Hug Knees To Chest
Also works: Glutes
Lying on your back and drawing both knees toward your shoulders with your arms hooked under the thighs. Full spinal flexion with the floor supporting every vertebra, which makes it the lowest-risk way to take a stiff or sore lower back through its full flexion range.
Own the movement
Set up first, then execute. Every cue below is something you can check on your next set.
Before the first rep
- Lie flat on your back on a mat, knees bent and feet on the floor to start.
- Draw one knee up at a time rather than throwing both up together, especially if your back is sore.
- Hook your hands underneath the thighs, just above the back of the knee — not over the top of the shins.
- Let your head and shoulders stay down on the floor; there is no reason to curl up.
Every rep
Breathing & tempo — Breathe into your belly against your thighs. Take five seconds to draw the knees in, hold while breathing normally, and take five seconds to release.
How much, how often
Where to start, and what to change when it stops being hard.
No load. Two or three holds of 20-30 seconds, or 8-10 slow rock-and-release repetitions if a static hold feels stiff. Safe to do daily, even twice daily. Progress by taking the knees wider and further toward the shoulders rather than by pulling harder.
What goes wrong
The errors that show up most often, and the cue that fixes each one.
Move your hands to the backs of the thighs above the knee. The pull should compress the hip, not squeeze the kneecap into the joint.
Rest your head on the floor or a thin cushion and keep it there. If you are curling up, this has quietly become an abdominal exercise.
Start with feet planted, bring one knee up and hold, then add the second. Ease into the tuck over five seconds instead of yanking.
Return one foot to the floor at a time with the knee bent. Lowering two straight legs loads the hip flexors and pulls the lumbar spine into an arch — the exact thing you were just decompressing.
Why bother
Pulling both knees up tips the pelvis backwards and flattens the lumbar curve, opening the space between the vertebrae at the back. Because you are lying down, the spine carries almost none of your bodyweight while it moves — the same range standing would load every disc.
Aiming the knees toward the shoulders rather than straight into the chest adds glute maximus, since flexing the hip past about 120 degrees with the knee bent is where that muscle actually lengthens. That is the difference between this and a plain double knee tuck.
Where it fits
First thing in the morning if your back is stiff overnight, at the end of a lifting session, or before bed — two or three holds of 20-30 seconds, and cheap enough to do daily. Pair it with a hip flexor stretch, because it does nothing for the front of the hip. The one slot to avoid is the last few minutes before heavy hinging: a fully flexed spine is not what you want to load immediately afterwards.
If this one isn't it
No kit, too hard, or too easy — here's where to go instead.
Same job, different kit
Start here instead
When this gets easy
Asked and answered
Is this safe when my lower back is already sore?
Usually yes, and it is often the first movement people tolerate after a back episode, because the floor carries the load. The exception is symptoms that run down a leg — if the tuck produces or worsens tingling, numbness or shooting pain below the knee, stop and get it looked at.
One knee or two?
Two if the goal is lumbar flexion, since both legs are needed to tip the pelvis fully. One knee at a time, with the other leg flat, biases the glute and hip of the pulled side and is the gentler option on a sore day. Do both if you have the time.
Should I rock side to side while holding?
It feels good and does no harm, but the small side-to-side roll is massaging the erectors rather than adding range. Keep it slow, and treat it as a comfort addition rather than the point of the drill.
Can I do it in bed?
Yes, and for morning stiffness that is a practical time to do it. A soft mattress gives the spine less support than a mat, so keep the movement slow and be a bit less ambitious with the pull than you would be on the floor.