Development of Body Composition chapter 17 Development of Body Composition

Importance of Body Composition Body composition determines appearance. It affects self-concept. It is related to working capacity. Excess weight adds to workload. Excess fat limits range of motion. Obesity places one at risk of diseases.

Body Composition and the Model of Constraints How might excess fat tissue be a rate-limiting constraint for performance of fundamental motor skills? For activities of daily living?

Development of Body Composition Genetic and environmental factors have an effect. Two environmental factors can be manipulated. Diet Exercise (continued)

Development of Body Composition (continued) Fat tissue increases rapidly in first 6 months and early adolescence. Increases continue in girls throughout adolescence. Muscle tissue development follows the sigmoid pattern.

Body Composition and Exercise in Youth Wolanski & Parizkova (1976; ctd. in Parizkova, 1977): Preschoolers in physical education had less subcutaneous fat. Parizkova (1968, 1977) Study followed 100 boys, four activity-level groups, longitudinally for 4 years from age 10.7 years. Active boys maintained level of fat weight; inactive boys increased in fat weight. (continued)

Body Composition and Exercise in Youth (continued) Parizkova (1972) Study followed 41 of the boys for another 3 years. The pattern continued. Parizkova (1977) Study followed 16 of the boys for another 6 years. By age 21 years, fat weight was variable and reflected lifestyle. (continued)

Body Composition and Exercise in Youth (continued) Parizkova (1973, 1977) Study simultaneously followed boy and girl swimmers from age 12 to age 16. By age 15, boys were taller, heavier, leaner. Both boys and girls showed increased lean body mass at the expense of fat weight.

Body Composition and Exercise in Teenage Girls Parizkova (1963, 1977) Study followed 32 gymnasts and 45 nontraining girls for 5 years. Girls who did not train gained fat weight. Those who trained showed no overall trend to add fat weight gained subcutaneous fat during inactivity lost fat and gained muscle during training increased caloric intake during training

Parizkova’s Study Results \insert fig17_02\

Implications Is adolescence a critical period for addressing the importance of healthy, active lifestyles? Why or why not? How might various teachers and health care professionals play a role in promoting active lifestyles?

Short-Term Research on Body Composition Dollman, Olds, Norton, & Stuart (1999) Study compared two cohorts of 10-year-olds in 1985 and 1997. In 1997, the least fit children were associated with lower average performance in walking and running. Olds & Dollman (2004) Continued study of the 1997 group described above. Decreased performance was tied to decreasing levels of physical activity in the children studied. (continued)

Short-Term Research on Body Composition (continued) Muscatine Study (Janz, Burns, & Mahoney, 1995) Study involved 2-year follow-up of 120 children starting at age 10. Higher systolic blood pressure and body fat were associated with decreased physical fitness.

Body Composition and Exercise in Adulthood The average middle-aged adult loses fat-free body mass and gains fat. Regular exercisers are known to maintain muscle and fat levels. Research studies generally find beneficial effects of exercise among groups, but individual results are variable.

Obesity Obesity rates are increasing around the world and at all ages. Chances are that obese children remain obese into adulthood. About one-quarter of U.S. children and adolescents are obese. (continued)

Obesity (continued) Metabolic and thyroid disorders account for less than 1% of cases. Rapid increase implicates environmental rather than genetic factors. People are less active. Diets have increased in fat and sugar.

Prevalence of Obesity With Advancing Age

Exercise as a Strategy to Reduce Obesity Exercise can offset the decrease in basal metabolic rate that accompanies caloric restriction. Exercise promotes development of muscle tissue, which requires more calories for maintenance. Exercise expends calories. Exercise is effective in controlling obesity over the life span.

Exercise Promotion How might exercise be made more enjoyable for the following groups? Children Teenagers Adults Older adults

Development of Body Composition: Summary Diet and exercise greatly affect relative levels of fat and lean body mass. Regular exercise promotes muscle mass and increases basal metabolic rate. Over the long term, exercise can alter the body’s structural constraints for movement.