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The aim of the present study was to examine the time course of changes of the effects of static stretching on straddle jump, vertical jump height and flexibility after performing dynamic movements in artistic gymnasts. The study was participated by 14 female artistic gymnasts aged between 9 and 14. Vertical jump heights were measured using the New Test 2000 testing device. Flexibility measurement was performed with sit and reach flexibility test. Artistic gymnastics-specific jump movement was evaluated looking at the angle between lower extremities using the Dartfish motion analysis program. Baseline measurements taken before the standard warm-up and the measurements taken after static stretching were assessed. Four sets of gymnastics moves each lasting two minutes were performed. The tests were repeated after each set. Static stretching was found to affect vertical jump performance significantly. Significant differences were found between Jump2 and Jump1 (p=0.01), Jump2 and Jump3 (p=0.03), Jump2 and Jump4 (p=0.01), Jump2 and Jumop5 (p=0.004), and Jump2 and Jump6 (p=0.009). In flexibility-related changes, significant differences were found between Reach2 and Reach3 (p=0.03), and Reach2 and Reach6 (p=0.006). Static stretching was found to have no significant effect on the lower extremity straddle jump degree. In conclusion, although the static stretching protocol reduced vertical jump performance significantly, it did not affect the artistic gymnastics-specific jump move. The negative effects of static stretching on jump height approached the baseline value approximately 4 minutes later.

Background: People are divided into different chronotypes in relation to their circadian rhythm features. The Morningness–Eveningness Questionnaire (MEQ), developed by Horne and Östberg, was the first and is the most used questionnaire for determining the chronotype of people. The reliability and validity of MEQ were tested in this study due to some deficiencies and inconsistencies in previous reliability and validity studies for the Turkish versions of MEQ and deficiencies regarding the validity and reliability of other versions of MEQ. Subjects and Methods: MEQ was translated into Turkish based on the opinions of five academics who were experts in their respective fields and the suitability and content validity of the questionnaire were ensured. The Turkish MEQ was administered to 419 undergraduate students aged 18–34 years. Robust minimum rank factor analysis (MRFA) was used to reveal the construct validity of the questionnaire. Results: As a result of the analyses, the questionnaire was examined in three factors. None of the items were excluded from the study and all items were collected under three factors. The explained total variance value was 42.7%, and the factors explained 64% of common (shared) variance in MRFA. According to the reliability analysis, Cronbach's alpha value for the MEQ Turkish version was satisfactory for the overall questionnaire (0.765). Conclusions: The MEQ version developed in this study is more valid and reliable compared with other versions. However, these results support that a more detailed instrument for morningness and eveningness can be developed.

Background: Sleep quality plays a principal role in the protection of health. There is an increasing number of studies in the literature demonstrating that internet addiction and smartphone addiction impair sleep quality. However, the number of studies on Turkish adolescents is very limited. Therefore, this study examined the effects of internet addiction and smartphone addiction on sleep quality among Turkish adolescents. Methods: Participants in this cross-sectional study were 910 adolescents aged 13–18 years. Data were collected with the Short Internet Addiction Test, Smartphone Addiction Scale, and Pittsburgh Sleep Quality Index. In addition, a questionnaire was used to gather information about the demographic, socioeconomic, and health-related characteristics. Pearson’s Chi-square test, Chi-square test for trend, Mann–Whitney U test, logistic regression analysis, and Spearman’s correlation analysis were used in the analysis. Results: The sleep quality of 58.7% of the adolescents was poor. Additionally, girls and adolescents ≥16 years old had poor sleep quality. Sleep quality deteriorated as perceived health status and perceived economic status of family deteriorated. Compared to participants with normal internet addiction scores, poor sleep quality was 1.83 (95% CI [1.22–2.74]) times higher in those with problematic internet addiction and 1.99 (95% CI [1.23–3.87]) times higher in those with pathological internet addiction. One point increase in Smartphone Addiction Scale total score increased poor sleep quality 1.01 (95% CI [1.00–1.02]) times. Sleep quality scale were positively correlated with the smartphone addiction and internet addiction. However, there was no positive correlation between habitual sleep efficiency subcomponent of sleep quality and smartphone addiction and internet addiction. Conclusions: Internet addiction and smartphone addiction were associated with poor sleep quality in adolescents. Older adolescents (≥16 years), gender (female), poor health perception, and perception of moderate economic status of the family were other factors associated with poor sleep quality.