Lance C. Dalleck

Dose-response relationship between moderate-intensity exercise duration and coronary heart disease risk factors in postmenopausal women.

PURPOSE This study was designed to investigate whether, in a dose-response manner, there would be greater health benefits in a group of postmenopausal women completing 45 minute- vs. 30 minutes of moderate intensity (50% maximal oxygen uptake reserve, VO2R) exercise 5 days . wk(-1). METHODS Apparently healthy but sedentary postmenopausal women (n = 33) were randomized to a nonexercise control group, a 30-minute exercise duration group, or a 45-minute exercise duration group. Exercise training was performed 5 days . wk(-1) for 12 weeks at 50% VO2R. Participants were instructed to not change their usual diet throughout the study. RESULTS Twenty-six women completed the study. After 12 weeks, VO2max increased significantly (p < 0.05) in both 30-minute (0.20 +/- 0.21 L . min(-1)) and 45-minute (0.41 +/- 0.10 L . min(-1)) groups. Repeated measures ANOVA identified a significant interaction between exercise duration and VO2max values (F = 4.72, p < 0.05), indicating that VO2max responded differently to 30-minute and 45-minute exercise durations. Trend analysis showed that body mass, body composition, waist circumference, and high-density lipoprotein cholesterol (HDL-C) changed favorably (p < 0.05) across control, 30-minute, and 45-minute groups. CONCLUSIONS Although most health organizations agree that 150 min . wk(-1) of physical activity will reduce the risk of all-cause and cardiovascular mortality, few randomized, controlled studies have examined whether completing more physical activity than the recommended amount will yield additional benefits. Findings from the present study suggest that there is a dose-response relationship between exercise duration and numerous health outcomes in postmenopausal women, including cardiorespiratory fitness, body mass, body composition, waist circumference, and HDL-C.

Cardiac rehabilitation outcomes in a conventional versus telemedicine-based programme:

We studied patients who were eligible for phase II cardiac rehabilitation. Rehabilitation was delivered either conventionally or by telemedicine using videoconferencing. There were 226 participants: 173 at the conventional site and 53 at the telemedicine site. At baseline, blood pressure, anthropometric measurements, lipid profiles, activity levels, dietary intake and behaviours were assessed. Assessments at baseline were repeated after 12 weeks, at the end of the rehabilitation programme. There were no significant differences (P > 0.05) in the change from baseline to post-programme values between the conventional and the telemedicine groups. The results show the suitability of telemedicine for delivering cardiac rehabilitation for risk factor modification and exercise monitoring to patients who otherwise would not have access to it.

The Prevalence of Metabolic Syndrome and Metabolic Syndrome Risk Factors in College-Aged Students

Purpose. Metabolic syndrome (MetS) is characterized by a constellation of metabolic risk factors that consist of the following: atherogenic dyslipidemia, elevated blood pressure, elevated glucose associated with insulin resistance, prothrombotic state, and proinflammatory state. The objective of the study was to quantify the prevalence of MetS among college students and to determine whether fatness (body mass index [BMI] and waist circumference) or physical activity was more strongly associated with individual components of the MetS. Design. A cross-sectional study. Setting. Eau Claire, Wisconsin, United States. Subjects. Authors collected health history information and performed assessments of individual MetS components for 207 college students aged 18 to 24 years. Measures. Physical activity levels were self-reported, while direct measurements were obtained for MetS components (waist circumference, blood pressure, high-density lipoprotein (HDL)–cholesterol, triglycerides, blood glucose). Analysis. Descriptive statistics and multiple regression analysis. Results. The prevalence of MetS was found to be 6.8% according to the National Cholesterol Education Program Adult Treatment Panel III guidelines. The authors also found that 42.5% and 13.0% of our sample had one and two MetS components, respectively. Waist circumference was independently associated (p < .05) with HDL-cholesterol, triglycerides, and systolic blood pressure. Conclusion. Our findings provide evidence for the presence of MetS on college campuses. It also appears, in part, that central adiposity contributes to the high incidence of individual MetS components. Given the elevated lifetime risk for cardiovascular disease and lower survival for those with risk factors in young adulthood, there appears to be a need for primary prevention programs within university and college settings.

