Richard R. Suminski

Physical activity among ethnically diverse college students

Abstract The authors compared physical activity patterns among 874 Asian, 332 African, 1,101 White, and 529 Hispanic American college students aged 18 to 25 years. According to self-report responses, 46.7% of the sample did not engage in vigorous physical activity and 16.7% were physically inactive. Among women, ethnic-specific rates of physical inactivity were Asian, 28.1%; African, 23.5%; White, 17.4%; and Hispanic, 20.3%. For men, rates of inactivity were Asian 11.7%; African, 7.7%; White, 12.0%; and Hispanic, 13.8. Weight-training activity, youthful physical activity, and TV viewing accounted for a significant portion of the variance in physical activity levels (13.1% for women and 14.8% for men). The results of this study support the need for physical activity interventions for college students, particularly minorities.

Metabolic efficiency during arm and leg exercise at the same relative intensities.

This study was conducted to compare gross efficiency (GE), net efficiency (NE), work efficiency (WE), and delta efficiency (DE) between arm crank and cycle exercise at the same relative intensities. Eight college-aged males underwent two experimental trials presented in a randomized counterbalanced order. During each trial subjects performed three intermittent 7-min exercise bouts separated by 10-min rest intervals on an arm or semirecumbent leg ergometer. The power outputs for the three bouts of arm crank or cycle exercise corresponded to 50, 60, and 70% of the mode-specific VO2peak. GE, NE, and WE were determined as the ratio of Kcal.min-1 equivalent of power output to Kcal.min-1 of total energy expended, energy expended above rest and energy expended above unloaded exercise, respectively. DE was determined as the ratio of the increment of Kcal.min-1 of power output above the previous lower intensity to the increment of kcal.min-1 of total energy expended above the previous lower intensity. GE and NE did not differ between arm crank and cycle exercises. However, WE was lower (P < 0.05) during arm crank than cycle exercise at 50, 60, and 70% VO2peak. DE was also lower (P < 0.05) during arm crank than cycle exercise at delta 50-60 and at delta 60-70% VO2peak. It is concluded metabolic efficiency as determined by work and delta efficiency indices was lower during arm crank compared with cycle exercise at the same relative intensities. These findings add to the understanding of the difference in metabolic efficiency between upper and lower body exercise.

Associations between the built environment and physical activity in public housing residents

BackgroundEnvironmental factors may influence the particularly low rates of physical activity in African American and low-income adults. This cross-sectional study investigated how measured environmental factors were related to self-reported walking and vigorous physical activity for residents of low-income public housing developments.MethodsPhysical activity data from 452 adult residents residing in 12 low-income housing developments were combined with measured environmental data that examined the neighborhood (800 m radius buffer) around each housing development. Aggregated ecological and multilevel regression models were used for analysis.ResultsParticipants were predominately female (72.8%), African American (79.6%) and had a high school education or more (59.0%). Overall, physical activity rates were low, with only 21% of participants meeting moderate physical activity guidelines. Ecological models showed that fewer incivilities and greater street connectivity predicted 83% of the variance in days walked per week, p < 0.001, with both gender and connectivity predicting days walked per week in the multi-level analysis, p < 0.05. Greater connectivity and fewer physical activity resources predicted 90% of the variance in meeting moderate physical activity guidelines, p < 0.001, and gender and connectivity were the multi-level predictors, p < 0.05 and 0.01, respectively. Greater resource accessibility predicted 34% of the variance in days per week of vigorous physical activity in the ecological model, p < 0.05, but the multi-level analysis found no significant predictors.ConclusionThese results indicate that the physical activity of low-income residents of public housing is related to modifiable aspects of the built environment. Individuals with greater access to more physical activity resources with fewincivilities, as well as, greater street connectivity, are more likely to be physically active.

Substrate utilization and glucose turnover during exercise of varying intensities in individuals with NIDDM.

