The adductor muscle group, commonly known as the groin muscles, is a collection of muscles that primarily pull the legs together. Assessing the length or flexibility of these muscles is standard practice in physical therapy and sports medicine. This evaluation helps identify athletes at risk for groin strain injuries or assess mobility limitations that may contribute to chronic hip or pelvic pain. The Adductor Test provides a measurable way to determine if a person’s inner thigh flexibility falls within a functional range.
Understanding the Adductor Test Procedure
The Adductor Test, often referred to in clinical settings as the passive hip abduction test, is a standardized procedure designed to measure hip flexibility. The patient lies supine on an examination table, with the leg being tested positioned straight. The core principle of the test is to isolate the movement to the hip joint, specifically hip abduction, which lengthens the adductor muscles.
The examiner passively moves the patient’s leg outward until a clear resistance is felt, or until a compensating movement occurs in the pelvis. Stabilization of the pelvis is a highly important part of the procedure, with the examiner applying firm pressure over the anterior superior iliac spine (ASIS) on the opposite side to prevent rotation or tilting. This pelvic stabilization ensures that the measurement truly reflects the adductor muscle length.
A universal goniometer is typically used to measure the angle of the leg relative to the midline of the body. The angle recorded is the maximum passive hip abduction achieved just before the pelvis begins to move or “compensate.” This measurement provides a specific, objective number representing the current length and extensibility of the adductor complex.
Establishing the Range of Normal Mobility
Normal mobility for the Adductor Test is generally defined by the range of passive hip abduction achieved before the pelvis tilts, which is the point of true muscle-length restriction. For a healthy, non-athletic adult population, a passive hip abduction range of approximately 40 to 45 degrees is often cited as a standard reference for normal flexibility. This range represents the point at which the soft tissues of the adductors restrict further outward movement of the leg.
The specific adductor test protocol used can influence the expected normal measurement. Some protocols measure hip abduction with the knee straight, while others perform the test with the hip flexed to 90 degrees and the knee bent. The straight-leg version primarily assesses the entire adductor group, including the adductor magnus, while the bent-knee version isolates the monoarticular adductors, which cross only the hip joint.
A range slightly above 45 degrees is common in athletic populations, particularly in sports like gymnastics or dance where high levels of flexibility are trained. Conversely, a measurement below 35 degrees is considered a sign of hypomobility or tightness. A change of more than 5 to 6 degrees between two measurements signifies a real change in muscle flexibility, as this degree of difference is greater than the expected measurement error.
Clinical Significance of Deviations
Results from the Adductor Test that fall outside the established normal range carry important clinical implications for a person’s joint function and injury risk. Hypomobility (tightness) is strongly associated with an increased risk for groin pain and adductor muscle strains, particularly in sports requiring rapid acceleration or sudden changes in direction. Low adductor flexibility is considered a risk factor in athletes, such as soccer and hockey players, where the muscles are repeatedly stressed into a lengthened position.
Conversely, hypermobility (excessive flexibility) can indicate an underlying issue with joint stability. While high flexibility can be an advantage in certain activities, excessive range of motion in the hip joint may lead to microtrauma, instability, and chronic pain. Hypermobility can be a sign of a generalized condition, such as Hypermobility Spectrum Disorder, which involves generalized joint laxity. The hip joint may be prone to subluxations or early joint degeneration due to insufficient soft tissue restraint.
Factors Influencing Baseline Mobility
The baseline measurement of adductor mobility is influenced by several individual characteristics, causing the normal range to vary.
- Age is a significant factor, as the amplitude of most hip motions, including adduction, tends to decrease as a person gets older. Children and adolescents generally exhibit greater flexibility than adults, though this gradually declines into adulthood.
- Gender also plays a role in mobility norms, with females typically demonstrating a higher range of total hip motion and greater hip abduction flexibility compared to males across different age groups.
- Activity level and sports participation heavily influence the baseline measurement. Athletes in sports that demand high flexibility, such as martial arts or running, often possess greater adductor length than sedentary individuals or those involved in power-focused sports like throwing.
- Prior injury history, especially a previous adductor strain, can affect the baseline by leading to scar tissue formation, which may restrict the muscle’s ability to lengthen fully.