Mean or Peak, and why does the Jump(Switch) Mat seem to read higher?
When comparing to a jump(switch) mat we do expect a difference, as they both measure height using different methods.
Jumps mats (switch mats) they only use flight time
Jump Height = 9.81 x (flight time) ^ 2 / 8
Jump Height = 9.81 x (flight time) ^ 2 / 8
Force plates user can use either flight time or the impulse-momentum method.
Peak velocity ^ 2 / (2 * 9.81) (with peak Vel being previously calculated)
Peak velocity ^ 2 / (2 * 9.81) (with peak Vel being previously calculated)
Measuring jump Height -
GymAware measures jump height directly, like a tape measure. The jump mat estimates height based on impulse momentum equation with final take off velocity.
GymAware protocol for jumping -
To get the most accurate and repeatable results, we recommend a tight protocol.
• Set GymAware to Manual Record
This will ensure that you start the REC on the iPad when the athlete is "Standing Tall"
• Ensure that the athlete is "Standing Tall" with a pause just prior to performing the jump.
• Tap REC - This will set the starting position point.
• Jump
Provided that is protocol is followed closely then you should find that GymAware gives you a more accurate and true reading of the jump height. It's a direct measure as apposed to an estimation.
Typically the Jump Mat gives a higher result, so its conducive to the athletes and coaches as a bigger number is better.... Right? ;)
Q: Is there a way to calculate mechanical work and create a fatiguability index?
A: For work itself then this is calculated as Force x Distance - so in a jump we automatically include the athletes body mass in with the external mass of the bar (if its used).
My preference is for using mean power as apposed to peak power, as mean power captures the entire movement (concentric phase), where as peak power is only on point in time within that complete phase.
Having said that, the rebound style jumps can be more difficult to measure, as the system. including the athlete can be effected by a build up of momentum.
Performing a jump, then reset and repeat the jump. This we find this gives a more consistent metrics than the repeated, continuous jumps.

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