How to Extend Yoga: Poses, Benefits, and Safety Tips
To extend yoga means two things at once: moving your body into extension positions that open the spine, hips, and chest, and building a longer, more sustainable home practice over time. Most people searching this topic need both answers, and this article gives you both clearly.
Yoga’s effect on flexibility and spinal mobility is well-documented. According to the National Center for Complementary and Integrative Health (NCCIH), yoga is one of the most practiced complementary health approaches in the United States, with flexibility improvement ranking among its most consistently reported benefits across research populations.
This article covers what extension means anatomically, which poses target the spine, hips, hamstrings, and shoulders, how to safely extend your session duration, and how to modify everything for beginners, seniors, and people managing back conditions. You’ll also find prop guidance, hold-time recommendations, and a full-body extension sequence to use at home.
What Does Extension Mean in Yoga?
Extension in yoga refers to a movement that increases the angle between body parts, most often by opening the front of the body or lengthening the spine backward.
In anatomical terms, extension is the opposite of flexion. Flexion closes a joint angle; extension opens it. When your yoga teacher says “extend the spine,” they are asking you to create length and gentle backward movement through your vertebrae.
This matters because most people spend the majority of their day in spinal flexion: sitting, hunching over phones, driving. Extension poses counteract that pattern. They open the anterior chain, which includes the chest, hip flexors, and front of the thighs.
Extension also applies to individual joints. Hip extension lengthens the front of the hip. Shoulder extension moves the arms behind the torso. Knowing which joint you are extending helps you understand which muscle is stretching and which is contracting.
Key point: “Extend yoga” can mean extending the body in yoga poses, extending the duration of your practice, or extending the depth and consistency of your yoga habit. This article addresses all three.
Yoga Extension vs. Flexion: What Is the Difference?
Yoga extension and yoga flexion are opposite movement patterns: extension opens the body forward and upward, while flexion folds the body inward.
Every yoga class contains both. Forward folds like Paschimottanasana (Seated Forward Fold) are spinal flexion movements. Backbends like Bhujangasana (Cobra Pose) are spinal extension movements. Most styles balance the two within a single session.
Understanding this distinction helps you self-assess what your body actually needs. If you feel tight across your chest and your upper back rounds forward habitually, you likely need more extension work. If your lower back is chronically compressed, excessive extension without core support can make it worse.
| Movement Type | Direction | Example Pose | Primary Muscles Working |
|---|---|---|---|
| Spinal Extension | Spine bends backward | Bhujangasana (Cobra) | Erector spinae, gluteus maximus |
| Spinal Flexion | Spine rounds forward | Paschimottanasana (Forward Fold) | Hamstrings, lumbar fascia |
| Hip Extension | Leg moves behind body | Virabhadrasana I (Warrior I) | Glutes, hamstrings |
| Hip Flexion | Knee moves toward chest | Apanasana (Knees-to-Chest) | Hip flexors, iliopsoas |
| Shoulder Extension | Arms move behind torso | Gomukhasana (Cow Face arms) | Posterior deltoid, triceps |
Experienced teachers at Iyengar and Vinyasa studios typically program a roughly equal balance between flexion and extension within each 60-minute class.
Benefits of Yoga Extension for the Body
Practicing yoga extension poses regularly can improve spinal mobility, reduce postural compression, and open the muscles along the entire front of the body.
A study published in the International Journal of Yoga found that consistent yoga practice, including backbend and extension sequences, produced measurable improvements in spinal flexibility and thoracic mobility in adult practitioners over an 8-week period.

Extension poses also train the muscles of the posterior chain. The erector spinae, glutes, and mid-back rhomboids all contract to lift and hold extension positions. That means extension isn’t only about stretching the front body; it also strengthens the back body at the same time.
Posture benefits are well-supported by research. The American Council on Exercise notes that yoga’s emphasis on spinal mobility and body awareness is directly linked to improvements in standing posture, particularly in desk workers and older adults who tend toward thoracic kyphosis.
Key benefits of yoga extension practice include:
- Improved thoracic and lumbar spinal mobility
- Lengthened hip flexors and iliopsoas, which are shortened by prolonged sitting
- Opened pectoral muscles and anterior shoulder girdle
- Strengthened erector spinae and posterior chain
- Reduced postural rounding through active mid-back engagement
Key Takeaway: Extension in yoga is a specific movement pattern that opens the front of the body. It simultaneously stretches the chest and hip flexors while strengthening the back muscles, and it counteracts the forward-folded posture that most people carry from daily life.
