Why it matters: top speed decides game-breaking moments, and upright sprinting is also where many hamstring injuries happen. A stopwatch gives you a time.
The Fly test also shows how that time was produced, step by step.
The athlete enters the capture zone already at speed. One iPhone filmed side-on records the run. VueMotion returns split times, speed, step-by-step kinematics, kinograms and a PDF report.
1
iPhone, filmed side-on
≈ 5 min
to set up and record
12
SMAS checks per leg, plus sprint profile
Why it matters
A stopwatch tells you how fast. VueMotion shows how.
Every Fly gives you three layers on top of time and speed. Together they turn one sprint into decisions for performance, injury risk, return to play, benchmarking and scouting.
SQ
Step Quality
Six key metrics from the kinogram positions, scored against sport- and demographic-specific norms, left and right. Shows where in the step speed is lost.
SM
SMAS
12 technique faults linked to hamstring strain injury, 0–12 per leg. Points to which movement pattern to fix.
Q
Sprint quadrant
Bounder, Strider, Bouncer or Spinner, from cohort z-scores. Shows the athlete's strategy and its injury profile.
01
Performance monitoring
Is the athlete getting faster, holding steady, or fatiguing?
Time & speed Splits and max speed vs baseline, previous session and cohort norms.
Step Quality Total score (%) tracked each session: a drop can flag fatigue before times slow.
Quadrant A shifting position or rising L2 norm shows the running strategy is changing.
02
Performance improvement
What exactly should we coach to make them faster?
Step Quality The lowest-scoring metric is the target, e.g. touchdown too far ahead of the hip or a soft knee at full support.
SMAS The focus pattern (Backside, Overstride or Lumbo-Pelvic) comes with cues, drills and gym exercises.
Step length × frequency Shows whether the gain lies in longer or quicker steps, and re-testing shows if the change stuck.
03
Injury risk reduction
Who is running in a way linked to hamstring or calf injury?
SMAS Each extra fault point raised sprint-related hamstring injury risk by 33% in elite footballers; scores above 5.5 flag higher risk (Bramah et al., 2025). Screen the squad, flag high scorers and left–right gaps.
Quadrant Spinners showed over 2.5× hamstring risk and Bounders over 2.5× calf risk (Wild & Bezodis): tailor prevention to the profile.
Step Quality Explains the SMAS faults: overstriding at touchdown, a collapsing stance knee or backside mechanics at toe-off. Left–right gaps point to overload on one side.
04
Safer, faster return to play
Is the athlete really ready to sprint at full speed again?
Baseline match Compare speed and mechanics with the athlete's own pre-injury Fly, not just a time.
SMAS + symmetry Injured leg's fault score and step metrics back in line with the healthy leg.
Graded exposure Run-ups of 10 → 20 → 30 m (≈ 80 → 90 → 100% speed) track mechanics as intensity rises, with objective data at each step.
05
Benchmarking
How does the athlete compare with their peers?
Cohort norms Every metric is compared with athletes of the same sport, sex, age and level: Effective (> +2%), Monitor (±2%) or Attention (< −2%).
Step Quality Six metrics placed against sport- and demographic-specific normative ranges, so you see where mechanics sit, not just speed.
Squad view Rank the squad on max speed, SMAS and quadrant to set standards by position and track the whole group over a season.
06
Scouting & talent ID
Who has top-end speed, and how much headroom is left?
Objective speed Timed, calibrated flying 10 / 20 m and max speed from one iPhone: comparable across trials, venues and recruits.
Mechanics Fast athletes with low step-quality scores have untapped potential; fast athletes with a high SMAS may carry more injury risk.
Profile fit The quadrant shows how a recruit produces speed, to compare with the demands of the position.
SMAS and quadrants describe movement patterns linked to injury in research. They support clinical and coaching judgement; they do not diagnose or predict an individual injury.
01 · Setup
The 5-cone setup and camera position
Five cones mark a 1.22 m lane, with the start, halfway and finish lines on one side and the start and finish lines on the other. The athlete runs up outside the zone and is already at speed when crossing the start line.
