Abstract

The purpose of this study was to examine whether vertical jump height differed between two assessments performed within a standardized physiological testing sequence in elite soccer players. A total of 227 elite male outfield soccer players completed a standardized sequence consisting of a general warm-up, baseline vertical jump assessment, isokinetic knee strength testing, maximal cardiopulmonary exercise testing, and a second jump assessment. Squat jump (SJ), countermovement jump (CMJ), and countermovement jump with arm swing were assessed using an Optojump system. Test-retest reliability of the jump assessments was excellent (ICC = 0.990–0.994). A 2 × 3 repeated-measures analysis of variance showed a significant main effect of time [F(1,226) = 284.44, p < 0.001, ηp² = 0.557], whereas the time × jump-type interaction was not significant [F(2,452) = 2.25, p = 0.107, ηp² = 0.010]. SJ increased from 40.74 ± 5.33 to 42.79 ± 5.31 cm (Δ = 2.05 cm; dz = 0.97), CMJ from 43.03 ± 5.10 to 44.91 ± 5.30 cm (Δ = 1.87 cm; dz = 0.87), and CMJ with arm swing from 48.32 ± 5.79 to 50.52 ± 5.76 cm (Δ = 2.20 cm; dz = 0.89). Jump height was higher at the second assessment across all three jump conditions. However, because the study did not include a control condition or counterbalanced testing order, the observed within-session differences cannot be attributed specifically to the intervening physiological testing procedures.