Throughout our last chapter of “The ABC of Football Medicine®”, we’ve been exploring the assessment of the injury factors regarding muscle injuries in football. This has led us to identify four specific areas that should be investigated: load management; athletic development/muscle strength; mobility and neuromuscular control.
We will now introduce and further dig into the prevention strategies that should be taken to aim these specific areas identified in our injury risk factor assessment.
Our first disclaimer is regarding timing: you might be familiar with the common saying
“Don’t leave until tomorrow, whatever you can do today”;
however, if you’re reading this in the middle of your season, ignore the saying and wait for the next season preparation (or for the competitive break, if there is any).
The reason for this advice is that the strategies that we will now discuss may represent an additional increase in the load imposed on athletes (e.g.: strength training) and, as mentioned previously, such a sudden increase/change in training methodology/load may be the factor that ultimately contributes to muscle injury risk. And that would be very counterproductive.
In the following pages we will introduce each strategy. Similarly to the previous sections, in which we ran through the epidemiology and specificity of injury, the aim of this chapter is to provide the reader with some basic knowledge regarding prevention, empowering the reader with the ability to further read and study these topics. However, we do believe that this theme – Prevention – awakens a special interest among all the readers.
Therefore we will specify and present some of the scientific evidence and clinical experience on specific details on each one of these strategies, as well as our personal opinions, that we expect may positively bias your further studies.
Jumping towards the specific strategies, we start with the strategy that has been (rightfully) mentioned the most: (Training and Match Sessions) Load Management
Regarding injury factors that are modifiable, load management is the one that has the highest impact in the risk of muscle injury. This is enough of a justification for you to not only be aware of the variables of training and recovery, but to measure, manage and manipulate them individually. The ultimate goal is to reduce rates of over- or underloading, leading the athletes to a state of optimal load habit/load imposed ratio and therefore, prevent injury.
By measuring these variables, an individually drawn pattern can be found (the Athletes’ Profile as mentioned in previous chapters) and deviations of this pattern may provide an insight into changes in the life of the athlete, affecting in performance and therefore, his injury risk.
Bellow, we present some of these identified measurable variables and some associated questions/motivations regarding their interpretation:
- Total distance;
- Total distance at high intensity (>5.5 m/s)
- Total sprinting distance (>7 m/s)
- Number of accelerations/decelerations >2m/s
- Maximum velocity reached during the training week. Why is this relevant?
- This could be a relevant risk factor if the athletes don’t reach their highest velocity during the training week, by the simple fact that this lack of exposure to this stimulus during training is probably be counterbalanced by reaching it during the match. In other words, he will be performing something he hasn’t trained.
This may be explained by a difference in motivation or in demand during the match; however, being under-exposed during the training week appears to be enough to increase the injury risk. An exception to this may be applied to the goalkeeper and, eventually, to the centre-back, in which this exposure during match isn’t has predictable has with other roles.
- Periodization of the high intensity stimulus in the training cycles. Are the athletes being able to conveniently recover from and towards a match?
- It is known that, after an intense effort that involves eccentric contractions (e.g.: match; intense field training; specific muscle training) the neuromuscular fatigue markers remain altered even at 72h passed. Therefore, by consensus, it is assumed that most athletes require (at least) 48h to be significantly recovered and ready to compete/train again. Needless to say, there may be several exceptions depending on the individual’s quality of the recovery (e.g.: sleep) or even regarding age.
- With this said, imposed load is a key determinant in specific in the two days before and after every match, warranting the readiness to train and compete. Recovery is a key part of training. So how can we schedule and organize our week to meet the demands?
- External load, as mentioned in previous chapters, Internal Load Measurements, as session Rate of Perceived Effort (s-RPE) and Readiness (through questionnaires or Counter Movement Jump Performance);
- Besides the objective internal load (such as Hearth Rate – HR – related measures) and subjective internal load measures (sRPE) as stated and explained in chapter 4, we should use Readiness questionnaires to gather insights related to the within-athlete internal load response to a given external training load. As an example of this, we can’t only rely on HR exercise as a proxy indicator of athlete’s fitness/readiness (I.e. for a given submaximal drill, a lower HR response would indicate a better training adaptation), since this variable can be highly influenced by factors such as sleep disturbance, hydration and nutrition status, psychological or social stressors). As such by identifying and correlating changes in this assessment tools alongside the daily clinical monitoring, we can better interpret team as well athlete changes, helping us managing our athletes and developing strategies to increase our player readiness (I.e. pharmacological and nutritional interventions, traveling and sleeping plan, re-scheduling training sessions – morning/afternoon, session content and or modified training plan for a given athlete).
