Adolescent ballet dancer student aged 7-17 years who have been actively attending a ballet dance school for at least 1 year will be form ballet dancer group. The age, body weight (kg) and height (centimeter) of each individual included in the study will record. The assessment form, which includes demographic data such as, ballet duration(min/day), frequency (times/week) and continuity (year) will record by asking the parents. All measurements will be take before lesson and without warm-up. All measurements will be evaluate by an experienced physiotherapist. Postural alignment will assess with New York Posture Rating Scale (NYPR). Static and dynamic balance will determine with Romberg's Test, Flamingo Balance Test (FBT) and Star Excursion Balance Test (SEBT). Participants will be evaluate for flexibility outcomes by applying following test: sit up and reach test, Thomas test and straight leg raise test. Quality of life will be assess with SF36.

The control group (Sedentary Adolescent) of the study, are not ballet dance students who aged 7-17 years and have not experience in competitive sport or activity. The age, body weight (kg) and height (centimeter) of each individual included in the study will record. All measurements will be take before lesson and without warm-up. All measurements will be evaluate by an experienced physiotherapist. Postural alignment will assess with New York Posture Rating Scale (NYPR). Static and dynamic balance will determine with Romberg's Test, Flamingo Balance Test (FBT) and Star Excursion Balance Test (SEBT). Participants will be evaluate for flexibility outcomes by applying following test: sit up and reach test, Thomas test and straight leg raise test. Quality of life will be assess with SF36.

The NYPR applies a quantitative approach to assess proper and improper alignment of various body segments for an individual in the anatomical position. The NYPR published in 1958 includes a set of three figure drawings for each of 13 body alignment segments contributing to overall postural alignment. The 13 body alignment segments include posterior views of the head, shoulders, spine, hip, feet, and arches, and lateral (left side) views of the neck, chest, shoulders, upper back, trunk, abdomen, and lower back. Short verbal descriptions are provided to indicate the visual cues to use as criteria in deciding the score. In this original version, each body segment was scored 5 (correct posture), 3 (slight deviation), or 1 (pronounced deviation). The standard evaluation criteria developed for this test were determined as "very good" if the total score was ≥45, "good" if 40-44, "moderate" if 30-39, "poor" if 20-29 and "bad" if ≤19.

SLS test is used to assess static balance control. Participants will be asked to stand on a hard floor, on one leg without using any assistive devices, and without support from any surface. SLS times of the participants will be recorded in seconds with the stopwatch and the test will be repeated for both feet.

The FBT indicates static balance that is simplicity, low cost and it is capable for mass investigations. In this test the participant is standing on his preferred foot, bends his free leg backwards and grips the back of the foot with hand on the same side, standing like a flamingo. The measurement time was kept for one minute. The electronic chronometer was stopped as soon as the participant lost balance or touched the ground. The balance was restored and the electronic chronometer was continued until one minute has passed. Score: Attempts to keep balance within one minute were recorded.