Grip strength performances by 5- to 19-year-olds.

Accurate measures of muscular strength can yield insights about children's growth and development. The purpose of this study was to examine grip strength performances by boys and girls ages 5 to 19 years. A Jamar dynamometer was used to measure grip strength by 736 boys and girls ages 5 to 19 years. Multiple regression equations were applied to analyze the data. Overall, age-sex trends were similar to previous reports as boys and girls increased their performances across age levels. After age 12, boys' mean grip strength increased at a faster rate than girls'. However, participants in the present study performed better in the upper age ranges (13-19 yr.) than did boys and girls tested a generation ago. Potential associations between activity choices and grip strength are discussed.

Growth rates in running speed and vertical jumping by boys and girls ages 11-13.

This study examined growth rates in running speed and vertical jump among middle school children. 45 boys and 31 girls ages 11-13 years were tested on running speed and vertical jump three times (September, February, and May) during the school year. Hierarchical linear modeling was used to estimate initial status and growth rates for the entire sample (base model) and the association of running and vertical jump with height, weight, and sex (conditional model). Positive overall growth rates were found for both running speed and vertical jump. Increased heightand weight at the time of measurement were not significantly associated with growth rate for running. The growth rate for vertical jump was positively associated with height but unrelated to increased weight. Boys showed steeper growth rates than girls in jumping. No sex differences were found in running speed for either initial status or in growth rate. Furthermore, these results suggest highly variable rates of physical maturation but no general period of 'adolescent awkwardness'.

Age, sex, and body mass index in performance of selected locomotor and fitness tasks by children in grades K-2.

The purpose of this study was to examine the contributions of 3 predictor variables (age, sex, and body mass index) to performance of 7 fundamental movement skills (locomotor; run, gallop, hop, leap, jump, skip, and slide) and 4 fitness tasks (grip strength, step test, sit and reach, and timed sit-ups) by 65 children in Grades K-2 (M=6 yr.). A multiple regression analysis indicated that running, leaping, and skipping improved with age. No sex differences were observed on any of the seven skills. In terms of the four fitness tasks, age was positively associated with timed sit-ups and grip strength and inversely associated with step-test performance. Sex was associated with step-test and sit and reach performance (girls performed better on both). Finally, body mass index was related to increased grip strength and fewer timed sit-ups.