PhaseRun-up
Time0.00 s
Split ½–
Speed–
Cones (9 in)Camera field of viewTiming lines (chest crossing)Front camera (optional)
Run-up before the start line:
C1
Sagittal camera
On a tripod, perpendicular to the lane at the halfway cone, about 10 m back. Lens height 1.5 m, landscape, 1× lens. The frame covers about 13 m: the zone plus 1.5 m either side.
C2
Front camera (optional add-on)
About 5 m beyond the nearest exit (finish) cones, in line with the lane and facing the athlete, at the same height as the sagittal camera (1.5 m), in portrait with 3× zoom on the athlete. Record both phones in sync with Controller-Capture. The front view adds coronal (frontal-plane) angles at the synchronised touchdown and toe-off events, such as knee alignment (FPPA), pelvic drop, and trunk side lean. Safety first: the athlete must be able to slow down well before reaching the camera — athletes leave a Fly at or near top speed, so move it further back if they need more room to stop.
⏱
Timing lines
The clock starts when the athlete's chest crosses the start line (STF), splits at the halfway cone (MTF) and stops at the finish line (ETF).
↻
Run-up
Start 10, 20 or 30 m before the start line to reach roughly 80, 90 or 100% of top speed. Use the same run-up every time so trials can be compared. Runs can go left-to-right or right-to-left.
Start recording before the athlete enters the frame and stop after they cross the finish line. Other athletes should queue outside the camera's view. Supported distances: 10–20 m or yd, with a 3 m buffer.
02 · Capture
Record in about five minutes
1
Equipment
iPhone 11 or newer, tripod, five 9-inch yellow cones and a measuring tape (10 m minimum).
2
Camera
Set the tripod side-on at 1.5 m height, landscape, 1× lens, with the whole zone in frame. Optional front camera: about 5 m past the exit cones, 1.5 m high, portrait, 3× zoom, synced with Controller-Capture.
3
Cones
Lay out the 5-cone zone: 10 or 20 m long, 1.22 m wide, with a halfway cone.
4
Tag + record
In the VueMotion app choose the test tag (e.g. Fly-20m-10m) and the athlete, then record.
5
Upload
In the app, Select → Select all → Upload All, then submit the AI request from the Cloud screen.
Camera settings (important)
4K at 60 fps (runs longer than 10 m). At least 50 fps is needed for step-quality metrics
Outdoor mode outdoors; indoor mode indoors with a fast shutter (S = 1/500–1/600)
Auto-FPS off (Settings → Camera → Record Video)
Do Not Disturb on, Auto-Lock never
Athlete
Full warm-up guided by a coach, finishing with build-up runs
Same run-up distance on every trial
Sprint all the way through the finish line
Only the tested athlete in frame
Upload tips
Upload the original file from the VueMotion app
Apple's default sharing can silently change the frame rate, so avoid AirDrop, Photos exports and messaging apps
Missing tags? Email support@vuemotion.com
03 · What the camera sees
Every step, every phase
Markerless pose tracking follows the athlete through each step. It detects touchdown and toe-off for each foot, and captures kinograms at six key positions.
TOUCH DOWN
Touch Down (TD / GD)
Real stick-figure kinogram frames from a 10 yd Fly, with joint angles as they appear in your results. The frames cycle through one step; tap an event to hold it.
In your results: kinograms in three views
The six positions are captured for the left and right leg, with the video frame number on each tile. Switch views below. (Example: 10 yd Fly; faces blurred.)
Step quality: six key metrics against norms
The PDF report's Step Quality page gives a total score (%) that combines six kinematic metrics, each benchmarked against sport- and demographic-specific norms. It needs video recorded at 50 fps or more. (Example: 10 yd Fly.)
Total step-quality score · example
61 %
0%100%
Body mass and leg length from the athlete profile are used for leg stiffness.
