Stretching the Hip Flexors: Exercises and What the Research Shows

Why the hip flexor shortens when sitting

You get up from your desk after eight hours, and your first steps feel stiff. Your back aches, and your hip feels as if it needs to thaw out again. The muscle that’s usually responsible for this isn’t located in your back. It’s called the iliopsoas—commonly known as the hip flexor—and it’s the only muscle that directly connects the lumbar spine to the thigh.

When sitting, this muscle remains constantly shortened. The hip is flexed, and the muscle’s origin and insertion are close together, hour after hour. The body adapts to this just as it adapts to everything else: whatever it doesn’t need, it breaks down. The muscle remains shorter than it should be.

When you stand up, this shortened muscle pulls on the lower back from the inside. The pelvis tilts forward, the swayback becomes more pronounced, and the lumbar spine bears more weight than intended. A 2024 study of first-year college students measured just how much of a burden this places on the body: Sitting for about 8 hours of sitting at a time, the risk of back pain increased, and about half of those affected reported sitting for long periods without back support. In other words, young people at desks—not the 55-year-old tile setter. Nevertheless, this trend aligns with what our customers have been telling us for years about their workdays.

How to Tell if You Have Tight Hip Flexors

The simplest test can be done on a sturdy table. Sit with your buttocks right at the edge, just far enough so that your sit bones are barely touching the surface. Pull one knee toward your chest with both hands and slowly lower yourself backward into a supine position. Let the other leg hang freely.

If the thigh of the free leg drops to table height, everything is fine. If it remains above the table, the hip flexor is tight. If the knee of the free leg also extends on its own, the rectus femoris muscle contracts as well. In physical therapy, this is called the Thomas test.

While you're measuring your body anyway: The 13-page " Body Check " explains which measurements matter when choosing an armchair and how you can tell if an armchair isn't right for you.

Two other signs point to the same thing: You can't stand without arching your back, and your back starts to ache especially after standing up, not while sitting.

Thomas test, side view. On the left, the thigh of the unsupported leg drops to table height. On the right, it remains above table height; the hip flexor is shortened.

Four Exercises to Stretch the Hip Flexors

1. Half-kneeling position with the pelvis upright

One knee on the floor, the other leg extended forward, both knees bent at about 90 degrees. And now comes the part that most people skip: Pull your pubic bone toward your navel and squeeze your glutes on the back side. Only then does the pelvis align properly, and only then is the stretch truly felt in the hip flexors. If you simply push your hips forward instead, you’re mainly stretching the lumbar spine.

The stretch should be felt in the front of the groin of the back leg. Hold for 30 to 60 seconds, then switch sides.

2. Thomas position as a stretch

The starting position is the same as in the test, except you stay lying down. Bring one knee firmly toward your chest; the other leg hangs freely over the edge. Your leg’s own weight does the work—you just hold the position. 60 seconds is enough, several times a week.

3. Stretching the front of the thighs while lying on your stomach

Lie on your stomach and pull one heel toward your buttocks, using your hand or a belt. Keep your pelvis on the floor, and do not let your lower back arch. This exercise targets the rectus femoris muscle, which crosses two joints and becomes just as short as the hip flexors when you sit.

4. Stretching the piriformis while lying down

Lie on your back, place your right ankle over your left knee, then use both hands to pull your left leg toward your chest. You’ll feel the stretch deep in your glutes. The piriformis muscle lies directly over the sciatic nerve, and when it becomes tight, the pain radiates down the leg. That’s why about 4,400 people search every month for exercises to address this very problem.

How often and for how long should you stretch?

The literature reviews are now largely in agreement on this point. The minimum recommended is about 5 minutes per week per muscle group. That’s not a high bar: two sets three times a week, each lasting 45 seconds per side, and you’ll meet the requirement.

It’s best to hold each stretch for 30 to 60 seconds. Shorter holds aren’t very effective, and significantly longer ones don’t offer much more benefit. And the effects take weeks, not days. Your flexibility right after a session is always better than it is the next morning. Lasting results develop over 4 to 8 weeks.

Let's be honest: that's exactly where most people fall short. By Day 9, no one is doing it anymore.

What Enhances the Effect

Two things have been well studied, and neither requires any extra practice.

Heat first. A systematic review analyzed 12 studies involving a total of 352 participants. Applying heat before or during stretching resulted in greater flexibility than stretching alone. The reason lies in the tissue: collagen becomes more pliable at higher temperatures, blood flow increases, and muscle tension decreases. Fifteen minutes of heat applied to the lower back is sufficient for this.

