Are Bulgarian Split Squats Bad for Your Knees?
What biomechanics research actually says about Bulgarian split squats and knee safety, why the exercise causes pain when it does, and how to do it correctly.
The Bulgarian split squat has a reputation for being a glute and quad builder that also wrecks knees. Both halves of that reputation get repeated a lot online without much nuance. Here’s what the actual biomechanics research says.
What the Research Actually Found
A musculoskeletal modeling study comparing back squats, split squats, and good mornings, with a specific focus on women given their higher rate of ACL injuries, found that the split squat produces meaningfully less peak knee joint displacement than the traditional two-legged back squat. In plain terms, the knee travels less and works under different loading than in a heavy barbell back squat, which is the opposite of the reputation the exercise often gets.
When It Actually Can Cause Knee Pain
The exercise itself isn’t the problem in most cases, the form is. Three specific breakdowns account for most Bulgarian split squat knee pain:
- Knee traveling far past the toes. Some forward knee travel is normal and fine, but excessive travel shifts load onto the patellofemoral joint (behind the kneecap) more than the research supports as ideal.
- Knee caving inward (valgus). This is the same mechanical pattern linked to ACL injury risk in other research, and it shows up under fatigue or when the front foot is placed too close to the body.
- Loading too much weight before the movement pattern is grooved. Unilateral exercises expose stability weaknesses that bilateral squats can hide, so adding load too fast amplifies any existing form issue.
How to Do It Knee-Safely
- Set your front foot far enough forward that your shin stays close to vertical at the bottom of the rep, rather than driving your knee well past your toes.
- Track your knee over your second toe throughout the rep, actively resisting the inward cave, especially as reps get harder.
- Master bodyweight and light-load reps first. Build the balance and control before adding meaningful weight.
- Slightly increase forward trunk lean if you feel it too much at the front of the knee, this shifts more work to the hips and glutes and reduces anterior knee stress.
Who Should Be Extra Cautious
If you have an active patellofemoral pain flare-up, a recent ACL injury, or existing knee instability, this is a good exercise to reintroduce gradually and with guidance rather than loading heavily right away. For general knee-friendly training in the meantime, see our guide to fixing knee pain and our core exercises for after 40, which don’t carry the same unilateral loading demands.
Once form is solid, the split squat pairs well with the progressive overload principles that actually drive muscle growth, and fits naturally into a home training routine that doesn’t require a barbell.
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This article is for informational purposes only and is not medical advice. See our Medical Disclaimer before changing your exercise, diet, or supplement routine.
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Frequently asked questions
Are Bulgarian split squats bad for your knees?
Not inherently. A musculoskeletal modeling study found the split squat produces less peak knee joint displacement than a traditional back squat, so knee pain from this exercise usually comes from form breakdown rather than the movement itself.
Why do my knees hurt during Bulgarian split squats?
The most common causes are the front knee traveling too far past the toes, the knee caving inward under fatigue, or adding weight before the balance and stability demands of the movement are mastered.
Are Bulgarian split squats good for knees compared to regular squats?
Research comparing the two found less peak knee joint displacement in the split squat than in a back squat, suggesting it can be a knee-friendlier option when performed with good form, though individual factors still matter.
Should I avoid Bulgarian split squats if I have knee pain?
If you have an active flare-up or instability, ease back in gradually with bodyweight only and strict form rather than avoiding the exercise entirely, and consider other knee-friendly options in the meantime.