Metric
Left
Right
Touchdown position
Angle between hip and toe at touchdown
22°
23°
Knee separation at TD
Angle between the knees and hip at touchdown
−4°
−8°
Knee flexion at full support
Angle of the support knee (180° = straight)
134°
144°
Positive running
Half the thigh-separation angle to the vertical from the hip, at toe-off
24°
25°
Contact excursion
Hip-to-toe angle at touchdown + at toe-off
58°
56°
Leg stiffness
Stiffness of the leg during ground contact
15.4 kN/m
14.41 kN/m
Positive running, step by step
Every toe-off in the capture zone is measured. The boxed number at the hip is the positive-running angle (orange = left leg, purple = right leg); the thigh-separation angle and its half angle are printed under each step. The dotted lines trace the hip and upper-body path through the run. The report averages these for each leg. (Faces blurred.)
Linking step quality to injury risk
Most step-quality metrics measure the same positions that SMAS checks, and SMAS is linked to hamstring strain injury: in 126 elite footballers, each extra SMAS point raised the risk of a sprint-related hamstring injury by 33%, and scores above 5.5 best separated injured from uninjured players (Bramah et al., 2025). No study has yet tested the individual step-quality metrics as injury predictors, so use them to explain why an athlete scores as they do on SMAS and to track change.
Metric
Link to injury risk
Evidence
Touchdown position
How far ahead of the hip the foot lands. A large angle means overstriding and more braking.
Mirrors the SMAS Foot vs Centre of Mass and Shin Angle checks (Overstride pattern). The hamstrings are most loaded in late swing and early stance, when braking forces are highest.
SMAS item
Bramah 2024, 2025; Kenneally-Dabrowski 2019
Knee separation at TD
How far the swing knee has come through when the foot lands: a front-side mechanics marker.
Mirrors the SMAS Thigh Separation (Touch-down) check. Poor scissor action is part of the Overstride pattern linked to hamstring strain.
SMAS item
Bramah 2024, 2025
Knee flexion at full support
How much the stance knee bends under load.
A large bend (low angle) mirrors the SMAS Vertical Collapse check. A collapsing stance leg is part of the fault profile linked to hamstring strain.
SMAS item
Bramah 2024, 2025
Positive running
Thigh position at toe-off: front-side vs back-side mechanics.
Low values point to backside mechanics: a trailing leg that stays behind the body, matching the SMAS Trailing Limb Extension and Back Kick checks. The Backside pattern is linked to higher hamstring strain in mid-to-late swing.
SMAS item
Bramah 2024, 2025; Mendiguchia 2022
Contact excursion
How far the leg sweeps under the body during contact.
Large values often go with overstriding (foot landing far ahead) and more braking. No study has tested this metric on its own.
Mechanistic
Kenneally-Dabrowski 2019
Leg stiffness
How spring-like the leg is during contact.
Proposed as a double-edged factor: too stiff linked to bony injury, too compliant to soft-tissue injury. A prospective study in recreational runners found no link, so use it for left–right gaps and change over time, not as a risk score.
Mixed
Butler 2003; Davis & Gruber 2021
SMAS item linked through the SMAS check it mirrors Mechanistic biomechanical rationale only Mixed conflicting evidence
04 · Outputs
What you get after upload
Key metrics
Run time, average, maximum and minimum speed, plus left/right step length, frequency, contact and flight time.
Step-by-step table
Step length, step frequency, ground contact time and flight time for every step.
Graphs
Hip displacement, ground contact time, step frequency, air time, instantaneous speed and acceleration.
Kinograms + AR video
Six key positions per leg in three views (natural, pose-points, stick figure), and AR video with step length and instantaneous speed.
PDF report
Splits, speed, step metrics, angles and leg stiffness, left vs right.
Step quality score
Total score (%) plus six key metrics, left and right, against sport- and demographic-specific norms (≥ 50 fps).
SMAS fault score
12 sprint-mechanics checks per leg, movement-pattern focus and an intervention pathway.
Motor preference
Sprint quadrant (Bounders, Striders, Bouncers, Spinners) from cohort z-scores, tracked across sessions.
Session summary
Every metric banded against the population norm: Effective (> +2%), Monitor (±2%) or Attention (< −2%).
