The Real Causes Of Groin Strains

It is my opinion that non-contact groin injury is primarily caused by the following factors:

  • Deactivated glutes
  • Tight external hip rotators
  • Overworked internal hip rotators
  • Insufficient internal hip rotation

The groin musculature is primarily comprised of the three adductors:

adductor magnus—the largest

adductor longus—–the one usually injured

adductor brevis—–the smallest

There are also two extra muscles that aid the action of adduction which are pectineus and gracillus. Rupture either occurs to the muscle belly, the musculo-tendinous junction, or the tendon itself, near the origin at the pelvis. Groin pulls can keep athletes out of action for weeks, or even months. Sports involving twisting, turning, and kicking influence the risk of injury. Once injured, the risk of re-injury doubles.

Recognized causes of injury:

  • Overuse—–When we run, the adductors stabilize the hip with every footfall, and are subject to many forces. Adequate recovery is crucial between workouts, otherwise irritation to muscles and tendons increases.
  • Inadequate warm-up.
  • Sudden fast actions, such as explosive “starts” in sprinting, but more importantly, any sudden change in direction when the athlete has poorly functioning glutes, very tight external hip rotators, and over-burdened hip adductors. Alternatively, a sudden and explosive hip extension, such as in a basketball ‘shoot’.
  • Poor mechanics when lifting heavy objects—there is a tendency for the hip to abduct (move away from the centreline), thus placing excessive strain on the adductors. The reason for this is IMBALANCE between internal/external hip rotator strength ( butt muscles, inner and outer thigh, and also the hip flexors )
  • Compensatory motions due to the above-mentioned imbalances. Excessive external hip rotation will require the adductors to act eccentrically as de-celerators, rather than as stabilizers, and disadvantages the hip flexors, thus the adductors are forced to compensate—hence overload and eventual injury.
  • Acetabular labrum tears—roughly 20% of groin pain in athletes will involve  a torn A.L., which is a ring of fibro-cartilage that attaches to the circular outer edge of the acetabulum (hip socket). It’s main function is to improve hip joint stability. The five most common causes of A.L. tears are:

1. Trauma—-main cause in athletes who twist and pivot while weight-bearing.

2. Hip dysplasia (misalignment)—often seen in hyper-mobile individuals, such as dancers, track & field, etc.

3. Degeneration

4. Capsular laxity

5. Femoro-acetabular impingement

Co-factors : fatigue, poor pelvic stability due to weak transversus abdominus (TA) and obliques, plus improper stretching of adductor longus.

So these inefficient loading patterns explain the predisposition to groin pulls. Furthermore, excessive glute strength, as is often found in sprinters, for example, tends to overload their adductors. It has been demonstrated that decreased hip rotation range is a factor in acute adductor strain in soccer, (specifically reduced internal hip rotation), and in Aussie Rules football. So focus on hip rotation range of motion, rather than adduction range of motion.

The piriformis (external hip rotator) is of particular concern when it becomes very tight. Stretching the external hip rotators is vital! ( including the glute medius). Foam rolling on the external rotators is also highly recommended. Please understand this doesn’t mean you should neglect adductor stretching, as the key is “BALANCE”, and where potential for a groin injury is concerned, you should take extra precaution to stretch external hip rotators in conjunction with the foam roller techniques, otherwise they will become too strong for the internal rotators, and the unaddressed tightness will cause injury eventually. Couple this with strengthening your adductors, and stretching them. The foam roller can be used on these, too. If adductor: abductor strength is less than 80%, there is a 17-fold increase risk of injury. So strengthen the adductors!!

When the internal hip rotators are deficient, the lumbar spine compensates, causing increased loading and eventual low back pain (LBP). The adductors also overwork, especially for hip flexion motions. For example, in soccer this relates to frequent kicking and turning, where the femur moves across the body, requiring good internal hip rotation range.

When external rotation is limited, we tend to find increased frontal plane knee excursion, which is implicated with ACL ruptures. Lack of flexibility in the adductors has NOT been shown to have much significance in groin injuries.

People with anterior pelvic tilt (80% population), have excessive lordosis (lumbar spine curvature), tight rectus femoris (hip flexor), and usually a tight/shortened ITB, which will cause some degree of reduced range of hip extension, and reduced internal rotation/flexion. This causes compensations in other areas such as the lumbar spine.When anterior pelvic tilt is present, due to tight hip flexors pulling against it, the gluteus maximus loses function, making the pelvis very unstable during one leg support, thus overloading the tensor fascia lata (TFL), and further tightening the iliotibial band (ITB), both of which inhibit the gluteus medius and minimus further. It’s vital that the glutes stabilize the pelvis and trunk. When running, the gluteus maximus acts to maintain upright posture, and laterally rotate the femur as the leg pushes off, thus helping to achieve the toe-off position. The medius and minimus work to maintain a level pelvis when weight-bearing on one leg, preventing the free side from dropping down. They also control rotation of the pelvis as the free leg swings forward. So these stabilizers become inhibited and are not active enough for sufficient duration. For more in depth discussion, see article “Poor Pelvic Alignment”

A common factor is reduced posterior movement of the femur, thus also reducing range of flexion/internal rotation, and unfortunately this is usually accompanied by increased medial movement and range of hip abduction, which leads to over-stretching injuries in the groin.

It is a fact that pre-existing pathologies such as osteitis pubis or inguinal hernia is soon followed by adductor tear, or vice versa, which gives credence to  my belief that the root cause of most groin strain is due to excessive muscle tightness and hindered mobility. The balance needs to be restored between STABILITY and MOBILITY throughout the body.

In closing, I will re-cap some major points: the main joints associated with the groin are the hip joint, lumbar spine, and sacroiliac joints.

Hip issues are:

  • Dysplasia
  • Decreased internal rotation, with this being the most prevalent problem, as it causes a compensatory increase in hip abduction in stepping and cutting manoeuvres, thus overloading the adductors.

Lumbar spine issues are:

  • All to do with hip displacement, hence the importance to address pelvic tilt syndrome as part of your ongoing injury prevention program. Frequently, the left side loses mobility more often just a few days before an adductor tear; also with an extremely tight right side TFL (tensor fascia lata), right side psoas, and left side glute medius and gracillus.

Sacroiliac joint issues are: Restricted function causes excessive motion at the hip joint and adductor region.

Secondary issues are: weakness in transverse abdominus, obliques and rectus abdominus, all with inhibited reciprocal innervation that would be addressed through dealing with pelvic tilt issues, and probably inhibited serratus anterior.

An off-season maintenance program should be applied to pre-condition the athlete to futher minimize the chance of injury.

Shane  Shiels, Owner, Shashido Enterprises