Table 2. Descriptive statistics of performance, physiological and psychological measures according to the running test and the participants’ sex. Values are means (±SD). 15-15 20-m shuttle run Total Boys Girls Total Boys Girls Performance measures Net run duration (s) 566(156)*** 651(179) 500(149) 346(156)*** 433(163) 243(153) Vpeak (km·h-1) 13.09 (1.86)*** 14.05 (2.16) 12.36 (.72) 9.86 (1.29)*** 10.58 (1.33) 9.00 (.50) Physiological measures HRpeak (bpm) 190(5) 193(4) 187(6) 189(6) 190(8) 187(4) VO2peak (ml·min-1·kg-1) 34.2 (5.0) 36.0 (3.8) 33.5 (5.6) 38.4 (6.1) 41.7 (5.4) 34.4 (4.6) RER 1.12 (.02) 1.13 (.02) 1.11 (.02) 1.11 (.04) 1.10 (.05) 1.13 (.02) [La-]b (mmol·l-1) 6.8 (1.9) 6.9 (1.5) 7.1 (2.2) 6.3 (1.4) 6.1 (1.6) 6.4 (1.3) Physiological measures at 9 km/h VO2 (ml·min-1·kg-1) 28.3 (2.7)*** 28.9 (1.6) 28.2 (3.7) 35.4 (2.7)*** 36.3 (2.4) 33.4 (3.1) HR (bpm) 167(15) 159(16) 177(7) 174(12) 171(13) 178(11) Psychological measures RPE 16.0 (1.2)*** 16.0 (1.5) 16.0 (.7) 12.7 (1.6)*** 12.5 (1.8) 13.0 (1.7) ∆ GSW .2 (1.1) -.1 (1.1) .6 (1.1) .0 (1.1) -.4 (1.1) .6 (1.0) ∆ PSW .9 (1.8) .6 (1.3) 1.1 (2.3) -.2 (1.4) -.4 (1.8) .1 (.9) ∆ PC 1.4 (1.4)* 1.3 (1.4) 1.5 (1.5) .2 (1.0)* .2 (1.1) .2 (.9) ∆ SC 1.1 (1.9) 1.1 (2.1) 1.2 (2.0) -.2 (1.4) -.8 (1.2) .6 (1.3) ∆ PA .3 (1.0) -.3 (.9) 1.1 (.7) -.1 (.8) -.2 (1.0) .1 (.3) ∆ PS .6 (1.9) .5 (2.4) .7 (1.4) .1 (.9) .5 (.6) -.3 (1.1) Significant inter-test (15-15 vs. 20-m shuttle run) differences: * p < 0.05; ** p < 0.01; *** p < 0.001. SD = standard deviation. Vpeak = peak running velocity; HRpeak = peak heart rate; VO2peak = peak oxygen uptake; RER = respiratory exchange ratio; [La-]b = blood lactate concentration; RPE = rating of perceived exertion; GSW = global self-worth; PSW = physical self-worth; PC = physical condition; SC = sport competence; PA = physical attractiveness; PS = physical strength; ∆ = measures of the delta between post- and pre-test.