One Exercise Cut Groin Problems by 41%

The SparkNotes

• A cluster-randomised trial in 35 semi-professional Norwegian football teams, 652 players, across a full season.

• The intervention was ONE exercise with three difficulty levels. Three times a week in preseason, once a week in season.

• Average weekly prevalence of groin problems: 13.5% in the intervention group against 21.3% in the control group. A 41% lower risk.

• It did NOT significantly reduce SUBSTANTIAL groin problems. That result was 5.7% against 8.0% and did not reach significance.

• The in-season dose takes under five minutes a week, which is the part that makes it usable.

The Whole Story

Most injury prevention programs ask for a lot. Fifteen or twenty minutes, several exercises, three times a week, every week, forever. They work in trials and then quietly stop happening in February.

So this trial is interesting for the size of what it asked rather than the size of what it found.

Thirty-five semi-professional Norwegian football teams, 652 players, randomised by team rather than by player. One group added a single exercise to their warm-up. The other trained as normal. Everyone was followed for a full 28-week competitive season.

What they actually did

The exercise was the Copenhagen Adduction, with three levels so that a player in pain could still do something.

Level one is a side-lying hip adduction. Level two is the Copenhagen with a shorter lever arm. Level three is the full version.

Players were told to start at level three. If the exercise provoked groin pain above 3 out of 10, they dropped to level two. If level two did the same, they dropped to level one. Both sides, every time.

The dose was front-loaded. Preseason ran six to eight weeks and built from two sessions of three to five repetitions in week one up to three sessions of twelve to fifteen repetitions by week five. Then, once the season started, it dropped to a single set of twelve to fifteen repetitions, once a week.

That in-season session takes under five minutes.

What they found

The outcome was not injuries that cost time. It was the weekly prevalence of any groin problem, captured by asking every player every Sunday whether they had pain, stiffness, clicking or catching, or any reduction in training or performance because of their groin.

That distinction matters. Only about a third of groin problems result in a player missing anything, so counting time-loss injuries only ever captures the tip of it.

Averaged across the season, 13.5% of the intervention group reported a groin problem in any given week. In the control group it was 21.3%.

The risk of reporting a groin problem was 41% lower in the group doing the exercise, and that result was statistically robust.

Across the whole season, 55% of players in the intervention group reported a groin problem at some point, against 67% of controls.

What it did not do, and this is the honest half

The trial also measured SUBSTANTIAL groin problems, meaning moderate or severe reductions in training or performance, or being unable to participate at all.

There, the numbers were 5.7% against 8.0%. An 18% lower risk, and it did not reach statistical significance.

So the fair summary is that the exercise reduced how often players were bothered by their groin, and did not clearly reduce how often they were badly bothered by it. The authors report both, and so should anyone quoting this study.

One more piece of context they raise themselves: the program targets the adductors, which is one of the defined categories of groin pain. Adductor-related pain accounts for more than two-thirds of hip and groin injuries in football, so it is the right target. But which categories actually improved was not measured.

Why the dose is the point

Compliance is where most prevention programs die, and this one held up unusually well.

Players completed about 73% of the recommended preseason protocol, and in season averaged 0.7 sessions a week against a target of one. Forty-two percent of them did MORE than they were asked to in season.

For comparison, the paper notes compliance figures from other prevention trials ranging from 19% to 75%.

There were no adverse events. Soreness in the adductors was reported as very low, highest at the start, and it dropped off as players adapted.

A single exercise that takes five minutes a week gets done. That is not a small finding dressed up as a big one — it is the reason the effect showed up at all.

Who this was actually tested on

Senior male football players, semi-professional, at the second and third level of Norwegian football, over one season.

Whether the same effect holds for women, for youth players, or at the highest professional level is stated as unknown. The authors also note that other sports with similar movement patterns, such as ice hockey, rugby and Australian rules football, have the same risk factor, but this trial did not test them.

Two other limits worth knowing. Compliance was self-reported, so nobody can be certain the exercise was performed as often as recorded. And groin problems were self-reported rather than examined and classified, so the trial knows how many players had a problem but not precisely what each problem was.

Making it harder, and the mistake I see most

The three levels change the lever arm, but that is not the only dial you have. The same exercise can be progressed by changing the speed of the repetitions, the repetition range, or by adding isometric holds.

So a player who has reached the hardest level has not run out of road, and a player who cannot manage the hardest level still has plenty of ways to make their version harder over time.

The thing I see most people struggle with is not the adductors at all. It is keeping the trunk stable and in a good position while the adductors are working.

That matters more than it sounds. The adductor longus, magnus and brevis all have direct connections to the rectus abdominis, so trunk alignment and engagement is critical to doing this exercise properly.

What to do with it

If you play a sport with cutting, kicking or hard changes of direction, low hip adduction strength is an established and modifiable risk factor. This is the cheapest intervention anyone has tested against it.

Front-load it. The preseason block is where the strength is built. The in-season session maintains it.

Use the levels honestly. If the hardest version provokes pain above about 3 out of 10, drop a level rather than pushing through or abandoning it. That instruction is part of the protocol, not a concession.

Do not expect it to be a treatment. This was a prevention trial in players who were training, and it included players who already had symptoms, but it was not testing whether the exercise fixes an established problem.

And judge it on what it measured. It reduced how often players were bothered. It did not clearly reduce the serious end.

Follow along as Resurgo comes together.

SOURCE, verified from the PDF John supplied: Harøy J, Clarsen B, Wiger EG, Øyen MG, Serner A, Thorborg K, Hölmich P, Andersen TE, Bahr R. The Adductor Strengthening Programme prevents groin problems among male football players: a cluster-randomised controlled trial. British Journal of Sports Medicine. 2019;53(3):145–152. Epub 10 June 2018. doi:10.1136/bjsports-2017-098937. Trial registration ISRCTN98514933.

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