Genome-Wide Genetic Analysis of Dropout in a Controlled Exercise Intervention in Sedentary Adults With Overweight or Obesity and Cardiometabolic Disease.

BACKGROUND: Despite the benefits of exercise, many individuals are unable or unwilling to adopt an exercise intervention. PURPOSE: The purpose of this analysis was to identify putative genetic variants associated with dropout from exercise training interventions among individuals in the STRRIDE trials. METHODS: We used a genome-wide association study approach to identify genetic variants in 603 participants initiating a supervised exercise intervention. Exercise intervention dropout occurred when a subject withdrew from further participation in the study or was otherwise lost to follow-up. RESULTS: Exercise intervention dropout was associated with a cluster of single-nucleotide polymorphisms with the top candidate being rs722069 (T/C, risk allele = C) (unadjusted p = 2.2 × 10-7, odds ratio = 2.23) contained within a linkage disequilibrium block on chromosome 16. In Genotype-Tissue Expression, rs722069 is an expression quantitative trait locus of the EARS2, COG7, and DCTN5 genes in skeletal muscle tissue. In subsets of the STRRIDE genetic cohort with available muscle gene expression (n = 37) and metabolic data (n = 82), at baseline the C allele was associated with lesser muscle expression of EARS2 (p < .002) and COG7 (p = .074) as well as lesser muscle concentrations of C2- and C3-acylcarnitines (p = .026). CONCLUSIONS: Our observations imply that exercise intervention dropout is genetically moderated through alterations in gene expression and metabolic pathways in skeletal muscle. Individual genetic traits may allow the development of a biomarker-based approach for identifying individuals who may benefit from more intensive counseling and other interventions to optimize exercise intervention adoption. CLINICAL TRIAL INFORMATION: STRRIDE I = NCT00200993; STRRIDE AT/RT = NCT00275145; STRRIDE-PD = NCT00962962.

Regular participation in exercise can provide a myriad of health benefits. Although individuals recognize these benefits, many are unable or unwilling to adopt an exercise intervention once initiated. The purpose of this analysis was to identify genetic variants associated with dropout from an exercise training intervention. We found exercise intervention dropout to be genetically moderated through changes in gene expression and metabolic pathways in muscle. Thus, individual genetic traits may allow for the development of a biomarker-based targeted approach for identifying individuals who may benefit from more intensive counseling and interventions to optimize the adoption of an exercise intervention program.

Cardiopulmonary Exercise Testing in the Coronavirus Disease - 2019 Era: Safety and Protocol Considerations.

ABSTRACT: Cardiopulmonary exercise testing (CPX) is a valuable tool in both clinical practice and research settings. Therefore, it is advantageous for human performance laboratories to continue operating during the coronavirus disease 2019 (COVID-19) pandemic. All institutions should adhere to general COVID-19 guidelines provided by the Centers for Disease Control. Because of the testing environment, CPX laboratories must consider additional precautionary safety measures. This article provides recommendations for modifying the CPX protocol to ensure safety for all stakeholders during the pandemic. These modifications are universal across all populations, types of institutions and testing modalities. Preliminary measures include careful review of federal, local, and institutional mandates. The description outlines how to evaluate a testing environment and alter workflow. Guidelines are provided on what specific personal protective equipment should be acquired; as well as necessary actions before, during, and after the CPX test. These precautions will limit the possibility of both clients and staff from contracting or spreading the disease while maintaining testing volume in the laboratory.

Effect of Remotely Supervised Weight Loss and Exercise Training Versus Lifestyle Counseling on Cardiovascular Risk and Clinical Outcomes in Older Adults With Rheumatoid Arthritis: A Randomized Controlled Trial.