Front view (optional)
With the front camera: coronal angles at synchronised touchdown and toe-off, such as knee alignment (FPPA), pelvic drop, trunk side lean and step width.
CSV / API
CSV/Excel export for Enterprise and Academy users; API access for Enterprise.
Interactive results dashboard
Data ViewRadarPDF ReportKinogramMotor PrefSMASProgress*
Each Fly opens in a dashboard with these tabs, alongside the upright running PDF report and session summary report. Data View lists all 20 metrics (including a 0–5 m split) against population norms. *Progress appears once the athlete has earlier sessions.
Key metrics
01Average step length, right (m)
02Average step length, left (m)
03Average step length (m)
04Average step frequency, left (Hz)
05Average step frequency, right (Hz)
06Average ground contact time, left (s)
07Average ground contact time, right (s)
08Average flight time, left (s)
09Average flight time, right (s)
10Run time over the calibration distance (s)
11Average speed (m/s)
12Maximum speed (m/s)
13Minimum speed (m/s)
Metric definitions
Timing and speed
STF · MTF · ETF
Start, Mid and End Trip Frames: the frames where the athlete's chest crosses the start, halfway and finish cones.
CD · HCD
Calibration Distance (10 or 20 m/yd) and Half of the Calibration Distance.
Time 0–HCD
STF to MTF.
Time HCD–CD
MTF to ETF.
Total time 0–CD
STF to ETF, also reported as the run time.
Average speed 0–HCD / HCD–CD
HCD divided by the time for that half.
Average speed
CD divided by the total time. m/s or ft/s, with km/h or mph equivalents.
Maximum speed
Highest speed between STF and ETF, calculated over 0.25 s intervals and then smoothed.
Step metrics
Step length
Forward distance of the big toe between the current and previous step. The first step is skipped because it is measured from the start cone.
Ground contact time
Touchdown (TD) to toe-off (TO) of the same step.
Flight time
Toe-off of the previous step to touchdown of the current step.
Step frequency
1 ÷ (contact time + flight time) of the current step, in Hz.
Left / right averages
Mean of all left or all right steps.
Angles (PDF report)
Touchdown position / braking angle
Angle between the line from the ground-contact toe to the mid-hip and the vertical from the mid-hip, at TD. Averaged over left or right touchdowns.
Thigh split at TD
Left knee – mid-hip – right knee angle at touchdown. Negative if the swing knee is behind the stance knee.
Knee flexion at full support
Hip–knee–ankle angle at full support.
Contact excursion
Touchdown position angle + toe-off position angle for the same step.
Positive running
Half the knee separation angle, relative to the vertical line down from the hip, at toe-off. Negative if the swing knee is behind the stance knee.
Kinogram angles
Thigh separation, left and right knee, left and right ankle, elbow and trunk angle at each key position, plus shin angle at toe-off.
Leg stiffness
Estimated for each step with the spring-mass model of Morin et al. (2005), in kN/m, then averaged for left and right.
kleg = Fmax · ΔL−1 with ΔL = L − √(L² − (v·tc / 2)²) + Δyc
L = estimated leg length (proportional to athlete height) · v = step speed (step length ÷ step duration) · tc = contact time · Δyc = vertical drop of the centre of mass during contact.
05 · SMAS
SMAS: a sprint-mechanics fault score for every Fly
The Sprint Mechanics Assessment Score (S-MAS) checks 12 technique faults linked to hamstring strain injury, separately for each leg. VueMotion scores every check automatically from the Fly video: 0–12 per leg, lower is better.
Fault score · example (240 fps)
0 / 12
Green below 34% of the maximum, amber 34–66%, red 67% or more.
#
Check
Result
Intervention framework
Each check belongs to one of three movement patterns: Backside Mechanics (4 checks), Overstride Mechanics (5) or Lumbo-Pelvic Control (3). The pattern with the highest percentage of faults becomes the focus and decides the intervention pathway.
06 · Motor preference
Sprint profile: the four quadrants
Every Fly is placed on a quadrant chart using two z-scores against the athlete's cohort: ground-contact time relative to flight time (horizontal) and step length relative to step rate (vertical). The quadrants follow James Wild and Neil Bezodis's sprint profiles.
