716 research outputs found
HRR and V˙O2R Fractions Are Not Equivalent: Is It Time to Rethink Aerobic Exercise Prescription Methods?
No full textIntroduction: According to current guidelines, the intensity of health-enhancing aerobic exercise should be prescribed using a percentage of heart rate reserve (%HRR), which is considered to be more closely associated (showing a 1:1 relation) with the percentage of oxygen uptake reserve (%V̇O2R) rather than with the percentage of maximal oxygen uptake (%V̇O2max) during incremental exercise. However, the associations between %HRR and %V̇O2R and between %HRR and %V̇O2max are under debate; hence, their actual relationships were investigated in this study. Methods: Data from each stage of a maximal incremental exercise test performed by 737 healthy and physically inactive participants of the HERITAGE Family Study were screened and filtered, then used to calculate the individual linear regressions (ILR) between %HRR and either %V̇O2R or %V̇O2max. For each relationship, the mean slope and intercept of the ILRs were compared to 1 and 0 (i.e., the identity line), respectively, using one-sample t-tests. The individual root mean square errors (RMSE) of the actual vs. the 1:1 predicted %HRR were calculated for both relationships and compared using a paired-sample t-test. Results: The mean slopes (%HRR-%V̇O2R: 0.972±0.189; %HRR-%V̇O2max: 1.096±0.216) and intercepts (%HRR-%V̇O2R: 8.855±16.022; %HRR-%V̇O2max: −3.616±18.993) of both relationships were significantly different from 1 and 0, respectively, with high inter-individual variability. The average RMSEs were high and revealed that the %HRR-%V̇O2max relationship was more similar to the identity line (p<0.001) than the %HRR-%V̇O2R relationship (7.78±4.49% vs. 9.25±5.54%). Conclusions: Since both relationships are different from the identity line and using a single equation may not be appropriate to predict exercise intensity at the individual level, a re-thinking of the relationships between the intensity variables may be necessary to ensure that the most suitable health-enhancing aerobic exercise intensity is prescribed
Effect of individual characteristics and aerobic training on the %HRR-%V ̇O2R relationship
No full textThis study aimed to assess if, during incremental exercise, considering individual characteristics can make the relationship between the percentages of heart rate (HRR) and oxygen uptake (VO2R) reserve either 1:1 or more accurate. Cycle ergometer data of the maximal incremental exercise tests performed by 450 healthy and sedentary participants (17-66 years) of the HERITAGE Family Study, grouped for sex, ethnicity, age, body fat, resting HR, and VO2max, were used to calculate the individual linear regressions between %HRR and %VO2R. The mean slope and intercept of the individual linear regressions of each subgroup were compared with 1 and 0 (identity line), respectively, using Hotelling tests followed by post-hoc one-sample t-tests. Two multiple linear regressions were also performed, using either the slopes or intercepts of the individual linear regressions as dependent variables and sex, age, resting HR, and VO2max as independent variables. The mean %HRR-%VO2R relationships of all subgroups differed from the identity line. Moreover, individual linear regression intercepts (8.9±16.0) and slopes (0.971±0.190) changed (p<0.001) after 20 weeks of aerobic training (13.1±11.1 and 0.891±0.122). The multiple linear regressions could explain only 3.8% and 1.3% of the variance in the intercepts and slopes, whose variability remained high (standard error of estimate of 15.8 and 0.189). In conclusion, the %HRR-%VO2R relationship differs from the identity line regardless of individual characteristics and their difference increased after aerobic training. Moreover, due to the high interindividual variability, using a single equation for the whole population seems not suitable for representing the %HRR-%VO2R relationship of a given subject, even when several individual characteristics are considered
ENDURANCE EXERCISE TRAINING IMPROVES THE ANTI-OXIDATIVE PROPERTIES OF HIGH-DENSITY LIPOPROTEINS (HDL)
No full textCharles S. Schwartz1, Jacob L. Barber2,,1, Sujoy Ghosh3,,4, Anand Rohatgi5, Theodoros Kelesidis6, Claude Bouchard, FACSM4, Mark A. Sarzynski, FACSM1. 1University of South Carolina, Columbia, SC. 2Beth Israel Deaconess Medical Center, Boston, MA. 3Duke-National University of Singapore Medical School, Singapore. 4Pennington Biomedical Research Center, Baton Rouge, LA. 5University of Texas Southwestern Medical Center, Dallas, TX. 6University of California Los Angeles, Los Angeles, CA.
