###### Abstract  
The main aim of this study was to evaluate the effects of a 10-week sensorimotor exercise programme on body balance and agility in a group of adolescent athletes. Initially, 120 adolescent football players were included in the study. In the final analysis, 90 athletes aged 10-17 years participated. The study was designed as a single-blinded, randomised controlled trial. Healthy athletes who met the inclusion criteria were randomly divided into two comparative groups: experimental and control groups. Sensomotor exercises were conducted twice weekly for 10 weeks in the experimental group. The adolescent footballers were subjected to the following tests: a COP (Centre of Pressure) test on a stabilizer platform, a Y balance test (Y-BT), and an agility test. The experimental group showed improvement with respect to the following variables: COP-based path length, with eyes open, for 30 s duration--improved by 5.3 cm (mean: 20.0; 95% CI 15.3-24.8); area, with eyes open, for 30 s duration--improved by 1 cm\({}^{2}\) (mean 2.1; 95% CI 0.6-3.5); area, with eyes closed, for 30 s duration--improved by 0.4 cm\({}^{2}\) (mean 2.2; 95% CI 1.6-2.8). The Y-BT was significantly improved in terms of the final score for the following variables: left leg anterior by 2.1% (mean 73.1; 95% CI 70.7-75.2); right leg posterolateral by 3.8% (mean 112.3; 95% CI 109.3-115.3); right and left leg posteromedial by 5.6% (mean 111.7; 95% CI 108.6-114.9) and 5.7% (mean 112.3; 95% CI 109.7-115.1), respectively; medium posterolateral by 3.2% (mean 111.8; 95% CI 109.0-114.7); medium posteromedial by 6.0% (mean 112.0; 95% CI 109.2-115.0); and Y total score by 3.5% (mean 98.8; 95% CI 96.6-100.9). The agility test in the experimental group was improved by 1.6 s (mean 13.2; 95% CI 12.6-14.0). A 10-week programme of additional sensorimotor exercises improved selected parameters determining balance and agility in the young football players.  
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Footnote †: journal: Applied sciences  
Sensomotor exercises are designed to improve proprioception. In the literature, several other terms are used, such as proprioception exercises [13; 14], neuromuscular exercises [15; 16], balance exercises [17; 18], and stabilisation exercises [19; 20], but, practically speaking, all these terms refer to the same type of exercise. However, it is worth noting that sensorimotor exercises contain three exercise components: static, dynamic, and functional components [21; 22]. Some studies have suggested that additional balance training is an important part of regular athletic training because it improves athletes' performance [12] and prevents injury [8]. It has been confirmed that balance training reduces the angles and valgus moments of the knee and increases the activity of the hamstring muscles [23]. This is considered beneficial for the stabilisation of the knee joint [24]. Thus, sensorimotor exercises have been demonstrated to significantly mitigate knee pain, improve global knee function, and reduce the re-injury of anterior cruciate ligaments [25; 26].  
There is also some doubt concerning the effects of additional body balance exercises in children and adolescents if the duration of these exercises decreases [27]. A systematic review by [PERSON] et al. [28] showed that additional exercise improved body balance in a group of athletes when conducted for at least eight weeks. Therefore, we hypothesised that an additional sensorimotor exercise programme implemented for a period of 10 weeks should improve body balance and agility in adolescent football players. Thus, the main aim of this study was to evaluate the effects of a 10-week sensorimotor exercise programme on body balance and agility in a group of adolescent athletes. In this study, the exercises introduced contain all the elements of sensorimotor exercises.