01
Trailing limb extensionCTO
Score 1 when the trailing hip is oriented ≥45° from vertical with a fully extended knee (excessive hip extension behind the body).
Am J Sports Med 2024
Sprint mechanics, scored on a phone
S-MAS is twelve yes-or-no questions asked of five key positions in the running cycle. You film the sprint from the side, the app helps you find the right frames, and you score what you see.
Free, no account, no limits. Works in Safari and Chrome, including as a home-screen app.
Four steps
From footage to report, usually in a few minutes.
1
Film
Camera side-on, about 7 metres from the lane, at hip height. Slow motion, the maximal-velocity section.
2
Mark the range
You set the start and the end of the run. The app detects the frame rate and tracks the athlete in the frame.
3
Score the positions
Five phases, twelve questions. Each one comes with a cue for what to look at, plus an angle and a plumb-line tool.
4
Close the report
The score with its interpretation, a kinogram of the key positions and the list of areas to work on. Print or PDF.
The S-MAS scale
Each item is one question about what you see in a specific phase. The answer is yes or no — a point means the feature is present, that is, mechanics that depart from optimal. The score runs from 0 to 12.
Five phases of the cycle
CTO
Contralateral toe-off
The instant just before the contralateral foot leaves the ground.
MVP
Maximal vertical projection (MVP)
Mid-flight — pelvis at its highest point.
LSW
Late swing
Point of maximal knee extension during swing.
TD
Touch-down
First contact of the foot with the ground.
MST
Midstance
Pelvis directly over the ankle joint of the stance leg.
Twelve items
02
Back kickMVP
Score 1 when the trailing heel is above the calf / shin higher than parallel to the floor.
03
Trunk and pelvic rotationMVP
Score 1 for excessive rotation — large arm movements, trunk twisting, far-side shoulder/upper arm visible.
04
Thigh separation (late swing)LSW
Score 1 when the trailing knee remains behind the gluteal line.
05
Lumbar extension / anterior pelvic tiltLSW
Score 1 (MVP→late swing) when excessive lower-back arching, elevated chest, or hips drifting behind the body are visible.
06
Forward leanTD
Score 1 when forward trunk lean exceeds 15° from vertical at touch-down.
07
Lumbar extension / anterior pelvic tilt (TD)TD
Score 1 when increased lower-back arching or hips behind the trunk are visible at contact.
08
Thigh separation (TD)TD
Score 1 when the gap between thighs exceeds 20° or the trailing knee is behind the back at contact.
09
Foot contact ahead of the centre of massTD
Score 1 when “another foot would fit” between the contact point and the projection of the centre of mass (overstriding).
10
Shin angleTD
Score 1 when the shin looks extended — ankle joint centre in front of the knee at contact.
11
Foot inclinationTD
Score 1 when there is a visible gap between forefoot and floor (heel strike) or heel and floor (extreme forefoot strike).
12
Vertical collapse (midstance)MST
Score 1 when increased knee flexion / ankle dorsiflexion — sinking into the stride, knee over toes, foot flat.
A lower score means mechanics closer to optimal. The measurement error is about one point, so a one-point difference between tests sits within the noise and should not on its own change the training.
Bramah C. et al., Sprint Mechanics Assessment Score, American Journal of Sports Medicine 2024. Inter-rater ICC 0.828, intra-rater 0.799.
What happens to the footage
- Recordings never leave the phone. The whole analysis, AI skeleton included, runs in the browser on the device.
- Athletes, assessments and kinograms are stored in that device’s browser storage.
- Only anonymous usage statistics are collected: opens, language, features used, the score as a band. No cookies, no profiling.
- You can switch the statistics off with a single toggle in the Athletes tab.