Sprint Mechanics Assessment Score (S-MAS): the 12 checks, explained
The S-MAS is a 12-point video checklist for top-speed sprinting, built by sports scientists for use on the field. Here is what each check means, what the research found, and how to use it on your own running.
Coaches and physios have always watched sprinters and judged their mechanics by eye. The problem is that “by eye” means different things to different people. The Sprint Mechanics Assessment Score, or S-MAS, turns that judgement into a fixed checklist that anyone can score the same way from a phone video.
It was developed by Christopher Bramah and colleagues and published in the American Journal of Sports Medicine in 2024. Lab-based 3D motion capture is the gold standard for measuring sprint mechanics, but it isn’t practical on a training pitch. The S-MAS was built to fill that gap.
How the S-MAS works
- Film an athlete side-on during a maximal sprint, at top speed.
- Watch the video and check 12 items. Each fault you can see scores 1; if it isn’t there, it scores 0.
- Add them up for a total from 0 to 12. Higher scores mean poorer mechanics.
In the original study, 136 elite soccer players were filmed during maximal 35 m sprints. The S-MAS showed good reliability: the same rater scoring the same videos twice agreed well (intraclass correlation 0.83), and so did different raters (0.80), with a typical measurement error of about 1 point. Average scores were around 4, with no meaningful difference between men and women.
The 12 S-MAS checks explained
| # | Item | Scores a fault when… |
|---|---|---|
| 1 | Trailing limb extension | The back leg is fully straight as it leaves the ground, with the hip extended about 45° or more behind vertical. The leg is pushing out the back for too long. |
| 2 | Back kick | The trailing heel kicks up above the calf, or the shin rises above parallel with the ground behind the body. |
| 3 | Trunk and pelvic rotation | The trunk twists excessively, seen as big, sweeping arm movements or the far-side shoulder showing to the camera. |
| 4 | Thigh separation (late swing) | As the front leg comes down, the trailing knee is still behind the buttocks. |
| 5 | Lumbar extension / anterior pelvic tilt (in the air) | The lower back arches, the chest lifts, or the pelvis sits well behind the body. |
| 6 | Forward lean | The trunk leans more than about 15° forward of vertical, measured from the hip to the base of the neck. |
| 7 | Lumbar extension / anterior pelvic tilt (touchdown) | The lower-back arch or pelvic tilt increases as the foot lands. |
| 8 | Thigh separation (touchdown) | At touchdown the thighs are more than about 20° apart, or the trailing knee is behind the body. |
| 9 | Foot contact vs centre of mass | There is room for another foot between where the foot lands and the body’s centre of mass. This is overstriding. |
| 10 | Shin angle | At touchdown the ankle is in front of the knee, so the shin is leaning back. |
| 11 | Foot inclination | There is a clear gap under the heel or the forefoot at touchdown: a pronounced heel strike or toe strike. |
| 12 | Vertical collapse | At mid-stance the knee bends or the ankle flexes a lot, so the athlete visibly sinks into the step. |
Most of the items describe two patterns. Items 1, 2, 4, 5 and 8 are about the leg working behind the body: pushing out the back too long and recovering late. Items 9, 10 and 11 are about the foot landing too far in front. Both are things sprint coaches have long tried to fix, for speed as well as for injury.
What the research links it to
The reason the S-MAS gets attention is hamstring injury, the most common injury in sprinting and sprint-based sports. In a 2025 study in the British Journal of Sports Medicine, Bramah and colleagues scored 126 elite male footballers and followed them for six months.
- Players with a previous hamstring injury had higher S-MAS scores than uninjured players.
- So did players who went on to have a new sprint-related hamstring injury.
- After accounting for age and previous injury, each 1-point increase in S-MAS went with a 33% higher rate of sprint-related hamstring injuries.
That is a meaningful finding, but keep it in proportion. The confidence interval was wide (from about 1% to 76% higher per point), it was one group of male footballers, and an association doesn’t prove that changing your mechanics will prevent an injury. The authors themselves call for larger studies.
How to score your own sprint
- Film side-on at top speed. Stand at a right angle to the lane, level with the part of the run where you are fastest, with your whole body in shot. The original study used an iPhone on a tripod about 0.8 m high and 7 m from the lane, filming in slow motion at 240 frames per second.
- Pick a step at top speed, not one from the acceleration, where a forward lean and long push are normal.
- Pause at four moments: as the back foot leaves the ground, at the highest point of the flight, at touchdown, and at mid-stance.
- Score each item 0 or 1 using the table above, and add them up.
- Re-test the same way after a block of training. With a typical error of about 1 point, look for changes bigger than that.
Scoring it well takes practice, especially items like pelvic tilt that are subtle on video. If you work with a physio or strength coach, scoring the same clips together is a good way to calibrate.
Where SprintVision fits
SprintVision doesn’t calculate an S-MAS score. It measures several of the same things automatically, on every step of a normal-speed video: trunk lean, the shin angle and knee angle at touchdown, and how far the foot lands ahead of the hips. That makes it easy to see whether a fault shows up on one step or on every step, and to track it from session to session.
Used together, they complement each other: the S-MAS for a structured screen, and the step-by-step numbers to watch the change.
Sources
- Bramah, C., Tawiah-Dodoo, J., Rhodes, S., Elliott, J. D. and Dos’Santos, T. (2024). “The Sprint Mechanics Assessment Score: A Qualitative Screening Tool for the In-field Assessment of Sprint Running Mechanics”, American Journal of Sports Medicine, 52(6), 1608–1616. PMC11064464
- Bramah, C. et al. (2025). “Sprint running mechanics are associated with hamstring strain injury: a 6-month prospective cohort study of 126 elite male footballers”, British Journal of Sports Medicine.
Common questions
What is the Sprint Mechanics Assessment Score?
The Sprint Mechanics Assessment Score (S-MAS) is a qualitative screening tool for sprinting technique, published by Bramah and colleagues in the American Journal of Sports Medicine in 2024. A practitioner watches a side-on video of a maximal sprint and checks 12 items, such as overstriding, forward lean and back kick. Each fault seen scores 1, giving a total from 0 to 12, where higher scores mean poorer mechanics.
What is a good S-MAS score?
Lower is better, and 0 is the best possible score. In the original study of elite soccer players, the average was about 4. In a 2025 follow-up, players with higher scores had more sprint-related hamstring injuries, with each extra point linked to a 33% higher injury rate.
How do you film for the S-MAS?
From the side, at a right angle to the lane, with the whole body in shot while the athlete is at top speed. The original study used an iPhone on a tripod 0.8 m high and 7 m from the lane, filming at 240 frames per second, and assessed maximal 35 m sprints.
Does a low S-MAS score mean I will run faster?
Not necessarily. The S-MAS was built to screen movement linked to hamstring injury, not to predict sprint speed. Several of its items, like overstriding and excessive forward lean, also cost speed, but a low score is not a speed rating.
See your own numbers.
Film one rep on your iPhone. SprintVision measures every step and rates your positions against these targets, with a cue for anything outside the range.
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