The Sports Science Fingerprint: The Athlete Behind the Numbers
This post considers the impact of training and injury history on each unique athlete we work with.
As sports scientists, we spend much of our time measuring the current state of the athlete. We quantify force production with force plates, assess strength in the gym, monitor training load with heart rate and GPS, and ask our athletes, "How are you feeling today?"
Collectively, these assessments help us understand where an athlete currently sits and guide many of the decisions we make. Yet every assessment is simply a snapshot in time.
Behind every assessment, training session and competitive fixture lie years of accumulated training, injuries, coaching, competition and life experiences that have shaped the athlete standing in front of us. While we naturally focus on today's data, perhaps we should spend more time considering the journey that produced it.
Injury History as an Athlete Fingerprint
During my visit to this year's Isokinetic Conference in Athens, Dr Bryan Heiderscheit presented a slide that, on the face of it, was remarkably simple. It showed the injury histories of three athletes (see figure).
Knowing that previous injury is one of the strongest predictors of future injury, I have also included injury history on my athlete profiling reports. This wasn't a new idea. But perhaps it was the greater level of diagnostic detail that he included. Seeing those intricate histories laid out side-by-side got me thinking.
Of course, we have to be cautious with such medical data and respect athlete confidentiality alongside the relevant data privacy and security regulations wherever we're working. We can't go around announcing intricate injury histories of our athletes. That's partly why my approach has always been broader, for example, 'hamstring strain', 'ankle sprain' or 'ACL injury'.
But just considering 'hamstring injury' overlooks a lot of potentially important detail. Athlete B has suffered multiple biceps femoris long head strains on both sides, whereas Athlete A has suffered multiple left-sided semimembranosus strains in addition to multiple right-sided biceps femoris long head strains. And that's still without knowing the details of those strains, which are becoming increasingly more intricate thanks in part to technology developments such as the AI-driven MRI analysis of muscles from Springbok Analytics.
The slide also highlights potential weak links throughout each athlete's chain. My former boss, Joe Collins, Performance Director at the Buffalo Bills, taught me to look above and below when considering an injury. The body is a chain, a chain that force moves through, and it is too reductionist to consider each muscle or joint in isolation.
Athlete A has also experienced injuries immediately above and below the hamstrings, dealing with bilateral adductor strains in addition to unilateral tendinopathy, plus a partial meniscectomy on the left side and gastrocnemius tear on the right.
Athlete B's history is more concentrated around the thighs, with multiple rectus femoris strains in addition to the biceps femoris strains.
Athlete C has a much more distributed history, with foot and Achilles issues, calf and ankle injuries, intercostal problems and multiple left-sided oblique strains, in addition to right-sided biceps femoris and rectus femoris strains.
It got me thinking that every athlete arrives with their own unique fingerprint: a unique pattern of experiences that shapes how they move, adapt and respond to training. Like a fingerprint, no two histories are ever quite the same.
History Doesn't Just Explain the Past
Injury history doesn't simply explain where an athlete has been. It continues to influence where they are going.
Each injury leaves behind adaptations that may influence everything that follows. A significant ankle sprain may alter movement strategies years later. A hamstring strain may change sprint mechanics, force production or an athlete's confidence when running at maximal speed. An ACL reconstruction influences far more than the integrity of a ligament. It affects strength, neuromuscular control, training exposure, psychology and the countless decisions that shape rehabilitation and subsequent performance. I know this first-hand: my ACL reconstruction took place more than 15 years ago, yet I still have to manage strength and movement deficiencies on my right side.
every athlete arrives with their own unique fingerprint: a unique pattern of experiences that shapes how they move, adapt and respond to training.
A recently published study by Zhang and colleagues (2026) illustrates the dynamic nature of injury risk particularly well. Rather than viewing return to play as a single event, the authors examined how subsequent injury risk changed over time following different muscle injuries in professional football. The study demonstrated the time-varying nature of subsequent injury risk following specific lower-extremity muscle injuries, in this case in professional male footballers.
Injury risk isn't simply elevated after return to play. It evolves over time, with different trajectories observed according to the muscle group injured and whether the injury was acute or overuse.
We often describe previous injury as a risk factor, but perhaps it's more helpful to think of it as part of an athlete's evolving history. The injury changes the athlete, and in doing so contributes to the context in which everything that follows takes place.
Athletes Are Complex, Dynamic Systems
This way of thinking also overlaps with something I've written about previously: viewing athletes as complex, adaptive systems.
One of the defining characteristics of complex systems is that they are history-dependent. Their future behaviour depends not only on their current state but also on the path they took to get there, which feels particularly relevant when considering our athletes.
Every training session, every competition, every illness and every injury could subtly change the athlete. It's not just limited to injury either. Training history matters too.
By the time an athlete reaches elite sport, they have accumulated thousands of training sessions, hundreds of matches and years of coaching, learning and adaptation. Some will have been exposed to structured strength training from an early age, while others may only have entered a well-resourced performance environment much later in their career.
Today's adaptation becomes tomorrow's history. Tomorrow's history shapes the next adaptation. The athlete standing in front of us today is not simply a collection of physiological characteristics, but the product of years of interactions between biology, training, environment and experience. That's in part why we have a Training Adaptability Prediction Problem.
The fingerprint, if you like, is constantly evolving.
This is also why I think it's important that we don't become overly reliant on isolated metrics. Force plates, GPS, muscle strength testing and wellness questionnaires remain incredibly valuable, but they should always be interpreted within the context of the individual athlete producing them. The same score may tell a very different story depending on who produced it and how they arrived there.
What Does This Mean for Applied Sports Science?
Population research remains fundamental to improving our profession and should continue to guide the decisions we make. However, as I've previously discussed on the blog, individuality is greater than 'averagarian thinking' in sports science.
Rather than asking simply whether an athlete falls above or below a normative value, perhaps we should spend more time asking why. What experiences have shaped the profile we're looking at? How much of what we're seeing today reflects the programme they completed over the last six weeks, and how much reflects the previous ten years?
Those questions are undoubtedly more difficult to answer, but I think asking them gives us important context for interpreting the data we already have.
The athlete standing in front of us today is not simply a collection of physiological characteristics, but the product of years of interactions between biology, training, environment and experience.
Individualisation is often discussed in terms of changing exercises, adjusting training loads or tailoring rehabilitation programmes. Those things are important, but perhaps true individualisation starts a little earlier. It begins with recognising that every athlete arrives with a unique history, and that history inevitably shapes how they move, adapt and perform.
Final Thoughts
One of the strengths of sports science is our ability to identify patterns across large groups of athletes. Without those patterns, we wouldn't have normative data or arugably, evidence-based practice.
At the same time, our role as practitioners is to apply that evidence to the individual standing in front of us. That individual is far more than the numbers on a dashboard or the results of a testing battery. They are the product of years of accumulated training, injuries, coaching, successes, setbacks and adaptation.
Bryan Heiderscheit's slide was a simple reminder that behind every assessment is a history, and behind every history is an athlete whose journey has been unlike anyone else's.
The more we understand that journey, the better equipped we are to understand the athlete.
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