Why Do My Knees Go Inward When I Squat

The Real Culprit Behind Your Knee Collapse (It's Not What You Think)

The reason why your knees go inward when you squat isn't because your inner thighs are tight or you lack flexibility; for over 90% of people, it's a simple case of weak glute muscles and a poor mind-muscle connection. You've probably been told to "push your knees out" a hundred times. It might even work with an empty barbell. But the moment you add real weight, like 135 pounds, that familiar and frustrating knee cave comes right back. This isn't a flexibility issue you can stretch away. It's a strength and activation problem. Specifically, your gluteus medius-the muscle on the side of your hip-is asleep at the wheel. Its job is to stabilize your femur (thigh bone) and prevent it from rotating inward under load. When it's weak or inactive, your powerful adductors (inner thigh muscles) take over and pull your knees inward. Forcing your knees out is just a temporary band-aid that doesn't fix the root cause. To stop your knees from caving in permanently, you don't need to stretch more; you need to wake up and strengthen the correct muscles in your hips.

The 30-Second Test That Proves Your Glutes Are Asleep

You don't need a physical therapist to diagnose this. You can prove it to yourself in the next 30 seconds. Stand up, lift one foot off the ground, and balance on the other leg. Look in a mirror or film yourself. Do you see the hip of your raised leg drop down? Do you have to wobble your arms frantically to stay balanced? Does your standing knee immediately want to dive inward? That is called a Trendelenburg sign, and it's a clear signal that the glute medius on your standing leg is not strong enough to hold your pelvis level. Now, imagine that same instability with 150 pounds on your back. When your glute medius can't stabilize your femur during a squat, the bone rotates inward, and your knee has no choice but to follow. This is knee valgus. It's not a mystery; it's just physics. The weakness you feel balancing on one leg is the exact same weakness causing your knees to collapse in your squat. Until you fix this single-leg instability, you will always fight a losing battle against knee valgus when the weight gets heavy.

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The 3-Step Protocol to Permanently Fix Knee Valgus

Fixing knee valgus isn't about thinking "knees out." It's about reprogramming your body to use the right muscles automatically. This three-step protocol is designed to wake up your lazy glutes, groove the correct movement pattern, and then strengthen the muscles that keep your knees safe. You will need to reduce your squat weight, possibly to just the bar, for 2-4 weeks. This is not a step backward; it's building the foundation you never had.

Step 1: The 5-Minute Glute Activation Circuit

Before every single lower body workout, you must perform this activation circuit. The goal isn't to get tired; it's to establish a strong mind-muscle connection with your glute medius. You need to feel the muscles on the side of your hips working. All you need is a simple resistance band loop.

• Banded Clamshells: Lie on your side with your knees bent and a band around your thighs, just above your knees. Keeping your feet together, lift your top knee against the band's resistance. Squeeze for 2 seconds at the top. Perform 2 sets of 20 reps per side.
• Banded Glute Bridges: Lie on your back with your knees bent, feet flat on the floor, and a band around your thighs. While bridging your hips up, actively push your knees out against the band. Hold for 2 seconds at the top, squeezing your glutes. Perform 2 sets of 15 reps.
• Banded Side Steps: Stand with a band around your ankles or knees. Take 20 small, controlled steps to the right, then 20 steps back to the left. Stay in a slight squat position the entire time. This is one set. Perform 2 sets.

Step 2: Re-Learn the Squat with Goblet Squats

For the next 4 weeks, the barbell back squat is not your main lift. The goblet squat is. Holding a dumbbell or kettlebell in front of your chest acts as a counterbalance, making it much easier to sit back and maintain an upright torso. This position naturally encourages your knees to track correctly.

• How to perform it: Grab a moderate-weight dumbbell (start with 20-30 lbs) and hold it vertically against your chest. Set your feet shoulder-width apart, toes pointed slightly out (about 15 degrees). As you descend, think about spreading the floor apart with your feet. Go as deep as you can while keeping your heels on the ground and your chest up.
• Your workout: Perform 3-4 sets of 8-12 reps. The weight should be challenging but allow for perfect form on every single rep. If your knees start to cave, the weight is too heavy. This exercise is your teacher.

