Measure the adductor longus with a handheld myotonometer, patient supine, hips and knees neutral, legs in a fixed and repeatable degree of abduction. Hip position changes this reading more than it changes most muscles, so reproduce the exact setup every visit and take 3 to 5 readings per side.
Which Adductor Should You Actually Measure?
The adductor longus, in most cases. It is the most superficial muscle of the group, it has a palpable proximal tendon near the pubic tubercle that gives you a repeatable landmark, and it is the muscle most often involved in athletic groin pain. The adductor magnus can be measured too, but it sits deeper and the probe reads through more overlying tissue. Pick one muscle, document the landmark, and stay with it across the course of care rather than switching targets between visits.
Where Should the Probe Go?
Over the adductor longus muscle belly, roughly a hand's width distal to the proximal tendon, along the line from the pubic tubercle toward the medial femoral condyle. Palpate the tendon first with the hip in slight abduction so the muscle stands out, then move distally onto the belly. Mark the distance from the pubic tubercle in your notes. This region has enough anatomical variation that "medial thigh" is not a specific enough record to reproduce.
Why Does Hip Position Matter So Much Here?
Because the adductor longus changes mechanical state dramatically with hip angle. A 2023 study in Scientific Reports quantified adductor longus shear modulus across hip positions and found stiffness was significantly higher in hip extension, especially when combined with internal rotation, than in flexion. That means a reading taken with the patient's legs slightly flexed on a bolster is not comparable to one taken flat on the table. If you change the setup between visits, any change you see may be the setup rather than the tissue.
| Setup variable | Why it matters for the adductors | How to control it |
|---|---|---|
| Hip flexion angle | Shear modulus differs significantly between flexion and extension | Flat supine, no bolster, documented at baseline |
| Hip rotation | Internal rotation raises measured stiffness in extension | Neutral rotation, feet allowed to rest naturally |
| Degree of abduction | Changes muscle length and therefore resistance | Fixed, comfortable abduction reproduced each visit |
| Probe distance from pubic tubercle | Muscle belly thickness varies along its length | Record the distance in centimeters at baseline |
| Recent adductor training | Loading can raise the reading for days | Ask about training in the last 48 to 72 hours |
How Reliable Is the Measurement?
High, when the setup is controlled. A 2026 randomized controlled trial on the Copenhagen Adduction Exercise used a handheld myotonometer on the adductor longus and adductor magnus in physically active adults and reported intra-rater reliability at or above 0.93. Separately, a 2021 study comparing handheld myotonometry with shear wave elastography in major lower limb muscles found moderate to strong correlation between the two methods at rest and during contraction. The handheld device is the realistic choice for a clinic that needs a number at every visit.
What Does a Rising Adductor Reading Mean?
Often it means the patient trained, not that something went wrong. The same 2026 trial found adductor longus stiffness rose significantly after a single bout of the Copenhagen Adduction Exercise, and the rise showed a moderate positive correlation with perceived soreness. Adductor magnus did not change. That is a normal eccentric loading response. Ask what the patient did in the last 48 to 72 hours before you interpret an increase as a setback, and say so out loud to the patient so the number does not read as bad news.
Can the Reading Predict a Groin Injury?
No, and claiming otherwise will not survive contact with the evidence. Stiffness readings may reflect mechanical resistance in the tissue, and position-specific data suggests certain hip positions raise passive tension in ways that are relevant to sport. None of that supports telling an individual athlete their number means they are about to get hurt. Use the reading to track change over a rehab block alongside adductor strength testing and symptom reports.
Survey data: In a 2026 survey of 455 patients who stopped chiropractic care, 58% cited perception-based reasons: 36% felt no progress, and 22% felt better and stopped. Groin cases are especially prone to the second pattern, since athletes often feel ready to return before the tissue measurements have settled.
Frequently Asked Questions
Which adductor muscle should you measure?
The adductor longus is the practical target. It is the most superficial of the adductor group, the easiest to locate reliably from its palpable proximal tendon, and the muscle most often implicated in athletic groin pain.
What position should the patient be in for an adductor reading?
Supine with hips and knees neutral, legs resting in a consistent, comfortable degree of abduction. Hip position matters more here than for most muscles, so record the exact setup at baseline and reproduce it at every follow-up.
Does hip position really change the adductor stiffness reading?
Yes, substantially. A 2023 study using shear wave elastography found adductor longus shear modulus was significantly higher in hip extension, particularly combined with internal rotation, than in flexion. Comparing readings taken in different hip positions is not a valid comparison.
How reliable is handheld myotonometry on the adductors?
A 2026 randomized controlled trial reported high intra-rater reliability for handheld myotonometry of the adductor longus and adductor magnus, with intraclass correlation coefficients at or above 0.93. Reliability still depends on consistent probe placement and patient position.
Does a stiff adductor reading predict a groin injury?
No. A stiffness reading may reflect increased mechanical resistance in the tissue, but no evidence supports using it to predict injury in an individual athlete. Treat it as one tracked variable alongside strength testing and symptom history.
Will a stiffness reading go up after adductor training?
It can. A 2026 trial found adductor longus stiffness increased significantly after a single bout of the Copenhagen Adduction Exercise, with a moderate positive correlation to perceived soreness. That likely reflects normal eccentric loading rather than injury, so ask about recent training before interpreting a rise.
Should you measure both sides in a groin case?
Yes. Athletes often have meaningful baseline asymmetry from sport demands, so the uninvolved side gives you a within-patient reference. Track whether the gap narrows across the course of care rather than judging a single absolute value.
One approach is to add a second channel of objective data alongside subjective pain reports. Options include soft tissue stiffness measurement (such as MuscleMap), range-of-motion testing, and posture analysis. Each gives you something concrete to show the patient rather than asking them to take your word for it.