What Is an Adductor Strain?
Adductor strain — also referred to as muscular groin pain — is a partial or complete injury to the musculotendinous fibers of the hip adductor muscles, most commonly the adductor longus. It is the most frequent cause of groin pain in athletes, accounting for approximately 62% of all groin strains in sports populations.
The injury occurs predominantly in sports involving rapid changes of direction, acceleration, deceleration, and kicking — such as soccer, ice hockey, tennis, and combat sports. The typical mechanism is forced eccentric contraction of the adductors during sudden hip abduction or lateral change of direction, generating stress on the proximal myotendinous junction of the adductor longus.
Differential diagnosis of groin pain in athletes is broad and often challenging, as several structures converge in the inguinal region. Adductor strain may coexist with other causes of groin pain — such as hip pathology or sports hernia — making systematic evaluation essential.
Adductor Longus
The adductor longus muscle is the most frequently injured (62% of groin strains), with the proximal myotendinous junction as the predominant site.
Eccentric Mechanism
The injury typically occurs during forced eccentric contraction in abduction — change of direction, kick, lateral slide.
Copenhagen Protocol
The Copenhagen adductor exercise is the gold standard for prevention, with up to 41% reduction in adductor injury incidence in regular programs (Thorborg et al.).
Pathophysiology
The hip adductor muscles — adductor longus, adductor brevis, adductor magnus, gracilis, and pectineus — originate at the inferior pubic ramus and pubic symphysis, inserting along the linea aspera of the femur. The adductor longus is the most vulnerable due to its anatomic and biomechanical position: it has the largest mechanical lever during adduction, a relatively short proximal tendon, and a narrow myotendinous junction.
The main biomechanical risk factor is the adductor/abductor strength ratio. Prospective studies show that athletes with an adductor/abductor strength ratio below 80% have a significantly increased risk of strain (Thorborg et al., 2011). This imbalance is particularly common in soccer players, in whom the abductors are frequently stronger because of the repetitive kicking motion.
The injury typically occurs at the proximal myotendinous junction of the adductor longus — the transition zone between tendon and muscle belly, where force distribution is most heterogeneous. Strains are classified by grade: Grade I (rupture of a few fibers, without significant functional loss), Grade II (partial rupture with strength loss and functional limitation), and Grade III (complete rupture or avulsion, with functional disability).
Symptoms
Clinical presentation varies by injury grade. In acute strain, the athlete often identifies the exact moment of injury — sudden groin pain during acceleration, change of direction, or kicking. In chronic or insidious forms, pain develops progressively and may be hard to localize at first.
Symptoms of Adductor Strain
- 01
Groin pain (medial inguinal region)
Pain in the medial groin, over the adductor longus origin at the pubic ramus or at the proximal myotendinous junction.
- 02
Pain on resisted hip adduction
Resisted adductor contraction (squeezing a ball between the knees) reproduces pain with high specificity.
- 03
Pain on passive hip abduction (stretching)
Passive adductor stretching strains the injured region and reproduces pain — especially in acute strains.
- 04
Pain when kicking, accelerating, or changing direction
Sports activities that actively recruit the adductors reproduce pain consistently.
- 05
Bruising on the medial thigh (grade II-III injuries)
Visible hematoma on the inner thigh, indicating significant fiber rupture with bleeding.
- 06
Weakness when squeezing the legs (positive squeeze test)
Loss of adductor strength, assessed by squeeze test with a dynamometer at 45° hip flexion.
Diagnosis
Diagnosis of adductor strain combines clinical history (injury mechanism, groin pain worsened by resisted adduction) with provocative physical examination. MRI is the gold standard to confirm injury extent and guide return-to-sport prognosis.
