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The Validity of Hawkin Dynamics Wireless Dual Force Plates for Measuring Countermovement Jump and Drop Jump Variables^{ †}

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## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### 2.1. Participants

#### 2.2. Design

#### 2.3. Force Plate Setup

#### 2.4. Countermovement Jump

#### 2.5. Drop Jump

#### 2.6. Statistical Analysis

## 3. Results

## 4. Discussion

#### 4.1. Agreement Considerations

#### 4.2. Drop Jump Considerations

#### 4.3. Practical Considerations

## 5. Conclusions

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 3.**A representative example of an original (

**top**) and time-aligned (

**bottom**) countermovement jump trial recorded by the AMTI (solid grey line) and HD (dotted black line) force plate systems. The bottom graph also illustrates the occurrence of key events. vGRF = vertical ground reaction force.

**Figure 4.**A representative example of an original (

**top**) and time-aligned (

**bottom**) drop jump trial recorded by the AMTI (solid grey line) and HD (dotted black line) force plate systems. The bottom graph also illustrates the occurrence of key events. vGRF = vertical ground reaction force.

Variables | Calculation | CMJ? | DJ? |
---|---|---|---|

RSI (AU) | Jump Height divided by Ground Contact Time. | X | |

mRSI (AU) | Jump Height divided by Time to Takeoff. | X | |

Jump Height (m) | The change in centre of mass position between the instant of take-off and peak positive vertical displacement of the centre of mass during the flight phase, calculated as takeoff velocity squared divided by 19.62. | X | X |

Flight Time (s) | The time taken to complete the flight phase. | X | X |

Ground ContactTime (s) | The total time taken from instant of touchdown the instant of take-off. | X | |

Time toTakeoff (s) | The total time taken from the onset of movement to the instant of take-off. | X | |

Mean PropulsivePower (W) | The mean mechanical power applied to the centre of mass during the propulsive phase. | X | X |

Peak PropulsivePower (W) | The peak instantaneous mechanical power applied to the centre of mass during the propulsive phase. | X | X |

Peak PropulsiveVelocity (m/s) | The peak instantaneous vertical velocity of the centre of mass during the propulsive phase. | X | X |

Net PropulsiveImpulse (N.s) | The net vertical impulse applied to the centre of mass during the propulsive phase. | X | X |

Mean PropulsiveForce (N) | The mean vertical ground reaction force applied to the centre of mass during the propulsive phase. | X | X |

Peak PropulsiveForce (N) | The peak instantaneous vertical ground reaction force applied to the centre of mass during the propulsive phase. | X | X |

Stiffness (N/m) | Peak braking force divided by braking depth. | X | |

Braking Depth (m) | The peak negative vertical displacement of the centre of mass during the braking phase. | X | |

CountermovementDepth (m) | The peak negative vertical displacement of the centre of mass during the braking phase. | X | |

Mean BrakingPower (W) | The mean mechanical power applied to the centre of mass during the braking phase. | X | X |

Peak BrakingPower (W) | The peak negative instantaneous mechanical power applied to the centre of mass during the braking phase. | X | X |

Net BrakingImpulse (N.s) | The net vertical impulse applied to the centre of mass during the braking phase. | X | X |

Mean BrakingForce (N) | The mean vertical ground reaction force applied to the centre of mass during the braking phase. | X | X |

Peak BrakingForce (N) | The peak instantaneous vertical ground reaction force applied to the centre of mass during the braking phase. | X | X |

**Key:**RSI, reactive strength index; mRSI, modified reactive strength index; AU, arbitrary unit; m, metres; s, seconds; W, watts; N, Newtons; CMJ, countermovement jump; DJ, drop jump; X, included.

Variables | AMTI | HD | Intercept | Slope | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|

(Mean ± SD) | (Mean ± SD) | 95% CI | 95% CI | |||||||||

mRSI (AU) | 0.43 | ± | 0.10 | 0.43 | ± | 0.10 | 0.00 | 1.01 | ||||

−0.01 | to | 0.00 | 0.99 | to | 1.04 | |||||||

Jump Height (m) | 0.31 | ± | 0.07 | 0.31 | ± | 0.06 | −0.01 | 1.03 | ||||

−0.02 | to | 0.01 | 0.98 | to | 1.08 | |||||||

Flight Time (s) | 0.51 | ± | 0.05 | 0.51 | ± | 0.05 | 0.00 | 1.00 | ||||

−0.01 | to | 0.01 | 0.99 | to | 1.01 | |||||||

Time toTakeoff (s) | 0.76 | ± | 0.09 | 0.77 | ± | 0.09 | −0.01 | 1.01 | ||||

−0.06 | to | 0.00 | 0.96 | to | 1.04 | |||||||

Mean PropulsivePower (W) | 2316.23 | ± | 481.89 | 2302.91 | ± | 480.00 | 4.24 | 1.00 | ||||

