Normative data and predictors of trunk muscle endurance performance in young tennis players

Introduction Trunk muscle endurance is important for injury prevention and performance in tennis due to repetitive rotational and high-range motion loads. Normative data for youth tennis players is have not been established and the influence of body size and competitive rank on these measures remains unclear. The aim of this study was to establish age- and sex-specific reference values for trunk endurance and to examine the influence of body size and competitive success on endurance capacity Methods A total of 214 young tennis players (115 males, 99 females; age=14.1 ± 2.3 years) registered with the Croatian Tennis Association. Participants were stratified by national ranking into high-achieving (HA; ranked top 30) and low-achieving (LA) groups. Trunk flexor endurance was measured using the plank test, and trunk extensor endurance was measured using the Biering-Sørensen (s). Covariates included age, sex, height, and weight. Results In female players, HA participants demonstrated significantly better trunk extensor endurance than LA participants (F = 5.35, p = 0.023) after controlling for body size. No significant differences in endurance were found between HA and LA males ( p > 0.05). Regression analysis showed that body height and weight were not significantly associated with test performance in either sex ( p = 0.08–0.98). Females in the U18 category significantly outperformed males in the Biering-Sørensen test ( p < 0.01). The key findings of the present study indicate that neither height nor weight are significantly correlated with the core strength and endurance of the back muscles in both male and female young tennis players. Player level significantly influences the results of the plank and Biering-Sørensen tests in females, whereas in males, differences are not statistically significant after accounting for body size. Discussion These results highlight the importance of structured trunk endurance training, particularly for female players, where core performance appears to be closely related to competitive success. Age and sex-specific normative values for these tests may assist coaches and researchers in evaluating, monitoring, and developing core strength and endurance in youth tennis populations, with potential implications for improving performance and injury prevention.