The deep single-leg squat, aka pistol squat, has long been celebrated as a minimalist’s dream for building leg strength.
It requires no equipment, challenges your balance, and loads your legs through a full range of motion.
But beneath its tough-guy appeal lies a hidden danger that most people never talk about: serious risk to your knee, especially the meniscus.
Let’s break that down.
The Rise of the Pistol Squat (and Its Sibling)
The pistol squat gained popularity over a decade ago through books like Convict Conditioning and Pavel Tsatsouline’s The Naked Warrior. The appeal was clear: you could build strength without a gym, and supposedly do so safely, as long as your technique was “correct.”
In recent years, a sibling exercise—the ATG split squat—has taken the internet by storm. Like the pistol, it emphasizes full knee flexion, often loaded with dumbbells or a barbell. Advocates claim it builds “knee ability”—basically, tolerance to stress and load.
But just because an exercise is popular doesn’t mean it’s safe for everyone.
What Really Happens to Your Knee in Deep Flexion
Here’s the issue: when you perform these exercises, especially through the full range of motion, your knee goes into deep flexion under load. That means you’re not just squatting a bit past 90 degrees—you’re going all the way down. In this position, multiple structures inside the knee are under significant stress:
- Patellofemoral joint: High compressive forces build between the kneecap and the femur.
- Quadriceps and patellar tendons: Both experience heavy tension as you descend and try to come back up.
- Menisci: These cartilage pads absorb shock and stabilize your knee. In deep flexion, especially under load, the posterior horns—especially on the medial (inner) side—are crushed and twisted (sheared) as the femur moves over the tibia.
And that’s the danger zone.
Even with perfect form, the posterior horn of the medial meniscus is especially vulnerable. Why? Because this area gets pinched between the femur and tibia in deep flexion and can be torn by the combined compressive and shearing forces.
Real Stories, Real Injuries
You’ll find plenty of stories online of people tearing their medial meniscus doing full-range pistol squats or ATG split squats.
Sometimes there’s a loud pop during the movement, followed by swelling or stiffness. MRIs often reveal meniscus lesions—serious injuries that may require months of rehab, or even surgery.
And these injuries don’t just happen to people with sloppy form. They happen to people who are experienced, careful, and fully warmed up. I know because that’s exactly what happened to me a few years ago.
Symptoms of a Meniscus Tear
If you’re wondering whether you’ve suffered this kind of injury, here are the red flags:
- A sudden popping sound or sensation during the exercise
- Swelling that worsens over the next 1–2 days
- Locking or catching in the knee
- Persistent inflammation, heat, or stabbing pain
- Limited range of motion
In these cases, it’s essential to consult a medical professional. Meniscus injuries don’t always require surgery, but some do, especially if the tear prevents normal movement or leads to recurring swelling. Unfortunately, meniscus surgeries have long-term risks:
- Increased risk of osteoarthritis, especially if a large portion of the meniscus is removed
- Reduced shock absorption in the knee, leading to more wear on cartilage
- Persistent pain or swelling, even after recovery
- Joint instability or stiffness in some cases
- Re-tear if the meniscus was repaired rather than removed
- Degenerative changes visible on MRI or X-ray over time
The more meniscus is removed, the higher the risk—especially for active individuals or those with existing joint wear.
Why take this risk?
A Safer Alternative: The Sliding Lunge
So what should you do instead?
Try the sliding lunge. This exercise mimics many of the benefits of the pistol or ATG split squat but it’s significantly safer for your knees.
Here’s how it works:
- Stand on one leg on a slippery surface (like hardwood or with a plastic slider).
- The rear foot rests lightly behind you and slides backward as you lower yourself.
- Go as deep as feels safe, then push yourself back up.
Why it’s safer:
- You can control your depth to stay within a pain-free range.
- The shin of the front leg stays more vertical, reducing pressure on the kneecap.
- If you get stuck, you can easily assist with your rear leg—no awkward bailout needed.
- You can load it with dumbbells and drop them instantly if needed—unlike a barbell on your back.
Bottom Line
Pistol squats and ATG split squats may look impressive and offer strength gains, but they come with a serious risk to one of the most sensitive structures in your knee. Even perfect form can’t fully protect your posterior medial meniscus from the compressive and shearing forces of deep loaded flexion.
If knee longevity matters to you—and it should—ditch the pistol squat and switch to safer, smarter alternatives like the sliding lunge.
Your knees will thank you later.
