Preface
It’s about that time of the year, coming toward the end of the first quarter and new year’s resolutions are in full force! People are finding their stride, and probably committing to a workout routine or ramping up their physical activity volume. As allied health professionals, we are ecstatic about this – people are moving more and staying consistent, however there often exists a caveat to this acute spike in volume and his name is ‘injury risk.’
Acute on chronic workload ratio
One of the most discussed measures pertaining to injury risk literature is ‘acute on chronic workload ratio’ (ACWR in short). The model of the ACWR surfaced and spread in 2016, whereby Hulin et al. detailed their findings regarding injury risk. The article proposed that coaches could predict injury risk by calculating the ratio between acute training loads (what has been done recently, over the past week) and chronic training loads (average training accumulated over a longer period, normally >1month). The theory is that if the acute training load is too high in relation to the chronic training load, the athlete is doing more training than what they’re used to. This ‘spike’ in workload served as a warning sign for increased injury risk due to factors discussed below.
Factors that help maintain balance and reduce injury risk
Put simply, there needs to be a balance between our training load vs tissue load capacity in order to reduce the risk of injury (notice I didn’t type ‘prevent injury’ as sometimes the demands of life/sport are unpredictable and injuries still occur despite adequate tolerance!) Things that make up training load: volume, intensity, frequency, type of exercise, and other kinesiological (movement) behaviour throughout the day (work/leisure). Things that make up tissue load capacity: strength, motor control, proprioception, mobility, tissue sensitivity, biomechanics, tendon resilience, joint health, and previous injury (likely negative correlation toward load capacity). There needs to be a cohesive balance between load and capacity for the whole system to not feel overwhelmed. You can also build up capacity to a point where it is healthily at a threshold above potential loads, facilitating injury risk reduction – if you’ve specifically built up resilience through exercise, the training loads won’t be as novel and excitatory (which usually is a main factor in causing injury).
Move more, move better – reduce injury
Another way to mitigate loads which are potentially harmful is breaking out of those static postures that put ongoing demand on specific systems of the body. Your best posture is your next posture, we don’t want to be stuck in the same positions for prolonged periods because this would put stress and load onto a few tissues (trying to sit perfectly erect for the whole day would stress your spinal extensors), which would be better off being dispersed to various tissues (through movement or changing postures). Moving more gives your body neuromuscular control over more ranges of movement as well as prime the system for randomness as well, most injuries will be at end uncontrollable range + too much random unprepared load. Move better pertains to the (p)rehab continuum which involves various muscle contractions and exercise types to build resilience in all soft tissues and not just the big superficial muscles you can easily see.
The (p)rehab continuum
People move in all sorts of ways and there isn’t a gold standard for prescribing exercise, however when we are looking into the realm of system equilibrium in physical activity as well as injury risk reduction, we have to take into account a few things. Mobility, strength, neuromuscular control, proprioception and reactivity/plyometrics; likely trained in a clinical or gym setting which is a controlled environment, but often also on a sporting field with specific tasks/demands (yoga, pilates, crossfit, Olympic lifting, general resistance training, HIIT, sport). Aforementioned are the pillars of building a resilient body that pushes the scales to favour tissue capacity, meaning even if there are planned or random increases in load, the scales still don’t tip too far toward the load continuum and cause injury! Here in the clinic, the multidisciplinary team all prescribe exercise. These will be tailored toward what areas of tissue load capacity might be lacking in a healthy or injured individual.
Continuing to check in with your (p)rebab is like an investment into your own body – we aim to be mobile, strong, balanced/controlled and able to have springy reactive tendons so we can avoid tissue overload/injury (prehabilitation). On the flip side if we do find ourselves injured, we still want to rebuild those same things back to and past their baseline levels (rehabilitation).
Soft tissue, joints, central nervous system and injury
A common misconception is that if our muscles are strong, we will be able to prevent injury. Most of the time, injuries have been researched to occur within the first 50ms after initial contact during rapid deceleration. We need pre-activation/skill and co-contractions of certain muscles to fire – not just muscles built in the one plane for show.
Although strength is a component of resilience, we must also think about the connective tissues from muscle to bone, bone to bone, and the articular joint spaces as well (tendon compliance, ligament health, and labral/joint capacity respectively). If your muscles are strong enough to complete a movement, however your connective tissues are not trained to handle capacity, you can still injure those parts of your body!
Certain things that we like to prescribe may be controlled articular rotations (joint/labral), heavy slow resistance (tendon), reactive plyometrics/proprioception (ligaments/tendons/joint) and full range compound exercises for skilled co-contractions (soft tissue generally).
The last point to discuss is central nervous system or CNS. General physical preparedness, self-efficacy and confidence in movement plays a huge role in injury risk reduction. You can build your body in order to be ready, however if your mind still believes you’re not ready, that the task is too novel/dangerous, it might not be able to send those excitatory signals to pre-activate those resilient muscles. Another thing to consider is, if you have low alertness due to CNS overload – you are more likely have poor motor planning and injure yourself. Set yourself up to optimally return to physical activity. Train smart and recover well!
