Bench Tested, never driven
Bench Tested, Never Driven
Every test in the building came back clean. The athlete kept breaking.
Same hamstring. Same side. The first one the better part of a decade ago, and two more recent enough that everybody in the building is now worried about it. He has been through everything you own. Nordbord. Force frame. Dual force plates. GPS on his back at every session for years. And not one of those tests will tell you why it keeps happening to that leg.
I was asked to look at a player exactly like this by a pro team this week, and the reason I could see something is not that I am cleverer than the people who tested him. It is that they were bench testing an engine and nobody had driven the car.
Every one of those tools is a bench test. You have the engine out on the stand, you run it up, and it passes. Then it goes back in, the car goes out on the road, and it breaks again. Everybody stands around the workshop holding a clean printout.
I do not have a problem with any of that equipment. The Nordbord tells you what it was built to tell you. The plates measure exactly what you asked them to measure. The dyno is not lying to you. It is answering the question you put to it, honestly, and the question you put to it was not the question you actually have. Your question is about running. So measure running.
What The Running Actually Showed
Start where the literature tells you to start. Previously injured hamstrings show up as a horizontal force deficit. Brughelli and colleagues documented it in AFL players, injured limb against uninjured limb, with no vertical difference between the two.1 Lord and colleagues showed the same capacity falling away across a repeated sprint test in footballers with a previous hamstring injury.2 We are replicating that kind of work every time we put an athlete down a straight line.
This athlete did not do that. He was unimpressive on horizontal force, but he was unimpressive on both sides. No left to right difference worth talking about. Weak is not a finding on its own. Experience tells you that when the asymmetry is not there, the story is probably not sitting where you are looking.
So look further afield. On the right side, the same side as every one of those hamstrings, ground contact time and the vertical force surrogate were both a long way down on the other limb. That is not a hamstring signature. That is an inability to beat gravity on one leg.
Then the rest of it falls into line. Step frequency is low, and it is lower on that side. Go a layer deeper into step length and touchdown distance and there it is, the foot landing further out in front of the centre of mass on the limb that cannot punch. He is overstriding. He is reaching for the ground because he cannot get off it, and he is doing it at speed, and he has been doing it for years.
Now the honest part, and it is the part that matters most.
I cannot tell you that the vertical limitation caused the hamstring injuries. It is a very plausible chain, and every practitioner reading this has watched that pattern produce exactly that injury. But the arrow could point the other way. A decade of tearing the same hamstring is more than enough to produce a limb that will not punch. I do not know which way it runs. Neither does anybody else, and anybody who tells you they do is selling you something.
That is not just my caution talking. Every piece of that data was collected after the injury had already happened.
The largest review of neuromotor function after lower limb injury, sixty three studies and 1,796 participants, says it plainly in its own limitations. Because all of it was collected retrospectively, it is not possible to say whether the differences found were the result of the injury or the cause of it.3
What I can tell you is that there is a specific, repeatable, side-matched signal in that athlete's running, and nothing in the gym found it. The next step is not a diagnosis. It is a test. Go and load that limb vertically. Bent knee calf work, single leg calf raise, a squat test, your basic hop parameters. Find out whether the capacity deficit is real, and now you have two independent signals pointing at the same leg instead of one clean printout and a shrug.
Why This Keeps Coming Up
The questions I got this week all had the same shape. Is the injured muscle the deficient one, or the compensating one? Is what we are looking at the symptom or the cause?
We have been asking that for twenty five years. I have worked with excellent physiotherapists who talked about inter-limb compensation for their entire careers, and they were right to. If one limb cannot do the job, something takes it up. And it happens inside a muscle too. We see it in athletes who rupture a T junction, get it repaired, and then strain further north up the same hamstring. That load went somewhere. I have a whole separate argument about how thin the evidence for that is, and it is not this post.
None of it gets measured at the muscle level in a training environment. Somebody will do it one day, and it will not be me. But we can measure at a locomotory level. We can ask whether the athlete is able to demonstrate all the things running requires, and the most basic of those is getting up off the ground.
That is why the straight line test exists. Not to find out whether your midfielder is a sprinter. To find out whether the fundamental step in that athlete's evolution is actually in place before you send him into chaos, which is the game, whatever the sport. Because as soon as it goes curvilinear, as soon as there is a change of direction, the mechanics get worse and every weakness gets exaggerated. Straight line running is not the test. It is the last place the picture is still clean enough to read.
I had a long conversation with Stu McMillan this week and we came out the same door. There are a great many of us, physiotherapists, physical therapists, strength and conditioning coaches, biased all the way through toward the information we happen to hold. As Stu put it, we are running coaches. Football, soccer, rugby, AFL. They are running sports.
So go and look at the running.
Stop fitting the data you own to the question you have.
Test the gym. Then test the straight line. Then let them play.
Two signals on the same leg beats one clean printout.
And when the printout is clean and the athlete keeps breaking, believe the athlete.
The information we have is not enough.
1. Brughelli M, Cronin J, Mendiguchia J, Kinsella D, Nosaka K. Contralateral leg deficits in kinetic and kinematic variables during running in Australian rules football players with previous hamstring injuries. Journal of Strength and Conditioning Research. 2010;24(9):2539-2544.
2. Lord C, Blazevich AJ, Drinkwater EJ, Ma'ayah F. Greater loss of horizontal force after a repeated-sprint test in footballers with a previous hamstring injury. Journal of Science and Medicine in Sport. 2019;22(1):16-21.
3. Andringa-Bate J, Almusallam M, Coventry M, Murphy MC, Rio E, Pizzari T. Neuromotor function following lower-limb muscle or tendon injury: systematic review and meta-analysis. Sports Medicine and Health Science. 2026;8(4):390-406.
Take Three Pieces Of It Free
One of them is an audit that makes you say what you measured and what you assumed, in separate columns. Same discipline as the test order above, pointed at your own reasoning. No cost, no card.
Send me the three