🏥Diagnosis of Adductor Strain
Fonte: Doha Consensus on Groin Pain (Weir et al., 2015)
Physical Examination
- 1.Squeeze test: pain on resisted adduction with hip at 45° flexion — most sensitive test for adductor pathology
- 2.Resisted adduction in supine: pain reproduced when adducting the lower limb against the examiner's hand
- 3.Insertion palpation: pain on direct palpation of the adductor longus origin at the inferior pubic ramus
- 4.Passive stretching: pain on passive hip abduction with the knee extended (adductor stretch)
Imaging Studies
- 1.MRI: gold standard for grading (grade I-III), assessment of injury extent, and prognosis; muscle edema on T2/STIR
- 2.Ultrasound: dynamic assessment of the myotendinous junction, identification of intramuscular hematoma; good sensitivity for grade II-III injuries
- 3.Radiograph: assessment of heterotopic calcification, bone avulsion (rare), and exclusion of pubic osteitis (symphyseal irregularity)
DIAGNÓSTICO DIFERENCIAL
Differential Diagnosis
Inguinal Hernia (Sports Hernia)
- Groin pain that worsens with abdominal effort
- Palpable bulge in the inguinal region may be present
- Pain on coughing or Valsalva maneuver
Testes Diagnósticos
- Palpation of the inguinal canal with Valsalva maneuver
- Resisted adduction typically painless (or less painful)
Pubic Osteitis
- Bilateral pain at the pubic symphysis
- Bone pain on symphysis palpation
- Frequently coexists with adductor pathology
Testes Diagnósticos
- Pain on direct palpation of the symphysis (not the muscle insertion)
- Radiograph with sclerosis and symphyseal irregularity
Pubic Ramus Stress Fracture
- Insidious groin pain in long-distance female runners
- Progressive pain with impact loading
- May radiate to groin and medial thigh
Testes Diagnósticos
- Localized bone pain at the pubic ramus
- MRI with bone marrow edema in the pubic ramus
Hip Labral Tear
- Deep anterior groin pain
- Hip clicking or locking
- Pain on internal rotation and hip flexion
Testes Diagnósticos
- Positive FADIR (flexion-adduction-internal rotation)
- MR arthrography with identifiable labral lesion
Piriformis Syndrome
Read more →- Deep gluteal pain with posterior radiation
- Worsens with prolonged sitting
- May radiate to the posterior thigh
Testes Diagnósticos
- Pain on piriformis palpation and resisted internal rotation
- Positive FAIR test (flexion-adduction-internal rotation in prone)
L2-L3 Radiculopathy
- Pain radiating from low back to groin and anterior thigh
- Possible sensory changes
- Associated low back pain
Testes Diagnósticos
- Neurologic examination with L2-L3 sensory changes
- Lumbar MRI with herniation or foraminal stenosis
Treatments
Treatment of adductor strain is predominantly conservative, with excellent results in most grade I and II cases. The therapeutic pillar is rehabilitation with progressive loading — progressing from isometrics to eccentric exercises and, finally, to sport-specific load. The Copenhagen adductor protocol, with strong evidence in the literature (Thorborg et al.), is integrated into both rehabilitation and prevention of recurrences.
Initial management involves pain control and relative protection of the injured region, but prolonged absolute rest is avoided — as with other musculotendinous injuries, early controlled loading accelerates recovery and improves tissue healing quality.
EXERCISES IN THE ADDUCTOR STRAIN REHABILITATION PROTOCOL
| EXERCISE | TARGET | PROTOCOL | NOTE |
|---|---|---|---|
| Adduction isometrics (squeeze) | Adductors — analgesic isometric loading | 5×45s at 60-70% of maximal load, 2×/day | Ball between the knees at 45° hip flexion; no pain during contraction |
| Copenhagen adductor (modified) | Adductors — submaximal eccentric loading | 3×6-8 each side, weekly progression | Modified version (knee support) initially; progress to the full version |
| Eccentric adduction with cable/elastic | Adductor longus — targeted eccentric loading | 3×10, 3s eccentric phase | Controlled abduction against resistance; focus on the lengthening phase under load |
| Side lunge | Adductors — functional loading with stretching | 3×8-10 each side, load progression | Progressive range; eccentric control on the lateral descent |
| Progressive change of direction | Neuromuscular integration — sport-specific | Sets of 6-10 repetitions, speed progression | Cutting drills at progressive speed; final stage before return to sport |
Rehabilitation Schedule
Phase 1
0-1 week (Grade I) / 0-2 weeks (Grade II)Protection and Isometrics
Pain control (cryotherapy, anti-inflammatories if indicated by the physician), adduction isometrics at a painless angle (ball squeeze at 45°), painless gait as the progression criterion.
Phase 2
1-3 weeks (Grade I) / 2-6 weeks (Grade II)Eccentric Loading and Modified Copenhagen
Modified Copenhagen adductor (with knee support), eccentric adduction with cable, hip mobility. Acupuncture as an adjunct for pain control.
Phase 3
3-6 weeks (Grade I) / 6-10 weeks (Grade II)Functional Strengthening
Full Copenhagen, side lunge with progressive load, closed kinetic chain exercises. Criterion: painless squeeze test at 80% of contralateral strength.
Phase 4
4-8 weeks (Grade I) / 8-16 weeks (Grade II)Return to Sport
Changes of direction at progressive speed, running with acceleration/deceleration, sport-specific training. Copenhagen adductor continued as ongoing prevention.