PURPOSE This investigation was undertaken to examine substrate utilization and glucose turnover during exercise of varying intensities in NIDDM patients. METHODS Six male NIDDM patients (N) and six male controls (C) of similar age, body weight, % body fat, and VO2peak were studied in two experimental sessions administered in a randomized counterbalanced order. During each session the subjects cycled at a power output corresponding to 50% of VO2peak or 70% of VO2peak. Duration of exercise was adjusted so that energy expenditure (EE) was equal in both the 50% and 70% trials. Isotope infusion technique and indirect calorimetry were used to assess substrate utilization and glucose turnover during exercise. RESULTS Rates of carbohydrate (CHO) and lipid oxidation increased (P < 0.05) during both the 50% and 70% trials. Rates of CHO oxidation were greater (P < 0.05) during the 70% than during the 50% trial. However, rates of lipid oxidation were similar in the two trials. No differences in rates of CHO and lipid oxidation were observed in N and C. Rates of hepatic glucose production (Ra) and plasma glucose utilization (Rd) increased (P < 0.05) during exercise, and the increases were similar in the 50% and 70% trials. Ra did not differ between N and C. However, Rd was greater (P < 0.05) in N than in C. Plasma glucose concentration decreased (P < 0.05) in N, with the decrease being similar in the 50% and 70% trials. In contrast, plasma glucose concentration remained unchanged during both the 50% and 70% trials in C. CONCLUSIONS Exercise results in a greater increase in plasma glucose utilization in patients with NIDDM compared with that in normal individuals, and this increase mediates the decline in plasma glucose concentrations in patients with NIDDM. Under isocaloric conditions, the changes in plasma glucose utilization and plasma glucose concentrations are similar during exercise of varying intensities. Despite a greater glucose utilization, carbohydrate and fat oxidation are similar in the two groups and their relations to exercise intensity are not altered by NIDDM.

Evaluation of a culturally appropriate intervention to increase physical activity.

OBJECTIVE To evaluate a culturally appropriate intervention to increase activity in overweight Mexican American women. METHODS Participants were randomly assigned to a physical activity program or wait-list control. RESULTS Treated participants were not more active than controls at 6 or 12 months. In addition, we found no significant differences in the proportion of individuals who met an objective criterion for physical activity from baseline to 6 months in the treatment or control groups. CONCLUSION The intervention did not increase physical activity in this population. Differences in baseline activity and contamination of the control group may partially account for the outcome.

Regular maternal exercise dose and fetal heart outcome.

PURPOSE Our previous research found lower fetal HR and increased HR variability (HRV) in women who exercised during pregnancy. This finding is similar to the adult heart training response at rest due to aerobic exercise. Dose-response associations have been found between physical activity and cardiorespiratory fitness in adults. Therefore, our objective was to determine whether there is a dose-response relationship between maternal physical activity and fetal HR, HRV, and sympathovagal balance. METHODS Pregnant women completed a physical activity questionnaire and magnetocardiogram (magnetic correlate to ECG) recordings at 36-wk gestational age. Women reported the duration, intensity, and frequency of each activity for each month of pregnancy as well as 3 months before pregnancy. These values were used to calculate maternal physical activity measures for each participant. Relationships between fetal HR, HRV, and sympathovagal balance at 36-wk gestational age and maternal physical activity (n = 50 pairs) during the third trimester were assessed by Spearman correlations. Regression analysis was performed to further examine these relationships after controlling for maternal and fetal covariates (maternal age, maternal resting HR, maternal weight gain, prepregnancy body mass index (BMI), and fetal activity state). RESULTS The regression analyses showed that maternal physical activity intensity (kcal·min(-1)) was negatively associated with HR in the active fetal state (P < 0.05), and physical activity duration (minutes during the third trimester) was positively associated with fetal HRV (P < 0.05). There were no statistically significant relationships with maternal physical activity on measures of fetal sympathovagal balance. CONCLUSIONS Maternal physical activity dose during the third trimester is associated with resting fetal heart effects similar to a trained response. Future studies on the health benefits of this fetal response are highly warranted.

