Groin injuries: do prevention exercises work?

Short answer

Yes. One exercise that builds the inner thigh, the Copenhagen adduction, cut groin problems by 41%. Teams that did not keep up the planned sessions saw no drop.

Groin injuries: do prevention exercises work?
'Stronger inner thighs → fewer groin injuries' — does this formula hold?
Groin injuries are common in sports with kicking and quick changes of direction. The claim is that building the inner-thigh muscles (the adductors) prevents them. We checked this formula against the research.
Who gets groin injuries?
Weaker inner thighs meant more injuries
A review of 29 studies found three things that raised groin injury risk: a past groin injury, a higher level of play, and weak inner-thigh strength. Of these, strength is the one you can change with training.
What about programs mixing many exercises?
Risk went down, but not by a meaningful margin
In a study of football clubs using 6 exercises around the pelvis (977 people finished), groin injury risk was 31% lower, but the difference was not statistically meaningful. An analysis pooling 7 studies with 4,191 people found only a 19% drop, also not a meaningful difference.
One exercise, done regularly
The Copenhagen exercise cut groin problems by 41%
35 football teams with 652 people were split, and one side did a single exercise: the Copenhagen adduction, a side plank held up by the inner thigh. It was 3 times a week for 6-8 weeks of preseason, then 1 session a week for the 28-week season. Groin problems during the season: 13.5% vs 21.3%, a 41% lower risk.
Another study pointed the same way
Pain risk was 0.42 times as high
In a 16-week study of 202 people, those doing the Copenhagen exercise had 0.42 times the risk of groin pain compared with those training as usual. Adding a hamstring exercise (the Nordic) brought it to 0.19 times. Only 4 people in the combined group had groin pain, versus 18 in the usual-training group.
Why did it work?
Inner-thigh strength rose 35.7% in 8 weeks
When 24 people did the Copenhagen exercise for 8 weeks, the force their inner-thigh muscles produced while resisting rose 35.7%. In a study that split 45 people, the standard warm-up (FIFA 11+) alone left this strength unchanged (-0.7%), while adding the Copenhagen exercise raised it 8.9% more.
What was different in the study where it failed?
Teams did not do the planned sessions
In a study of 502 people, teams doing inner-thigh exercises had no fewer groin injuries. They planned 2-3 sessions a week in preseason but actually did 1.7, and in season did 0.7 a week instead of 1. The study that cut injuries by 41% used 3 sessions a week in preseason.
Summary: it works when you keep it up
One Copenhagen exercise cut groin problems by 41%
Weak inner thighs meant more groin injuries, and the Copenhagen exercise built that strength in 8 weeks. In the study that kept to 3 sessions a week in preseason and 1 a week in season, groin problems fell 41%. Teams that did not keep up the sessions saw no drop.