Massage first. In a study of the calf, stretching alone resulted in 3.1 degrees more range of motion in the ankle joint. Massage plus stretching resulted in 6.2 degrees. That’s twice as much, with the same stretching time.

Tense, then release. The technique is called PNF. You stretch to the limit, tense the stretched muscle against resistance for a few seconds, release, and go a little further into the stretch. This works through inhibitory mechanisms in the nervous system and because the body tolerates more stretching. In comparative studies, PNF is at least on par with static stretching, and often slightly better.

Stretching on your own or being stretched

A question that often comes up during counseling: Is there any point at all if I don't stretch on my own, but instead am stretched by someone else?

There is a controlled study involving 33 patients, all of whom had limited hip extension. One group performed active stretching, while the other performed passive stretching. By the end of the study, both groups had improved, with no significant difference between them. Passive stretching works.

What’s important is what happened in these studies. In those studies, a person performed the stretching, not a machine. No massage chair has ever been examined in a study like that. We list all existingstudies on massage chairs, including the number of participants, the results, and who funded them.

Anyone who tells you otherwise either hasn't read the study or is hoping you won't.

What a massage chair does in this regard

What can be said is this: A recliner with a stretching program combines three things that are typically performed separately—heat to the lower back, a muscle massage, and then a stretch of the legs and pelvis. In that order. And it does it on the very evening when you wouldn’t be able to do it yourself anymore.

One example featured in the exhibition is the Bodyfriend Quantum Beauty Capsule. You lie down inside it to receive a massage, and the leg rests move independently to the left and right. This stretches one side at a time, while the other side stabilizes the body. Heat is applied at four points: the feet, calves, lower back, and in the massage rollers themselves. The chair is suitable for people between 155 and 190 cm tall. Below that height, the foot massage doesn’t reach properly; above that, the neck massage doesn’t.

Bodyfriend Quantum Beauty Capsule, backrest reclined. The legs rest on two separate supports.

A second model will be added in the coming weeks, featuring 8 custom stretching programs, including one each for the hip flexors and the piriformis. As soon as it’s set up, you can try both one right after the other. That’s the only way to really tell the difference anyway.

When You Shouldn't Stretch

There are a few situations that should be discussed with your doctor or physical therapist beforehand, regardless of whether you are stretching on your own or having someone else help you stretch:

• recent hip, knee, or spine surgery, and the first few months following joint replacement surgery
• Acute herniated disc with pain radiating down the leg or accompanied by numbness
• advanced osteoporosis
• known history of thrombosis or a coagulation disorder
• Pregnancy, because the connective tissue is already more flexible and you can easily stretch beyond the limit

And the question we’re asked most often: Does the chair replace physical therapy? No. It doesn’t replace it. It fills the 6 days between two appointments when nothing else happens. Anyone currently undergoing treatment should discuss this with their therapist beforehand.

Try it out instead of reading about it

You'll know within the first 2 minutes of lying in the chair whether a stretching program will be beneficial for you. You'll also know whether your height is a good fit for the leg rest. That's not something you can tell just by reading about it or deciding based on a spec sheet.

In our showrooms, the armchairs are set up, and you sit in them one after another. There isn't just one best armchair—there are several. You'll find out which one is right for you when you sit in it.

Where to find it and when to visit: Test drives and appointments

Sources

The figures listed above are taken from these studies. All of them are freely available, so you can see for yourself who measured what and on whom.

• Sitting and Back Pain. Abbas J et al., “Is Hip Muscle Flexibility Associated with Low Back Pain Among First-Year Undergraduate Students?” J Clin Med 2024;13(24). PubMed The study examined first-year students, not the general population.
• Heat Before Stretching. Nakano J et al., “The effect of heat applied with stretch to increase range of motion: a systematic review.” Phys Ther Sport 2012;13(3):180-8. PubMed
• Massage before stretching. Capobianco RA et al., Self-massage prior to stretching improves flexibility in young and middle-aged adults. J Sports Sci 2019;37(13):1543-50. PubMed
• Passive or active stretching. Winters MV et al., Passive versus active stretching of hip flexor muscles in subjects with limited hip extension. Phys Ther 2004;84(9):800-7. PubMed
• Tension-Release (PNF). Hindle KB et al., Proprioceptive Neuromuscular Facilitation: Its Mechanisms and Effects on Range of Motion and Muscular Function. J Hum Kinet 2012;31:105-13. PubMed
• How often and for how long. Konrad A et al., Chronic effects of stretching on range of motion with consideration of potential moderating variables. J Sport Health Sci 2024;13(2):186-94. PubMed

We list all work related to massage chairs separately, including the number of participants, the results, and who paid for it.