How to Extend Your Yoga Session at Home
You can extend your yoga session at home by adding one extra pose block at a time, using a structured sequence plan, and building gradually from 20-minute to 45 to 60-minute sessions over four to six weeks.
Yoga teachers and physical therapists generally recommend increasing practice duration by no more than 10 to 15 minutes per week. Adding too much time too fast leads to mental fatigue and form breakdown, not better results.
The simplest method is to pick one phase of your practice to expand. If your current 20-minute session includes a warm-up, a pose block, and a closing, add three to four more poses to your main block first. Once that feels natural, add a longer Savasana or a short pranayama opening.
Home practice without a teacher requires honest self-assessment. If your form is breaking down in the final 10 minutes of a session, that is a signal to stop, not push through. Quality of movement always takes priority over session length.
| Current Session Length | Extension Goal | Realistic Timeline | What to Add |
|---|---|---|---|
| 15 to 20 minutes | 30 minutes | 2 to 3 weeks | 2 to 3 additional poses |
| 30 minutes | 45 minutes | 3 to 4 weeks | Add a pranayama opening or extra cool-down |
| 45 minutes | 60 minutes | 4 to 6 weeks | Add a full standing sequence or longer holds |
| 60 minutes | 75 to 90 minutes | 6 to 8 weeks | Introduce a dedicated extension or yin block |
Practice three to five days per week rather than daily when you are increasing duration. Rest days allow connective tissue to recover and adapt.
Spinal Extension Yoga Poses
Spinal extension yoga poses lengthen the spine into a gentle or deep backbend, working the vertebrae from the lower lumbar up through the thoracic and cervical regions.
These poses range from very gentle (like low Bhujangasana (Cobra Pose)) to more demanding (like Ustrasana (Camel Pose)). The intensity depends on how high you lift, how far you lean back, and whether you support yourself with your arms or hands.
To practice Bhujangasana (Cobra Pose):
- Lie face down on your mat. Place your palms flat under your shoulders.
- Hug your elbows toward your ribs. Do not let them flare out.
- Press the tops of your feet and pubic bone gently into the mat.
- On an inhale, lift your chest and head. Keep a slight bend in your elbows for low cobra.
- Broaden across your collarbones. Draw your shoulder blades toward each other.
- Hold for 3 to 5 breaths. On an exhale, slowly lower back to the mat.
Pose Tip:
- Keep your gaze slightly downward to protect the cervical spine from compression.
- If you feel sharp lower back pain, lower your lift by keeping more bend in the elbows.
- Beginners: Stay in low cobra with forearms on the mat (Sphinx Pose / Salamba Bhujangasana).
Setu Bandha Sarvangasana (Bridge Pose) is another core spinal extension pose that also strengthens the glutes and hamstrings simultaneously.
Hip Extension Yoga Poses
Hip extension yoga poses move the leg behind the body from the hip joint, stretching the iliopsoas, hip flexors, and quadriceps while engaging the glutes and hamstrings.
Think of your hip flexors like a bungee cord that has been held in a shortened position all day. Every hour you spend seated keeps that cord contracted. Hip extension poses are what return it to its natural resting length.
Virabhadrasana I (Warrior I) is one of the most effective hip extension poses for beginners. The back leg drives into hip extension while the front knee bends in a deep lunge. The lift of the arms overhead deepens the stretch through the entire front of the back-leg side.
To practice Virabhadrasana I (Warrior I):
- Start in Tadasana (Mountain Pose) at the top of your mat.
- Step your left foot back roughly three to four feet. Turn the foot to a 45-degree angle.
- Bend your right knee directly over your right ankle.
- Press your left heel firmly into the mat.
- On an inhale, raise both arms overhead. Palms face each other.