A community-based exercise intervention transitions metabolically abnormal obese adults to a metabolically healthy obese phenotype

Background Lower habitual physical activity and poor cardiorespiratory fitness are common features of the metabolically abnormal obese (MAO) phenotype that contribute to increased cardiovascular disease risk. The aims of the present study were to determine 1) whether community-based exercise training transitions MAO adults to metabolically healthy, and 2) whether the odds of transition to metabolically healthy were larger for obese individuals who performed higher volumes of exercise and/or experienced greater increases in fitness. Methods and results Metabolic syndrome components were measured in 332 adults (190 women, 142 men) before and after a supervised 14-week community-based exercise program designed to reduce cardiometabolic risk factors. Obese (body mass index ≥30 kg · m2) adults with two to four metabolic syndrome components were classified as MAO, whereas those with no or one component were classified as metabolically healthy but obese (MHO). After community exercise, 27/68 (40%) MAO individuals (P<0.05) transitioned to metabolically healthy, increasing the total number of MHO persons by 73% (from 37 to 64). Compared with the lowest quartiles of relative energy expenditure and change in fitness, participants in the highest quartiles were 11.6 (95% confidence interval: 2.1–65.4; P<0.05) and 7.5 (95% confidence interval: 1.5–37.5; P<0.05) times more likely to transition from MAO to MHO, respectively. Conclusion Community-based exercise transitions MAO adults to metabolically healthy. MAO adults who engaged in higher volumes of exercise and experienced the greatest increase in fitness were significantly more likely to become metabolically healthy. Community exercise may be an effective model for primary prevention of cardiovascular disease.

Development of a Submaximal Test to Predict Elliptical Cross-Trainer Vo2max

The purpose of this study was to develop an equation to predict VO2max from a submaximal elliptical cross-trainer test. Fifty-four apparently healthy subjects (25 men and 29 women, mean +/- SD age: 29.5 +/- 7.1 years, height: 173.3 +/- 12.6 cm, weight: 72.3 +/- 7.9 kg, percent body fat: 17.3 +/- 5.0%, and elliptical cross-trainer VO2max: 43.9 +/- 7.2 ml x kg(-1) x min(-1)) participated in the study and were randomly assigned to an original sample group (n = 40) and a cross-validation group (n = 14). Each subject completed an elliptical cross-trainer submaximal (3 5-minute submaximal stages) and a VO2max test on the same day, with a 15-minute rest period in between. Stepwise multiple regression analyses were used to develop an equation for estimating elliptical cross-trainer VO2max from the data of the original sample group. The accuracy of the equation was tested by using data from the cross-validation group. Because there was no shrinkage in R2 between the original sample group and the cross-validation group, data were combined in the final prediction equation (R2 = 0.732, standard error of the estimate = 3.91 ml x kg(-1) x min(-1), p < 0.05): VO2max = 73.676 + 7.383(gender) - 0.317(weight) + 0.003957(age x cadence) - 0.006452(age x heart rate at stage 2). The correlation coefficient between the predicted and measured VO2max values was r = 0.86. Dependent t-tests resulted in no significant differences (p > 0.05) between predicted (43.8 ml x kg(-1) x min(-1)) and measured (43.9 ml x kg(-1) x min(-1)) VO2max measurements. Results indicate that the protocol and equation developed in the current study can be used by exercise professionals to provide acceptably accurate estimates of VO2max in non-laboratory-based settings.

Graded Exercise Testing Protocols for the Determination of VO2max: Historical Perspectives, Progress, and Future Considerations

Graded exercise testing (GXT) is the most widely used assessment to examine the dynamic relationship between exercise and integrated physiological systems. The information from GXT can be applied across the spectrum of sport performance, occupational safety screening, research, and clinical diagnostics. The suitability of GXT to determine a valid maximal oxygen consumption (VO2max) has been under investigation for decades. Although a set of recommended criteria exists to verify attainment of VO2max, the methods that originally established these criteria have been scrutinized. Many studies do not apply identical criteria or fail to consider individual variability in physiological responses. As an alternative to using traditional criteria, recent research efforts have been directed toward using a supramaximal verification protocol performed after a GXT to confirm attainment of VO2max. Furthermore, the emergence of self-paced protocols has provided a simple, yet reliable approach to designing and administering GXT. In order to develop a standardized GXT protocol, additional research should further examine the utility of self-paced protocols used in conjunction with verification protocols to elicit and confirm attainment of VO2max.

Suitability of Verification Testing to Confirm Attainment of VO2max in Middle-Aged and Older Adults

The aim of the present study was to test the utility of the verification testing procedure in confirming “true” VO2max in older adults completing maximal cycle ergometry. Eighteen physically active men and women (age = 59.7 ± 6.3 yr, ht = 173.0 ± 8.8 cm, body mass = 83.2 ± 16.4 kg, VO2max = 27.7 ± 5.0 mL/kg/min) completed incremental exercise, and returned 1 h after incremental exercise to complete a verification phase of constant load exercise at 105% peak work rate. During exercise, gas exchange data and heart rate (HR) were continuously monitored. VO2max was similar (p > 0.05) between incremental and verification bouts (2329 ± 762 mL/min vs. 2309 ± 760 mL/min). Findings support use of the verification procedure to confirm VO2max attainment in active, middle-aged and older adults completing incremental cycle ergometry. This is particularly relevant to interpretation of studies that have used repeated measurements of VO2max to establish a training effect or when VO2max is used for designing exercise prescriptions.

