Janu Sirsasana: A Complete Guide to Head-to-Knee Pose
Also called Janu Sirsasana
Quick Intro
Janu Sirsasana (Head-to-Knee Pose in English) is a yoga exercise performed seated, with one leg extended and the sole of the other foot resting against the inner thigh, rotating the torso slightly toward the extended leg and folding forward over it while reaching the hands toward the foot.
Equipment Needed
No equipment is needed to perform Janu Sirsasana. A yoga mat is optional and mainly cushions the sit bones during the seated fold.
Why Janu Sirsasana Matters
The back of the extended thigh (hamstrings, biceps femoris and semitendinosus) takes the main stretch of this pose, and the inner thigh (adductors) of the bent leg opens to allow the foot to rest against the inner thigh. The outer thigh (IT band, TFL) lengthens along the extended leg, and the muscles along the spine (erector spinae) keep the torso hinging forward from the hips rather than rounding through the middle back.
Flexibility is the main demand of a pose built entirely around a single-leg hamstring stretch.
When to Do It
Janu Sirsasana works well for anyone wanting a single-leg hamstring stretch with a mild rotation component, distinct from a two-legged seated fold. Most sessions built around seated poses can include it comfortably.
- Tight hamstrings on one side more than the other. Working one leg at a time makes it possible to address side-to-side differences that a two-legged fold tends to average out.
- Lower back discomfort in a fully symmetrical seated forward fold. The slight rotation and bent-leg support here changes the load on the spine compared to folding over two straight legs at once.
- A desire to build toward a deeper two-legged fold gradually. Training one leg at a time can build confidence and range before combining both legs in a symmetrical fold.
For most people, this is a useful seated stretch on its own, and it exists specifically to train each leg individually before, or alongside, any two-legged version.
Getting Ready
A couple of minutes of gentle seated hip openers and a few slow knee circles warm the hips before this seated fold. Sitting tall with both legs extended, without folding yet, previews the long spine this pose is built around before any forward reach begins.
Hinge from the hips over a long spine, keeping the reach for the foot secondary to that length. A common compensation is letting the extended leg’s knee bend, which should stay straight and active throughout.
Step-by-Step Instructions
1. The base. Sit with one leg extended straight ahead and the other bent, sole of the foot against the inner thigh.
2. The square. Square the torso toward the extended leg, rotating slightly if the hips allow.
3. The hinge. Hinge forward from the hips, reaching the hands toward the foot, shin or ankle.
4. The hold. Keep the extended leg’s knee straight and the spine long, breathing steadily, for the target breath count.
5. The release. Engage the core and lead with the chest to rise back upright before switching sides.
How Many, How Often
Janu Sirsasana is dosed by breath count per side, since a steady breath allows the hamstring to release gradually deeper into the fold.
| Level | Where you’re at | What to do |
|---|---|---|
| Beginner | Limited reach or tight hamstrings | Hold for 3 to 5 breaths per side, using Janu Sirsasana — Strap Variation looped around the extended foot. |
| Intermediate | The strap version feels stable | Hold for 5 to 8 breaths per side, reaching the hands directly to the shin or ankle. |
| Advanced | The foot is reachable with a long spine | Hold for 8 breaths per side, or move toward Janu Sirsasana — Full Fold once the fold deepens with good control. |
Keeping the extended leg’s knee straight and the spine long matters more here than how far forward the fold reaches, since a bent knee removes the exact stretch this pose is meant to build.
Modifications and Variations
Janu Sirsasana sits in the middle of its own progression, with an easier step below it and a harder step beyond it.
For an easier entry point, Janu Sirsasana — Strap Variation loops a strap around the extended foot, letting the spine stay long even when the hands can’t yet reach the foot directly.
For more difficulty, Janu Sirsasana — Full Fold deepens the fold until the forehead rests on the shin, requiring significantly more hamstring and lower-back flexibility.
Progression path: Janu Sirsasana — Strap Variation → Janu Sirsasana → Janu Sirsasana — Full Fold
Use the strap for as long as it takes for the hamstring to lengthen, keeping the spine long the entire time.
Common Mistakes to Avoid
Rounding the back to reach the foot. This fault shows up in any seated forward fold, and it shifts the stretch away from the hamstring and into the lower back. Using a strap keeps the spine long regardless of current flexibility.
Letting the extended leg’s knee bend during the fold. A bent extended knee removes most of the hamstring stretch this pose is built around. Keeping that leg straight and active, even if the fold stays shallow, protects the pose’s purpose.
Forcing the torso to square fully when the hips don’t allow it. Some hips can’t square completely toward the extended leg without strain. Allowing a slight rotation is a normal part of this pose, not a fault to correct away.
Holding the breath while sinking into the stretch. A demanding hamstring stretch tempts bracing and shallow breathing. Breathing slowly and audibly through the hold helps the muscle release.
After Your Set
Hugging both knees into the chest and rocking gently side to side releases the hips and lower back that worked through the seated fold. A few slow ankle circles on the extended foot ease the leg that held straight throughout the hold.
Going Deeper
This pose is usually trained by anyone wanting a single-leg hamstring stretch, or by anyone building gradually toward a deeper two-legged seated fold. The most common way it stalls isn’t the hamstring’s length, but the back rounding to chase a deeper reach, which shifts the stretch away from the hamstring and into the lower spine instead. Keeping the spine long at whatever depth is available, rather than sacrificing that length for a lower reach, is what keeps this pose training the right muscle.
Someone new to this pose generally holds a steady 5-breath version with a strap within the first two to three weeks, and reaches the foot directly with a long spine somewhere in the four to eight week range, depending on existing hamstring flexibility.
How to Know You’re Improving
- A 5-breath hold on both sides with the extended knee staying straight
- A spine that stays long through the fold, with the reach a secondary bonus
- Hands that reach progressively closer to the foot over time without a strap
- A comfortable 8-breath hold on both sides with even depth
A spine that stays long through the whole fold, not how far forward it reaches, is what progress looks like here.
Muscles Worked
- Biceps Femoris (the outer hamstring at the back of the thigh, stretched along the extended leg)
- Semitendinosus (the inner hamstring at the back of the thigh, lengthened as the torso turns slightly toward that leg)
- Adductors (the inner thigh muscles, opened on the bent-leg side by the turned-out knee)
- Erector Spinae (the muscles running along the length of the spine, lengthening as the fold deepens)
- IT Band and Tensor Fasciae Latae (a band of connective tissue running down the outside of the thigh, drawn long on the extended leg by the slight rotation)
FAQ
Do I need to square my hips completely toward the extended leg? No. A slight rotation is normal and expected for many bodies. Forcing a full square when the hips resist tends to cause strain without adding any benefit.
Why does one side feel much tighter than the other? This is common and doesn’t indicate a problem. Training each side individually, exactly what this pose is built for, is a sound way to address that difference over time.
Should I use a strap even once I can almost reach my foot? Yes, if reaching the foot means rounding the back even slightly. The strap exists to protect the spine, not just for those who can’t reach at all.
How is this different from a two-legged seated forward fold? This pose works one leg at a time and adds a mild rotation, letting each side’s flexibility be trained individually and tracked separately.
Next in this series: Janu Sirsasana — Strap Variation for a strap-supported entry, and Janu Sirsasana — Full Fold for the fullest expression of the fold.