- Hold for 4 to 6 breaths. Repeat on the other side.
| Hip Extension Pose | Intensity | Primary Muscle Stretched | Modification |
|---|---|---|---|
| Virabhadrasana I (Warrior I) | Moderate | Iliopsoas, hip flexors | Shorten stance; use blocks under hands |
| Anjaneyasana (Low Lunge) | Moderate to deep | Iliopsoas, rectus femoris | Place back knee on folded blanket |
| Hanumanasana (Monkey Pose) | Advanced | Iliopsoas, hamstrings | Use blocks under both hands; 90% of the way |
| Ustrasana (Camel Pose) | Deep | Hip flexors, abdominals | Hands on lower back instead of heels |
Shoulder Extension Yoga
Shoulder extension in yoga moves the arms behind the torso, stretching the anterior deltoid, pectorals, and biceps while strengthening the posterior shoulder and rhomboids.
Most people are chronically tight in the front of their shoulders. Years of forward-reaching movements (typing, driving, carrying bags) pull the shoulder heads forward and inward. Shoulder extension poses reverse that pull.
Gomukhasana (Cow Face Pose) arms are a classic shoulder extension and external rotation exercise. The top arm stretches overhead and reaches behind the back. The bottom arm reaches behind and up. Together, they work both aspects of shoulder mobility simultaneously.
A 2019 review in Complementary Therapies in Medicine found that yoga-based shoulder mobility exercises produced meaningful improvements in shoulder range of motion in office workers after six weeks of three-sessions-per-week practice.
Key shoulder extension and opening poses include:
- Garudasana (Eagle Pose) arms for shoulder girdle compression and release
- Gomukhasana (Cow Face Pose) arms for combined extension and external rotation
- Purvottanasana (Upward Plank Pose) for full anterior chain opening with arm extension behind the torso
- Dhanurasana (Bow Pose) for shoulder extension combined with spinal backbend
Modification: If reaching the hands behind the back in Cow Face arms is not possible, use a yoga strap looped between the hands. This allows the arms to find the correct position without shoulder strain.
Key Takeaway: Hip and shoulder extension poses address the specific tightness created by modern seated posture. Hip flexors, iliopsoas, anterior deltoids, and pectorals all respond well to consistent extension work, and props like straps and blocks make these poses accessible at every level.
Hamstring Extension Yoga Poses
Hamstring extension yoga poses lengthen the biceps femoris, semimembranosus, and semitendinosus muscles along the back of the thigh, improving both hip flexion range and knee extension.
Tight hamstrings are among the most common complaints in beginner yoga practitioners. They limit forward folds, affect posture, and often contribute to lower back tension because the hamstrings attach at the sitting bones and pull on the pelvis.
Utthita Trikonasana (Extended Triangle Pose) is one of the most anatomically precise hamstring extension poses in yoga. It combines hip flexion with spinal lateral extension and hamstring lengthening all at once.
To practice Utthita Trikonasana (Extended Triangle Pose):
- Stand with feet approximately three to four feet apart.
- Turn your right foot out 90 degrees. Turn your left foot in slightly.
- Extend both arms out at shoulder height.
- On an exhale, shift your hips left and reach your right hand toward your right shin, ankle, or a block.
- Extend your left arm straight up. Stack your shoulders vertically.
- Keep both legs as straight as your hamstrings allow. Do not lock the knee into hyperextension.
- Hold for 5 to 8 breaths. Rise on an inhale. Repeat on the left side.
Pose Tip:
- Place a yoga block under the lower hand at whatever height allows the spine to stay long.
- Never collapse the torso forward. If that happens, raise the block height.
- People with hamstring injuries should work with a bent knee and a block until tissue has healed.
Yoga Extension for Beginners
Beginners should start yoga extension practice with supported, low-range poses before progressing to deeper backbends or full hip extension positions.
According to the American Council on Exercise, beginners to any flexibility training program should emphasize range of motion they can control with good form rather than pushing to maximal range. That principle applies directly to yoga extension work.
The goal for beginners is not to do the deepest version of a pose. It is to feel the correct muscles engaging and stretching in a position your body can sustain for several breaths without gripping, pain, or compensating elsewhere.
Best beginner extension starting points:
- Salamba Bhujangasana (Sphinx Pose): Forearms on the mat, gentle lumbar curve, chest open. Accessible for almost everyone.
- Anjaneyasana (Low Lunge): Back knee down on a blanket. Front foot flat. Upright torso with hands on front knee.
- Setu Bandha Sarvangasana (Bridge Pose): Feet flat on the mat, hip-width apart. Lift hips only as high as comfortable. Hands pressing the mat.
- Utthita Parsvakonasana (Extended Side Angle Pose): Front arm reaching forward and overhead; back body long and open.
