The psoas is the most anatomically significant hip flexor in the body, and it is also one of the most commonly neglected in training programmes. Most hip flexor work addresses the rectus femoris (the quad muscle that also crosses the hip) or treats all hip flexors as an interchangeable group. But the psoas has a unique anatomy, a unique function, and specific weaknesses that generic hip flexor exercises do not fully address.
This guide covers what makes the psoas distinct from other hip flexors, why strengthening it specifically matters, how to identify whether your psoas is weak, and the best exercises for developing genuine psoas strength across a progressive loading system.
What the Psoas Is and Why It Is Different
As covered in the psoas muscle pain and pull symptoms article on this site, the psoas major is one of the deepest muscles in the body, originating from the bodies and transverse processes of the lumbar vertebrae (T12 to L5) and inserting on the lesser trochanter of the femur via the iliopsoas tendon.
What makes the psoas anatomically unique:
It connects the spine to the leg: The psoas is the only muscle that directly connects the lumbar spine to the femur. This connection means that the psoas does not simply flex the hip: it also provides segmental lumbar support during hip loading. A strong, well-coordinated psoas stabilises the lumbar vertebrae from the front during movements that load the hip, providing anterior lumbar support that no other muscle can replicate.
It is primarily a stabiliser, not just a mover: While the psoas can produce hip flexion, its most important function in many activities is the stabilisation of the lumbar spine and the hip joint during loaded movement. Research has established that the psoas is heavily involved in stabilising the lumbar spine against rotational and translational forces, making it functionally more similar to a core stabiliser than a simple hip flexor.
It has a leverage advantage for high-load hip flexion: The psoas is the primary hip flexor during resisted hip flexion (lifting the leg against resistance) rather than during low-load swing activities. Walking and easy running rely primarily on the rectus femoris and other hip flexors during the swing phase, but loaded hip flexion (climbing stairs with a heavy pack, lifting the knee against resistance, resisting passive hip extension forces) specifically demands psoas strength.
Why these distinctions matter for training:
The exercises that most effectively strengthen the psoas are not the same as those that strengthen the rectus femoris or the general hip flexors. Seated knee raises primarily challenge the rectus femoris in its hip flexor role. The exercises that specifically load the psoas are those that involve resisted hip flexion at or near the end range, or that require the psoas to stabilise the lumbar spine during loaded hip movement.
The Difference Between Psoas Stretching and Psoas Strengthening
The most common approach to the psoas is to stretch it. This is appropriate when the psoas is tight from prolonged sitting, but stretching alone does not develop the strength of the psoas. In fact, a psoas that is chronically tight is often tight because it is weak: it holds tension as a protective mechanism around a lumbar segment that it cannot adequately stabilise through dynamic contraction.
Signs the psoas is tight but needs strengthening rather than stretching:
- Hip flexor stretching provides only brief relief before the tightness returns
- The tightness is accompanied by a sense of hip instability or lower back weakness
- The tightness is on the same side as lower back pain that worsens during single-leg activities
- Stretching the hip flexors makes the lower back feel less stable
As covered in the hip tightness article on this site, this pattern (tightness that needs strengthening rather than stretching) is one of the most common mismanaged hip problems. The psoas is particularly prone to this pattern because its lumbar stabilisation role means that a weak psoas creates an instability that the nervous system responds to with increased muscle tone (tightness) as a protective strategy.
How to Identify Psoas Weakness
The modified Thomas test:
- Lie on the edge of a table with both legs hanging off
- Pull one knee toward the chest
- Observe the hanging leg: if the thigh does not lower to the horizontal position, hip flexor tightness is present
- Now, while the leg is in this position, attempt to lift the thigh upward against gentle manual resistance from a partner
- If this resisted movement is significantly weak compared to the other side, psoas weakness on the hanging side is likely
The prone hip extension test:
As described in the hip lower back exercises article on this site, the order of muscle activation during prone hip extension (glute first, then hamstring) reveals gluteal inhibition. The reverse test (supine hip flexion activation order) can reveal psoas inhibition in a similar manner.