OBJECTIVE: To compare a remotely supervised weight loss and exercise intervention to lifestyle counseling for effects on cardiovascular disease risk, disease activity, and patient-reported outcomes in older patients with rheumatoid arthritis (RA) and overweight/obesity. METHODS: Twenty older (60-80 years), previously sedentary participants with seropositive RA and overweight/obesity were randomized to 16 weeks of either Supervised Weight loss and Exercise Training (SWET) or Counseling Health As Treatment (CHAT). The SWET group completed aerobic training (150 minutes/week moderate-to-vigorous intensity), resistance training (two days/week), and a hypocaloric diet (7% weight loss goal). The CHAT control group completed two lifestyle counseling sessions followed by monthly check-ins. The primary outcome was a composite metabolic syndrome z-score (MSSc) derived from fasting glucose, triglycerides, high density lipoprotein-cholesterol, minimal waist circumference, and mean arterial pressure. Secondary outcomes included RA disease activity and patient-reported outcomes. RESULTS: Both groups improved MSSc (absolute change -1.67 ± 0.64 in SWET; -1.34 ± 1.30 in CHAT; P < 0.01 for both groups) with no between-group difference. Compared with CHAT, SWET significantly improved body weight, fat mass, Disease Activity Score-28 C-reactive protein, and patient-reported physical health, physical function, mental health, and fatigue (P < 0.04 for all between-group comparisons). Based on canonical correlations for fat mass, cardiorespiratory fitness, and leg strength, component-specific effects were strongest for (1) weight loss improving MSSc, physical health, and mental health; (2) aerobic training improving physical function and fatigue; and (3) resistance training improving Disease Activity Score-28 C-reactive protein. CONCLUSION: In older patients with RA and overweight/obesity, 16 weeks of remotely supervised weight loss, aerobic training, and resistance training improve cardiometabolic health, patient-reported outcomes, and disease activity. Less intensive lifestyle counseling similarly improves cardiovascular disease risk profiles, suggesting an important role for integrative interventions in the routine clinical care of this at-risk RA population.

Effects of exercise amount and intensity versus a combined exercise and lifestyle intervention on metabolic syndrome in adults with prediabetes: a STRRIDE-PD randomized trial.

The purpose of this secondary analysis was to determine what portion of the effects of a Diabetes Prevention Program-like intervention on metabolic syndrome (MetS) could be achieved with exercise alone, as well as to determine the relative importance of exercise intensity and amount to the total exercise effect on MetS. Sedentary, overweight adults with prediabetes were randomly assigned to one of four 6-month interventions: 1) low-amount/moderate-intensity (10 kcal/kg/week at 50% peak V˙O2); 2) high-amount/moderate-intensity (16 kcal/kg/week at 50% peak V˙O2); 3) high-amount/vigorous-intensity (16 kcal/kg/week at 75% peak V˙O2); or 4) diet (7% weight loss) plus low-amount/moderate-intensity (10 kcal/kg/week at 50% peak V˙O2). The primary outcome of this secondary analysis was change in the MetS z-score. A total of 130 participants had complete data for all five Adult Treatment Panel (ATP) III MetS criteria. The diet-and-exercise group statistically outperformed the MetS z-score and the ATP III score compared to the exercise alone group. Aerobic exercise alone achieved 24%-50% of the total effect of the combined diet-and-exercise intervention on the MetS score. Low-amount moderate-intensity exercise quantitatively performed equal to or better than the interventions of high-amount moderate-intensity or high-amount vigorous-intensity exercise in improving the MetS score. The combined diet-and-exercise intervention remains more efficacious in improving the MetS z-score. However, all three exercise interventions alone showed improvements in the MetS z-score, suggesting that a modest amount of moderate-intensity exercise is all that is required to achieve approximately half the effect of a diet-and-exercise intervention on the MetS. Clinical Trial Registration: clinicaltrials.gov, identifier NCT00962962.

Remotely Supervised Weight Loss and Exercise Training to Improve Rheumatoid Arthritis Cardiovascular Risk: Rationale and Design of the Supervised Weight Loss Plus Exercise Training-Rheumatoid Arthritis Trial.

Patients with rheumatoid arthritis (RA) remain at an increased risk for cardiovascular disease (CVD) and mortality. RA CVD results from a combination of traditional risk factors and RA-related systemic inflammation. One hypothetical means of improving overall RA CVD risk is through reduction of excess body weight and increased physical activity. Together, weight loss and physical activity can improve traditional cardiometabolic health through fat mass loss, while also improving skeletal muscle health. Additionally, disease-related CVD risk may improve as both fat mass loss and exercise reduce systemic inflammation. To explore this hypothesis, 26 older persons with RA and overweight/obesity will be randomized to 16 weeks of a usual care control arm or to a remotely Supervised Weight Loss Plus Exercise Training (SWET) program. A caloric restriction diet (targeting 7% weight loss) will occur via a dietitian-led intervention, with weekly weigh-ins and group support sessions. Exercise training will consist of both aerobic training (150 minutes/week moderate-to-vigorous exercise) and resistance training (twice weekly). The SWET remote program will be delivered via a combination of video conference, the study YouTube channel, and study mobile applications. The primary cardiometabolic outcome is the metabolic syndrome Z score, calculated from blood pressure, waist circumference, high-density lipoprotein cholesterol, triglycerides, and glucose. RA-specific CVD risk will be assessed with measures of systemic inflammation, disease activity, patient-reported outcomes, and immune cell function. The SWET-RA trial will be the first to assess whether a remotely supervised, combined lifestyle intervention improves cardiometabolic health in an at-risk population of older individuals with RA and overweight/obesity.

