Sedentary behavior and physical activity predicting depressive symptoms in adolescents beyond attributes of health-related physical fitness.

BACKGROUND: Sedentary behavior (SB), physical activity (PA), and attributes of physical fitness have been shown to be related to depressive symptoms in adolescents. The purpose of the present study was to investigate whether SB and fitness-producing activity predicted depression in active adolescents over and above gender and fitness attributes. METHODS: Participants were 249 adolescents (age: 12.85 ± 0.89 years, mean ± SD) from 3 public middle schools who wore Actical accelerometers to assess their SB and PA. Participants also completed the FITNESSGRAM health-related fitness assessment and a brief depression questionnaire. A 3-step hierarchical regression analysis was conducted with gender and fitness attributes (i.e., body mass index (BMI), maximal volume oxygen uptake (VO2max), curlups, and pushups), moderate- and vigorous-intensity activity, and SB entered in respective steps. RESULTS: Regression analysis indicated activity variables (i.e., moderate- and vigorous-intensity activity) significantly predicted depression (ΔR 2 = 0.12, p < 0.01) beyond gender and fitness attributes. Overall, gender, fitness attributes, activity variables, SB explained 31% of the variance in depression. Structure coefficients revealed VO2max (r s = -0.77), moderate-intensity activity (r s = -0.67), vigorous-intensity activity (r s = -0.81), and SB (r s = 0.57) were substantially correlated with the criterion variable; thus, they were the strongest predictors of depression. CONCLUSION: The findings of the current study indicated SB and PA were both significant predictors of depression; however, sufficient fitness-producing activity and adequate cardiorespiratory fitness may nullify the negative influence of SB on depressive symptoms in active adolescents.

Developmental gender differences for overhand throwing in Aboriginal Australian children.

In a review of 46 meta-analyses of gender differences, overhand throwing had the largest gender difference favoring boys (ES > 3.0). Expectations for gender-specific performances may be less pronounced in female Australian Aborigines, because historical accounts state they threw for defense and hunting. Overhand throwing velocities and kinematics were recorded in 30 female and male Aboriginal Australian children 6-10 years old. Results indicated the Aboriginal girls and boys were more similar in horizontal ball velocities than U.S. girls and boys. Throwing kinematics between girls and boys were also more similar in Australian Aborigines than U.S. children. Aboriginal girls threw with greater velocities than U.S., German, Japanese, and Thai girls, while the boys were similar across cultures.

Developmental differences in children's ballistic aiming movements of the arm.

An experiment was conducted to examine the change in the relation between programming and "on-line" correction as a developmental explanation of children's arm movement performance. Each of 54 children in three age groups (5, 8, and 10 yr.) completed two types of rapid aiming arm movements in the longitudinal plane on the surface of a digitizer. Percent primary submovements and timing variability were dependent variables. Analysis suggested that the 5-yr.-olds used "on-line" monitoring during the arm movement and did not perform the movement sequence as a functional unit. Compared with 8- and 10-yr.-olds, the 5-yr.-olds planned a smaller portion of movements, executed the arm movements with more variability in time to peak velocity. The 8- and 10-yr.-olds appeared to plan their movements and execute the sequence as a unit. The developmental implications were discussed.