Acupuncture
Acupuncture can contribute as a complementary therapy to progressive-loading rehabilitation in adductor strain, modulating groin pain and potentially supporting muscle healing. The approach combines local points in the inguinal region and medial thigh with regional and distal points for neuromodulation.
The point SP-10 (Xuehai), on the medial thigh above the patella, and LR-8 (Ququan), on the medial knee, are located along the meridians that course down the medial aspect of the lower limb and are relevant references for pain in this region. Ashi points over the injured myotendinous junction, identified by careful palpation, allow perilesional needling with potential local modulatory effect.
Electroacupuncture at a frequency of 2-4 Hz applied between points flanking the injury region can stimulate the release of endogenous opioids and inflammation modulators. Experimental evidence suggests that electroacupuncture may promote the expression of growth factors involved in muscle regeneration and reduce excessive scar fibrosis formation — although translation of these findings to clinical practice still requires more studies in humans.
ACUPUNCTURE POINTS IN ADDUCTOR STRAIN
| POINT | LOCATION | THERAPEUTIC FUNCTION |
|---|---|---|
| SP-10 (Xuehai) | Medial thigh, 2 cun above the patella | Medial-thigh modulation; proximal point for adductor pain |
| LR-8 (Ququan) | Medial knee, at the end of the popliteal crease | Liver-meridian modulation; regional point for groin pain |
| Ashi inguinal points | Over the injured myotendinous junction, palpation-guided | Direct perilesional needling; local analgesia and modulation |
| SP-6 (Sanyinjiao) | Medial leg, 3 cun above the medial malleolus | Confluence of the yin meridians; modulates the medial lower limb |
| LR-3 (Taichong) | Dorsum of the foot, between 1st and 2nd metatarsals | Distal liver-meridian point; modulates pain along the inguinal pathway |
When to Seek Medical Help
Frequently Asked Questions about Adductor Strain
Adductor strain is an injury to the musculotendinous fibers of the hip adductors — most commonly the adductor longus, which originates at the pubic ramus and pulls the thigh toward the midline. Groin pain occurs because the proximal myotendinous junction (near the pubic-bone origin) is the most vulnerable region, where eccentric traction forces during changes of direction and kicking concentrate stress.
Pubalgia is a broad term that encompasses several causes of pain in the pubic and inguinal region. Adductor strain (muscular pubalgia) is one of the most common causes, involving injury to the adductor fibers. Other causes include pubic osteitis (inflammation of the pubic symphysis), sports hernia, and hip pathology. The Doha Consensus (2015) recommends using specific terms instead of "pubalgia" to improve diagnostic and therapeutic precision.
The Copenhagen adductor is an eccentric adductor-strengthening exercise performed in a side plank, with the upper limb supported on a bench and the body held up by lower-limb adduction. It is the gold standard for preventing adductor strains, with a meta-analysis showing up to 41% fewer groin injuries in teams that include it in the regular warm-up. The modified version (knee support) allows safe progression in rehabilitation.
The time depends on the grade of injury: Grade I (microtears without significant functional loss) typically requires 1-3 weeks; Grade II (partial rupture with hematoma) requires 4-8 weeks; Grade III (complete rupture) may require 3-4 months or surgical intervention. Adherence to the progressive loading protocol and inclusion of prevention exercises (Copenhagen) directly influence return time and risk of recurrence.
Prevention rests on three pillars: (1) regular adductor strengthening with the Copenhagen adductor in the warm-up (2-3x/week); (2) keeping the adductor/abductor strength ratio above 80%, checked periodically with the squeeze test; and (3) training-load management, avoiding abrupt increases in volume and intensity. Preseason squeeze-test screening identifies at-risk athletes who benefit from intensified preventive programs.
Acupuncture can contribute as a complementary therapy to rehabilitation, modulating groin pain and potentially improving adherence to the progressive exercise program. Perilesional electroacupuncture may promote endogenous analgesia and modulate the inflammatory process. The greatest benefit is enabling the patient to perform the Copenhagen adductor and eccentrics at the appropriate therapeutic dose, especially in early rehabilitation. A medical acupuncturist can integrate this approach into the treatment plan.
Surgery is rarely necessary and reserved for: complete ruptures (Grade III) with significant tendon retraction, bone avulsions of the pubic ramus, and cases of failure of conservative treatment for 3-6 months. The most common procedure is reinsertion (repair) of the adductor tendon to the pubic ramus. Most athletes return to competition within 3-4 months after surgical repair, with rates of return to pre-injury level varying between 75-90% in the available literature.
Related Reading
Deepen your knowledge with related articles