One of the biggest mistakes we make in sports medicine and performance is confusing mechanism with cause.
You see it all the time on social media.
An athlete gets hurt, the clip gets paused at the “injury moment,” and people crawl out of the woodwork to circle a knee angle or a foot position and say, “This is exactly what caused it.”
And sure, sometimes they’re right about the mechanics. But that’s not the full story.
The mechanism explains how the injury happened
The mechanism is the action or chain of actions that leads to tissue failure.
Examples:
- Knee valgus + rotation during deceleration
- High-speed sprinting during late swing
- Landing stiff with high braking forces
- Shoulder in abduction + external rotation during contact
That’s the how.
But here’s the problem…
The mechanism doesn’t explain why the injury happened
That same exact movement pattern happens hundreds of times in sport. So why does it cause an injury this time, but not the other 999 times?
Because injury isn’t just about the movement.
The “why” lives in the context
The difference between “mechanism happened” and “injury happened” is usually a mix of:
- Training history (what they’ve actually been exposed to)
- Workload (acute spike vs normal volume)
- Strength and tissue capacity (can they tolerate that load?)
- Fatigue (neuromuscular + decision-making)
- Previous injury (residual deficits, compensation, fear)
- Readiness (sleep, stress, soreness, travel)
- Technique under pressure (not in warmups, in chaos)
Same mechanism. Different outcome.
Have you ever been in a car accident?
I like to think of an injury like a car accident.
The mechanism is what you can see on video. One car hits another. A car hits the center divider. A car clips a parked car. That’s the how.
But that doesn’t tell you the why.
Because the same crash can happen for totally different reasons. Maybe the driver was distracted. Maybe they were drunk or exhausted. Maybe the road was slick. Maybe visibility was bad.
Same accident. Different story. Sport injuries work the exact same way.
The mechanism might be a knee collapsing on a cut, a hamstring popping at top speed, or an Achilles going on a jump stop. That explains what happened in the moment, but it doesn’t explain why that moment turned into an injury.
The “why” usually lives in the context: training load, fatigue, strength capacity, recovery, previous injury history, and whether the athlete has actually been prepared for the speed and chaos of the sport.
Practical takeaway for coaches + clinicians
Understanding the mechanism helps you describe how injuries happen. That’s useful.
But if you want to build robust athletes, you have to prepare for the why.
So instead of obsessing over a freeze-frame and trying to “fix the movement,” zoom out and ask:
- Did this athlete have the capacity for the demands of today?
- Was their workload progressed or spiked?
- Were they fatigued and losing stiffness/control late in sessions?
- Are we building tissue resilience (strength, tendon, sprint exposure)?
- Are we preparing them for the real speed and chaos of sport?
Mechanisms matter. But the context is usually the difference between a close call and an injury.
I hope this helps,
Ramsey
