Table 1.

Descriptive characteristics of the study population (N=34)

Age (years)	14±1.6
Minimum–maximum	12–17
Sex, n girls/boys (%)	13/21 (38.2/61.8)
Height (cm)	164.0±10.6
Mass (kg)	52.5±10.5
Years of playing tennis	7.2±2.4
Hours of tennis training/week	4.8±2.3
Hours of physical training/week	2.0±1.4
Number of tennis tournaments/year	12.3±7.2
Hours of alternative training/week	1.3±2.2
Subjects participating in other sports, n (%)	14 (41.2)
Current injury in upper body, n (%)	3 (8.8)
History of leg/foot injury in last 6 months (%)	6 (17.2)
History of infection in last month (%)	14 (41.2)

Notes: Continuous data are presented with mean ± standard deviation. Categorical data are presented as absolute numbers and proportions.

Abbreviation: n, number.