Sex differences in static strength and fatigability in three different muscle groups

Maximal voluntary static muscle force production was assessed both in strength trials and during 2-min contractions by three muscle groups (right-hand finger flexors [RHF], right-leg extensors [RLE], and both leg extensors [BLE]) in young males (n = 13) and females (n = 14). There was a significant difference (p less than .01) between males and females for RHF strength and BLE strength but no significant difference between sexes for RLE strength. During the 2-min task, impulse (force x time) declined significantly (p less than .001) and there was a significant difference (p less than .001) between muscle groups, but there was no difference between sexes. There was a significant (p less than .05) sex x time interaction for the impulse values indicating that the fatigability was greater in males than females.     

The Jig Experiment: Development and Evaluation of a Cultural Dance Active Video Game for Promoting Youth Fitness

School physical education teachers promote fitness by offering children a variety of aerobic activities. Our interdisciplinary team developed a cultural dance active video game (AVG) and tested whether the AVG was equivalent to traditional face-to-face instructor lessons or hybrid instruction at dance mastery, increasing heart rates, and student satisfaction. The study participants (N = 404) were elementary children, Grades 1 to 5, at a Midwestern suburban school. We employed a quasi-experimental design to compare outcomes across groups of children exposed to different teaching approaches. Group 1 received AVG instruction. Group 2 received face-to-face lessons by a certified Irish dance teacher. Group 3 received AVG and face-to-face lessons. Group assignment was stratified by age, ethnicity, gender, and socioeconomic status. During daily physical education class, students received five days of intervention exposure. AVG students achieved comparable levels of mastery, significantly elevated heart rates, and high levels of satisfaction.     

Life and Honorary Members

Abstract

The relative importance of body size, body composition, cardiovascular-respiratory capacity, and running speed in determining individual differences in performance on 600-yd run and mile run tests was investigated using data on 196 children, ages 7 to 12 years. A multivariate, multistage path model was developed in which height, % fat, [Vdot]O₂ max (ml/kg FFW · min) and the 50-yd dash time were postulated as determinants of individual differences on the two distance-running tests. These four independent variables accounted for 71% and 66% of the variance in the 600-yd run and mile run, respectively. All four independent variables had significant associations with the two distance runs when the influence of the other independent variables was taken into account. The 50-yd dash time and % fat were found to be the most important determinants of both distance runs. It was concluded that determinants of the 600-yd run and mile run in elementary-school-age children are complex and that individual differences on these tests reflect a number of attributes in addition to cardiovascular-respiratory capacity.     

Relationship of Somatotype and Body Composition to Physical Performance in 7- to 12-Year-Old Boys

The purpose of this study was to determine the association of somatotype, body composition, and physical performance in 7- through 12-year-old boys. Two objective methods of measuring somatotype, Sheldon's trunk index method and Heath–Carter's anthropometric method, were used. Body composition was estimated as fat and lean body mass from ⁴⁰K measurement, using a whole-body counter, and from two skinfold thickness measures. Physical performance measures consisted of three tests of running (mile run, 600-yd run and 50-yd dash) and two tests of jumping (standing broad jump and vertical jump). In general, somatotype components had lower correlations with running and jumping variables than did body composition or body size variables such as height, weight, and percent fat. Heath and Carter's third component, derived from the inverse ponderal index, correlated more closely with performance scores than did other components of somatotype. Somatotype components in combination with each other and with body size and body composition variables in a multiple regression analysis indicated little association with running performance, but some association with jumping. Mesomorphy and second component were the least significant somatotype components, as indicated by the standardized regression coefficients.