Biomechanics of Copenhagen Adduction Exercise and Eccentric Hip Adductor Exercises on a Novel Isokinetic Dynamometer With Within-Session Repeatability.
Marušič J, Cvjetičanin O, et al. • Scandinavian journal of medicine & science in sports • 2026
The Copenhagen adduction exercise produced significantly lower peak eccentric torques than all eccentric hip adductor dynamometer variations, while increasing lever length during CAE effectively raises hip adductor loading, and EHAD exercises demonstrated pronounced bilateral facilitation of 27.9% ± 16.5%.
Key Findings
Results
The Copenhagen adduction exercise (CAE) produced significantly lower peak eccentric torques than all eccentric hip adductor dynamometer (EHAD) variations, regardless of lever length or unilateral/bilateral performance.
Fifteen participants completed two CAE variations and five EHAD exercises.
Three-dimensional kinematics and force data were collected to compute peak hip joint torque, range of motion (ROM), and angle at peak torque as primary dependent variables.
This finding held regardless of whether CAE lever length was short or long, and regardless of whether EHAD exercises were performed unilaterally or bilaterally.
Results
Long lever CAE elicited greater peak and average torques than short lever CAE, but range of motion was significantly lower in the long lever condition.
Both peak and mean external force and body-mass-normalized torque were higher in the long lever CAE compared to the short lever CAE.
ROM was significantly lower in the long lever condition across exercises.
Increasing lever length during CAE effectively raises hip adductor loading.
Results
EHAD exercises generated significantly greater peak torques during bilateral performance compared to unilateral performance, demonstrating bilateral facilitation.
Bilateral facilitation magnitude was 27.9% ± 16.5%.
This bilateral facilitation effect was present across EHAD exercise variations.
Bilateral facilitation refers to the phenomenon where force output during bilateral performance exceeds that during unilateral performance.
Results
The angle at peak torque was similar across all exercises, ranging from 31° to 39°.
This consistency was observed across both CAE variations and all five EHAD exercises.
The similar angle at peak torque suggests that the hip joint position at which maximal loading occurs is relatively consistent across these exercise modalities.
Results
With the exception of angle at peak torque during the CAE, all measurements showed good to excellent relative and moderate to good absolute within-session repeatability.
Relative and absolute within-session repeatability were evaluated for all primary dependent variables.
Angle at peak torque during CAE was the one measure that did not meet the good-to-excellent relative repeatability threshold.
Peak hip joint torque, ROM, and other force measures demonstrated good to excellent relative repeatability and moderate to good absolute repeatability within a session.
Methods
A novel eccentric hip adductor dynamometer (EHAD) was evaluated as a device for performing eccentric hip adductor exercises with measurable force and kinematic output.
Five different EHAD exercise variations were tested, including unilateral and bilateral conditions.
Three-dimensional kinematics and force data were simultaneously collected during EHAD exercises.
The EHAD enabled quantification of peak and mean external force and body-mass-normalized torque.
What This Means
This research suggests that a machine specifically designed for eccentric hip adductor strengthening (called EHAD) produces much higher muscle loading at the hip than the widely-used Copenhagen adduction exercise (CAE), regardless of how the CAE is performed. The study had 15 participants perform two versions of the CAE (short and long lever) and five variations on the EHAD device, while measuring joint forces, angles, and range of motion in three dimensions. Even the least demanding EHAD exercise produced greater peak muscle torques than the most demanding version of the CAE.
Within the CAE itself, using a longer lever arm (i.e., supporting the leg further from the hip) increased the load on the adductor muscles, but also reduced how much the hip could move through its range during the exercise. On the EHAD device, performing exercises with both legs simultaneously produced about 28% more force than doing the same exercise one leg at a time — a phenomenon known as bilateral facilitation. Notably, the joint angle at which peak force occurred was consistent across all exercises, falling between 31° and 39°. The measurements from the EHAD device were also shown to be reliably repeatable within a single testing session, supporting its use in research and clinical settings.
This research matters because hip adductor injuries and groin strains are common in sports, and rehabilitation or prevention programs depend on exercises that adequately load these muscles. The findings suggest that the CAE, while popular and accessible, may not provide as much muscle loading as dynamometer-based alternatives. The authors note that future studies are needed to determine whether the higher loading provided by EHAD exercises actually translates into better injury prevention or rehabilitation outcomes in practice.
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Marušič J, Cvjetičanin O, Supej M, Babič J, Šarabon N. (2026). Biomechanics of Copenhagen Adduction Exercise and Eccentric Hip Adductor Exercises on a Novel Isokinetic Dynamometer With Within-Session Repeatability.. Scandinavian journal of medicine & science in sports. https://doi.org/10.1111/sms.70365