**Below are the metrics as defined by and used by Hawkin Dynamics in Countermovement Jump analyses.*
Unweighting Phase (Yellow) – Braking Phase (Red) – Propulsive Phase (Green)
System Weight is the 1-second period prior to the athlete initiating movement. It is important that the athlete remains as still as possible during this time for an accurate measurement of weight. It is a combination of the athlete’s bodyweight, gravity, and any additional load (i.e. dumbbells, vest).
- Average Braking Force – Average force during the braking phase.
- Average Braking Power – Average power during the braking phase.
- Average Braking Velocity – Average velocity during the braking phase – always negative.
- Average Landing Force – Average force during the landing phase.
- Average Propulsive Force – Average force during the propulsive phase.
- Average Propulsive Power – Average power generated during the propulsive phase.
- Average Propulsive Velocity – Average velocity during the propulsive phase – always positive.
- Average Relative Braking Force – Average braking force as a percentage of system weight – higher is better.
- Average Relative Braking Power – Average power per kilogram during the braking phase.
- Average Relative Propulsive Force – Average propulsive force as a percentage of system weight.
- Average Relative Propulsive Power – Average power per kilogram the subject produced during the propulsive phase.
- Braking Impulse – Impulse the subject generated during the braking phase.
- Braking Net Impulse – Impulse of braking phase above system weight (red shaded area of the graph).
- Braking Phase – The time of the braking phase (seconds).
- Braking Phase % – The length of the braking phase relative to the entire movement.
- Braking Rate of Force Development (RFD) – The rate of force development during the braking phase – higher is typically better for explosive athletes. Can be highly variable between tests.
- Countermovement Depth – The distance the athlete’s center of mass travelled downwards during the countermovement. Can be useful in analyzing changes in jumping strategy overtime.
- Flight Time – Time spent in the air, begins at take-off (athlete leaves the force plate) and ends upon landing (athlete comes back into contact with the force plate).
- Impulse Ratio – The ratio of propulsive net impulse to braking net impulse – useful to understanding how an athlete utilizes the braking phase and the transition from braking to propulsive.
- Landing Stiffness – The force at the lowest point after landing divided by the depth (in meters) at the lowest point – higher means more force is generated with less movement, resulting in higher landing stiffness.
- L/R Average Braking Force – Asymmetry during the braking phase – positive means left dominance, negative means right dominance.
- L/R Average Braking Rate of Force Development (RFD) – Asymmetry of each individual limb’s Rate of Force Development – positive means left dominance, negative means right dominance.
- L/R Average Landing Force – Asymmetry during landing – positive means left dominance, negative means right dominance.
- L/R Average Propulsive Force – Asymmetry during the propulsive phase – positive means left dominance, negative means right dominance.
- L/R Braking Impulse Index – Left/Right asymmetry of total braking impulse – positive means left dominance, negative means right dominance.
- L/R Landing Impulse Index – Total impulse asymmetry during landing – positive means left dominance, negative means right dominance.
- L/R Peak Braking Force – Left/Right asymmetry at moment of peak braking force – positive means left dominance, negative means right dominance.
- L/R Peak Landing Force – Left/Right asymmetry at moment of peak landing force – positive means left dominance, negative means right dominance.
- L/R Peak Propulsive Force – Left/Right asymmetry at moment of peak propulsive force – positive means left dominance, negative means right dominance.
- L/R Propulsive Impulse Index – Left/Right asymmetry of total propulsive impulse – positive means left dominance, negative means right dominance.
- Peak Braking Force – Peak force during the braking phase.
- Peak Braking Power – Peak (lowest in this case) power during the braking phase – this will always be negative because the athlete is moving downward with negative velocity.
- Peak Landing Force – Peak force during the landing phase.
- Peak Propulsive Force – Peak force during the propulsive phase – commonly used to assess maximal concentric force output.
- Peak Propulsive Power – Peak power during the propulsive phase – commonly used to assess power output.
- Peak Relative Braking Force – Peak force during the braking phase relative to system weight.
- Peak Relative Braking Power – Peak (lowest) power per kilogram during the braking phase – this will always be negative because the athlete is moving downward with negative velocity.
- Peak Relative Propulsive Force – Peak force during propulsive phase relative to system weight.
- Peak Relative Propulsive Power – Peak power per kilogram during the propulsive phase.
- Peak Velocity – Peak velocity of the athlete during the entire movement.
- Positive Impulse – Total impulse of the propulsive and braking phase. Impulse is the product of Force x Time.
- Positive Net Impulse – Total impulse of the propulsive and braking phase above system weight (green and red shaded area of the graph).
- Propulsive Impulse – Impulse the subject generated during the propulsive phase.
- Propulsive Net Impulse – Impulse of the propulsive phase above system weight (green shaded area of the graph).
- Propulsive Phase – Time of the propulsive phase (seconds).
- Propulsive Phase % – The length of the propulsive phase relative to the entire movement.
- Reactive Strength Index (RSI) – Flight Time divided by contact time (beginning of movement to flight) – useful to assess quickness and reactivity ( Flight Time / Contact Time = RSI ) *not to be mistaken with modified RSI.
- Modified RSI (mRSI) – Jump Height (in meters) divided by contact time (beginning of movement to take-off). Also useful to assessment of quickness and reactivity in athletes. There is some good quality research on mRSI as an ideal metric to use for general assessments of athletes.
- Relative Braking Impulse – Impulse per kilogram the subject generated during the braking phase.
- Relative Braking Net Impulse – Impulse per kilogram the subject generated during the braking phase above system weight.
- Relative Peak Landing Force – Highest force during landing as a percentage of system weight.
- Relative Propulsive Impulse – Impulse per kilogram the subject generated during the propulsive phase.
- Relative Propulsive Net Impulse – Impulse per kilogram the subject generated during the propulsive phase above system weight.
- Stiffness – The force at the lowest point in the movement divided by the depth (in meters) at the lowest point (see countermovement depth) – higher means more force is generated with less movement, resulting in higher stiffness.
- System Weight – Average force during the quiet phase (the period of time before the test).
- Takeoff Velocity – The velocity right before the athlete leaves the force plates – this metric dictates jump height – higher is always better.
- Time To Takeoff – Time from the initiation of movement (unweighting) to takeoff.
- Time To Stabilization – Time to stabilize after landing – starts when the athlete lands back onto the force plates after flight and ends when system weight returns stabilizes back to normal.
- Unweighting Phase – Time of the unweighting phase (seconds).
- Unweighting Phase % – The length of the unweighting phase as a percentage relative to the entire movement.