Validity and Reliability of the Plyomat Device for Vertical Jump Height Measurement

Abstract

VALIDITY AND RELIABILITY OF THE PLYOMAT ® DEVICE FOR VERTICAL JUMP HEIGHT MEASUREMENT

Adam E. Feit1, Michael P. Blazejowksi3, Richard P. Burnett2, Nicholas A. Coker1

1 Department of Exercise Science and Athletic Training, Springfield College, Springfield MA
2 Triple F Elite Sports Training, Knoxville TN
3 Indianapolis Colts, Indianapolis IN

While many devices have been designed to improve the accessibility of vertical jump height measurement, these systems can be very costly for practitioners to purchase and maintain. Recently, a new switch mat was developed but has not currently been assessed for its validity and reliability. PURPOSE: The purpose of this study was two-fold: to investigate the criterion validity of the Plyomat® (PM; Athletic Assessment Technology, Lawrenceville, GA, USA) jump testing device when compared to a force plate (FP) and to assess the test-retest reliability of the Plyomat® jump testing device. METHODS: Forty-eight Division III football players (age: 19.63 ± 1.27 yrs, height: 175.9 ± 24.1 cm; body mass: 80.0 ± 11.0 kg) were recruited from a college in the northeastern United States. Each participant completed a total of three maximal countermovement jumps with their hands on their hips with 30 seconds of rest between attempts. Participants then repeated this testing protocol 24-48 hours later. To maintain consistency with the Plyomat®, all jump heights were calculated using time in the air derived from the force plate rather than takeoff velocity. RESULTS: A very strong, positive correlation was observed between FP and PM (r = 0.95 [0.91, 0.97], p < 0.001). Independent samples t-tests indicated jump heights from PM were significantly higher than FP (p < 0.001), though the effect size was negligible (d = 0.16, mean difference = 1.01 cm). Additionally, results indicated PM yielded a high degree of test-retest reliability of the highest jumps measured on each testing day (ICC(2,1) = 0.85 [0.69, 0.92]; SEM = 2.36 cm). CONCLUSION: The Plyomat ® provides a valid and reliable performance testing solution for the vertical

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VERTICAL(JUMP(HEIGHT(MEASUREMENT
Adam%E.%Feit!,%Michael%P.%Blazejowksi",%Richard%P.%Burnett#,%Nicholas%A.%Coker!
ABSTRACT
CONCLUSIONS
RESULTS
METHODS
INTRODUCTION
FUTURE DIRECTION
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•The$vertical$jump$exercise$is$a$frequently$tested$
key$performance$indicator$of$lower$body$power,$
neuromuscular$fatigue,$and$athlete$readiness.
•However,$access$to$laboratory-based,$gold-
standard$equipment$such$as$force$plates$may$be$
limited$amongst$researchers$and$practitioners.
•Increasing$the$availability$of$valid$and$reliable$
field-based$testing$equipment$may$improve$the$
frequency$of$performance$assessment$which$
may$drive$further$evidence-based$training$
protocols.
•Forty-eight$Division-III$football$
players$came$to$laboratory$on$
two$separate$occasions,$
separated$by$at$least$24$hours.
•Participants$completed$a$brief$
dynamic$warm-up$and$then$
performed$three$successive$
countermovement$jumps$from$
low$to$moderate-self$perceived$
intensity.
•Participants$stood$with$their$left$
foot$on$the$force$plate$and$their$
right$foot$on$the$Plyomat$®.$Each$
participant$completed$three$
maximal$countermovement$
jumps$with$their$hands$on$their$
hips.
•30s$rest$was$given$between$
jumps •Results$of$the$study$indicate$that$the$Plyomat$
®$is$a$valid$and$reliable$performance$testing$
solution$for$the$vertical$jump$exercise.
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3O,.&+,+65'&1)_5'41;)O,.&+,+65'&1)Ob
RESULTS (CONT.)
•High$degree$of$test-retest$reliability$of$the$
highest$jumps$from$Plyomat$(ICC(2,1)$=$0.85$
[0.69,$0.92];$SEM$=$2.36$cm).
•Jump$height$measured$using$the$Plyomat$was$
significantly$higher$than$jump$height$
measured$using$the$force$plate;$however,$the$
effect$size$was$negligible$(t(47)$=$3.54;$p<$
0.001;$d=$0.16).$
•Very$strong,$positive$correlation$between$jump$
height$from$force$plate$and$Plyomat$(r=$0.95$
[0.91,$0.97],$p<$0.001).
•Bland-Altman$plot$indicated$a$mean$difference$
between$the$of$1.01$cm$favoring$the$Plyomat,$
with$±95%$limits$of$agreement$of$-4.87$to$2.85$
cm.$
Figure'1.'Relationship$between$
Force$plate$and$Plyomat$
measurements.$
•Force-time$curves$recorded$
from$left$side$during$bilateral$
countermovement$jumps$using$
a$force$plate$sampling$at$200$
Hz$(Accupower-ACP,$AMTI,$
Watertown,$MA$USA).
•Jump$height$was$calculated$
based$on$the$time$in$the$air$for$
each$jump.$
•Highest$jump$recorded$from$
the$Plyomat$during$visit$1$was$
used$for$validity.
•Highest$jumps$recorded$in$both$
visit$1$and$visit$2$for$Plyomat$
were$used.
•Dependent$samples$t-tests,$
Pearson$correlations,$Bland-
Altman$plots$for$validity,$
ICC(2,1)$for$reliability
Figure'2.'Bland-Altman$plot$
comparing$force$plate$with$
Plyomat.$
•Future$research$should$evaluate$the$validity$
and$reliability$of$other$performance$measures$
of$contact$mats$such$as$reactive$strength$
indices$(RSI)$of$the$lower$and$upper$body.
ACKNOWLEDGMENTS AND
CONFLICTS OF INTEREST
•This$study$was$preregistered$with$the$Center$
of$Open$Science$at$https://osf.io/wnj48.
•Athletic$Assessment$Technology$LLC$donated$
the$Plyomat$®$for$the$purpose$of$this$study.$No$
financial$payments$were$received$by$the$
research$team.