Jan Ekstrand, Håkan Bengtsson, Markus Waldén, Michael Davison, Martin Hägglund. Still poorly adopted in male professional football – but teams that used the Nordic Hamstring Exercise in team training had fewer hamstring injuries: a retrospective survey of 17 teams of the UEFA Elite Club Injury Study during the 2020-21 season.
Tell us more about yourself and the author team
I, the first author Jan Ekstrand, usually introduce myself as a football doctor. I have worked with football and football medicine all my life and wrote my PhD thesis about ‘soccer injuries and their prevention’ in the early 80ties. I even had a football coach education in Sweden at that time. Later, I served as team doctor for the Swedish male national football team during the 80 ties and 90ties (I do have a bronze medal from the WC 1994 in the US). I was then appointed as a member of the UEFA Medical Committee and was asked to be the lead expert on the UEFA Elite Club injury studies starting in 1991.
However, I belong to a research group, and we carry out our studies together and, of course, in full cooperation with UEFA. Our research group is very narrow-minded. We only carry out football research. We even call ourselves ¨The Football Research Group (FRG)¨.
The coauthors of the present study all belong to FRG, and we all work on the UEFA injury studies on behalf of UEFA. Markus Waldén, Martin Hägglund, Håkan Bengtsson and Mike Davison are all well known after being involved in and carrying out many of the total 80 studies we have carried out during the 21 years the UEFA injury studies have been ongoing.
What is the story behind your study?
The main advantage of carrying out studies that are continuously ongoing for many years, like the UEFA Elite Club Injury Study (ECIS), is that it is possible to follow trends of injuries if certain injuries increase or decrease over the years. In our time trend studies, we have found that muscle injury is the big problem at the male elite level, and the proportion of muscle injuries has been increasing over the years. Actually, during the latest season /2021-22), muscle injuries constituted over 50% of all injuries among muscle injuries. Hamstring injuries are the most common, and the consequence of absences due to hamstring injuries is a major problem for clubs and players at the male elite level.
This is a bit surprising sínce there are several well-designed and controlled studies that have shown that the rate of hamstring injuries can be significantly lowered by using the Nordic Hamstring Exercise (NHE). Roald Bahr, Kristian Thorborg and I wanted to find out why this discrepancy between good scientific studies and low effect in real life on the football field. In a study on using the Nordic Hamstring Exercise (NHE) programmes in professional football teams in Europe from 2012-to 2014, we found low adoption (13%).
With the still increasing rates of hamstring injuries eight years after the previous study, we wanted to study the adoption of the NHE programme in European football teams in the 2020/21 season and compare it to the previous study. But we wanted to go one step further as well. We had also information that teams used the NHE. Differently, some teams had the NHE included in the team training while others only used it for players with a previous hamstring injury, so we also wanted to compare hamstring injury rates between teams that used the NHE programme in the team training and teams that used the NHE only as individual training for players with previous or current hamstring injuries.
In your own words, what did you find?
First of all, all team doctors know of and were familiar with the NHE, and the attitudes towards the NHE were generally positive. This is an improvement compared to the 2012-14 study, where a few team doctors were unfamiliar with the NHE.
Second, all teams but one used the NHE in some form in their team, but only one team used the NHE programme fully as recommended by the researchers (an initial 10-week progression followed by a weekly maintenance programme during the rest of the season).
Third, the teams used the NHE in different ways, most of them using modifications of the programme researchers have recommended.
Fourth, teams that used the NHE in their team training for all or most players had lower match hamstring injury rates, less severe injuries and lower recurrence rates than teams that only used the NHE for individual players with a history of hamstring injury or current hamstring injury.
Fifth, none of the teams reported that the NHE programme would be the only hamstring prevention measure in the future for their team
What was the main challenge you faced in your study?
The challenge in these types of studies is always to get information and data for those invited to participate. However, since UEFA and FRG have carried out these injury studies for 20 years, we have very good contact with the participating teams and their medical staff. Several teams have sent us data every month for 20 years. They don’t do that to be nice to UEFA or FRG. They do it because they get a lot of information back where they can compare with other teams and evaluate their strength and weaknesses on the injury side. Creating a win-win situation for participating teams and UEFA, and the research group has been our philosophy to receive feedback and data.
If there is one take-home message from your study, what would that be?
The results from this study might be helpful since it provides clear practical information. Our findings indicate that teams that implemented NHE in team training and used it with most players had fewer hamstring injuries than teams that only used the NHE for individual players with current or a history of a hamstring injury. The current study indicates that even a modified programme might work if used by all or the majority of players in the team and used primarily as a maintenance program once a week throughout the whole season.
However, it is important to get coaches on board because they decide the content of training sessions and the load on players.
Further, using the NHE is only a part of the prevention measures for hamstring injuries. We need to widen the horizon and look for alternative risk factors like lack of internal communication within the team, lack of high-velocity football actions in training etc.