- So considering this, we can say that External Load tells us about what the player has done and it is a quantitative metric of work while Internal Load gives us an insight on how the player is responding to the applied load and at last the Readiness Scores allow us to assess the degree of recovery from the player. These are the three main components that form the athlete’s monitoring cycle, nonetheless these are not separate, and we can always infer on how the player is coping with these demands by assessing these components.
In Figure 1 the example of a “full team assessment” during an entire season:
Figure 1- Total Distance [in Blue]; High Intensity [in Green]; Sprint [in Purple]; Superior border of the optimal load [in Red]; Inferior Border of the optimal load [in Yellow].
The training load as been manipulated to attenuate the load spikes outside of the defined optimal load borders.
In Figure 2, we see the same assessment but regarding one athlete. The interesting component on this example is that this athlete has suffered a muscle injury, after a sprinting/high intensity running spike. The colour scheme is the same as above, with the black spots marking the injury component.
Figure 2- Single Athlete data throughout one season, overload injury
In Figure 3, we see the same measurement on another athlete, this time with an injury occurring after a period of undertraining/lack of exposure to the stimulus. The injury occurred after an increase in the solicitation of the athlete to take part in competition.
Figure 3 – Single Athlete data throughout one season, underload injury
With these examples, we hope to provide you with a clear idea of both the need and the operability of integrating these measurements in the intervention of injury prevention. One the first example, a correct monitoring of the load would lower the risk of injury. In the second example, the continuous exposure to “match-alike” load, even if the athlete isn’t on the “most used” list, would also allow for better preparation for the demand.
We should aim to training levels that are alike to competition/match demands, but also, we need to achieve these levels in a smart and progressive way, paying always attention to how the athletes are responding to the training demands. In a future chapter, we will go deeper on some strategies on how to manage highly required players, without overloading, and how to maintain the ones who are less required ready to action.
Athletic Development (Muscular Strength but not only)
The existence of muscular imbalances or low levels of muscle strength constitute a clear injury risk towards muscle injury. This makes the assessment (as mentioned in the previous chapters) and the intervention to minimize their existence a key concern that should be integrated in the strength training of any professional football team, on a systematic and coherent periodic basis.
Current evidence leaves no margin to doubt regarding the importance of the implementation of training programs that aim to enhance the physical abilities of the athlete (e.g.: strength), not only being clear on its effects on injury prevention, but also in the optimization of sports performance, such as enhancing acceleration/deceleration, jumping and sprinting capacities. However this concept might already be rather agreed among the football community, the means to develop these capacities aren’t fully incorporated; traditionally, the football athletes don’t have a “weight room culture”.
This lack of habit has both an up and a down side: one the up side, these athletes who don’t have a weigh room habit will benefit from easy, low volume and low load exercises, with these being enough to produce the initial adaptations to training and therefore increasing the capacity of strength production in said individuals; one the down side, this introductory exercise scheme will only be enough to affect the non-habituated individuals, making the transition towards a more complete and progressive exposure to load/volume scheme a future need.
In specific, regarding muscle injury prevention, the evidence appears to show that there is some importance in obtaining symmetry in the maximum strength produced regarding the contralateral limb (e.g.: the adductor muscles in each side), as well and a correct balance between muscle groups that produce opposite actions (e.g.: anterior vs posterior thigh). Nevertheless, the symmetry in other physical competencies such as the ability to produce power and reactivity should not be overlooked, since these may be indicators of economic faults in certain movements, that may lead the further overload in these movements. These physical competencies are very correlated we force-velocity profile of the player, so we need to address every part of the curve, optimizing these capacities. Beyond these capacities, we should also give special attention to things like contraction type (sometimes, isometric work is somehow neglected) and also think about load sharing strategies within same muscle group or synergists (an example is the relationship between semitendinosus and bicep femoris).
Regarding timing of this programmed strength training and its incorporation on the microycle, there appears to be benefit in the post-training implementation, to reduce the risks of injury during practice related to “strength training induced fatigue”. Within the microcycle, we suggest incorporating the most demand (most muscle damage and peripheral fatigue) day early in the week and let the speed-strength work for later during the week (MD-2, MD-1 for priming and to optimize performance).
Figure 4 -Muscle Strength training examples that can be included in the strength routine of the team.
In addition to strength training, energy systems development should not be overlooked. Aerobic and Anaerobic Fitness should also be considered because they underpin our capacity to express repeated efforts and sustain the same performance levels throughout the game. In addition, we know that most of the injuries occur during or at the end of the second half of a sport match, have this being said we can assume that endurance is likely a contributing factor. Taking this into account we should aim to fill the gaps of training with our additional work at the gym, a great way to work these capacities without adding to much stress/load on our players, is with off-feet work, where can stimuli our energy systems taking off some load on our lower limbs. This is just an example, in a future chapter we will discuss in greater detail this theme and show how we can address these physical capacities in a weekly basis, without interfering with the recovery of our players.
