title: Validity of a Jump Mat for assessing Countermovement Jump Performance in Elite Rugby Players.
abstract: This study determined the validity of the Just Jump System®(JJS) for measuring flight time, jump height and peak power output (PPO) in elite rugby league players. 37 elite rugby league players performed 6 countermovement jumps (CMJ; 3withand 3withoutarms) on a jump mat and force platform. A sub-sample (n=28) was used to cross-validate the equations for flight time, jump height and PPO. The JJS systematically overestimated flight time and jump height compared to the force platform (P<0.05), but demonstrated strong associations for flight time (withR2=0.938;withoutR2=0.972) and jump height (withR2=0.945;withoutR2=0.987). Our equations revealed no systematic difference between corrected and force platform scores and an improved the agreement for flight time (Ratio limits of agreement:with1.00 vs. 1.36;without1.00 vs. 1.16) and jump height (with1.01 vs. 1.34;without1.01 vs. 1.15), meaning that our equations can be used to correct JJS scores for elite rugby players. While our equation improved the estimation of PPO (with1.02;without1.01) compared to existing equations (Harman: 1.20; Sayers: 1.04), this only accounted for 64 and 69% of PPO.
authors.affiliation: Sport and Exercise Science, University of Chester, Chester, United Kingdom of Great Britain and Northern Ireland.
authors.forename: Nick
authors.initials: N
authors.lastname: Dobbin
authors.affiliation: Rugby Football League, Human Performance, Leeds, United Kingdom of Great Britain and Northern Ireland.
authors.forename: Richard
authors.initials: R
authors.lastname: Hunwicks
authors.affiliation: Sport and Exercise Science, University of Chester, Chester, United Kingdom of Great Britain and Northern Ireland.
authors.forename: Jamie
authors.initials: J
authors.lastname: Highton
authors.affiliation: Sport and Exercise Science, University of Chester, Chester, United Kingdom of Great Britain and Northern Ireland.
authors.forename: Craig
authors.initials: C
authors.lastname: Twist
mesh_terms: D000328:Adult; D056352:Athletes; D054874:Athletic Performance; D005080:Exercise Test; D005538:Football; D006801:Humans; D055815:Young Adult