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Single-Leg Hop

A single-leg hop for distance, one side at a time.

17
metrics
0
gradable today
7
events detected
Start an assessmentMetric reference
What this test measures

What it tests, what QOOM measures, what you get

What it tests
A single-leg hop for distance, one side at a time.
What QOOM measures
Hop distance, contact time, RSI, take-off angle, knee flexion at contact, peak knee flexion and dynamic valgus, trunk lean, knee and hip excursion.
What you get
Per-side results for limb-to-limb comparison, with metric zones.
How it is captured

The protocol

Two phones on tripods, stereo-calibrated once. The protocol below is the one the analysis pipeline is written against.

Subject stands on one leg, hops forward for maximum distance, and lands on the same leg. Must stabilise for >= 2 s after landing. For triple/crossover variants, 3 consecutive hops are performed. One trial per leg.

Category
Jump
Environment
Overground
Trial structure
Single repetition, repeated as needed
Minimum capture
2 s

Camera setup guide

Events detected

The moments the analysis finds first

Every metric is measured between events. These are detected from the reconstructed skeleton before any metric is computed.

  1. 1

    Trial Start

    trial_start

    First frame of the captured trial.

  2. 2

    Pre-Load

    pre_load

    Frame where the subject begins the countermovement prior to takeoff.

  3. 3

    Take-Off

    takeoff

    Frame where the foot leaves the ground.

  4. 4

    Flight Peak

    flight_peak

    Frame of maximum COM height during flight.

  5. 5

    Landing

    landing

    Frame of first ground contact after flight.

  6. 6

    Stabilization Start

    stabilization_start

    Frame where COM velocity settles below a threshold after landing (subject is stable).

  7. 7

    Trial End

    trial_end

    Last frame of the captured trial.

Every metric

The full metric list

This is the complete list the analysis produces for this assessment — the same list the metric reference documents. A metric with a reference distribution shows the direction that reads as better and the evidence level behind it; where the evidence gate withholds the zone, the reason is shown instead of a grade.

  • Hop Distancem
    hop_distance_m
    Zone withheld — no recorded sourceevidence: approximate

    Horizontal distance from takeoff position to landing position.

  • Contact Timems
    contact_time_ms
    Zone withheld — no recorded sourceevidence: approximate

    Duration of the pre-load phase (ground contact before takeoff). Shorter = more reactive.

  • Reactive Strength Index—
    rsi
    Zone withheld — no recorded sourceevidence: approximate

    Hop distance divided by contact time. A composite index of reactive strength.

  • Take-Off Angle°
    takeoff_angle_deg
    No reference distribution

    COM velocity vector angle at the moment of takeoff, measured from horizontal.

  • Peak Knee Extension Speed°/s
    peak_knee_extension_speed_dpsPer side
    No reference distribution

    Maximum angular velocity of knee extension during push-off.

  • Knee Flexion at Contact°
    knee_flexion_at_contact_degPer side
    No reference distribution

    Knee flexion at the moment of landing. Soft landing indicator.

  • Peak Dynamic Knee Valgus°
    peak_dynamic_knee_valgus_deg
    No reference distribution

    Maximum medial knee collapse at landing. Frontal-plane knee alignment marker on landing.

  • Peak Knee Flexion°
    peak_knee_flexion_degPer side
    Zone withheld — a provenance trace found no sourceevidence: approximate

    Maximum knee flexion during the landing absorption phase.

  • Peak Trunk Lean°
    peak_trunk_lean_deg
    No reference distribution

    Maximum lateral trunk lean during landing. A lateral-lean marker for left/right comparison.

  • Knee Excursion°
    knee_excursion_degPer side
    No reference distribution

    Total knee flexion range from IC to peak flexion during landing.

  • Hip Excursion°
    hip_excursion_degPer side
    No reference distribution

    Total hip flexion range from IC to peak flexion during landing.

  • Pelvis Vertical Excursionm
    pelvis_vert_excursion_m
    No reference distribution

    Trial-aggregate range of vertical pelvis-COM motion. Indexes how much the centre of mass rises and falls relative to the support base.

  • Pelvis Lateral Excursionm
    pelvis_lateral_excursion_m
    No reference distribution

    Trial-aggregate range of medio-lateral pelvis-COM motion. Quantifies side-to-side sway, including during single-leg stance.

  • Pelvis Forward Excursionm
    pelvis_forward_excursion_m
    No reference distribution

    Trial-aggregate range of anterior-posterior pelvis-COM motion. Forward progression in gait; forward travel and braking depth in jumps.

  • Pelvis Vertical Excursion (SD)m
    pelvis_vert_excursion_sd_m
    No reference distribution

    Cross-cycle (or cross-rep) standard deviation of vertical pelvis-COM excursion. Higher SD signals movement variability.

  • Pelvis Lateral Excursion (SD)m
    pelvis_lateral_excursion_sd_m
    No reference distribution

    Cross-cycle standard deviation of lateral pelvis-COM excursion. Used as a stability marker for repeated gait/jump tasks.

  • Pelvis Forward Excursion (SD)m
    pelvis_forward_excursion_sd_m
    No reference distribution

    Cross-cycle standard deviation of forward pelvis-COM excursion. Used as a stability marker for repeated gait/jump tasks.

What the report contains

Sections of the report

The per-trial report is assembled from these sections, in this order.

  1. 1

    Key Metrics

    Headline hop metrics.

  2. 2

    Metric Zone Overview

    All metrics as gradient zone bars.

  3. 3

    Phases & Events

    COM trajectory with event markers.

  4. 4

    Joint Kinematics

    Lower-body kinematics through the hop.

  5. 5

    Description of Metrics

    Full-text description of every metric in the report and what each one measures.

  6. 6

    Quality Assurance

    QA verdict, reasons, warnings, schema version, report hash.

Quality checks

What can stop a result

Each trial is checked before metrics are reported. A failed check either blocks the result or marks it partial — it is never silently graded.

  • Mean pose-estimation confidence across trial must be >= 0.60

    min_pose_confidence
    Blocked

  • No contiguous occlusion > 0.5 s on key landmarks (hip, knee, ankle)

    no_major_occlusion
    Partial

  • All 7 events must be detected with confidence >= 0.5

    hop_all_events
    Partial

  • Flight phase (takeoff to landing) must be >= 50 ms

    hop_flight_phase
    Blocked

  • Subject must stabilise within 5 s of landing

    hop_stabilization
    Partial
Blocked —
No metrics are reported for the trial.
Partial —
Metrics are reported with a warning; the affected values are flagged.
How grading is decided

When a metric gets a zone

A metric can be graded only when the norms registry holds a reference distribution for it, and a zone is shown only when the evidence gate admits that distribution’s provenance and evidence level. A distribution the gate refuses stays in the registry, auditable, with no zone.

0 of 17 metrics can be graded today

4 carry a reference distribution · 4 zones withheld by the evidence gate: 3 × no recorded source, 1 × a provenance trace found no source

Evidence levels behind this assessment’s reference distributions

  • published0

    Values traceable to a peer-reviewed population study. Reserved; nothing in the registry currently qualifies.

  • consensus0

    Anchored to a recognised clinical guideline or expert-consensus cutoff. Values are approximate, but the cutoff is citable.

  • approximate4

    Informal literature ranges or general-adult estimates, not validated against a specific cohort. The honest default.

  • unvalidated0

    A two-point estimate or an inferred value. A distribution is declared, but the evidence gate withholds the zone.

How the evidence gate worksFull metric reference

Run this assessment.

Two phones, one guided protocol, and a report at the end.

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