An accurate VO2max nonexercise regression model for 18-65-year-old adults

The purpose of this study was to develop a regression equation to predict maximal oxygen uptake (VO2max) based on nonexercise (N-EX) data. All participants (N = 100), ages 18-65 years, successfully completed a maximal graded exercise test (GXT) to assess VO2max (M = 39.96 mL x kg(-1) x min(-1), SD = 9.54). The N-EX data collected just before the maximal GXT included the participant's age; gender; body mass index (BMI); perceived functional ability (PFA) to walk, jog, or run given distances; and current physical activity (PA-R) level. Multiple linear regression generated the following N-EX prediction equation (R = .93, SEE = 3.45 mL x kg(-1) x min(-1), % SEE = 8.62): VO2max (mL x kg(-1) x min(-1)) = 48.0730 + (6.1779 x gender; women = 0, men = 1) - (0. 2463 x age) - (0.6186 x BMI) + (0.7115 x PFA) + (0.6709 x PA-R). Cross validation using PRESS (predicted residual sum of squares) statistics revealed minimal shrinkage (R(p) = .91 and SEE(p) = 3.63 mL x kg(-1) x min(-1)); thus, this model should yield acceptable accuracy when applied to an independent sample of adults (ages 18-65 years) with a similar cardiorespiratory fitness level. Based on standardized beta-weights, the PFA variable (0.41) was the most effective at predicting VO2max followed by age (-0.34), gender (0.33), BMI (-0.27), and PA-R (0.16). This study provides a N-EX regression model that yields relatively accurate results and is a convenient way to predict VO2max in adult men and women.     

Free operant measurement of taste preferences in prosimian primates

The sucrose preferences of two prosimian primate species, slow loris and greater galago, were determined under aperiodic reinforcement of a free operant. Stimuli were solutions of the following concentrations: 5%, 10%, 20%, 30%, and 40%. Solutions of intermediate concentration were preferred, and thus the function relating barpresses to concentrations was nonmonotonic.     

Psychometric properties of child- and teacher-reported curl-up scores in children ages 10-12 years

The purpose of this study was to examine the psychometric properties of child- and teacher-reported curl-up (CU) scores in children ages 10-12 years in both a norm-referenced (NR) and criterion-referenced (CR) framework. Eighty-four children, 36 boys and 48 girls, performed the FITNESSGRAM (Cooper Institute for Aerobics Research, 1992) CU test on 2 days separated by 48-72 hr. Two video cameras were used to record students' CU performances. Two students performed the CU at the same time, with each child's performance recorded by one camera. The test was terminated when the child stopped due to fatigue or after two form errors occurred. Teacher-reported scores were the average of two independent ratings of each video performance, while child-reported scores came from data collected and recorded by the children. Single trial norm-referenced reliability was R = .75 for girls and R = .80 for boys for teacher-reported CU and R = .69 and R = .70 for child-reported CU for girls and boys, respectively. CR reliability was examined using P, proportion of students who consistently passed or failed the test across 2 days, and km, defined as reliability with chance removed. For teacher-reported scores, P = .89 and km = .78 for boys and P = .81 and km = .62 for girls. For child-reported scores, P = .86 and km = .72 for boys, while P = .79 and km = .58 for girls. For teacher-reported data, 39% of boys passed and 50% failed the test on both days, while for girls the percentages were 27% pass and 54% fail. For child-reported data, 64% of boys passed and 22% failed on both days, while 54% of girls passed and 25% failed. NR validity was examined by correlating teacher and child-reported scores. The resultant coefficient was r = .42 (95% CI = .11-.66) for boys and r = .67 (95% CI = .58-.74) for girls. Additionally, child-reported scores were significantly higher than teacher-reported scores. CR validity was examined with a contingency coefficient, and results indicated C = .55 with 44% false master errors for boys and C = .65 with 29% false master errors for girls. The findings of this study suggest that while NR reliability estimates were moderate for teacher-reported scores, single trial estimates suggest that child-reported CU should be viewed with caution. In regard to CR reliability, both teacher-reported and child-reported reliability were moderate. However, there were marked differences between teacher- and child-reported scores, with children reporting higher percentages of students passing and lower percentage of student failing the test when compared with scores reported by teachers. Validity was rather moderate when viewed in either a NR and CR framework. It is suggested that problems with child-reported scores may be due to the need for additional practice or simplification of the testing protocol.     

Familial aggregation of aerobic power: the influence of age, physical activity, and body mass index

Whereas modest familial aggregation of VO2max has been documented after controlling for variables such as physical activity habits, the effect of adjustment for moderating variables has not been directly tested. This issue was addressed in 95 Anglo and 111 Mexican-American families who underwent submaximal cycle ergometer testing. Zero-order correlations of predicted VO2max between pairs of family members were generally weak for both Anglo families (r = 0.04 to 0.35) and Mexican-American families (r = 0.03 to 0.50). Five of 12 correlations were significant. Similar results were found for combined ethnic groups. Adjustment for age, physical activity, and body mass index by partial correlation had few significant effects on aggregation of predicted VO2max. Adjustment for body mass index produced significant decreases in the correlation for Anglo spouses and mother-older child and sibling pairs in the combined group. Although influential moderating variables were not identified, body mass index was found to be a significant, though inconsistent, mediator of aggregation of VO2max. Genetic factors were not strongly supported because of generally weak aggregation in the two ethnic groups.