Exercise effects on lipids in persons with varying dietary patterns-does diet matter if they exercise? Responses in Studies of a Targeted Risk Reduction Intervention through Defined Exercise I.

BACKGROUND: The standard clinical approach for reducing cardiovascular disease risk due to dyslipidemia is to prescribe changes in diet and physical activity. The purpose of the current study was to determine if, across a range of dietary patterns, there were variable lipoprotein responses to an aerobic exercise training intervention. METHODS: Subjects were participants in the STRRIDE I, a supervised exercise program in sedentary, overweight subjects randomized to 6 months of inactivity or 1 of 3 aerobic exercise programs. To characterize diet patterns observed during the study, we calculated a modified z-score that included intakes of total fat, saturated fat, trans fatty acids, cholesterol, omega-3 fatty acids, and fiber as compared with the 2006 American Heart Association diet recommendations. Linear models were used to evaluate relationships between diet patterns and exercise effects on lipoproteins/lipids. RESULTS: Independent of diet, exercise had beneficial effects on low-density lipoprotein cholesterol particle number, low-density lipoprotein cholesterol size, high-density lipoprotein cholesterol, high-density lipoprotein cholesterol size, and triglycerides (P < .05 for all). However, having a diet pattern that closely adhered to American Heart Association recommendations was not related to changes in these or any other serum lipids or lipoproteins in any of the exercise groups. CONCLUSIONS: We found that even in sedentary individuals whose habitual diets vary in the extent of adherence to AHA dietary recommendations, a rigorous, supervised exercise intervention can achieve significant beneficial lipid effects.

A Pilot Study of Home-Based Exercise and Personalized Nutrition Counseling Intervention in Endometrial Cancer Survivors.

INTRODUCTION: To assess the feasibility of a home-based aerobic exercise and nutrition counseling intervention and effect on cardiorespiratory fitness, cardiovascular disease risk profile, and immune response in obese endometrial cancer survivors. METHODS: A longitudinal pilot study assessed a 12-week home-based aerobic exercise and nutrition counseling intervention in obese endometrial cancer survivors. The primary outcome was feasibility defined as 80% adherence to weekly walking sessions calculated among individuals that completed the intervention. Secondary outcomes comprised pre- and post-intervention differences in cardiorespiratory fitness, cardiovascular risk factors, and T-cell function. Descriptive statistics summarized data. Wilcoxon sign tests identified differences between and pre and post-intervention variables. RESULTS: Nineteen women with stage 1 endometrial cancer consented; 9 withdrew and one was a screen failure. Median adherence to weekly walking sessions was 83.3%. Body composition was significantly altered with a reduction in median fat mass from 52.5 kg to 46.9 kg (p=0.04), and BMI from 37.5 kg/m2 to 36.2 kg/m2 (p = 0.004). There was no significant difference in cardiorespiratory fitness or cardiovascular parameters. The percentage of CD4+ and CD8+ T-cells producing IFNγ towards MAGE-A4 significantly increased from and 5.9% to 7.2% (p=0.043) and 13.9% to 14.8% (p=0.046), respectively. There were 3 related adverse events: hip pain, back sprain, and abdominal pain. DISCUSSION: Our home-based exercise and nutrition counseling program was feasible based on 80% adherence to walking sessions and favored altered body composition. However, the discontinuation rate was high and further research is needed to overcome barriers to implementation. Improvement in cardiovascular parameters will most likely require longer and more intensive programs.

Branched-Chain Amino Acid Catabolism and Cardiopulmonary Function Following Acute Maximal Exercise Testing in Adolescents.

