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Motor Performance Study Charts Growth and Maturation of Children In the world of kinesiology, motor performance refers to the ability to complete a physical task, such as a jump or a sprint. In the Department of Kinesiology, motor performance has come to signify one of the landmark studies in its history. The Motor Performance Study, begun by Professor Emeritus Vern Seefeldt some 30 years ago, is still in existence today with researchers continuing to add to what is now a mountain of data on children’s physical growth and motor development. "At the time we started the study, there were no data on motor performance of children in Michigan," Seefeldt said. "I was interested in the relationship of physical growth to biological maturation and, in turn, to motor performance. I suspected that certainly there was some influence of maturation and physical size on the capabilities of young people. But there simply were no studies at the time that could provide insight." Begun with a group of 15 boys and 15 girls ages 5 to 7 in December 1967, the study was designed to take physical measurements to gauge growth, and to log scores on seven motor performance skills that included tasks like a shuttle run and a vertical jump. The key was that it would be longitudinal. Seefeldt originally thought it would last perhaps 10 years. From the beginning, however, the study had a second component. Participants and later other children in the community would also be part of an activity program. That meant that all of the children would attend a Saturday morning physical activity program during the school year and a five-week program in the summer. And, initially, it was free. The study quickly became popular in the Lansing area. John Haubenstricker, who became involved with the study as a graduate student in 1968 and has directed it since 1978, recalls that a few parents even called from the hospital after giving birth to get their newborns on the waiting list. Over the 30 years, faculty members and graduate students have been taking measurements of children and youths twice a year. Children are requested to stay in the study until they stop growing in height, which can be as early as age 14 or as late as age 20. The study has had more than 1,200 participants, and amassed some 20,000 data sets on growth and more than 17,000 sets on motor performance. Since 1978, the study has only occasionally accepted new participants for measurement--most of them second-generation children--but continues to accept youths for the activity component. Some initial work already has yielded interesting findings. Haubenstricker and his colleagues have been able to chart the motor development of boys and girls over the age groups. In the 30-yard dash, for instance, researchers can see that during ages 4-7 there is very little difference in times between boys and girls. But the times start to diverge during middle school and by high school the differences are substantial with boys outperforming girls. These gender differences |
exist in all of the other performance measures except for the sit-and-reach in which girls demonstrate more flexibility than boys. What will be particularly interesting, Haubenstricker said, is to try to correlate the performance numbers with the body changes of boys and girls through adolescence. Researchers also have looked at skin fold data and how skin folds affect motor performance. Haubenstricker said that the study has found that body fat can account for as much as 30 percent of a child’s performance on a given physical task. The study also has allowed Haubenstricker and his colleagues to compare different generations of children. They compared children in the program from 1968 to 1970 to those from 1980 to 1982. "When we looked at at 6-, 9- and 13-year-olds, we found out that in terms of growth, the kids in the 80s were not significantly different from those in the 60s and early 70s." So it appears, he said, that the growth trend has stabilized. Researchers also have looked at what percentage of adult performance is already in place by age 5. The study has found that boys display 20 to 40 percent of their adult performance on a given task at 5. Girls, however, tend to have 40 to 60 percent of their adult performance as 5-year-olds. "In general, we can say that females are closer to their adult performance at younger ages than boys," he said. This is a fascinating finding for Haubenstricker because it yields as many questions as it answers. Are girls closer to their adult performance sooner because of societal influences that discourage their physical activity during childhood and adolescence? Will greater opportunity for girls to become involved in sports and other activities change those numbers in the future? Associate Professor Crystal Branta is the principal investigator for the data involving children ages 2-and-a-half to 5 collected between 1975 and 1992. Haubenstricker is heading the research on the other age groups, and Seefeldt remains involved as well. For Seefeldt, Haubenstricker and Branta, the many years of work have been a rare opportunity to chart the development of the human body through its growing years. They are convinced that in the years to come, the study will yield many valuable findings and provide the field with insight into the motor development and performance of children and adolescents.
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