This paper is a meta-analysis of the role of nutritional supplements in strength training focusing on the effects of placebo treatments. We address specifically the results from meta-analysis of 334 fi.ndings from 37 studies of the effect of nutritional supplements and physical fitness interventions on strength, stamina, and endurance outcomes, controlling for main effects of the group on which the results were obtained (placebo, treatment, control, for pretest or posttest), with covariates for age, gender, randomization, double-blind procedures, study duration, training load, training frequency, and training status. Finding show that there are significant placebo effects accounting for a substantial portion of the effect size typically associated with treatment interventions. In addition to produce the best evaluations of treatment effects, both control and placebo groups should be included in a double-blind research design using participants who are well familiarized with the study procedures.
Tarra Rawdon, Rick L. Sharp, Mack Shelley and Jerry R. Thomas
Gregory J. Welk, Jodee A. Schaben and Mack Shelley
Homeschooling is increasingly popular, but little is known about how homeschooling affects physical activity patterns or fitness levels. This study compares patterns of physical fitness, physical activity, and psychosocial correlates of physical activity in homeschooled youth and youth attending public school. Fitness levels were obtained using the PACER aerobic fitness test, physical activity levels were assessed with 3 days of accelerometry, and psychosocial correlates were assessed with the Children’s Physical Activity Correlates scale. There were no significant main effects for fitness comparisons, but significant age and gender interactions indicate that variability exists within these samples for fitness. No school type effects were evident for the physical activity measures or the psychosocial correlate measures, but trends in the data suggest the possibility of age-related interactions for the psychosocial measures. Additional research on possible differences between homeschooled youth and youth attending public school is needed to better understand these trends.
Ashleigh J. Sowle, Sarah L. Francis, Jennifer A. Margrett, Mack C. Shelley and Warren D. Franke
Rural-residing older adults (OA) are not meeting physical activity (PA) recommendations, such that identifying methods of increasing PA among OA remains an ongoing challenge. This study evaluated the effect of a community-based exergaming program on PA readiness-to-change and self-efficacy among rural-residing OA (n = 265). There was a significant (p = .008) increase in readiness-to-change classification from PRE to POST. Significant increases in self-efficacy, or confidence in their ability to be physically active for a prescribed period of time, were detected for 35 (p = .011) and 40 min (p = .035) of continuous PA. PA self-efficacy change for 35 min of continuous PA (F [3,137] = 3.973, p = .010) and 40 min of continuous PA (F [3,137) = 2.893, p = .038) were influenced by the interaction between PRE self-reported health and PRE PA readiness-to-change levels. Results suggest that an exergaming-themed PA intervention is effective at increasing PA participation and self-efficacy for PA among rural-residing OA.