Beginners should hold extension poses for 3 to 5 breaths and gradually increase to 8 to 10 breaths over four to six weeks as the body adapts. Rushing into deeper extension before the supporting muscles are ready is the most common cause of beginner back strain in yoga.
Yoga Extension for Seniors
Seniors can safely practice yoga extension poses using chair support, wall assistance, and reduced range of motion to improve spinal mobility and hip flexibility without joint stress.
Spinal extension becomes particularly important as we age. Research published in the Journal of Alternative and Complementary Medicine found that yoga practice in adults over 60 produced statistically meaningful improvements in spinal mobility and balance compared to control groups over a 12-week period.
The thoracic spine tends to stiffen with age due to reduced disc hydration and changes in connective tissue. Gentle extension work keeps those segments mobile. Even a small increase in thoracic extension range can improve breathing capacity by allowing the ribcage to fully expand.
Safe extension practices for seniors:
- Chair-assisted Bhujangasana (Cobra Pose): Seated in a chair, hands on thighs, gently lift the chest and draw shoulder blades together.
- Wall-supported backbend: Stand facing away from the wall, hands on the wall at shoulder height, gently extend the upper back.
- Setu Bandha Sarvangasana (Bridge Pose) with a block under the sacrum: Place a yoga block (on the lowest height) under the sacrum for supported passive extension.
- Seated cat-cow extension: Alternating spinal flexion and extension while seated in a chair with hands on thighs.
Seniors with osteoporosis should avoid deep spinal flexion (rounding forward aggressively) more than deep extension. A qualified yoga teacher with senior yoga or bone health training can provide a personalized modification plan. Ask about their Yoga Alliance certification level and any specialty training in adaptive yoga.
Key Takeaway: Yoga extension is accessible at every age and ability level. Seniors and beginners should prioritize range of motion that can be held with ease and good alignment, using props and chair support to make every extension pose manageable and safe.
Yoga Extension with Props
Props make yoga extension poses accessible by reducing the range of motion required, supporting the body’s weight, and helping practitioners find correct alignment before building strength to hold poses independently.
The most common props used for extension work are yoga blocks, yoga straps, bolsters, and the wall. Each serves a specific function depending on the pose and the practitioner’s needs.
| Prop | Best Used For | Extension Application |
|---|---|---|
| Yoga block (cork or foam) | Reducing reach distance | Under lower hand in Triangle, under sacrum in Bridge |
| Yoga strap | Connecting body parts that don’t reach | Between hands in Cow Face arms, around foot in lying quad stretch |
| Bolster | Passive supported extension | Under thoracic spine for supported fish or chest opener |
| Wall | Stability and range control | Supported backbend, Warrior I balance assist |
| Folded blanket | Joint cushioning | Under back knee in Low Lunge, under forehead in Sphinx |
| Chair | Full accessibility adaptation | Chair cobra, seated backbend, modified Warrior I |
Iyengar yoga is the style most associated with systematic prop use for extension poses. B.K.S. Iyengar’s approach, which is taught in Iyengar-certified studios worldwide, uses props specifically to allow practitioners to hold correct alignment longer and more safely than unaided attempts would allow.
If you’re practicing at home, a foam block and a six-foot yoga strap cover the majority of extension pose modifications. A bolster or a tightly rolled blanket can substitute for a bolster when needed.
Restorative and Yin Yoga Extension Holds
Restorative and Yin yoga extension poses are held passively for 2 to 5 minutes, using props to support the body completely while targeting deep connective tissue, fascia, and joint capsules rather than muscle alone.
This is different from active extension poses. In an active backbend like Ustrasana (Camel Pose), your muscles are working to maintain the position. In a restorative extension like a supported Matsyasana (Fish Pose) over a bolster, the prop does all the work and your muscles can fully release.
Yin yoga, developed by Paul Grilley and popularized through the work of Bernie Clark, specifically targets the connective tissue layers of the body through long-hold, low-intensity positions. A 2018 study in the International Journal of Yoga found that Yin yoga practice over 5 weeks produced measurable improvements in hip and lumbar range of motion in adult practitioners.
Restorative extension setup (supported Fish Pose / Matsyasana):
- Place a bolster or rolled blanket horizontally across your mat, roughly at mid-back height.
