The SwingVision (SV) application represents software for the automatic analysis of movement and specific parameters in tennis, but no study evaluated its applicability so far. Therefore, the aim of this research is to determine the validity of SwingVision for monitoring speed and placement parameters when performing serve and the frequency, type, and rotation of each stroke in the game. The sample of participants (N = 5) consisted of elite male junior tennis players (mean age 15.6 ± 0.35 years, mean height 179.16 ± 5.71 cm, and mean weight 72.62 ± 3.89 kg). Video analyses of closed and open character exercises were used to compare real data and those obtained using SV. The placement results determined good and very good validity (ICC = 0.83–0.87). In terms of speed, the results were found to have good validity (Speed_AD-ICC = 0.76–0.80). SV provided very good validity (ICC = 0.97) in the stroke detection parameter and also presented good validity in recognizing the rotation of shots (ICC = 0.76). SV provides valid objective feedback on tennis performance. Thus, the results justify the use of SV as a helpful tool in the training process, both in training and matches.

Purpose: The aim of this research is to analyse and to determine the differences between tennis players in younger age categories (U12, U and U16) in certain motor skills.Methods: A total of 60 tennis players ranked in the rankings of the Croatian Tennis Federation were measured by using 10 tests for assessing explosive strength in jump, speed, agility, and trunk strength. The tennis players were divided into three groups of 20 respondents, depending on the age category in which they compete. Statistically significant differences (p < 0.05) between all age categories were found in indicators of frontal and lateral agility, running speed in the 20-m shuttle run test, and explosive strength in jump and repetitive trunk strength.Results: The results of the conducted tests indicate a linear development trend for the mentioned skills in relation with the increase of chronological age of the tennis players. Statistically significantly better results were shown between test subjects under 14 years compared to test subjects under 12 years in tests for the assessment of agility (SST,A9-3-6-3-9), in the 20 m sprint test, in tests of explosive strength of lower extremities (CMJ, CMJmax,SJ) and in the test of repetitive trunk strength (TF). Subjects under 16 years achieved significantly better results compared to subjects under 14 years in tests for assessing agility (SST, A9-3-6-3-9), speed (SRT5m, SRT10m, SRT20m) and explosiveness (CMJ, CMJmax, SJ). Players under 16 years recorded significantly better results in all tests for assessing agility (SST,A9-3-6-3-9), speed (SRT5m, SRT10m, SRT20m), explosiveness of the lower extremities (CMJ, CMJmax, SJ) and in the test for assessing repetitive trunk strength (TF). Statistically significant differences were not detected in tests of running speed in the 5-m and 10-m shuttle run tests among U12 and U14 tennis players, nor between U14 and U16 tennis players in the 60-s trunk flexion test. The highest heterogeneity of results in a single age category was determined in the test for assessing isometric trunk strength, and thus tennis players of different age categories do not differ significantly in this skill.Conclusion: The results of this research point to the development of specific motor skills in accordance with the increase of game demands and chronological age, however, also refer to the problem of muscle imbalance between front and back trunk musculature. Physical conditioning of young tennis players should be multilaterally directed in order to enable injury prevention and adjustment of tennis players to competitive demands.