Reading the chart
Dashed squares mark 0.5, 1.5 and 2.5 SD from the cohort average.
L2 norm = distance from the centre: how distinct the athlete's profile is.
Bubble = session average, coloured by maximum speed vs cohort (red below, amber around, green above average). Left and right legs are plotted separately to show asymmetry.
Relative risks (RR) are from 85 professional rugby players followed for seven seasons; * marks a statistically significant difference. That study profiled acceleration technique. VueMotion applies the same quadrants to Fly data, so use them to individualise risk reduction, not as a diagnosis.
07 · Practitioner value
Speed test and running-mechanics test in one
Maximal sprint speed
Measures peak velocity once acceleration is complete: a key part of sprint performance in speed-based sports.
Mechanics at full speed
Posture, front-side and back-side mechanics, step length, step frequency and contact time.
Complements acceleration
Comparing Acceleration and Fly results shows whether the limiter is force production or elastic, reactive speed.
Hamstring and return-to-play
Track left/right asymmetries and change over time, and confirm return to pre-injury sprint mechanics.
Training response
Repeat tests to see the effect of speed work, resisted sprints and technique drills, or signs of fatigue.
Efficiency and stiffness
Leg stiffness and contact time describe how well the athlete uses elastic energy at top speed.
08 · Support
FAQs
Which test tag should I use?
Tags follow Fly-[distance]-[run-up], e.g. Fly-20m-10m is a 20 m capture zone with a 10 m run-up. Yard versions are available. If you don't see a tag, email support@vuemotion.com.
Can the athlete run in either direction?
Yes. Left-to-right and right-to-left are both supported.
Why are some step-quality metrics missing from my report?
Touchdown position, knee separation, knee flexion, positive running, contact excursion and leg stiffness need video recorded at 50 fps or more. Record at 4K/60 fps.
Is SMAS a diagnosis of hamstring injury risk?
No. SMAS flags technique faults that research has linked to hamstring strain injury. Use it with training load, strength testing and clinical judgement, and track it over time.
Are CSV exports and APIs available?
CSV/Excel export is available for Enterprise and Academy users, and API access for Enterprise users.
Bramah C, Tawiah-Dodoo J, Rhodes S, Elliott JD, Dos'Santos T. The Sprint Mechanics Assessment Score: a qualitative screening tool for the in-field assessment of sprint running mechanics. American Journal of Sports Medicine. 2024;52(6):1608–1616.
Bramah C, Rhodes S, Clarke-Cornwell A, et al. 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. 2025 (online); 2026;60(3):178–185. doi:10.1136/bjsports-2024-108600
Mendiguchia J, et al. Can we modify maximal speed running posture? Implications for performance and hamstring injury management. International Journal of Sports Physiology and Performance. 2022;17(3):374–383.
Wild JJ, Bezodis NE. Sprint acceleration technique is associated with lower limb injury epidemiology in professional male Rugby Union players: a seven-season analysis. Journal of Science and Medicine in Sport. 2026. doi:10.1016/j.jsams.2026.05.009
Kenneally-Dabrowski CJB, Brown NAT, Lai AKM, Perriman D, Spratford W, Serpell BG. Late swing or early stance? A narrative review of hamstring injury mechanisms during high-speed running. Scandinavian Journal of Medicine & Science in Sports. 2019;29(8):1083–1091.
Butler RJ, Crowell HP, Davis IM. Lower extremity stiffness: implications for performance and injury. Clinical Biomechanics. 2003;18(6):511–517.
Davis JJ, Gruber AH. Leg stiffness, joint stiffness, and running-related injury: evidence from a prospective cohort study. Orthopaedic Journal of Sports Medicine. 2021;9(5).
Morin JB, Dalleau G, Kyröläinen H, Jeannin T, Belli A. A simple method for measuring stiffness during running. Journal of Applied Biomechanics. 2005;21(2):167–180.
VueMotion · Movement Analysis