Functional indicators of psoas weakness:
- Difficulty climbing stairs with heavy loads without the lower back fatiguing first
- Lower back fatigue during activities that should load the hip (sprinting, running uphill, carrying heavy loads)
- Hip flexor fatigue during running that feels deep in the groin or anterior hip rather than in the thigh
- Difficulty performing and maintaining a high knee during sprint mechanics
- Lower back discomfort that increases specifically during hip flexion loading (running, stair climbing) rather than during extension activities
The standing hip flexion test:
Stand upright and drive one knee forward and upward against the resistance of your hand placed on the thigh. Compare the strength and ease between sides. A significant strength asymmetry, or difficulty driving the knee to hip height against moderate resistance, indicates psoas weakness on the weaker side.
The Best Psoas Strengthening Exercises
Level 1: Establishing Psoas Activation
These exercises develop the basic neuromuscular connection to the psoas before progressive loading is applied.
Supine Hip Flexion (Active)
The most fundamental psoas activation exercise, performed without resistance to establish the basic activation pattern.
How to do it:
- Lie flat on the back with legs extended
- Slowly lift one leg toward the ceiling, keeping the knee straight
- Lift to approximately 60 to 70 degrees of hip flexion
- Hold for 3 seconds at the top
- Lower slowly under control
- Complete 3 sets of 10 per leg
Why this specifically activates the psoas: The straight-leg hip flexion against gravity requires the psoas to work against the full weight of the leg, which is a higher relative demand than the knee-bent version where the rectus femoris and TFL share the load more equally.
Psoas March (Supine)
Specifically activates the deep psoas in a position that also develops the anti-extension core stability the psoas supports.
How to do it:
- Lie on the back with both knees bent, feet flat on the floor
- Press the lower back gently into the floor
- Lift one knee toward the chest while the other foot presses into the floor
- Place both hands on the lifted knee and press downward while the knee resists upward
- Hold the isometric contraction for 5 to 10 seconds
- Release and switch sides
- Complete 3 sets of 8 per side
The isometric resistance specifically loads the psoas as a hip flexor against resistance without the momentum or compensation patterns that can occur during concentric-only exercises.
Seated Knee Raise
Seated hip flexion develops the psoas in the position most relevant to sitting and rising from chairs.
How to do it:
- Sit upright at the edge of a chair with feet flat on the floor
- Lift one knee upward as high as possible using the hip flexors
- Hold for 3 to 5 seconds at the maximum height
- Lower slowly under control
- Complete 3 sets of 12 per leg
Key cue: The trunk must remain upright. Leaning backward to achieve greater knee height means the hip flexors are not strong enough to achieve the range and the movement is being supplemented by trunk extension. Only lift to the height where the trunk can remain vertical.
Level 2: Progressive Resistance Loading
These exercises add external resistance to specifically challenge the psoas beyond the load of the leg alone.
Seated Knee Raise With Weight
Adding a dumbbell or weight plate on the thigh significantly increases the psoas demand.
How to do it:
- Sit upright at the edge of a chair
- Place a dumbbell end-on the thigh of one leg
- Lift the weighted thigh upward against the additional resistance
- Hold for 2 to 3 seconds at the top
- Lower slowly
- Complete 3 sets of 10 per side
Loading progression: Begin with 2 to 4 kilograms on the thigh and progress by 1 to 2 kilograms per week as strength develops. Most people can progress to 8 to 15 kilograms over 8 to 12 weeks of consistent training.
Standing Hip Flexion With Band
Develops the psoas in the standing position most relevant to running, stair climbing, and athletic hip flexion demands.
How to do it:
- Anchor a resistance band at ankle height behind you
- Loop the band around one ankle
- Stand upright with the core engaged
- Drive the knee forward and upward against the band resistance to hip height
- Hold for 2 to 3 seconds at the top
- Lower slowly against the band
- Complete 3 sets of 10 per leg
Why this is more functional than the seated version: The standing position requires the psoas to work while the body is upright against gravity, which is the position it must function in during running and athletic activity. The standing version also requires the contralateral core and hip stabilisers to work simultaneously, developing the integrated function of the psoas alongside the rest of the hip and core system.
