good base to move off of.
Lunges can be more difficult because the knees can be harder to guide, due to having a smaller base. Start with a shallow lunge instead of a deep one. The front foot remains stationary and descend only as far as you can, such that the front knee still traces roughly toward the center of your toes. If the knee collapses inward, reduce the range of motion, slow your tempo, or grab onto a chair or wall for stability. This is not cheating; this allows you to work on the alignment cue, separate from balancing yourself.
A quick check can make this easier to spot. Stand in front of a mirror (or use your phone from the front, if that’s possible). Do a few repetitions of a slow squat, and stop midrange. Check whether one knee tracks differently than the other, if the feet roll in, and whether the hips drift. Keep the repetitions low so that you can see this in real time. When you get fatigued, it’s very hard to spot the patterns when the movement is accelerating.
The breath may affect your alignment more than many beginners are aware. If you hold your breath and grip too much, the movement can get stiff. If you lose control, then the knees and hips can collapse. Try inhaling before the repetition, then exhale gently as you stand back up. Combine that with a light core activation, like you’d do to brace the trunk but not lock it. A squat should feel more natural and comfortable with the breathing and tempo working in concert.
Try not to adjust your knees by forcing them to flare out, which could produce another form of stress that forces your feet to turn out. It’s typically a quieter cue: the knees track the toes, the feet stay on the floor, the hips are controlled, and the tempo is slow enough to spot when it’s changing. In a lunge, the same holds true, though you’ll also have to pay extra attention to your balance and front-foot placement.
A good sign isn’t that every rep is perfect. A better sign is that you start to be able to notice when your alignment breaks down, and you can adjust before you get to the sloppy end. You may shorten your lunge, choose a variation where you can use a chair, you may lower your reps, or take more time to rest. That means you’re learning the movement, not just counting reps.