External and internal load in tennis have been the subject of many studies, mostly limited to specific exercises and competitive demands. The area of daily training external and internal loads experienced by tennis players is still largely unexplored. This poses a problem, as determination of the optimal training stimulus is most often done only intuitively, without objective insight into the actual training demands.
The aim of our study was to determine the level of tennis-specific external and internal loads of training sessions during the preparation period, according to the age and gender of young tennis players. The study included 17 competitive tennis players (10 boys, 7 girls), who were divided into 3 age categories: ≤ 13 years, 14-16 years and ≥ 17 years. Using Armbeep sensors and smartphones, we obtained data from at least 10 training sessions for each player during as condensed training preparation period as possible. For all players, we captured training loads only (excluding competition loads), which included training duration, tempo, number of shots per hour, power of shots, hitting load and cardio load.
We found that all external loads, except training duration, were statistically significantly correlated to age. The strongest positive correlation was between age and the power of stroke, while the correlation between age and cardio load was negative. 23 % of variation in the power of shots, 9 % in tempo, 7 % in hitting load and 6 % in shots per hour was explained by our regression model (age). Further findings revealed that an increase in age for 1 year, results in an increase of: tempo for 0,13 (strokes/min), number of shots per hour for 5,77, power of shots for 0,23, hitting load for 5,39, and a decrease in cardio load for 2,50. For the shot’s power and tempo, we also performed an analysis between age groups, where we found that statistically significant differences occurred between the groups ≥ 17 years and ≤ 13 years, as well as the groups ≥ 17 years and 14-16 years. When comparing genders, statistically significant differences were found in the number of shots per hour and the hitting load, where boys achieved higher values regardless of age. Results were the same in the age group ≤ 13 years, demonstrating statistically significant differences for the number of shots per hour and the hitting load, again with higher values for boys.
The findings provide an objective insight into the volume, type and intensity of specific tennis training loads. We can conclude that age has a significant influence on the external loads as well as the physical response. Boys reach higher loads already in the category under 13 years, a large part of which is received by the hitting arm (hitting load), which may lead to an increased risk of shoulder or back injuries. A better understanding and optimization of the workloads could improve the player's development and concurrently reduce the chances of injury and overloading.
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