What exactly is a hip flexor strain?

It is a tear in one of the muscles at the front of your hip that lift your thigh — most often the iliopsoas or rectus femoris. It ranges from a mild overstretch (Grade I) to a complete tear (Grade III), and it is common in running, sprinting and kicking sports.

How long does it take to recover?

It depends on severity. Mild strains often settle in one to three weeks, moderate ones in several weeks, and severe tears can take a few months. Return to sport should be guided by being pain-free with full strength, not by the calendar alone.

Should I stretch and strengthen it, or rest completely?

Brief protection early on helps, but complete prolonged rest is not ideal. Once the sharp pain settles, gentle pain-free movement followed by progressive strengthening, ideally guided by a physiotherapist, gives the best recovery and lowers re-injury risk.

My teenager felt a sudden pop while sprinting and cannot run — what could it be?

In growing athletes, a forceful sprint or kick can pull a small piece of bone away where the muscle attaches to the pelvis (an avulsion injury), rather than just straining the muscle. This deserves prompt medical assessment and may need an X-ray, so see a doctor rather than pushing through.

Do I need a scan for a hip flexor strain?

Usually not — most are diagnosed by examination. A scan is used if the injury is severe, the diagnosis is unclear, an avulsion or bony injury is suspected (an X-ray, especially in teenagers), or recovery is slower than expected.

Hip Flexor Strain in Singapore: Causes & Recovery

Written & reviewed by the BestDoctors.sg editorial team · Last updated 24 Aug 2026 · General information, not medical advice

A hip flexor strain is a tear of one of the muscles at the front of the hip and groin that lift the thigh and drive the knee up when running or kicking — most often the deep iliopsoas or the rectus femoris. Like other muscle strains it is graded from a mild overstretch (Grade I) to a complete tear (Grade III), and it usually happens with a sudden, forceful hip flexion or overstretch. Most recover well with early protection and progressive rehabilitation, though in adolescents a forceful pull can injure the growth area instead.

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In a medical emergency, or for severe or sudden symptoms such as breathing difficulty, chest pain, fainting or stroke signs, call 995 immediately.

In a growing athlete, a sudden “pop” while sprinting or kicking with severe hip or pelvic pain may be a bony avulsion at the pelvis and needs assessment; and groin pain with fever, a lump or bulge, or abdominal or testicular pain needs review for other causes.

How it happens

The hip flexors power sprinting, kicking and knee lift. A strain occurs when they are contracted forcefully while being lengthened, or from overuse with repetitive flexion. In young, still-growing athletes, the growth areas where these muscles attach to the pelvis are vulnerable, so a forceful contraction can pull off a small fragment of bone — an avulsion injury — rather than tearing the muscle itself.

Common causes

Explosive movements are the usual trigger — sprinting, kicking in football, jumping, sudden changes of direction, hurdling or martial arts. Inadequate warm-up, a sudden increase in training, muscle fatigue, poor conditioning, and weak or tight hip flexors and core all raise the risk, as does a previous hip or groin strain. A direct blow in contact sport can also cause an acute strain.

Symptoms

Pain is felt at the front of the hip or groin, sometimes into the upper thigh, and worsens with lifting the knee, sprinting, kicking, climbing stairs or getting up from sitting. There is tenderness at the front of the hip, with possible swelling and bruising in more significant tears, and a feeling of tightness, cramping, weakness or giving way when flexing the hip. Acute higher-grade tears bring sudden sharp pain, sometimes a “pop,” and difficulty continuing.

Red flags

Seek prompt care for an inability to bear weight or walk, or a severe injury with a “pop” and immediate severe pain, which may indicate a significant tear. In adolescents and teenage athletes, a forceful sprint or kick causing severe front-of-hip or pelvic pain with marked weakness can be a bony avulsion and should be assessed, often with an X-ray. Significant swelling, a large bruise or a visible muscle defect, numbness or spreading pain also warrant review. Importantly, front-of-hip or groin pain is not always a muscle strain — hip-joint problems, hernias and other conditions can mimic it, so groin pain with fever, feeling unwell, a bulge, or abdominal or testicular pain needs prompt medical review.

How it is assessed and treated

A history and examination — the mechanism, site of tenderness, pain on resisted hip flexion and on stretching the hip, strength and gait — usually make the diagnosis. An X-ray is used if an avulsion or bony injury is suspected, particularly in adolescents, and ultrasound or MRI characterises the tear or clarifies an uncertain or slow-healing case. GPs assess initially, with sports physicians and orthopaedic surgeons for significant tears or avulsions and physiotherapists leading rehabilitation. Early care uses brief protection with optimal loading rather than prolonged rest, plus ice and simple pain relief, and rehabilitation then restores pain-free range of motion before progressing to graded hip-flexor and core strengthening, flexibility and sport-specific drills.

Graded return to sport

Recovery timelines vary widely with grade — roughly one to three weeks for mild strains, three to six weeks or more for moderate ones, and many weeks to months for severe tears or avulsions, sometimes needing specialist input. Because early return risks re-injury, the comeback is staged: rebuild strength and flexibility, then reintroduce running and kicking progressively, completing the running progression before full sport. Warming up thoroughly, keeping the hip flexors and core strong, and building training in small increments all reduce the chance of a repeat. For an adolescent recovering from an avulsion, following the specialist’s timeline matters, as the bone needs time to heal before loading resumes.

When to see a doctor

See a doctor if you cannot walk or bear weight, felt a “pop” with severe pain, or have a large bruise or muscle defect; for an adolescent with sudden severe hip or pelvic pain after sprinting or kicking; for groin pain with fever, a lump or abdominal or testicular pain; or for pain not improving after a couple of weeks. Recurrent hip flexor or groin strains deserve a proper review too, as they often respond to a structured strengthening and flexibility programme; and because front-of-hip and groin pain has several possible causes, an accurate diagnosis ensures the right problem is treated rather than the injury being managed as a simple strain when something else is going on. Warming up thoroughly and building training load gradually remain the most effective ways to avoid a repeat, especially in sports with a lot of sprinting and kicking where these strains are common.

Sources

OrthoInfo (AAOS) — Hip Strains: orthoinfo.org
Cleveland Clinic — Hip Flexor Strain: clevelandclinic.org
SingHealth — Acute Groin Strain: singhealth.com.sg
NHS — Sprains and strains: nhs.uk

General information only. This guide is general information about a sports injury and is not a diagnosis or personalised medical advice. See a doctor, sports physician or physiotherapist for assessment and a treatment plan. Seek urgent care for an inability to bear weight after an injury, a joint that locks or gives way, significant deformity, or a hot, swollen, painful calf with no clear injury (a possible blood clot). Call 995 for sudden breathlessness or chest pain (a clot may have travelled to the lungs), or for a severe injury.

Hip Flexor Strain in Singapore: Front-of-Hip Pain