−33.80 | to | 42.29 | 0.99 | to | 1.02 | |||||||

Peak PropulsivePower (W) | 4124.56 | ± | 907.17 | 4107.07 | ± | 913.99 | 48.12 | 0.99 | ||||

−17.08 | to | 113.32 | 0.98 | to | 1.01 | |||||||

Peak PropulsiveVelocity (m/s) | 2.59 | ± | 0.25 | 2.58 | ± | 0.24 | −0.07 | 1.03 | ||||

−0.19 | to | 0.04 | 0.99 | to | 1.08 | |||||||

Net PropulsiveImpulse (N.s) | 210.34 | ± | 41.74 | 209.25 | ± | 42.08 | 2.79 | 0.99 | ||||

−1.04 | to | 6.62 | 0.97 | to | 1.01 | |||||||

Mean PropulsiveForce (N) | 1667.56 | ± | 291.81 | 1664.07 | ± | 290.81 | −2.26 | 1.00 | ||||

−12.43 | to | 7.91 | 1.00 | to | 1.01 | |||||||

Peak PropulsiveForce (N) | 2042.72 | ± | 343.63 | 2040.87 | ± | 343.97 | 3.92 | 1.00 | ||||

−5.25 | to | 13.09 | 1.00 | to | 1.00 | |||||||

CountermovementDepth (m) | −0.30 | ± | 0.06 | −0.30 | ± | 0.06 | 0.01 | 1.01 | ||||

−0.01 | to | 0.02 | 0.97 | to | 1.06 | |||||||

Mean BrakingPower (W) | −1092.83 | ± | 274.27 | −1097.65 | ± | 273.88 | 6.37 | 1.00 | ||||

−2.11 | to | 14.85 | 0.99 | to | 1.01 | |||||||

Peak BrakingPower (W) | −1518.54 | ± | 426.54 | −1524.72 | ± | 426.16 | 7.53 | 1.00 | ||||

−0.77 | to | 15.83 | 1.00 | to | 1.01 | |||||||

Net BrakingImpulse (N.s) | 106.79 | ± | 25.06 | 107.32 | ± | 24.97 | −0.91 | 1.00 | ||||

−2.07 | to | 0.26 | 0.99 | to | 1.02 | |||||||

Mean BrakingForce (N) | 1495.80 | ± | 250.73 | 1498.44 | ± | 250.90 | −1.58 | 1.00 | ||||

−10.66 | to | 7.49 | 0.99 | to | 1.01 | |||||||

Peak BrakingForce (N) | 1951.83 | ± | 319.75 | 1952.70 | ± | 320.31 | 2.53 | 1.00 | ||||

−11.80 | to | 16.86 | 0.99 | to | 1.01 | |||||||

Body Weight (N) | 833.21 | ± | 141.92 | 833.69 | ± | 141.68 | −1.88 | 1.00 | ||||

−7.80 | to | 4.03 | 1.00 | to | 1.01 |

**Key:**AMTI, advanced mechanical technology, Inc.; HD, Hawkin Dynamics; SD, standard deviation; CI, confidence interval; AU, arbitrary unit; m, metres; s, seconds; N, Newtons.

Variables | AMTI | HD | Intercept | Slope | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|

(Mean ± SD) | (Mean ± SD) | 95% CI | 95% CI | |||||||||

RSI (AU) | 0.91 | ± | 0.30 | 0.89 | ± | 0.30 | 0.01 | 1.01 | ||||

−0.03 | to | 0.05 | 0.96 | to | 1.06 | |||||||

Jump Height (m) | 0.27 | ± | 0.05 | 0.26 | ± | 0.05 | 0.01 | 0.98 | ||||

−0.01 | to | 0.03 | 0.93 | to | 1.04 | |||||||

Flight Time (s) | 0.47 | ± | 0.05 | 0.47 | ± | 0.05 | −0.01 | 1.03 | ||||

−0.02 | to | 0.00 | 1.00 | to | 1.05 | |||||||

Ground ContactTime (s) | 0.32 | ± | 0.11 | 0.32 | ± | 0.11 | 0.00 | 1.00 | ||||

0.00 | to | 0.00 | 1.00 | to | 1.01 | |||||||

Mean PropulsivePower (W) | 2726.90 | ± | 585.09 | 2678.15 | ± | 575.27 | 3.03 | 1.02 | ||||

−91.00 | to | 97.06 | 0.98 | to | 1.05 | |||||||

Peak PropulsivePower (W) | 4525.16 | ± | 984.45 | 4448.20 | ± | 961.74 | −28.08 | 1.02 | ||||