- Sit in front of the bolster with knees bent.
- Slowly recline back so the bolster supports your thoracic spine (mid-back).
- Let your head rest on the mat or on a folded blanket.
- Arms rest by your sides, palms up.
- Hold for 3 to 5 minutes, breathing naturally.
- To come out, bring knees to chest and roll to one side before pressing up.
This pose is appropriate for most people, including beginners and seniors. Those with unresolved cervical disc injuries should keep the head supported to avoid neck hyperextension.
How Long to Hold Yoga Extension Poses
Hold times for yoga extension poses range from 3 breaths (about 15 seconds) in active Vinyasa flows to 5 minutes in Yin and Restorative yoga, depending on the style and the tissue you are targeting.
Different hold durations target different tissue types. Muscles respond to shorter holds of 15 to 60 seconds. Connective tissue and fascial layers require longer holds, typically 2 to 5 minutes, to experience any release. This is why Yin and Restorative yoga practitioners often report feeling deeper opening than they get from faster-paced classes.
According to the American Council on Exercise, static stretches held for 15 to 30 seconds are adequate for maintaining current range of motion. Improving range of motion requires holds of 30 to 60 seconds for muscle-targeted work and 2 to 5 minutes for fascial work.
| Yoga Style | Typical Hold Time | Tissue Targeted | Example Extension Pose |
|---|---|---|---|
| Vinyasa | 1 to 5 breaths (5 to 25 seconds) | Muscle, nervous system awareness | Cobra in a flow |
| Hatha | 5 to 10 breaths (30 to 60 seconds) | Muscle, early connective tissue | Warrior I |
| Iyengar | 1 to 3 minutes | Muscle and connective tissue | Triangle with block |
| Yin | 3 to 5 minutes | Connective tissue, fascia, joint capsule | Supported fish, low lunge |
| Restorative | 5 to 20 minutes | Parasympathetic nervous system reset | Bolstered chest opener |
Beginners should start at the lower end of any range. Three to five breaths per pose is appropriate for anyone new to extension work. Build toward longer holds over several weeks as tissue adapts.
Key Takeaway: Hold times are not arbitrary. Matching your hold duration to the tissue you want to affect — muscle versus fascia — is what separates yoga that creates lasting flexibility gains from yoga that only feels good in the moment.
Yoga Extension Safety and Who Should Avoid It
Yoga extension poses are safe for most people when practiced within a comfortable range, but certain conditions require modified approaches or full avoidance of specific extension patterns.
The National Center for Complementary and Integrative Health notes that yoga-related injuries, while uncommon in general, most often involve the spine, hamstrings, and knees, particularly when practitioners move beyond their current range without adequate preparation or instruction.
Who should modify or avoid deep spinal extension:
- People with herniated lumbar discs: Deep backbends can compress already stressed disc tissue. Work with a yoga therapist or physical therapist to identify safe ranges.
- People with spinal stenosis: Extension may temporarily narrow the spinal canal and aggravate nerve compression in some individuals.
- People with osteoporosis: Deep spinal extension can be safe, but aggressive forward flexion is more concerning. A teacher with bone health training can clarify your specific safe range.
- People with sacroiliac (SI) joint dysfunction: Asymmetric extension poses like Warrior I and Low Lunge may provoke SI joint symptoms. Modify by shortening stance and avoiding deep hip extension until symptoms resolve.
- Pregnant practitioners: Deep prone backbends (lying face down) are contraindicated in the second and third trimesters. Side-lying or all-fours extensions are safer alternatives.
Safety notes for all extension poses:
- Never extend to the point of sharp, shooting, or radiating pain.
- Dull muscular stretch is normal. Joint pain, nerve symptoms, or sharp back pain are signals to stop and reassess.
- If you have a diagnosed spinal condition, working with a yoga therapist registered with the International Association of Yoga Therapists (IAYT) alongside your medical care team is a reasonable approach.
Full Body Extension Yoga Sequence
A full body extension yoga sequence moves through the spine, hips, hamstrings, and shoulders in a logical progression, warming the body before deeper extension and cooling with supported holds at the end.
This 12-pose sequence works for home practice at beginner to intermediate level. It takes approximately 30 to 40 minutes with the recommended hold times.
Full Body Extension Sequence:
- Balasana (Child’s Pose): 10 breaths to settle and establish breath.