Effect of Carbohydrate Substrate Availability on Ratings of Perceived Exertion during Prolonged Exercise of Moderate Intensity

This investigation examined the effect of carbohydrate substrate availability on ratings of perceived exertion (RPE) during cycling at moderate intensity to exhaustion and the relation between submaximal endurance performance and RPE obtained following 2 hr. of cycling at moderate intensity. Seven male cyclists performed two exercise trials at power output corresponding to 70% of their peak oxygen uptake until exhaustion. Subjects ingested either a 6% glucose/sucrose solution at the rate of 0.6 g · kg−1 (Body Weight) · hr.−1 or an equal volume of artificially flavored placebo every 20 min. throughout the exercise trials. RPE for the legs, chest, and over-all body, and oxygen consumption, expired ventilation, carbohydrate oxidation rate, and blood concentrations of glucose, glycerol, and lactate were measured every 20 min. throughout exercise and at exercise termination. Statistical analysis of these dependent variables indicates that (1) an exercise-induced decrease in blood-borne carbohydrate substrate intensifies leg and over-all perceptions of exertion during the later stages of prolonged cycling at 70% VO2peak. (2) Factors other than availability of blood-borne carbohydrate substrate may influence perceptual intensity at exhaustion. (3) Ratings of perceived exertion for the legs and over-all body obtained after 2 hr. of cycling at moderate intensity may be useful in predicting submaximal endurance performance.

Stages of Change Among Ethnically Diverse College Students

Abstract The authors applied the stage-of-change construct in the transtheoretical model to examine the distribution of Asian (n = 869), African American (n = 373), White (n = 1322), and Hispanic (n = 535) American undergraduate students across the 5 stages of change for exercise. Stage of change varied as a function of ethnicity. Higher percentages of minorities were in the precontemplation and contemplation stages. The likelihood of being in these stages was from 43% to 82% greater for minorities than for White students. Also examined were the congruency between stage of change and self-reported levels of physical activity. Half of the sedentary students and 15.6% of the active students were misclassified by the stage-of-change procedure. Misclassification rates were higher for minority women (27.8%) than for White women (17.8%) and for Asian students (24.6%) compared with all others (20.6%). The results of this study have implications for the design of physical activity interventions based on stage of change.

Obesity Classification in Military Personnel: A Comparison of Body Fat, Waist Circumference, and Body Mass Index Measurements

OBJECTIVE The purpose of this study was to evaluate obesity classifications from body fat percentage (BF%), body mass index (BMI), and waist circumference (WC). METHODS A total of 451 overweight/obese active duty military personnel completed all three assessments. RESULTS Most were obese (men, 81%; women, 98%) using National Institutes of Health (NIH) BF% standards (men, >25%; women, >30%). Using the higher World Health Organization (WHO) BF >35% standard, 86% of women were obese. BMI (55.5% and 51.4%) and WC (21.4% and 31.9%) obesity rates were substantially lower for men and women, respectively (p < 0.05). BMI/WC were accurate discriminators for BF% obesity (theta for all comparisons >0.75, p < 0.001). Optimal cutoff points were lower than NIH/WHO standards; WC = 100 cm and BMI = 29 maximized sensitivity and specificity for men, and WC = 79 cm and BMI = 25.5 (NIH) or WC = 83 cm and BMI = 26 (WHO) maximized sensitivity and specificity for women. CONCLUSIONS Both WC and BMI measures had high rates of false negatives compared to BF%. However, at a population level, WC/BMI are useful obesity measures, demonstrating fair-to-high discriminatory power.

Web-Assisted Instruction for Changing Social Cognitive Variables Related to Physical Activity.

The authors examined the efficacy of Web-assisted instruction for promoting the use of social cognitive theory (SCT) strategies related to physical activity. They recruited college students attending health courses. The authors created 3 groups (Web-assisted, comparison, and control) based on the course structure. The Web-assisted group received information on exercise and fitness and a Web-based program (treatment, n = 127); 7 sections received the same exercise and fitness information as the treatment condition, but no Web-based program (comparison, n = 118); and 6 sections received information in unrelated areas (control, n = 178). The Web-based program consisted of 9 Web assignments (1 per week) that targeted key SCT variables. Satisfaction with the Web-based program was high. Use of self-regulation strategies was significantly higher at posttest in the treatment group than it was in the other groups. Knowledge concerning the skills taught by the Web assignments was significantly greater in the treatment group than it was in the comparison group. The results of this study demonstrate that a Web-based instructional program has a positive impact on knowledge and skills related to SCT strategies for changing physical activity behavior.