−315.54 | to | 259.37 | 0.95 | to | 1.10 | |||||||

Peak PropulsiveVelocity (m/s) | 2.42 | ± | 0.21 | 2.39 | ± | 0.22 | 0.12 | 0.96 | ||||

−0.17 | to | 0.42 | 0.85 | to | 1.07 | |||||||

Net PropulsiveImpulse (N.s) | 195.39 | ± | 32.36 | 192.60 | ± | 31.68 | −1.38 | 1.02 | ||||

−10.31 | to | 7.55 | 0.98 | to | 1.06 | |||||||

Mean PropulsiveForce (N) | 2042.37 | ± | 425.30 | 2030.98 | ± | 422.18 | −3.61 | 1.01 | ||||

−22.47 | to | 15.25 | 1.00 | to | 1.02 | |||||||

Peak PropulsiveForce (N) | 3056.82 | ± | 839.12 | 3047.28 | ± | 837.84 | 4.92 | 1.00 | ||||

−5.46 | to | 15.29 | 1.00 | to | 1.01 | |||||||

Stiffness (N/m) | 19.46 | ± | 10.54 | 19.00 | ± | 10.30 | 0.02 | 1.02 | ||||

−0.48 | to | 0.51 | 0.99 | to | 1.06 | |||||||

Braking Depth (m) | −0.23 | ± | 0.07 | −0.23 | ± | 0.07 | 0.00 | 1.00 | ||||

−0.01 | to | 0.01 | 0.96 | to | 1.04 | |||||||

Mean BrakingPower (W) | 3550.86 | ± | 925.72 | 3555.47 | ± | 890.29 | −146.10 | 1.04 | ||||

−304.22 | to | 12.02 | 0.99 | to | 1.09 | |||||||

Peak BrakingPower (W) | 8258.04 | ± | 2570.69 | 8119.93 | ± | 2228.50 | −1108.73 | 1.15 | ||||

−1853.27 | to | −364.18 | 1.06 | to | 1.25 | |||||||

Net BrakingImpulse (N.s) | 224.53 | ± | 39.35 | 225.68 | ± | 38.33 | −7.13 | 1.03 | ||||

−19.17 | to | 4.90 | 0.98 | to | 1.07 | |||||||

Mean BrakingForce (N) | 2611.15 | ± | 647.27 | 2602.91 | ± | 638.87 | −25.97 | 1.01 | ||||

−54.40 | to | 2.46 | 1.00 | to | 1.03 | |||||||

Peak BrakingForce (N) | 4134.00 | ± | 1163.00 | 4076.00 | ± | 1106.00 | −151.43 | 1.05 | ||||

−319.35 | to | 16.50 | 1.00 | to | 1.10 | |||||||

Body Weight (N) | 833.00 | ± | 142.00 | 833.00 | ± | 141.00 | −2.78 | 1.00 | ||||

−9.60 | to | 4.03 | 1.00 | to | 1.01 |

**Key:**AMTI, advanced mechanical technology, Inc.; HD, Hawkin Dynamics; SD, standard deviation; CI, confidence interval; AU, arbitrary unit; m, metres; s, seconds; N, Newtons; Red Text, indicates identified bias.

Variables | AMTI | HD | ||||
---|---|---|---|---|---|---|

(Mean ± SD) | (Mean ± SD) | |||||

Touch-downVelocity (m/s) | −2.36 | ± | 0.26 | −2.35 | ± | 0.25 |

Fall Height (m) | 0.35 | ± | 0.04 | 0.35 | ± | 0.04 |

**Key:**AMTI, advanced mechanical technology, Inc.; HD, Hawkin Dynamics; SD, standard deviation; m, metres; s, seconds.

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## Share and Cite

**MDPI and ACS Style**

Badby, A.J.; Mundy, P.D.; Comfort, P.; Lake, J.P.; McMahon, J.J.
The Validity of Hawkin Dynamics Wireless Dual Force Plates for Measuring Countermovement Jump and Drop Jump Variables. *Sensors* **2023**, *23*, 4820.
https://doi.org/10.3390/s23104820

**AMA Style**

Badby AJ, Mundy PD, Comfort P, Lake JP, McMahon JJ.
The Validity of Hawkin Dynamics Wireless Dual Force Plates for Measuring Countermovement Jump and Drop Jump Variables. *Sensors*. 2023; 23(10):4820.
https://doi.org/10.3390/s23104820

**Chicago/Turabian Style**

Badby, Andrew J., Peter D. Mundy, Paul Comfort, Jason P. Lake, and John J. McMahon.
2023. "The Validity of Hawkin Dynamics Wireless Dual Force Plates for Measuring Countermovement Jump and Drop Jump Variables" *Sensors* 23, no. 10: 4820.
https://doi.org/10.3390/s23104820