- Bitilasana/Marjaryasana (Cow/Cat Pose): 8 cycles to warm the spine.
- Salamba Bhujangasana (Sphinx Pose): 8 breaths. Active lumbar extension warm-up.
- Bhujangasana (Cobra Pose): 5 breaths. Moderate spinal extension.
- Anjaneyasana (Low Lunge), right side: 6 breaths. Hip flexor extension.
- Anjaneyasana (Low Lunge), left side: 6 breaths. Repeat.
- Virabhadrasana I (Warrior I), right side: 6 breaths. Combined hip and spinal extension.
- Virabhadrasana I (Warrior I), left side: 6 breaths. Repeat.
- Utthita Trikonasana (Extended Triangle Pose), right side: 6 breaths. Hamstring extension with lateral spine opening.
- Utthita Trikonasana (Extended Triangle Pose), left side: 6 breaths. Repeat.
- Setu Bandha Sarvangasana (Bridge Pose): 6 to 8 breaths. Full posterior chain activation with hip and spinal extension.
- Supported Matsyasana (Fish Pose) over bolster: 3 to 5 minutes. Passive thoracic extension cool-down.
Close with Savasana (Corpse Pose) for 5 to 10 minutes.
Modification for this entire sequence: Any standing pose can be performed with hands on a chair back for balance support. Any prone pose can be replaced with the seated chair equivalent described in the seniors section above.
Key Takeaway: A full body extension sequence progresses from gentle spinal warm-up through active hip and hamstring extension poses to passive restorative holds. Following that order protects the body, maximizes the benefits, and makes the sequence accessible for repeated home practice.
Frequently Asked Questions About Extend Yoga
What does it mean to extend in yoga?
Extending in yoga means moving a joint or the spine into extension, which is the opposite of flexion, opening the front of the body and increasing the angle between body segments.
It applies to the spine (backbends), hips (lunges and Warrior poses), hamstrings (Triangle and forward folds with straight legs), and shoulders (arms reaching behind the torso).
“Extend yoga” can also refer to making your yoga sessions longer or deepening your overall practice over time.
How do I extend my yoga session as a beginner?
Add no more than 10 to 15 minutes to your session at a time, and wait at least two to three weeks before extending again.
Start by adding two to three poses to your existing sequence rather than trying to follow a longer class all at once.
Your form and breath quality are better indicators of when to stop than a clock.
Which yoga poses are best for extending the spine?
Bhujangasana (Cobra Pose), Setu Bandha Sarvangasana (Bridge Pose), and Ustrasana (Camel Pose) are the three most effective spinal extension poses across beginner, intermediate, and advanced levels.
Cobra and Bridge are appropriate for most beginners; Camel requires more thoracic mobility and hip flexor flexibility and should be approached gradually.
Sphinx Pose (Salamba Bhujangasana) is the gentlest starting point for people new to spinal extension.
Is yoga extension safe for people with back pain?
Gentle yoga extension is safe and often beneficial for people with general low back tightness, but the safety depends entirely on the type and cause of back pain.
People with herniated discs, spinal stenosis, or sacroiliac joint dysfunction should work with a yoga therapist or physical therapist to identify which extension poses are appropriate for their specific condition before practicing independently.
Any extension pose that causes sharp, shooting, or radiating pain should be stopped immediately.
How long should I hold yoga extension poses?
Hold times depend on what you are targeting: 3 to 5 breaths (15 to 30 seconds) for active extension poses in Hatha or Vinyasa yoga, and 3 to 5 minutes for deep connective tissue release in Yin or Restorative yoga.
Beginners should start at the shorter end and build gradually over several weeks.
The American Council on Exercise recommends at least 30 seconds per static stretch to begin improving range of motion rather than just maintaining it.
Start Where You Are, Not Where You Think You Should Be
Extension poses work best when you respect your current range and build from there. One session of Cobra Pose practiced carefully and consistently will do more for your spinal health over six months than one ambitious backbend that strains your lower back today.
Pick one pose from this article and add it to your next practice. Try Sphinx Pose if you are brand new to extension work. Add Bridge Pose if you have been practicing for a few months. Use the bolster-supported Fish Pose if your back needs gentleness right now.
Three sessions a week, honest range, and props when you need them. That is how you extend yoga in a way that actually lasts.






