Overview of Hip Flexor Muscles and Injuries

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The hip flexors are several muscles that bring your legs and trunk together in a flexion movement. They allow you to move your leg or knee up towards your torso, as well as to bend your torso forward at the hip. You can strain or tear your hip flexor muscles through sudden movements or falls.

What the Hip Flexors Do

Flexion means pulling closer together. When a flexor muscle contracts, it draws two bones together, typically bending at a joint. In the case of the hip flexors, they draw together the bones of the leg and the bones of the hip or spine at the hip joint. If the hip is already flexed, such as when you are sitting, these muscles aren't working.

A sedentary lifestyle can lead to having weak and tight hip flexors as they are always in the shortened position. Tight hip flexors can lead to a limited range of motion, poor posture, lower back, and hip pain, and even injuries. These muscles need to get a workout when you are standing and doing movements such as raising your leg to climb stairs, run, or ride a bicycle.​

Hip Flexor Muscles

The muscles that make up the hip flexors include:

  • Psoas major muscle: The psoas muscle is a deep muscle that connects your spine to your leg. In fact, it's the only muscle that does so. It runs from your lower back through your pelvis, passing to the front of your hip where it attaches to the top of your femur, which is your thigh bone.
  • Iliacus muscle: The iliacus is a flat, triangular muscle that lies deep within your pelvis. It attaches from your pelvis to your thigh bone (femur). Its primary action is to flex and rotate your thigh.
  • Rectus femoris muscle: This muscle is one of the four quadriceps muscles, attaching your pelvis to the patellar tendon of your knee. Squats and lunges exercise the rectus femoris.
  • Pectineus muscle: The pectineus muscle is a flat, quadrangular muscle that lies at the top of your inner thigh, often referred to as your groin muscle. It's primarily responsible for hip flexion, but it also rotates your thigh and adducts, which means it pulls your legs together when the muscles contract.
  • Sartorius muscle: The sartorius muscle 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.

    Hip Flexor Injuries

    You can strain or tear one or more of your hip flexors when you make sudden movements such as changing directions while running or kicking. Sports and athletic activities where this is likely to occur include running, football, soccer, martial arts, dancing, and hockey. In everyday life, you can strain a hip flexor when you slip and fall, for example.

    Muscle injury grading systems and classifications are currently in the process of being revamped and studied in order to be more comprehensive so they can include more precise diagnostics. However, the traditional grading system is often still used and includes:

    • Grade I (mild): 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 weeks to fully recover.
    • Grade II (moderate): A larger tear in your muscle that makes it difficult to move and causes a moderate amount of pain, especially when you move the affected muscle, swelling, and tenderness. You may have 5 percent to 50 percent loss of function and you may be limping. You can't go back to sporting activities until the tear is completely healed. These injuries can take anywhere from a couple weeks to a few months to heal, depending on how bad they are.
    • Grade III (severe): A complete tear in your muscle that causes severe pain and swelling and you can't bear weight on that leg, making it difficult to walk. You've also lost more than 50 percent of your muscle function. These injuries are less common and may need surgery to repair the torn muscle. They can take several months or more to completely heal.

      Risk Factors

      You're more likely to get a hip flexor injury if you've had one in the past, you don't warm up properly before engaging in athletic activity, your muscles are already tight or stiff, or your muscles are weak from being overused. If, while exercising, you try to do too much at once in too short an amount of time, you can also put yourself at risk for a hip flexor injury.

      Symptoms

      The chief symptom of a strained or torn hip flexor is pain in the area at the front of your hip where it meets your thigh. Your experience can vary and may involve:

      • Mild pain and pulling
      • Cramping and sharp pain and/or severe pain
      • Bruising
      • Swelling
      • Muscle spasms (in the case of a complete tear)

      You may feel pain or a pulling sensation when you come up from a squat or when you stand up after sitting. With a complete tear, which isn't as common as a strain, it may be hard to walk.

      Treatment

      As long as it's not severe, you should be able to treat your hip flexor strain or tear at home using the PRICE (protection, rest, ice, compression, elevation) protocol and pain relievers. Here's what to do:

      • Protection: Protect your injury to keep it from getting worse or injured again. For example, you can use a brace or support or wrap it with a bandage.
      • Rest: Stay off of your hip as much as you can for the first few days and avoid any activities that cause pain.
      • Ice: Using ice or a reusable ice pack can help relieve pain and reduce any swelling in your muscles. Apply immediately after you get the injury for 20 minutes and repeat every three to four hours for the next two to three days.
      • Compression: If you're worried about swelling or find that it's increasing, try wrapping the injured area lightly with a bandage or wearing compression shorts.
      • Elevation: Put your leg up so that it's higher than your heart as often as you can. This helps reduce swelling and inflammation.

      You can use over-the-counter remedies such as Motrin or Advil (ibuprofen) or Aleve (naproxen) to help with pain and swelling. Tylenol (acetaminophen) works for pain relief, but it doesn't treat inflammation and swelling. If you have heart disease, high blood pressure, kidney disease, or if you've had ulcers or internal bleeding, check with your doctor before taking any of these medications.

      If it doesn't improve within a couple of weeks or you start having a hard time moving your leg and/or hip, it's time to see your doctor. Your injury could be more severe than you originally thought, requiring other treatments, or be unrelated to the hip flexors entirely.

      You may be given exercises to do at home. 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. Soft tissue release is an advanced form of massage therapy that targets specific muscles 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.

      Prevention

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

      • Always warm up before engaging in any exercise or physical activity, even if it's just practice.
      • Make sure you do a cool down after activity. Slowly stretch each muscle group and hold the stretch for a few seconds.
      • Keep your muscles in good shape by regularly exercising. Exercises that help stretch and strengthen your hip flexors include pigeon pose, bridges, lunges, seated butterfly stretch, straight leg raises, and squats. Don't push too hard; these shouldn't hurt.
      • Work on strengthening all of your core muscles and glutes. These muscles work together to give you balance and stability and to help you move through the activities involved in daily living, as well as exercise and sports. When one set of these muscles is weak or tight, it can cause injury or pain in another, so make sure you pay equal attention to all of them.
      • Before you go back to your regular exercise or sports, be sure that your injury has fully healed and that the muscles are back to the same strength and flexibility you had before the injury (or better). Not taking enough time to heal can lead to reinjuring yourself, which can set you back even further.
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