BACKGROUND: The functional properties of high-density lipoproteins (HDL), such as reduced antioxidant function that is linked to increased HDL lipid peroxidation (HDLox), may be more indicative of cardiovascular risk than HDL cholesterol (HDL-C) concentrations. Although exercise is well known to improve HDL-C, the effects of chronic exercise on HDLox are less understood. PURPOSE: To examine changes in HDLox in response to exercise training and how these changes relate to concomitant changes in other HDL-related traits. METHODS: HDLox was quantified in apoB-depleted serum before and after 20 weeks of endurance exercise training in 149 subjects (age 34.3±13.3 years, 60% female, 30% self-identified Black) from the HERITAGE Family study using the Amplex Red cholesterol assay (Invitrogen). A lower HDLox indicates improved HDL function. Exercise induced changes were calculated as the difference between post-training and baseline values. Exercise response was examined via paired t-tests in the total sample and stratified by sex. Partial correlations controlling for age, sex, and race were performed to investigate associations between HDLox and HDL traits in response to exercise training. RESULTS: HDLox significantly decreased following exercise training (mean -3.1%, standard error (SEM) 2.0, p=0.004). HDLox training response differed by sex (p=0.01), with females showing a significant decrease (-7.3%, SEM 2.6%, p=0.0006), whiles males exhibited no change (3.2%, SEM 3.0%, p=0.87). Exercise-induced changes in HDLox were inversely correlated with concomitant changes in HDL-C (r= -0.57, p\u3c0.0001), apoA-I (r= -0.30, p\u3c0.0001), and HDL-TG (r= -0.20, p=0.03). Additionally, changes in HDL particle size (r= -0.33, p=0.002) and the concentrations of total (r= -0.20, p=0.03), large (r= -0.27, p=0.002), and medium (r= -0.19, p=0.03) HDL particles were inversely correlated with change in HDLox. Change in small HDL particle concentration and cholesterol efflux capacity were not associated with change in HDLox. CONCLUSION: Endurance exercise training improved HDL function with respect to its anti-oxidative properties. Improvements in HDLox appear stronger in women and related to increases in HDL-C, HDL size, and the concentration of medium and large HDL subclasses. Further studies are needed to identify the mechanisms underlying sex differences, including differences in endogenous hormone levels
Mountain megas: America\u27s newest metropolitan places and a federal leadership to help them prosper
No full textThe Initiative The Brookings Institution and the University of Nevada, Las Vegas, are collaborating to bring Brookings’ high-quality, independent and impactful research to the issues facing the dynamic and fast-growing Mountain West region: the states of Arizona, Colorado, Nevada, New Mexico, and Utah. Every year, Brookings will send scholars from each of its five research programs to spend three weeks at UNLV to conduct research, meet with faculty, and deliver lectures and seminars. The project begins September 8, 2009, with presentations on national and local trends. The new initiative builds upon the work of Brookings’ Metropolitan Policy Program, which focuses on helping metropolitan areas like Las Vegas grow in robust, inclusive, and sustainable ways. But Brookings Mountain West will go farther by bringing to the region the perspective of Brookings experts on domestic and international economic policy, foreign policy, and governance
Mountain megas: America\u27s newest metropolitan places and a federal leadership to help them prosper
No full textThe Initiative The Brookings Institution and the University of Nevada, Las Vegas, are collaborating to bring Brookings’ high-quality, independent and impactful research to the issues facing the dynamic and fast-growing Mountain West region: the states of Arizona, Colorado, Nevada, New Mexico, and Utah. Every year, Brookings will send scholars from each of its five research programs to spend three weeks at UNLV to conduct research, meet with faculty, and deliver lectures and seminars. The project begins September 8, 2009, with presentations on national and local trends. The new initiative builds upon the work of Brookings’ Metropolitan Policy Program, which focuses on helping metropolitan areas like Las Vegas grow in robust, inclusive, and sustainable ways. But Brookings Mountain West will go farther by bringing to the region the perspective of Brookings experts on domestic and international economic policy, foreign policy, and governance
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