Lauren Gulka, James Dziura and Loretta DiPietro
Little attention has been paid to the study of transient growth hormone (GH) responses to exercise in older women. We determined the effect of a single bout of exercise on GH in fit and unfit older (age 55 to 81 y; n = 19) and younger (age 18 to 25 y; n = 19) women.
Exercise consisted of five 15-min intervals of treadmill exercise at 75% VO2peak. Blood samples were taken before, during, and following exercise for determination of plasma GH and insulin concentrations.
GH responses to exercise were attenuated in older compared with younger women (P < 0.01); however, these age differences were minimized in older age by fitness level. Adjusted area under the curve for GH was 5.50 and 1.76 µg/L · 102 for fit and unfit older women (P < 0.01), and 8.46 and 8.46 µg/L · 102 for fit and unfit younger women.
Low levels of cardiorespiratory fitness in older women may require a greater relative exercise stimulus to augment meaningful GH responses.
Mira Kahn, Kim Robien and Loretta DiPietro
Preterm birth is a leading cause of infant death and the role of maternal physical activity on this risk remains unclear. This systematic review examined low, moderate and vigorous leisure-time physical activity (LTPA) during pregnancy and the outcome of preterm birth.
Key words related to preterm birth and physical activity were used to search relevant databases (Medline, Cochrane, CINAHL, Sports Discuss and Scopus). Studies were excluded if they did not measure physical activity as an exposure in pregnant women, did not provide information on gestational age at delivery, and were not published in English. All study designs and sample sizes were considered.
The search generated 1472 studies. There were 27 studies included in this review of which 23 received high quality reporting scores. Eleven studies reported a lower risk of preterm birth for women who performed LTPA during pregnancy, while 14 studies reported null findings. Only 2 studies detected a significantly higher risk of preterm birth with LTPA during pregnancy.
This review of literature up to 2014 provides additional evidence to support the assertion that healthy pregnant women can engage in low, moderate, and even some vigorous levels of LTPA without risk for preterm birth.
Emily Goodman, W. Douglas Evans and Loretta DiPietro
The school setting could be a primary venue for promoting physical activity among inner-city children due to the structured natured of the school day. We examined differences in step counts between structured school days (SSD) and weekend days (WED) among a sample of public school children in Washington, DC.
Subjects (N = 29) were third- to sixth-grade students enrolled in government-funded, extended-day enrichment programs. Step counts were measured using a pedometer (Bodytronics) over 2 SSD and 2 WED. Differences in mean step counts between SSD and WED were determined using multivariable linear regression, with adjustments for age, sex, and reported distance between house and school (miles).
Recorded step counts were low on both SSD and WED (7735 ± 3540 and 8339 ± 5314 steps/day). Boys tended to record more steps on SSD compared with girls (8080 ± 3141 vs. 7491 ± 3872 steps/day, respectively), whereas girls recorded more steps on the WED compared with boys (9292 ± 6381 vs. 7194 ± 3669 steps/day). Parameter estimates from the regression modeling suggest distance from school (P < .01) to be the strongest predictor of daily step counts, independent of day (SSD/WED), sex, and age.
Among inner-city school children, a safe walking route to and from school may provide an important opportunity for daily physical activity.
Loretta DiPietro, Catherine W. Yeckel and James Dziura
Few studies have compared long-term moderate-intensity aerobic versus light-resistance training on serial improvements in glucose tolerance in older people.
Healthy, inactive older (74 ± 5 [SD] years) women (N = 20) were randomized into either a high-volume, moderate-intensity aerobic (ATM, n = 12) or a lower-intensity resistance training (RTL, n = 8) group. Both groups exercised under supervision 4 times per week for 45- to 60-minute sessions over 9 months. Measurements of plasma glucose, insulin, and free fatty acid (FFA) responses to an oral glucose tolerance test (OGTT) were performed at baseline and at 3, 6, and 9 months 48 hours after the last exercise session.
We observed significant improvements in 2-hour glucose concentrations at 3, 6, and 9 months among women in the RTL (152 ± 42 vs 134 ± 33 vs 134 ± 24 vs 130 ± 27 mg · dL−1; P < .05), but not the ATM (151 ± 25 vs 156 ± 37 vs 152 ± 40 vs 155 ± 39 mg · dL−1) group. These improvements were accompanied by an 18% (P < .07) decrease in basal FFA concentrations in the RTL group, whereas basal and 30-minute FFA concentrations increased (P < .05) after training in the ATM group.
These findings suggest that the net physiological benefits of exercise might have been blunted in the ATM group, owing to higher circulating levels of FFA, which might have temporarily interfered with insulin action.
Kerem Shuval, Eyal Weissblueth, Mayer Brezis, Adan Araida and Loretta DiPietro
Ample research has assessed correlates of physical activity (PA) among college students; however, socioenvironmental correlates of PA have not been assessed in Arab and Jewish Israeli college students.
Cross-sectional study of 198 Arab and Jewish physical education college students. The dependent variable was meeting the CDC/ACSM guidelines for moderate/vigorous PA. Independent variables consisted of individual variables (eg, ethnicity, gender, religious observance) and socioenvironmental variables (eg, street lighting, family support, exercise facilities). Bivariate and multivariate analyses were used.
Thirty-three percent of the students met the recommended guidelines for PA. Individual variables were more highly correlated with PA than socioenvironmental variables. In the final logistic-regression model 3 individual covariates independently predicted PA: gender, race/ethnicity, and self-efficacy. Access to open space was the only environmental variable significantly correlated with PA.
The results underscore the need to implement an intervention program aimed at promoting the recommended levels of PA among Arab and Jewish Israeli physical education college students, while tailoring the intervention to individual risk markers for physical inactivity (eg, race/ethnicity, gender).
Nicole Alfonsin, Vienna McLeod, Angela Loder and Loretta DiPietro
Jean Gutierrez, Andrei Gribok, William Rumpler, Avinash Chandran and Loretta DiPietro
People with a family history of type 2 diabetes have lower energy expenditure (EE) and more obesity than those having no such family history. Resistance exercise (RE) may induce excess postexercise energy expenditure (EPEE) and reduce long-term risk for obesity in this susceptible group.
To determine the effect of RE on EPEE for 15 hr after a single exercise bout in healthy, untrained young men having a family history of type 2 diabetes.
Seven untrained men (23 ± 1.2 years, BMI 24 ± 1.1) completed a 48-hr protocol in a whole room calorimeter. The first day served as a control day, with a moderate 40-min RE bout occurring on the second day. Differences in postexercise EE were compared with matched periods from the control day for cumulative 15-min intervals (up to 150 min) and 15 hr after the RE bout was completed.
The most robust difference in EPEE between the experimental and control days was observed in the first 15-min postexercise period (M = 1.4Kcal/min; SD = 0.7; p < .05). No statistically significant differences in EPEE were noted beyond 90-min of continuous measurement.
Young people with a family history of type 2 diabetes may not show EPEE after a single RE bout when observed for 15 hr after RE and long-term resistance training may be required to promote EPEE.