What is an injury? Or generally, why does an injury happen?
In this article, when I refer to injuries I am speaking about acute onset injuries and perhaps will leave overuse injuries for a subsequent post. I will aim to outline common injuries in team-sports and provide some considerations to have in managing them; ultimately aiming to help get your athlete(s) safely back into full participation. For this purpose, we can use a typical definition of an injury:
"Injury resulting from playing [insert sport] and leading to a player being unable to fully participate in future training or match play (i.e., time-loss injury)."
First, some basic physics... Generally, deformation (or change in shape) of an object occurs when a mechanical stressor is induced on the object which surpasses the object's resistance to deform and structural stability (Radaj Dr-Ing habil, 1990). The case is similar with injuries in sports. Simplistically speaking, an injury occurs when the level of mechanical stress (e.g., trauma) induced on a musculoskeletal structure exceeds its level of tolerance (i.e., its ability to withstand stress). This threatens the structural integrity and function of the tissue itself as well as that of the proximal (i.e., nearby) structures.
It is true that looking deeper into individual injuries and individual case studies of injuries we can analyse mechanisms of trauma and identify more precise complications and risk factors that lead to the specific injury event (e.g., physiological and nutritional deficiencies, psychological factors, sub-optimal mobility, genetic pre-dispositions, etc.). But in general terms it comes to this: injuries occur when stress exceeds the tolerance of a tissue, and this results in some change in the function and morphology of the tissue. So in general terms as well, we can protect an athlete from injury by increasing their level of tolerance or by protecting them from exposure to the stress.
Below, I have created a table that summarises the most common (i.e., highest incidence) and the most severe (i.e., highest burden, or time lost due to injury) in a number of popular team sports. The content in the table has been extracted from rigorous epidemiological studies in some of the top journals in sports medicine and science. For the most part, studies in the table documented data from professional level sports. However, the netball study was a recent systematic review of studies across different levels of competition. Clearly, different sports induce different physical demands on the competitors and this is reflected by the differences in prevalent injuries across sports. Nonetheless, it is interesting that in most, if not all sports, a common risk factor to injury is previous injury and inappropriate rehabilitation of this one. This speaks volumes on the importance of being conservative and having a long-term vision during injury rehabilitation/ return to sport processes.
Table 1 - Most common and most severe injuries in popular intermittent team-sports
In rehabilitating the impaired structure, it is important to provide the right environment for the tissue to recover, remodel and regain pre-injury function (or better). The acute period following injury (particularly the first 1-3 weeks of muscle disuse) induces skeletal muscle losses and as a result there is a decline in metabolic health and functional capacity of the injured structures. There is a convincing amount of evidence in support that the extent of muscle loss during injury strongly influences the length of the rehabilitation process required. As such, ensuring that 1) regular blood supply and adequate nutrients reach the tissue, 2) that the tissue is exposed to appropriate and gradually progressive doses of stress, 3) that the athlete engages in optimal sleep, 4) that the athlete has opportunities for psychological stress relief and that multiple other "elements" of the athlete's immediate environment aid the recovery process, is very important. On this basis, there are some things that as physical performance practitioners we can aim for when rehabilitating any injury to increase chances of an appropriate return to sport. This is key as the number one risk factor for most musculoskeletal injuries is previous injury and a poor rehabilitation.
I will now cover three boxes one may want to tick.
1) Avoid unprecedented spikes in training load
A common risk factor for injury or re-injury is an unprecedented spike in load. This applies to all areas of physical training including high-speed/ sprint-running load, resistance training load, and metabolic load (i.e., fuel availability). In most (if not all) injuries structural and functional deformation/ damage results from of either an excessive force, an excessive range of motion or an excessive velocity of movement; all things to bear in mind when progressively exposing the athlete to different forms of load.
Although the return to sport process must be iterative, whereby modifications are made based on progress and observations, I tend to believe that it is a good idea to have a framework or "map" to at least guide you. For this, I have been working on a return to sport grid to inform the steps to take towards returning to full participation from the point of re-introduction of an athlete to field/ court based training (see below). The aim is to avoid rapid spikes in physical load experienced during sport training, while progressively exposing the athlete to closer to competitive exertions. I will do my best to explain it.