Step 3: Strengthen the Weak Links with Accessory Work

After your goblet squats, you'll finish your workout with exercises that directly target the muscles responsible for knee stability. This is how you build the long-term strength to prevent valgus collapse forever.

• Single-Leg Romanian Deadlifts (RDLs): This is the ultimate test of single-leg stability. Hold a light dumbbell (10-25 lbs) in the hand opposite your standing leg. Hinge at your hip, keeping your back flat, until you feel a stretch in your hamstring. Focus on keeping your hips level. Perform 3 sets of 8-10 reps per leg.
• Banded Goblet Squats: This is a more advanced version of Step 2. Place a resistance band around your thighs, just above the knees. Perform a goblet squat, but now you have to actively fight the band pulling your knees inward. This forces your glute medius to work overtime. Use a lighter weight than your normal goblet squat. Perform 3 sets of 12-15 reps.

Your 4-Week Timeline: What Progress Actually Looks Like

Fixing a motor pattern takes time and patience. You are overwriting years of bad habits. Do not rush this process. Here is what you should expect week by week.

Week 1-2: Rebuilding the Foundation

You will not be barbell squatting. Your entire focus is on the activation circuit and perfecting your light-weight goblet squat. It will feel frustratingly easy, but it's critical. Success in these two weeks isn't measured by weight lifted; it's measured by feeling. Can you feel your side-glutes burning during the clamshells? Can you perform 12 goblet squats with a 30 lb dumbbell without any knee cave? This is your new definition of progress.

Week 3-4: Reintroducing the Barbell

Continue your activation circuit. You can now add light barbell back squats back into your routine *after* your goblet squats. Start with just the 45 lb bar. Film your sets from the front. Your goal is 3 sets of 8 reps with zero knee cave. If you can do that, you can add 5-10 pounds next week. The moment you see your knees wobble, you've found your current limit. Hold at that weight until the form is perfect. You might end week 4 squatting only 95 pounds, but you'll be doing it with a stable base that can actually support future growth.

Month 2 and Beyond: Building Resilient Strength

By now, the activation should be automatic. You should be able to squat over 85% of your old max with significantly better form. A tiny bit of knee movement on a true one-rep max is acceptable, but your working sets of 3-8 reps should be clean. You've fixed the problem. Now your job is to continue getting stronger with good form, keeping the accessory work in your program to ensure the weak links never become weak again.

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Frequently Asked Questions

The Role of Ankle Mobility in Knee Valgus

Poor ankle mobility can force your body to compensate, sometimes leading to knee valgus. A quick test: sit in a deep squat with no weight. If your heels lift off the floor, you have an ankle restriction. If your heels stay down but your knees still collapse, the primary issue is weak hips, not tight ankles.

Using Bands Around the Knees During Squats

A light resistance band around your knees is an excellent teaching tool for warm-ups and light sets (under 60% of your max). It provides tactile feedback, forcing your glutes to fire to keep your knees out. However, do not become reliant on it for your heavy working sets, as it can alter your natural mechanics.

Is Knee Valgus Always Bad?

A small, momentary knee twitch on a true 1-rep max lift is not a major concern. However, consistent and noticeable knee collapse on your regular training sets (e.g., sets of 5 reps) is a pattern of instability that places cumulative stress on your knee ligaments over thousands of reps, increasing long-term injury risk.

How Foot Position Affects Knee Collapse

Your ideal stance allows your knees to track in line with your feet. For most people, this is feet shoulder-width apart with toes turned out 5-15 degrees. A stance that is too wide can sometimes make it harder to control the femur, worsening knee cave. Experiment within this range to find what feels most stable for your hips.

Fixing Knee Valgus on Only One Side

It is very common for one knee to cave in more than the other, usually on your non-dominant side. The solution is the same, but with an added focus on single-leg work. Add one extra set of single-leg RDLs and clamshells on the weaker side to help it catch up.