TRAINING LOAD, PERFORMANCE AND INJURY RISK IN RUGBY PLAYERS
A rugby player’s ability to perform high-intensity intermittent exercises is associated with a higher training load (TL) which takes place during matches.
Injuries are one of the main concerns in the world of sports as they are the primary reason which interrupts an athlete’s training program. Furthermore, when it comes to team sports, not only does it affect the player, but it also affects the whole team, from a tactical standpoint. Muscle injuries are the most common sports-related injuries, with hamstring injuries being the main cause in sports that involve running, a constant change in pace or abrupt leg decelerations such as the kicks that occur in football. One of the major issues with hamstring injuries, apart from their high incidence level, is the high rate of injury recurrence: around 13% of players suffer a recurrence in the first week after returning to their training, and around 8% have a recurrence in the second week (Seward & Orchard, 2004).
There are some risk factors for hamstring injuries that are non-modifiable, such as age, race or prior history of similar types of injury. Other risk factors are modifiable, such as a lack of strength and flexibility, fatigue or strength imbalance between agonist and antagonist muscles (de Hoyo et al., 2013). In the latter case, while there seems to be some level of controversy about the relationship between isolated hamstring muscle strength assessments and injury risk, scientific evidence leaves little doubt that there is an association between agonist muscles that are imbalanced with their antagonist (quadriceps muscles) and injury incidence.
The Hamstring:Quadriceps (H:Q) ratio refers to the relationship between the peak torque of these two muscle groups; an imbalance between them is associated with a significant risk of injury to the posterior leg musculature in professional football players (Croisier et al., 2008; Grygorowicz et al., 2017). The H:Q ratio has traditionally been calculated by dividing the maximum concentric force of the hamstrings by that of the quadriceps (Hcon:Qcon) at the same angular velocity. Over time, however, various authors have been suggesting that the agonist-antagonist strength relationship for extending and flexing the knee would be better described as the ratio between the peak torque in eccentric hamstring contraction and the peak concentric torque of the quadriceps (Hecc:Qcon). This has become known as the functional H:Q ratio. With this in mind, one study (Croisier et al., 2008) evaluated the isokinetic strength of 462 professional football players during the pre-season in order to determine whether an imbalance between the antagonist musculature of both legs could predict future hamstring injuries through its monitorization during the season (9 months), and whether the normalisation of that imbalance through compensatory training could reduce the risk of injury.
The results in table 1 show the 216 players (47%) who suffered from H:Q ratio imbalances, and the various types of ratios and angular speeds at which those imbalances were presented.
As a relevant data point, it can be observed that when using the traditional ratio (Hcon:Qcon), more than 30% (55% and 38% vs 87%) of the imbalances that were manifested while using the functional ratio (Hecc:Qcon) went undetected.
After they were assessed, the 462 participants were classified based on whether or not they demonstrated a muscular imbalance during the pre-season. The group that showed imbalances was subdivided into those who undertook compensatory training and those who did not. In turn, those who had undertaken the training were divided based on whether or not they underwent a post-test to determine if those imbalances had been corrected by the compensatory training (table 2).
Surprisingly, the data gathered indicated that the players with H:Q ratio imbalances in the pre-season had an injury incidence that was 4 times higher than those who did not have imbalances (16.5% vs 4.1%). Furthermore, undertaking compensatory training in order to correct existing imbalances, which were subsequently assessed via post-test, were found to reduce the injury risk. There was no significant difference in the frequency of injuries among this group compared to those who did not have imbalances during the pre-season. Lastly, the players with a functional Hecc:Qcon ratio higher than 1.4 did not suffer from any hamstring injuries. In other words, 1.40 could be proposed as the Hecc:Qcon ratio cut-off point, after which the risk of injury would be reduced. Based on the latest scientific research, various cut-off points have been suggested. One of the most widespread cut-off points still being used (erroneously) is that which establishes an H:Q ratio above 0.60 as the point after which the injury risk is lowered. However, this refers to the traditional Hcon:Qcon ratio which, as we have seen, is limited when it comes to detecting muscle imbalances.
Injury risk is one of the main limiting factors, if not the most limiting factor when it comes to performance. As a result, the role of injury prevention for increasing athletic performance is especially important. In this sense, assessing potential muscular imbalances using the H:Q ratio in sports involving frequent hamstring use, such as football, can play a role in a team’s success. Likewise, when an imbalance is present, correction through compensatory training is equally important.
The Barça Innovation Hub team
Croisier, J. L., Ganteaume, S., Binet, J., Genty, M., & Ferret, J. M. (2008). Strength imbalances and prevention of hamstring injury in professional soccer players: a prospective study. The American Journal of Sports Medicine, 36(8), 1469-1475.
De Hoyo, M., Naranjo-Orellana, J., Carrasco, L., Sañudo, B., Jiménez-Barroca, J. J., & Domínguez-Cobo, S. (2013). Revisión sobre la lesión de la musculatura isquiotibial en el deporte: factores de riesgo y estrategias para su prevención. Revista Andaluza de Medicina del Deporte, 6(1), 30-37.
Grygorowicz, M., Michałowska, M., Walczak, T., Owen, A., Grabski, J. K., Pyda, A., & Kotwicki, T. (2017). Discussion about different cut-off values of conventional hamstring-to-quadriceps ratio used in hamstring injury prediction among professional male football players. PloS One, 12(12), e0188974.
Seward, H., & Orchard, J. (2004). AFL injury report 2003. Sport Health, 22(2), 7.
Mental abilities, although not yet fully appreciated, are already considered a relevant part of performance. But their importance could go beyond that: Do they also influence the injury risk, including recurrence, once the player returns to play?
Although several studies have tried to evaluate the characteristics of the risk of injury in handball players, they have been unable to reach sufficiently reliable conclusions. A new study of all the FC Barcelona handball categories has attempted to shed more light on the subject.
Although there are several studies on this topic, many of them have analyzed these demands by looking at just a few variables or using very broad timeframes. A new study completed by physical trainers from F.C. Barcelona has analyzed several of these details more closely.
An article published in The Orthopaedic Journal of Sports Medicine —in which members of the club’s medical services participated— now suggests to consider the detailed structure of the area affected, and treating the extracellular matrix as an essential player in the prognosis of the injury.
In this article, Tim Gabbett and his team provide a user-friendly guide for practitioners when describing the general purpose of load management to coaches.
For the first time, it has been demonstrated that it does not take months of training to significantly improve both muscle volume and strength; instead, two weeks of an appropriate exercise are enough.
Training using eccentric exercises is important to prevent possible damage. However, intensive training can also cause muscle damage, so it is critical to be vigilant in order to keep injury risk to an absolute minimum.
Cardiovascular endurance manifests as a moderator of the load result to which the athlete is exposed.
Through the use of computer vision we can identify some shortcomings in the body orientation of players in different game situations.