The aim of this study was to investigate the effects of inter-limb vertical jump asymmetries in physical performance, given the large diversity of results found on this research topic. 19 elite Under-19 soccer players from a Spanish professional club performed a test battery including bilateral and unilateral countermovement jumps, bilateral and unilateral drop jumps, horizontal jumps, sprints from 10 to 30 meters, left- and right-leg change of direction sprints and the Nordic hamstring exercise. All measures were taken with an iPad device, using "My Jump 2 App", "My Sprint app", "Nordics App" and "COD timer App", previously validated, on the pitch where the team usually trains. The percentage of Inter-limb jump asymmetries was 8.05±6.77 for unilateral countermovement jumps and 9.70±5.41 for unilateral drop jumps. Pearson`s r correlations established a relationship between larger unilateral countermovement jumps asymmetries and a decrement in horizontal jumps (r= -0.489; P<0.05) and between the higher unilateral drop jumps asymmetries and a lesser nordic break point angle (r= -0.579; P<0.01). However, velocity in 10, 15, 20, 25 and 30 meters, left- and right-leg change of direction, countermovement jumps and drop jumps were not affected in a statistically significant manner. These results support previous researches which have suggested that asymmetries lower than 10 % do not affect physical performance. Results could be influenced by the high level of the sample, with a high level of expertise in their sport. In conclusion, the inter-limb jump asymmetries level found in this sample of soccer players obtained a low decrease in physical performance.
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