Cable Hip Flexion
The most progressible psoas strengthening exercise, allowing precise loading across the full hip flexion range with consistent resistance throughout.
How to do it:
- Attach an ankle cuff to the low pulley of a cable machine
- Face away from the machine
- Drive the knee forward and upward against the cable resistance
- Control the return phase slowly
- Complete 3 to 4 sets of 10 to 12 per leg
The advantage of the cable over a band: As discussed in the banded romanian deadlift article on this site, bands provide increasing resistance as they stretch. A cable provides consistent resistance throughout the entire range of motion, ensuring the psoas is equally challenged at both the beginning and end of the hip flexion. For progressive psoas strengthening, the cable is the preferred tool when available.
Hanging Knee Raise
Develops the psoas alongside the core flexors in a hanging position that eliminates ground support and maximises the hip flexion demand.
How to do it:
- Hang from a pull-up bar with both hands, shoulder-width grip
- Draw both knees upward toward the chest simultaneously
- Control the lowering phase slowly
- Complete 3 sets of 10 to 12 reps
Why this develops the psoas: The hanging position removes all ground support, making the psoas solely responsible for lifting the weight of the lower body against gravity. The psoas must also stabilise the lumbar spine against the traction force of the hanging legs, which specifically develops the lumbar stabilisation function of the psoas alongside its hip flexor role.
Progression: Once double knee raises are comfortable, progress to hanging straight leg raises where the legs are lifted with extended knees, significantly increasing the lever arm and the demand on the psoas.
Level 3: Integrated and Athletic Loading
These exercises develop the psoas in positions and patterns that replicate its function during athletic activity.
Dead Bug (Anti-Extension Psoas Stabilisation)
As covered in the isometric core exercises article on this site, the dead bug develops the psoas in its lumbar stabilisation role alongside the hip flexors.
How to do it:
- Lie on the back with arms toward the ceiling and knees at 90 degrees above the hips
- Simultaneously lower the right arm overhead and the left leg toward the floor
- Keep the lower back pressed against the floor throughout by maintaining psoas and core tension
- Return and repeat on the other side
- Complete 3 sets of 8 per side
The psoas-specific demand: Lowering the leg challenges the psoas to maintain the position of the lumbar vertebrae against the destabilising force of the lowering leg’s weight. This is the lumbar stabilisation function of the psoas that is not trained by simple hip flexion exercises.
Leg Lowering (Long Lever Psoas Challenge)
A more demanding version of the dead bug specifically challenging the psoas at long lever length.
How to do it:
- Lie on the back with both legs extended toward the ceiling
- Lower one straight leg toward the floor while maintaining the lower back flat against the floor
- Stop before the lower back peels off the floor
- Return to vertical and repeat on the other side
- Complete 3 sets of 10 per side
Sprint Drills (High Knee Marching and Running)
The most sport-specific psoas strengthening exercise for athletes. Sprint mechanics, particularly the high knee drive that determines stride rate in sprinting, are primarily driven by the psoas.
High knee march:
- March in place with deliberate, powerful knee drives to hip height or above
- Drive each knee up with maximum effort
- Pump the arms rhythmically
- Focus on the rate and force of each knee drive
- Complete 4 sets of 20 marches (10 per leg) with 90 seconds rest
Why sprint drills develop the psoas specifically: The high-speed, high-force knee drive of sprinting is the movement for which the psoas is most specifically designed. Research on sprinting identifies the psoas as the primary driver of the swing phase of sprinting and the muscle most closely correlated with maximum sprint velocity. Practising the sprint knee drive develops the rate of force development in the psoas alongside the strength.
Resistance Sled March and Sprint:
Marching or sprinting while pulling a resistance sled adds loading to the hip flexion phase of the sprint movement, specifically overloading the psoas in its most athletic function.
