Copenhagen Adduction – simple exercise strengthens thigh adductor muscles to prevent groin injuries

Acute thigh adductor muscles injuries are one of the most frequent muscle injuries among footballers and generally the most frequent groin injury in sport. This sort of injury is often associated with thigh adductor muscle weakness. When we do regular exercises responsible for strengthening thigh adductor muscles, we may reduce the number of such injuries. Scientists from several universities in Copenhagen cooperated with Sports Groin Pain Center – Aspetar clinic in Qatar – to check the impact of an 8-week training program on the strength and resistance of thigh adductor muscles. The aforesaid program required doing one simple exercise called Copenhagen Adduction (CA). This exercise was chosen due to its simplicity and easy implementation in real conditions because it can be done on the pitch without any tools. The only help is required from a partner, partners may take turns.

A person who does exercise lies on the forearm on his/her side and supports him/herself, while his/her partner supports his/her upper leg from the back by grabbing the area of the ankle and with another hand – under the knee. The person who does the exercise tries to keep the torso horizontally and position legs to form V shape. At this time he/she adducts a lower leg to the upper leg (supported by the partner) for 3 seconds, and then descends the leg (in eccentric movement) for 3 seconds until touching the floor. Partners who wish to make pairs must be similar in terms of height and body weight.

Separate studies have proved that during this exercise upper leg thigh adductor longus activation, measured electromyographically, is 108% of the maximum voluntary isometric contraction (MVIC), and lower – 69%.

Copenhagen adduction

In the experiment participated 20 football players from U19 groups from two Danish clubs playing in the second league. The eccentric strength of hip adduction muscles and torso muscles resistance was measured in the position of the support, when lying on the side, as well as eccentric strength of hip adduction muscles in order to calculate the relation of adduction muscle strength to abduction muscle. The players were divided into two groups: one of them performed two sessions per week for 8 weeks. Sessions included CA exercises and the number of series was gradually rising (2, then 3) the same applies to repetitions (starting from 6 and ending up with 15 per each side).

Training results have been presented in the diagrams below.

Fig. 1. (Fig. 3)
a) Eccentric hip adduction (EHAD) per study participant in an intervention and control group before and after intervention [Nm/kg].
b) Difference in eccentric strength of hip adduction muscles, expressed in percents, per participants in intervention and control group. Black lines stand for average difference.

* i ** – statistically significant difference: * – under the group, ** – between groups.

Fig. 2. (Fig. 5)
a) Resistance (time) w in the form of support, on the forearm, while lying on the side in the intervention group and control group [s] per study participant in the intervention group and control group before and after intervention.
b) Difference in resistance, expressed in percents, in support on the forearm, while lying on the side per member in the intervention and control group. Black lines stand for average difference.

An 8-week training, consisting of one exercise only, increased eccentric strength of thigh adductor muscles by 36% in the intervention group, thigh abductors muscles by 20%, and simultaneously increase the relation of adduction strength to abduction muscles by 12,3%. In the control group these parameters remained unchanged.

Resistance (time) in support on the forearm, while lying on the side in the intervention group increased by 7,8% while in the control group dropped by 4,4%.

The results prove that it is possible to increase the strength of thigh adductor muscles substantially and fast by doing a simple and easy-implementable exercise, though a direct influence of such muscle reinforcement on frequency of occurrence of muscles injuries has not been analyzed yet. Basing on the results from similar studies for posterior thigh muscles which demonstrate that reinforcement of this group with a single exercise (Nordic Hamstring) reduces a risk of this muscle injuries substantially, scientists hold that we may expect a similar effect.

Biomechanical analysis of the adductor longus at the moment of kicking a ball with top force after taking a run-up, with an internal side of the foot shows that maximum activation overlaps with top thigh abduction, which suggests that this sort of kicks increase the likelihood of such injury. The studies confirm that ball-kicks of this type often lead to severe groin injuries among footballers.

It is advisable to do CA exercise after a suitable training, when we are fatigue, which may prevent the impact of fatigue on injuries, especially frequent at the end of the match. It is also recommended that we do it regularly not only in the preparation period but throughout the year.

It is essential to remember that during this 8-week program none of the players complained about any negative consequences related to the exercise (certainly apart from a typical post-effort muscle ache).

“Large eccentric strength increase using the Copenhagen Adduction exercise in football: A randomized controlled trial.”
Ishøi L, Sørensen CN, Kaae NM, Jørgensen LB, Hölmich P, Serner A4.

Scand J Med Sci Sports. 2016 Nov;26(11):1334-1342. doi: 10.1111/sms.12585

Developed Mariusz Goliński
Rehasport Clinic Motor Skills Trainer