Physical activity recommendations and cardiovascular disease risk factors in young Hispanic women

Abstract Despite the benefits associated with regular physical activity, there is little epidemiological evidence to support positive health outcomes when meeting physical activity guidelines in high-risk ethnic groups, such as Hispanic women. We compared cardiovascular disease risk factors between young Hispanic women who meet and those who do not meet current physical activity guidelines. Height, weight, waist circumference, and blood pressure were measured in 60 Hispanic women aged 20–39 years. Lipids, C-reactive protein, insulin, and glucose were assessed. Body composition and cardiovascular fitness were assessed by BodPod and maximal oxygen uptake (VO2max) respectively. Participants wore an accelerometer and average minutes (assessed in 10-min bouts) spent in light, moderate, and hard daily activity for weekdays and weekends was determined. Seventy percent of participants did not meet the recommended physical activity guidelines, whereas 30% did so. Following current physical activity guidelines was associated with significantly lower mean cholesterol (mean ± s: 4.2 ± 0.8 vs. 4.7 ± 0.9 mmol · l−1) and triglycerides (0.7 ± 0.3 vs. 1.1 ± 0.6 mmol · l−1), and higher fat-free mass (43.3 ± 3.8 vs. 40.2 ± 5.1 kg) and relative (40.4 ± 7.6 vs. 35.6 ± 7.0 ml · kg−1 · min−1) and absolute (2.5 ± 0.3 vs. 2.1 ± 0.4 litres · min−1) VO2max (P < 0.05). These findings suggest an improved health status in women who meet versus those who did not meet current physical activity guidelines.

A moderate-intensity exercise program fulfilling the American College of Sports Medicine net energy expenditure recommendation improves health outcomes in premenopausal women.

The purpose of this study was to assess and quantify the health outcomes associated with a moderate-intensity (50% &OV0312;o2R) exercise program designed to achieve the American College of Sports Medicine net caloric expenditure guideline of 1,000 kcal·wk−1. Fifteen apparently healthy but sedentary premenopausal women with the baseline characteristics (mean ± SD age, height, weight, body composition, and &OV0312;o2max: 37.4 ± 6.3 yr, 166.2 ± 6.2 cm, 72.1 ± 11.2 kg, 32.5 ± 5.8%, and 34.8 ± 5.8 mL·kg−1·min−1, respectively) participated in and completed the study. Exercise training was performed 3-4 days per week for 10 weeks in a progressive manner at moderate intensity (50% &OV0312;o2R). There were significant (P < 0.05) improvements in &OV0312;o2max (+2.5 mL·kg−1·min−1), systolic (−13.7 mm Hg) and diastolic (−6.4 mm Hg) blood pressure, high-density lipoprotein cholesterol (+3.2 mg·dL−1), fasting blood glucose (−4.9 mg·dL−1), and percent body fat (−1.6%). Although the American College of Sports Medicine specifies that the energy expenditure goal should be a net caloric expenditure of 1,000 kcal·wk−1 and classifies relative moderate intensity as 40-59% of heart rate reserve or &OV0312;o2R, we are unaware of any previous investigations that have examined the specific health outcomes associated with an exercise program fulfilling these requirements. Results indicate that significant health benefits will be conferred to previously sedentary, premenopausal women who engage in a moderate-intensity, 10-week exercise program designed to fulfill the net energy expenditure guideline of 1,000 kcal·wk−1.

Effects of High-Intensity Interval Training on People Living with Type 2 Diabetes: A Narrative Review

People with type 2 diabetes typically present with comorbidities, such as elevated blood pressure, high cholesterol, high blood glucose, obesity and decreased fitness, all contributive to increased risk for cardiovascular complications. Determination of effective exercise modalities for the management of such complications is important. One such modality is high-intensity interval training (HIIT). To conduct the review, PubMed and EBSCOHost databases were searched through June 1, 2016, for all HIIT intervention studies conducted in people living with type 2 diabetes. Thereafter, the central characteristics of HIIT were analyzed to obtain a broader understanding of the cardiometabolic benefits achievable by HIIT. Fourteen studies were included for review, but the heterogeneity of the participants with type 2 diabetes, the training equipment and HIIT parameters, accompanied by variations in supervision, dietary advice and medications, prevented direct comparisons. However HIIT, regardless of the specific parameters employed, was a suitable option in pursuing improved glycemic control, body composition, aerobic fitness, blood pressure and lipidemia measures in individuals with type 2 diabetes. HIIT is a therapy with at least equivalent benefit to moderate-intensity continuous training; hence, HIIT should be considered when prescribing exercise interventions for people living with type 2 diabetes.