Butt Wink in the Squat: Should You Worry About It?
Butt wink is the small tuck of the pelvis, and slight rounding of the lower back, that some people show at the very bottom of a squat. For most people squatting with bodyweight or light loads, a little of it is not something to lose sleep over. It starts to matter when it is large, when it happens under a heavy barbell, or when it comes with pain. The useful question is not “do I have it?” but “how much, under what load, and does anything hurt?” The answer usually decides itself once you film a set from the side and run a couple of simple tests.
What follows is how I assess it with clients in the studio, what tends to cause it, and the fixes worth trying before you start blaming your anatomy.
What butt wink actually is
As you descend into a squat, your hips flex and your pelvis stays roughly in line with your spine. At some point near the bottom, one of two things runs out: the hip’s available range of flexion, or your ability to control the position. When that happens, the pelvis rolls under (a posterior tilt) and the lumbar spine follows, flexing a few degrees. On video it looks like the tailbone tucking under for the last few centimetres of depth.
A few points of perspective help here. The spine is designed to flex. Everyone’s lower back moves a little during a deep squat, even in lifters with textbook technique. What we care about is a large, sudden change in position under load, repeated over hundreds of reps, rather than a few degrees of movement you can barely see.
When it matters and when it does not
| Situation | Usually fine | Worth addressing |
|---|---|---|
| Load | Bodyweight, goblet squat, warm-up sets | Heavy back squats, especially sets of 1 to 5 |
| Size of the tuck | Barely visible, last few centimetres | Obvious rounding that starts well above parallel |
| Symptoms | No discomfort during or after | Lower back aches, tightness the next day, or pain down the leg |
| Goal | General strength and health | Pushing heavy loads or competing |
If you sit in the left column, you can keep squatting and simply stop your depth just before the tuck on heavier sets. If you sit in the right column, it is worth working through the checks below. Pain that travels into the leg, numbness or a back that does not settle within a few days is not a technique problem to solve on your own: see your GP or a physiotherapist first.
Three things that commonly cause it
1. Hip anatomy
Hip sockets vary a great deal in depth and angle from one person to the next. Some people simply run out of hip flexion earlier than others, and no amount of stretching will change the shape of bone. The good news is that stance width and toe angle can change how much room the hip has, which is why the stance test below is so useful.
2. Ankle range
If your ankles cannot let the knees travel forward over the toes, the hips have to do more of the work of getting you low. The torso tips forward, the hips reach the end of their range sooner, and the pelvis tucks. This is one of the most common causes I see in people who sit at a desk all day. Our guide to ankle mobility for squats covers the tests and drills in more detail.
3. Control, not flexibility
Plenty of people can pull their knee to their chest lying on their back, which shows the range is there, yet still tuck under in a squat. That points to bracing and control under load rather than tightness. Rushing the descent, relaxing at the bottom or losing the breath halfway down are the usual culprits.
A five-minute self-assessment
You need a phone and a few minutes. Do these in order:
- Film from the side. Prop the phone at hip height, side-on, about two metres away. Do five bodyweight squats to your natural depth. Mark the point where the pelvis starts to tuck.
- Do the rock-back test. Get on all fours, keep your back flat and rock your hips back towards your heels. If your lower back rounds at roughly the same hip angle as in your squat, you are likely at the end of your hip range. If it stays flat well past that point, look at ankles and control instead.
- Raise your heels. Put a small plate or a pair of wedges under your heels and film again. If the tuck reduces noticeably, ankle range is a big part of the story.
- Change your stance. Try a slightly wider stance with toes turned out 15 to 30 degrees. Many people find their hips suddenly have more room.
- Slow it down. Take three seconds to descend, brace hard before you start and keep the breath held until you are back up. If the tuck shrinks, control was the issue.
Fixes worth trying, in order
Most people do not need an elaborate mobility programme. Work through these in roughly this order and retest every couple of weeks.
- Find your stance. Settle on the width and toe angle where you squat deepest without tucking. This is free and often solves most of the problem.
- Squat to your real depth. For heavy sets, stop just above the point where the tuck starts. Use a box or bench as a target, which is the main idea behind box squats. Depth can be built gradually.
- Use a front-loaded squat. Goblet and front squats keep the torso more upright and make it easier to keep the pelvis neutral. They are excellent teaching tools.
- Improve bracing. Take a big breath into the belly and sides, tighten as if about to be prodded in the stomach, then descend. Hold that pressure until you have stood up.
- Work on ankles if the heel test helped. Knee-to-wall drills and calf work done a little and often tend to beat a long weekly stretch session.
- Pause at the bottom. A two-second pause at the depth you can hold well teaches you to own the position rather than bounce through it.
Common mistakes
Chasing depth for its own sake. Deep squats are a fine goal, but there is no prize for hitting depth with a rounded lower back under a heavy bar. Strength built through a slightly shorter range still carries over well.
Stretching hamstrings to fix it. This is a popular idea that rarely helps. In a squat with bent knees, the hamstrings are not usually the limiting factor.
Overcorrecting into an arched back. Some people try so hard to avoid the tuck that they crank the lower back into an exaggerated arch. That is not neutral either, and it tends to make the tuck at the bottom bigger because the pelvis has further to travel.
Judging it from the front mirror. You cannot see butt wink from the front. Film from the side or have someone watch you.
How a coach handles it
In a private personal training session in Highgate, this is usually a ten-minute job rather than a project. I watch a few reps from the side, run the rock-back and heel tests, try two or three stances, and then choose a squat variation and depth that suits your hips today. From there we build range over a few weeks while the heavy work stays in positions you control. If you are newer to the lift, our guide to squatting properly covers stance and bracing from scratch, and you can see how our 1-1 coaching packages are structured, with current prices, on the training page.
If you have a history of back problems, are returning after a long break, or are pregnant, check with your GP before adding heavy squats. The NHS also has sensible general guidance on back pain and when to seek help.
Questions we get asked
Is butt wink dangerous?
A small amount at light loads is generally not considered a problem. A large tuck under heavy loads, repeated often, is worth reducing because it puts more of the load through a flexed lower back. If you have pain, get it assessed.
Will stretching fix butt wink?
Sometimes, if ankle range is the limit. If the cause is your hip anatomy, stretching will not change it, and a stance change or slightly shorter range is the better fix.
Should I squat to parallel or below?
Squat as deep as you can while keeping a neutral pelvis and lower back. For some that is well below parallel, for others just above. Both build strength.
Do weightlifting shoes help?
Raised heels often reduce the tuck in people whose ankles are the limiting factor. They will not help much if the hip itself is the limit.
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