Accuracy of a Vertical Jump Contact Mat for Determining Jump Height and Flight Time

Abstract

Several devices are available to measure vertical jump (VJ) height based on flight time, VJ reach height, or ground reaction forces. The purpose of this study was to determine the accuracy of a VJ mat for measuring flight time and VJ height compared with a VJ tester or a force plate. Seventeen men and 18 women (X ± SD; age = 20.9 ± 0.7 years, height = 176.1 ± 0.9 cm, weight = 72.6 ± 13.5 kg) served as subjects. Subjects performed counter-movement vertical jumps while standing on both a force plate (1,000 Hz) and a VJ mat. A Vertec VJ tester was used to measure jump reach. Compared with the force plate, the VJ mat reported greater VJ height (VJ mat = 0.50 ± 0.12 m, force plate = 0.34 ± 0.10 m) and flight time (VJ mat = 0.629 ± 0.078 seconds, force plate = 0.524 ± 0.077 seconds). Comparison of VJ heights from the VJ mat and the Vertec revealed no significant differences (Vertec = 0.48 ± 0.11 m). Regression analyses indicated strong relationships between testing methods and suggested that high VJ performances may be underestimated with the VJ mat. This particular VJ mat compared favorably with the Vertec but not the force plate. It seems that the different flight times derived from the VJ mat may permit the VJ mat to be in closer agreement with VJ heights from the Vertec. Also, the VJ mat may not be an appropriate tool for assessing high VJ performances (i.e., ≥0.70 m; ≈28 inches). Practitioners and researchers using similar VJ mats may not obtain accurate flight times and may underestimate high performers.

Validity of a Jump Mat for assessing Countermovement Jump Performance in Elite Rugby Players

“…international) [35] and playing position [13,22]. Therefore, CMJ is regularly employed by practitioners to assess the ef fectiveness of a conditioning programme [29,34,26,39], to profile players and identify talent [35] and to monitor recovery status [21,27,36,37].…”

“…Whereas video analysis and force platforms are recognised as criterion methods for measuring jump height, flight time and muscle power, these are expensive and not easily accessible for most rugby league clubs [18,25,31]. Flight time and jump height during the CMJ are routinely measured by rugby league practitioners using commercially available equipment such as the Just Jump System ® (JJS), to provide estimates of jump performance [28,30,39]. However, the ability of the JJS to accurately measure flight time and jump height has recently been questioned [28,39].…”

“…Flight time and jump height during the CMJ are routinely measured by rugby league practitioners using commercially available equipment such as the Just Jump System ® (JJS), to provide estimates of jump performance [28,30,39]. However, the ability of the JJS to accurately measure flight time and jump height has recently been questioned [28,39]. The authors reported that flight time and jump height measured on the JJS and force platform are highly related but that flight time is on average 105 ms longer on the JJS resulting in an overestimation of jump height [28,39].…”

Developing a Criterion Method for Assessing Countermovement Jump Variables in Children Aged 7 to 11 Years

“…Micro switches in the instrumented jump mat create an electrical circuit when a participant takes-off, which starts a timer, and stops the timer when the participant lands again (Whitmer et al, 2014). The flight-time of the CMJ is then used to determine the flight height (FH) of a participant (Bosco, Luhtanen, & Komi, 1983;de Salles, Vasconcellos, de Salles, Fonseca, & Dantas, 2012), which is defined as the height gained by the whole body centre of gravity CoG after take-off (Bosco et al, 1983;Owen et al, 2014).…”

“…The limitation associated with the flight-time method may account for the problems reported within the literature with regards to instrumented jump mats measuring flight height. The instrumented jump mats have demonstrated inconsistent flight-times and consequently higher calculated FH values when compared to the criterion FP method (Whitmer et al, 2014). Other factors such as the sampling frequencies of the instrumented jump mat may account for some of this variation found when compared to the FP method.…”