Overview of Hip Flexor Muscles and Injuries (2023)

The hip flexor muscles are a group of muscles situated near the top of your thighs that allow you to lift your knee toward your chest and bend forward at the hip. This includes the iliacus, pectineus, psoas major, rectus femoris, and sartorius muscles that work together to enable hip flexion.

When these muscles are placed under extreme stress from explosive movements like jumping or running, they can be injured. This can lead to a hip flexor strain in which one or more of the muscles are stretched or torn.

This article explains how the hip flexor muscles work as well as the common causes of hip flexor pain, stiffness, or tightness. It also explains how to treat hip flexor injuries and how to prevent them with stretches and strengthening exercises.

Hip Flexor Anatomy and Function

Flexion refers to bending movements that decrease the angle between two body parts. When a flexor muscle contracts, it draws two bones together, bending at a joint.

In the case of the hip flexor muscles, they draw together the upper leg and torso at the hip joint. These muscles get a workout whenever doing movements like climbing stairs, running, or riding a bicycle.​ If the muscles are flexed while sitting, they aren't working.

A sedentary lifestyle can lead to weak and tight hip flexors. Tight hip flexor muscles can lead to a limited range of motion, poor posture, lower back or hip pain, and injuries.

The muscles that make up the hip flexors include:

• Psoas major: This deep muscle connects your spine to your leg. It runs from your lower back to the front of your hip and attaches to the top of your thigh bone (femur).
• Iliacus: This is a flat, triangular muscle situated deep within your pelvis. It attaches your pelvis to your femur. Its primary action is to flex and rotate your thigh.
• Rectus femoris: This is one of the four quadriceps muscles that attach your pelvis to the tendon of your knee. It enables squatting and lunging.
• Pectineus: This is a flat muscle situated at the top of your inner thigh, often called your groin muscle. It is primarily responsible for hip flexion but also rotates your thigh and pulls your legs together (adduction).
• Sartorius: This is a long, thin muscle that runs down the length of your thigh from your pelvis to your knee. It's the longest muscle in the human body and helps flex the knee and leg.

Causes of Hip Flexor Pain

Hip flexion pain can be due to an injury or postural issues that contribute to muscle tightness.

Injuries

You can strain or tear your hip flexors when you make sudden movements such as changing directions while running or kicking.

Sports and activities where this is likely to occur include:

• Running
• Soccer
• Football
• Hockey
  
• Martial arts
• Dancing
• Gymnastics

You're more likely to get a hip flexor injury if you've had one in the past, you don't warm up properly, or your muscles are weak from overuse.

You can also strain a hip flexor when you slip and have a bad fall.

Postural Issues

Postural issues contribute to hip flexor weakness, pain, and injury. According to the National Exercise Trainers Association, a large proportion of the population has dysfunctional hip flexors due to poor posture, faulty biomechanics, and sitting too much.

Prolonged sitting puts the hips in a constant state of supported flexion. This can cause the muscles to shorten and become chronically tight. When this happens, the lower back compensates by overarching, leading to low back pain.

Thereafter, if you engage in strenuous activity or simply take a wrong step, the shortened hip flexor muscles can become strained or sprained. The change in gait can also cause knee, ankle, and foot pain.

Hip Flexor Injury Symptoms

The chief symptom of a strained or torn hip flexor is pain where your hip meets your thigh. The symptoms can vary and may involve:

• Mild to stabbing pains
• Pulling sensations in the hip when rising
• Bruising
• Swelling
• Muscle spasms

With a complete tear, it may be difficult to even walk.

Diagnosing Hip Flexor Problems

Muscle injuries are commonly graded so the appropriate treatments can be prescribed and your healthcare provider has a better sense of your prognosis (likely outcome).

Grade 1 (Mild)

A grade 1 injury is a small tear in your muscle that's mildly painful and may cause some minor swelling and tenderness. You're able to continue doing your regular activities, including sports. It may take a couple of weeks to recover fully.

Grade 2 (Moderate)

A grade 2 injury is a larger tear that causes moderate pain when you move. Swelling, tenderness, and limping are common. You may have a 5% to 50% loss of function. You cannot go back to sports activities until the tear is completely healed.

