Blood flow restriction to improve performance and injury recovery
Blood flow restriction or BFR has become popular in the last few years in the training and physical therapy field.
Last year, the 30th of December, FC Barcelona issued a statement making it official that its goalkeeper Marc-André Ter Stegen suffered from tendinopathy in the right knee that required treatment and, consequently, it would cause a period off that would depend of its evolution. Afterwards, on the 18th of August, in a new official statement, FC Barcelona announced that Ter Stegen had successfully undergone surgery of the patellar tendon of the right knee with an estimated time off of approximately two and a half months. The patellar tendinopathy suffered by the blaugrana goalkeeper is a very common injury, especially in sports that imply prolonged stress on the knee extensor muscles. The clinical diagnosis presents pain and dysfunction in the patellar tendon area, which can lead to the interruption of sports practice (as in the case of Ter Stegen), and even in some cases it can lead to a premature end of the player’s sports career.1
It is especially prevalent in sports in which a multitude of jumps are performed (it is also known as jumper’s knee) such as volleyball and basketball (45% and 32%, respectively).2 In sports such as football it is also common, as the tendon is subjected to repetitive trauma with incredible high moments of force during striking actions, changes of direction, jumps, sudden accelerations and decelerations that take place during the game.
A study led by researchers from the Department of Medical and Health Sciences of the University of Linköping (Linköping, Sweden) and funded by UEFA, analysed the epidemiology of patellar tendinopathy in 2299 footballers belonging to 51 elite European clubs, in addition to identifying possible risk factors.3 In the study period between 2001 and 2009, there were 139 injuries to the patellar tendon, 4 affecting the distal part and the remaining 135 the proximal part. Besides, in 40% of the cases, the dominant leg was affected. Patellar tendinopathy constituted 1.5% of the total injuries registered in this period and caused 1.4% of players absence due to injury. Each season, 2.4% of players in the analysed clubs missed a training sesion or a match due to patellar tendinopathy, with an incidence of 0.12 injuries/1000 hours of sports practice. Although most injuries resulted in absences of less than one week (61%), 10% were serious (two of them required surgery), which produced absences of more than four weeks from both training and matches.
A big problem when facing any injury is relapse, with a recurrence of 12%–27% in this case, which reflects the chronic and recurrent nature of patellar tendinopathy. However, after a short period of rest, reduced workload, and treatment, it appears to become asymptomatic, allowing players to resume training and competition until symptoms worsen again.
The main risk factor is undoubtedly the total volume of exposure, with an association between the training load and the hours of sports practice and the prevalence of patellar tendinopathy.3 This finding is indicative of the nature of the injury, where repetitive stress over the patellar tendon is related to a greater harm.
It is important to note that no significant differences were observed in the prevalence or incidence of patellar tendinopathies among players of teams that play on artificial turf and those that play on natural turf.3 However, in sports such as volleyball, the prevalence of patellar tendinopathy increased with harder playing surfaces,4 while, its prevalence is lower for beach volleyball players compared to court players,5 indicating that the hardness of the playing surface could have to do with the risk of suffering from patellar tendinopathy.
Regarding the distribution of the season, clubs playing leagues that take place between autumn and spring, suffer from a higher incidence of patellar tendinopathy occurred in the months of July (coinciding with the start of the preseason), October and April. In northern European clubs that usually play between spring and autumn, the highest incidence took place from January to March, coinciding with the preseason,3 when the training load is high, possibly supporting the idea of the association between the load on the tendon and the development of symptomatic patellar tendinopathy.
Also, weight gain has been identified as a risk factor,3 which could be attributed to the increase of forces acting on the patellar tendon as a consequence of the increase in body mass itself. Finally, age does not appear to be associated with the risk of patellar tendinopathy in professional football players.
Patellar tendinopathies have shown lower stiffness values than those of unaffected tendons, which affects the transmission of force through the tendon.
Even though, as we have seen, patellar tendinopathy is a fairly common condition in professional football players, with a high recurrence rate, a recent study showed that elite football players have greater stiffness of the patellar tendon in comparison with the general population,6 which could be related to an improvement in the transmission of force during muscle contraction. This fact is especially important, as the patellar tendons affected by patellar tendinopathy have shown lower stiffness values than those of the unaffected tendons, which would have a negative impact on the transmission of forces through the tendon and, therefore, performance.7
In summary, patellar tendinopathy can have significant consequences for a footballer’s sports life and, consequently, for his team. For this reason, coordination between the technical staff and the medical services is extremely important when establishing the resulting treatment once the ailment has been diagnosed, in order to avoid its chronification and, ultimately, surgical intervention.
Javier S. Morales