How to do it:
- Attach a harness connected to a loaded resistance sled
- March or sprint forward with deliberate high knee drives
- The sled resistance specifically loads the hip flexion phase
- Complete 4 sets of 20 metres with 2 to 3 minutes rest
Programming Psoas Muscle Strengthening
For general population and rehabilitation:
The rehabilitation approach targets psoas activation and develops strength from the basic supine exercises before progressing to standing and loaded variations.
Week 1 to 2 (Activation):
- Supine hip flexion: 3 x 10 per leg
- Psoas march: 3 x 8 per side
- Seated knee raise: 3 x 12 per leg
- Daily, or 4 to 5 times per week
Week 3 to 4 (Loading):
- Seated knee raise with light weight: 3 x 10 per side
- Standing hip flexion with band: 3 x 10 per leg
- Dead bug: 3 x 8 per side
- 3 times per week
Week 5 to 8 (Progression):
- Cable hip flexion: 3 x 10 per leg
- Hanging knee raise: 3 x 10
- Leg lowering: 3 x 10 per side
- 2 to 3 times per week
For athletes (running and sprint focus):
The athletic approach develops the rate of force development alongside the strength.
Strength component (twice per week):
- Cable hip flexion: 3 x 10 per leg
- Hanging straight leg raise: 3 x 8
- Seated weighted knee raise: 3 x 10 per leg
Power component (twice per week):
- High knee march: 4 x 20
- Resistance sled march: 3 x 20 metres
- A-skip drill: 4 x 20 metres
Combining psoas strengthening with the broader hip programme:
The psoas strengthening programme complements rather than replaces the broader hip strengthening work described in the hip strengthening article on this site. The psoas strengthening exercises primarily address hip flexion strength and lumbar stabilisation, while the hip strengthening programme addresses extension, abduction, and external rotation. A complete hip programme includes both components.
Frequently Asked Questions
Can I stretch and strengthen the psoas at the same time?
Yes, and this is often the most effective approach. Stretching the psoas (kneeling hip flexor stretch as described in the hip tightness article on this site) before the strengthening exercises can reduce the inhibitory tension that limits the range and force available during the strengthening work. However, extensive stretching immediately before maximum-effort strengthening can temporarily reduce force output, so a brief stretch (30 seconds per side) before strengthening is appropriate, with longer stretching sessions reserved for after training or at separate times.
How long does it take to strengthen the psoas?
Neuromuscular activation improvements (being able to feel and coordinate the psoas during exercises) typically develop within 2 to 3 weeks of consistent practice. Measurable strength improvements are typically apparent within 4 to 6 weeks. Meaningful functional improvement in running mechanics, stair climbing ability, and lumbar stability typically takes 8 to 12 weeks of consistent training. The psoas responds to progressive loading like any other muscle and continues to develop strength with consistent training beyond this initial period.
Is a tight psoas the same as a weak psoas?
Not necessarily, but they frequently coexist. A tight psoas can be a strong muscle that has adaptively shortened from prolonged hip flexion positions. It can also be a weak muscle held in chronic tension as a protective strategy around an unstable lumbar segment. Assessing whether stretching or strengthening is the priority (as described in the identification section above) determines which approach is most appropriate.
Can psoas strengthening help with lower back pain?
Yes, in specific presentations. Lower back pain associated with single-leg loading activities (running, stair climbing, walking uphill), lower back instability feelings during hip flexion movements, and one-sided lower back pain that accompanies hip flexor weakness on the same side are all presentations where psoas strengthening can produce meaningful improvement. Lower back pain associated with disc pathology, facet joint irritation, or structural issues requires clinical assessment and management before adding loaded psoas exercises.
Are all hip flexor exercises the same as psoas exercises?
No. The hip flexors include the psoas, the rectus femoris, the TFL, the sartorius, and several smaller muscles. Generic hip flexor exercises (such as standing hip flexion without resistance, leg swings, or sitting up from a supine position) challenge all of these muscles collectively without specifically loading the psoas. The exercises in this guide are chosen specifically because they load the psoas in the ranges and directions that are most specific to its anatomy and function, distinguishing them from generic hip flexor work.