The grid profiles each injury based on severity (as per the estimated weeks off from full participation initially projected by the primary physician or medical staff). Accordingly, a given number of weeks is allocated to each percentage of full participation in the training session for the injured athlete; starting from re-introduction to field/ court training. When I say 'percentage of' I typically am referring to GPS-derived metrics including (total distances, distances at high-speed, accelerations, etc.); there is also some potential for using RPE too. To note, I have been conservative in the number of weeks allocated per percentage, especially because I am naturally quite paranoid on how many re-injuries occur in elite sport from inappropriate rehabilitation. Consistently, this means I have also allocated greater times on the higher-end percentages of participation prior to full return (to further minimise the chances of unwanted surprises). However, each rehabilitation process is iterative (where changes occur along the way), uncontrollable disruptions to the process may occur and there will be external pressures on getting an athlete back to participation, so this grid only serves as a general guideline. The grid starts on 60% on the basis that, from my experience, if an athlete is completing less than 60% of a training session they may be better off doing a greater volume of work using alternative activities. The reader may disagree.
The grid is a work in progress.
2) Prioritise a sufficient dietary protein intake and sleep
Muscle hypertrophy and tissue regeneration is the largely determined by the balance between myofibrillar protein synthesis and myofibrillar protein breakdown. A negative net protein balance results in a breakdown and removal of damaged and/ or dysfunctional proteins, whereas a positive protein balance results in the synthesis of new proteins for repair and growth (see figure below). Of the two main factors that stimulate protein synthesis are resistance exercise (must consider factors such as volume, time under tension and intensity, of course) and dietary protein (leucine-containing) intake. In this context, tissue repair and regeneration is critical for return to sport following a musculoskeletal injury. For this, it may be advisable to increase dietary protein intake and to consider supplementing with collagen peptides, fish oil and/ or Vitamin D during the rehabilitation process. More specifically, in football (soccer) expert advice endorsed by the UEFA proposed increasing daily protein intake from the standard 1.6 to 2.2 g/kg/day for non-injured (Collins et al., 2020, BJSM) to 2.0 to 2.5 g/kg/day for injured athletes (Wall et al., 2015, EJSS).
To note, protein synthesis is also an energy costly process. Therefore during the acute post-injury phase the injured athlete should be aiming to achieve energy balance by following recommended carbohydrate guidelines. This is because though the tissue repair and regeneration process is energy-costly, being away from full-participation will inevitably reduce physical activity energy expenditure. Finally, pre-sleep protein ingestion (approx 40 g) may be considered as studies have shown increased strength, muscle growth and recovery with pre-sleep protein ingestion. This may help the athlete to meet the recommended daily protein intake to meet rehabilitation and further performance goals (Snijders et al., 2015).
Most neural, metabolic, psychological and structural-anatomical recovery and repair processes take place during sleep. Therefore, it is critical to monitor sleep quantity and quality, with the aim of enhancing both, during sport injury rehabilitation processes. This may have profound implications on the rate and ultimate outcome of the rehabilitation and return to sport process. A cheap, valid and reliable tool for monitoring sleep quality in athletes is the Pittsburgh Sleep Quality Index (see Buysse et al., 1989). It may also be appropriate to identify existing maladaptive sleep hygiene practices using the Sleep Hygiene Index (American Sleep Disorders Association, 1990)
3) Psychological support
Undeniably, social support - the perception and actuality that one is cared for, that one has assistance available from other people, and that one is part of a supportive social network - is one of the most powerful resources of improving overall wellbeing across heterogeneous populations. People with high social support have for years documented better quality of life, lower risk of stress-related diseases, better ability to withstand and cope with adversity, and even better professional (i.e., career-related) outcomes. I highly recommend reading the book 'Why Zebras Don’t Get Ulcers' by Robert Sapolsky, for an extensive outline of the impact social networks can have on our physiology, psychology and functioning across numerous parameters of wellbeing.
During my time with Sydney University's Aussie Rules Football team they seemed to understand this very well. Now thinking about it, maybe it is a case of Australians... they just tend to be good at life in general... I seem to recall very vividly the case of one particular athlete who re-injured a hamstring on his first full-game after having spent over a year working on his return to competitive AFL. This was a particularly devastating moment for the whole team and especially the fitness and medical team, because all possible measures indicated (and had done for a while) that the player was more than ready for his first game back. So this player got injured and the amount of peer support that surrounded him in the following weeks was breathtaking. The first session back the week after, the head coach addressed the entire team encouraging everyone to reach out to the player and show their support and care for him. On his first session back days later, where he just came to watch and say hi of course, everyone received him with a round of applause and hugs, just a really supportive and warm environment. I am taking the freedom to speak for him right now, but I am almost certain that that collective effort from the players towards him made a big and positive difference for him as he processed his situation.
Thanks for taking the time to read.
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Adriano Arguedas S.