Effect of scaling equipment on U-10 players tennis serve during match-play: A nonlinear pedagogical approach

•Reducing the net height and court size, contributes to acquire successful serve patterns and behaviors for U-10 players.•Playing in an appropriate scaled competition format promotes a more offensive service style.•An appropriate scale competition format approaches the rally length to the adult stage values.•Coaches and sport organizations based on scientific evidences should redesign actual match-play for U-10 players. The aim of this study was to compare two scaled competition formats for under 10 years of age (U-10) tennis players analyzing: serve performance; serve performance according to the serve placement; rally length; rally length in function of the serve placement; serve performance according to the game status.. Twenty U-10 players (age = 9.46±0.66 years) played eighty single tennis matches. Forty matches were played according to the International Tennis Federation's Tennis 10s guide for U-10 players in the stage green (GC) and the remaining half in a modified competition (MC) decreasing net height (from 0.91 m to 0.80 m) and court size (from 23.77-m x 8.23-m to 18.00-m x 8.23-m) with green ball (lower compression ball). The study variables were collected using the “Observational Instrument for the Technical-Tactical Actions in Singles Tennis”. Results showed an increase in first serve success, hitting more aces (mean difference, ±90% CL= 1.48, 0.62-2.34) and unreturned serves (±90% CL= 0.74, 0.27 to 1.28) in Mc than GC. However, the players in GC hitting more first serves inside the net (CL= -1.14, -1.63 to -0.65). Therefore, reducing net height and court-size improves the serve performance, thus creating a meaningful learning environment for U-10 tennis players.