Grade 3 (Severe)

A complete tear in your muscle causes severe pain and swelling. You can't bear weight on that leg, making it difficult to walk. You will also have lost more than 50% of your muscle function. These injuries are less common and may need surgery to repair.

Hip Flexor Treatment

As long as it's not severe, you should be able to treat your hip flexor strain at home with pain relievers and the PRICE protocol.

The PRICE protocol is an acronym for protection, rest, ice application, compression, and elevation. It involves:

• Protection: This includes protecting your hip with a walking stick or crutches and avoiding any activities that cause pain.
• Rest: This means staying off your hip as much as possible for the first few days.
• Ice application: An ice pack can help relieve pain and swelling. Apply immediately after the injury for 20 minutes, and repeat every three to four hours for the next two to three days.
• Compression: If there is significant swelling, wrap the injured area with a compression bandage or wear compression shorts.
• Elevation: Raise your leg above your heart as often as possible to help relieve pain and inflammation.

You can use over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) like Advil (ibuprofen) or Aleve (naproxen) to reduce pain and swelling. Tylenol (acetaminophen) works for pain relief but doesn't treat inflammation and swelling.

With the appropriate treatment, recovery from mild to moderate hip flexor strain can take anywhere from one to three weeks. Severe grade 3 strains can take up to eight weeks and may require surgery.

Physical Therapy

You may be given exercises to do at home, including hip flexor stretches. If your strain is severe or it isn't getting better, you may need to see a physical therapist who will help you work on gradually strengthening and stretching your muscles. Complete tears may require you to use crutches until you're healed and to seek surgery to reconnect the muscle.

You can also consider soft tissue release techniques and trigger point therapy. These are both alternative therapies that help treat and relieve pain. A soft tissue release is an advanced form of massage therapy that targets specific muscle fibers that have become damaged or tangled up and helps stretch and strengthen them.

Trigger point therapy focuses on trigger points, which are areas that cause pain when they're compressed. However, when pressure is put on these trigger points, it can actually relieve pain. This can be done with dry needling, chiropractic care, or massage.

Preventing Hip Flexor Problems

To prevent hip flexor injuries, keep these tips in mind:

• Always warm up before engaging in any exercise or strenuous physical activity.
• Make sure you do a proper cool down after exercising.
• Work on strengthening yourcore musclesand glutes (buttock muscles). These muscles work together to balance and stabilize your body. When one of these muscles is weak or tight, it can cause injury to another.
  
• Before you go back to your regular exercise or sports, be sure that your injury has fully healed. Your healthcare provider or physical therapist can help you make the determination.
  

Hip Flexor Exercises

Keep your muscles in shape by stretching and exercising regularly. Exercises that help stretch and strengthen your hip flexors include:

• Pigeon pose: This is a floor stretch in which one leg is extended behind you while the other is splayed open in front of you with the knee pointed outward and the heel tucked toward your groin. Holding this position gradually stretches the hip flexor and groin.
• Seated butterfly stretch: This is a floor stretch in which you are seated on your sit bones with the soles of your feet placed together and your knees pointed outward. Gently pressing your knees toward the ground stretches the hip flexors and groin.
• Straight leg raises: This is a strengthening exercise you do lying on your back. Keeping your head and back on the ground, slowly lift your straightened legs together to a 45-degree angle. Hold for several seconds, and lower your legs to the ground with control.
• Squats: This can be done by sliding your back down a wall until you are in a squatted position with your knees positioned above your hips. If you are strong enough, you can squat up and down from a standing position, holding a wall or the back of a chair for balance.
• Lunges: This is done from a standing position by taking one step forward and lowering yourself until your front knee is at a 90-degree angle. Your knee should not be behind your foot. You can alternate between your right and left foot, holding the back of a chair for balance.

Don't push too hard or move too quickly. These stretches and exercises shouldn't hurt.

By Elizabeth Quinn
Elizabeth Quinn is an exercise physiologist, sports medicine writer, and fitness consultant for corporate wellness and rehabilitation clinics.