“Ultimately, individuals who are not strong enough, or not fit enough, to cope with the demands of their sport will eventually break down” Coles, PA (2017)
In our next chapters we will go deeper on the recommendations of how the aforementioned introductory phase of a strength training program in non-experienced athletes and the adequate progression of load/volume should be taken into account, and also how to incorporate strategies aimed at the development of energy systems, and how to organize these within the microcycle. We will also dig a bit on some the recommendations towards how do differentiate best practices from non-beneficial practices (that will not collect the benefits from the implementation of a structured strength training described in the evidence).
The implication of changes in mobility has also been mentioned in our previous chapter regarding the assessment of risk factors. These changes take a special role when taking into account changes in joints like the hip – with the existence of asymmetries or restrains possibly associated with the development of adductor muscle injuries and/or groin-related complains – or regarding the ankle – considered when referring to muscle injuries in the calf muscles and tendinous injuries in the knee.
The existence of these relationships underlines the need of concern regarding the development and maintenance of the necessary ranges of motion of the lower limb (but not only), in order to prevent the compensation or overload of adjacent structures.
This “joint hygiene” is recommended to be done on a regular basis, before the training sessions, potentiating and maintaining the range gains during the task performance in practice. Although these gains may be achieved with both active and passive exercises and either individually or in group, these aims should be individualized, taking into account each player needs, identified by the objective assessment and coherent with requirements of the players role.
Figure 5- Pre-training mobility
The specificity of the science behind mobility training is vast (as well as the existing myths that surround this topic). Clearing these concepts will be the goal and motivation for the future chapter on mobility.
Motor control is the sum of mobility integration within normal coordination (both intra and intermuscular) that, with proper coordination, result in optimum movement efficiency. Efficiency is defined as the output result in relation to the input cost; if there are deficits in our kinetic chain, then the movement becomes suboptimal (increase in the cost, decrease in output).
Awareness of motor control also reflects getting a hand on the strategies and patterns that the athlete utilizes in specific movements. The influence of changes in motor control are well described in ligament injuries (such as ACL injuries) and in some overload injuries (such as tendinopathies) but its influence is also relevant regarding the current topic: the occurrence of muscle injuries.
Several justifications be given but a simple one is that these patterns may affect the economy of the gesture (the efficiency), leading to earlier fatigue and, eventually, injury.
With this in mind, it is advisable that the teams include, in their exercise programming, goals like: the multiplane stability training (improvement of the transmissions of energy and movements), running/sprinting technique, deceleration control, and others.
Figure 6- Anti-inclination and anti-rotation exercises to enhance acceleration.
In order to better provide the rationale of implementing these training support, a future chapter will provide a deeper focus. This final chapter on prevention will also be one to wrap up all the above topics.
Through this segment, we touch several fronts that can be improved in order to increase the “preventiveness” aspect of the training. However, this also introduces us to one problem:
The utopia of the individualized training in team sports
After running a thorough assessment of the risk factors for muscle injury through a defined battery of tests, some characteristics will surely stand out. These will either be very common and found in part a large sum of the players or they may be very specific and limited to a minority.
Nowadays, individualization in training is hot topic and the goal is to take the weaknesses of each athlete into account in the training session. However, is this viable when talking about the gym routine in a football squat? The team of Football Medicine considers it certainly isn’t, by several reasons with one of them being the lack of familiarity and compliance of football players towards gym routines (which hardens this practice without tight supervision).
In this way and in order to obtain as many benefits as possible of implementing such a program (and taking into account these limitations), it is advisable that instead of implementing the perfect routine for each athlete individually, a group routine is created with exercises that benefits all athletes, organized by stations and groups.
In this set of exercises, the only change/adaptation of the exercises will be in very specific cases, with the adaptations being most frequently the manipulation of the frequency and volumes (programming) of the mentioned exercises to each athlete in order to obtain the adaptations intended.
As revealed throughout this chapter, the reader as now already an idea of the pillars of prevention and what to each pillar consists of. As stated in the start, we do believe that this topic is one of the most debatable and deep themes touched on The ABC of Football Medicine segment; this is why we will share some more guidelines in our future chapters, both to share our field experience, as to provide some more ground for debate and for further individual studies.
Authors:Lucas Brink, Ruben Ferreira, João Pedro Araújo, Micael Moreira