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Test protocol · Vertical deceleration · Recreational

Single-Leg CMJjump on one leg · land on the same leg · hold 2 s

1Record2Upload3See the results
Why it matters: a single-leg jump shows how much power each leg produces and how well it controls the landing, which a two-leg jump can hide. Jump-height symmetry is widely used in return-to-sport decisions (Grindem et al., 2016).VueMotion measures jump height, knee bend and landing control for each leg, from the side and front.

With hands on hips, the athlete jumps as high as possible from one leg, lands on the same leg and holds for 2 seconds. Two synced iPhones, side and front, record 3–5 valid trials per leg.

LSI
jump-height symmetry
2
synced iPhones
2 s
landing hold
PhaseSet
Why it matters

Each leg, on its own. VueMotion shows how.

Every trial gives you three layers.

OUT
Output

Jump height and flight time for each leg, and jump-height LSI.

MOV
Movement

Knee-flexion displacement in the dip, and time to stable hold after landing.

CTL
Control

FPPA at landing, frontal-plane wobble (relative frontal-to-sagittal motion) and trunk or pelvis compensation.

01

Performance monitoring

Is each leg getting more powerful?

  • Jump height Each leg vs baseline.
  • LSI Track the gap between legs.
  • Trend Across a training block.
02

Performance improvement

What limits the weaker leg?

  • Depth Knee-flexion displacement shows how the leg loads.
  • Control Wobble and FPPA show control issues.
  • Strategy Trunk and pelvis compensations.
03

Injury risk management

Who has a weaker or less controlled leg?

  • Symmetry Jump-height gaps between legs.
  • Knee alignment FPPA on landing.
  • Stability Failed or slow holds.
04

Return to play / rehab

Is the injured leg ready?

  • LSI target Hop and jump symmetry criteria are used before return to sport (Grindem et al., 2016).
  • Baseline Compare with pre-injury results, not just the other leg (Wellsandt et al., 2017).
  • Quality Symmetric height can hide different mechanics (Kotsifaki et al., 2022).
05

Benchmarking

How does the athlete compare?

  • Norms Jump height per leg against cohort.
  • Symmetry Squad-wide LSI.
  • Matched Same protocol only.
06

Scouting / screening

Who is balanced and powerful?

  • Objective Calibrated heights from video.
  • Balance Spot one-sided athletes.
  • Quick Few trials per leg.

These metrics describe movement patterns linked to performance and injury risk in research. They support coaching and clinical judgement; they do not diagnose or predict an individual injury.

01 · Setup

Jump marker and two cameras

Mark a jump spot on a firm, flat surface with clear landing space. Centre both cameras on the marker.

PhaseSet
Side cameraFront cameraLanding marker / line
C1

Sagittal camera

Side-on, perpendicular to the jump marker, about 3 m away, lens about 1 m high, on a tripod. Full body in frame through the whole landing and hold.

C2

Frontal camera

In front of the jump marker, facing the athlete, about 3 m away at the same height. Both knees and feet clearly visible. Record both phones in sync with Controller-Capture.

Capture at 60–120 fps, Auto-FPS off, iPhone 11 or newer. Keep distances the same between sessions.

02 · Capture

Record in a few minutes

1

Equipment

2 iPhones, tripods and tape for the jump marker.

2

Scene

Mark the jump spot with clear space around it.

3

Cameras

Side and front cameras centred on the marker, synced with Controller-Capture.

4

Tag + record

Choose the athlete, the test tag and the test leg, then record 3–5 trials per leg.

5

Upload

Upload the original files and submit the AI request.

Athlete

  • Warm up and practise on each leg
  • Hands on hips throughout
  • Jump as high as possible from one leg
  • Land on the same leg and hold still for 2 s; repeat if the other foot touches down

Camera settings

  • HD at 60 or 120 fps on iPhone (or 4K 120 fps on GoPro)
  • Auto-FPS off (Settings → Camera → Record Video)
  • Fixed tripod, 1× lens, no zoom or panning
  • Do Not Disturb on, Auto-Lock never

Scene & upload tips

  • Start recording before the athlete moves; stop after the hold or the last rep
  • No one else in either camera's view
  • Shorts or tights that show the knees help the front view
  • Upload original files from the app; avoid AirDrop or messaging apps
03 · Outputs

What you get after upload

Jump

Jump height and flight time for each leg (best and mean).

Symmetry

Jump-height LSI.

Movement

Knee-flexion displacement in the dip.

Landing

FPPA at contact and peak, frontal-plane wobble, time to stable hold.

Compensation

Pelvic drop and trunk position, reported descriptively.

Progress

Every metric across sessions.

Linking single-leg jumping to return to play

Thresholds marked as reference values come from the literature and are not validated injury-risk cut-offs for every population; compare limbs and track change over time.

MetricLink to performance or injuryEvidence

Performance linked to performance   Prospective linked to future injury in a cohort study   Mechanistic linked to tissue loading in lab studies   Practice coaching rationale

Metric definitions

Jump
Jump height (cm)
From flight time: h = g·t²/8.
Flight time (s)
Take-off → landing.
Jump-height LSI (%)
Lower-performing leg ÷ higher-performing leg × 100.
Movement & landing
Knee-flexion displacement (°)
Change in knee angle from the start of the dip to its deepest point.
FPPA (°)
2D frontal-plane knee alignment at landing contact and peak.
Frontal-plane wobble (RFM)
Relative frontal-to-sagittal knee motion at set knee-flexion points during early landing.
Time to stable hold (s)
Landing → still; valid hold = 2 s without extra steps.
04 · Practitioner value

Single-leg power and control

Unilateral

Shows each leg separately.

Return to sport

LSI plus mechanics for decisions.

Two views

Side and front in one trial.

Fits the battery

Between the drop-and-hold and hop tests.

05 · Support

FAQs

Hands on hips?

Yes, for every trial, so arm swing doesn't change the result.

How many trials?

3–5 valid trials per leg; best and mean are reported.

Are CSV exports and APIs available?

CSV/Excel export for Enterprise and Academy users, and API access for Enterprise users.

  1. Grindem H, Snyder-Mackler L, Moksnes H, Engebretsen L, Risberg MA. Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study. British Journal of Sports Medicine. 2016;50(13):804–808.
  2. Wellsandt E, Failla MJ, Snyder-Mackler L. Limb symmetry indexes can overestimate knee function after anterior cruciate ligament injury. Journal of Orthopaedic & Sports Physical Therapy. 2017;47(5):334–338.
  3. Kotsifaki A, Van Rossom S, Whiteley R, et al. Single leg hop for distance symmetry masks lower limb biomechanics: time to discuss hop distance as decision criterion for return to sport after ACL reconstruction? British Journal of Sports Medicine. 2022;56(5):249–256.
  4. Bosco C, Luhtanen P, Komi PV. A simple method for measurement of mechanical power in jumping. European Journal of Applied Physiology. 1983;50(2):273–282.
  5. Munro A, Herrington L, Carolan M. Reliability of 2-dimensional video assessment of frontal-plane dynamic knee valgus during common athletic screening tasks. Journal of Sport Rehabilitation. 2012;21(1):7–11.