Background: To provide energy for cardiopulmonary function and maintenance of blood glucose, acute aerobic exercise induces lipolysis, fatty acid oxidation (FAO), glycolysis, and glycogenolysis/gluconeogenesis. These adaptations are mediated by increases in cortisol, growth hormone (GH), and catecholamines and facilitated by a decline in insulin. Branched-chain amino acids (BCAA) also undergo catabolism during intense exercise. Here, we investigated the relationship between BCAA catabolism and metrics of cardiopulmonary function in healthy, well-developed, mature adolescent athletes undergoing an acute bout of maximal aerobic exercise. Hypothesis: We hypothesized: (a) acute maximal exercise in adolescents induces lipolysis, FAO, and BCAA catabolism associated with increases in GH and cortisol and a reduction in insulin; (b) increases in GH are associated with increases in ghrelin; and (c) metrics of cardiopulmonary function (aVO2, rVO2, aVO2/HRmax) following maximal exercise correlate with increases in GH secretion, FAO, and BCAA catabolism. Methods: Blood samples before and after maximal cardiopulmonary exercise in 11 adolescent athletes were analyzed by tandem-mass spectrometry. Paired, two-tailed student's t-tests identified significant changes following exercise. Linear regression determined if pre-exercise metabolite levels, or changes in metabolite levels, were associated with aVO2, rVO2, and aVO2/HRmax. Sex and school of origin were included as covariates in all regression analyses. Results: Following exercise there were increases in GH and cortisol, and decreases in ghrelin, but no changes in glucose or insulin concentrations. Suggesting increased lipolysis and FAO, the levels of glycerol, ketones, ß-hydroxybutyrate, and acetylcarnitine concentrations increased. Pyruvate, lactate, alanine, and glutamate concentrations also increased. Plasma concentrations of valine (a BCAA) declined (p = 0.002) while valine degradation byproducts increased in association with decreases in urea cycle amino acids arginine and ornithine. Metrics of cardiopulmonary function were associated with increases in propionylcarnitine (C3, p = 0.013) and Ci4-DC/C4-DC (p < 0.01), byproducts of BCAA catabolism. Conclusions: Induction of lipolysis, FAO, gluconeogenesis, and glycogenolysis provides critical substrates for cardiopulmonary function during exercise. However, none of those pathways were significantly associated with metrics of cardiopulmonary function. The associations between rVO2, and aVO2/HRmax and C3 and Ci4-DC/C4-DC suggest that the cardiopulmonary response to maximal exercise in adolescents is linked to BCAA utilization and catabolism.

Short-Term Changes in Cardiorespiratory Fitness in Response to Exercise Training and the Association with Long-Term Cardiorespiratory Fitness Decline: The STRRIDE Reunion Study.

Background Substantial heterogeneity exists in the cardiorespiratory fitness (CRF) change in response to exercise training, and its long-term prognostic implication is not well understood. We evaluated the association between the short-term supervised training-related changes in CRF and CRF levels 10 years later. Methods and Results STRRIDE (Studies of a Targeted Risk Reduction Intervention Through Defined Exercise) trial participants who were originally randomized to exercise training for 8 months and participated in the 10-year follow-up visit were included. CRF levels were measured at baseline, after training (8 months), and at 10-year follow-up as peak oxygen uptake (vo2, mL/kg per min) using the maximal treadmill test. Participants were stratified into low, moderate, and high CRF response groups according to the training regimen-specific tertiles of CRF change. The study included 80 participants (age: 52 years; 35% female). At 10-year follow-up, the high-response CRF group had the least decline in CRF compared with the moderate- and low-response CRF groups (-0.35 versus -2.20 and -4.25 mL/kg per minute, respectively; P=0.02). This result was largely related to the differential age-related changes in peak oxygen pulse across the 3 groups (0.58, -0.23, and -0.86 mL/beat, respectively; P=0.03) with no difference in the peak heart rate change. In adjusted linear regression analysis, high response was significantly associated with greater CRF at follow-up independent of other baseline characteristics (high versus low [reference] CRF response: standard ß=0.25; P=0.004). Conclusions Greater CRF improvement in response to short-term training is associated with higher CRF levels 10 years later. Lack of CRF improvements in response to short-term training may identify individuals at risk for exaggerated CRF decline with aging.

Ten-Year Legacy Effects of Three Eight-Month Exercise Training Programs on Cardiometabolic Health Parameters.

Background: STRRIDE (Studies Targeting Risk Reduction Interventions through Defined Exercise) was an eight-month exercise study conducted from 1998-2003. Subjects were randomized to control or one of three exercise groups differing in intensity and amount. To determine if there were legacy effects, we invited 161 individuals who completed the intervention phase to return for a 10-year Reunion study. Methods: Subjects completed medical history and physical activity questionnaires. Height, body weight, blood pressure, waist circumference, and peak VO2 were measured. Fasting blood samples were analyzed for glucose, insulin and lipids. Of 161 original subjects, 153 were within 10 years of STRRIDE completion. Of these, 28 were lost to follow-up and 21 declined to participate in the Reunion study. Overall, 104 subjects (83% eligible) participated. Change over time was computed as the 10-year Reunion value minus the pre-intervention value. Significant within group changes were calculated using two-tailed t-tests. ANCOVA determined differences among groups with pre-intervention values as covariates. Bonferroni corrections were applied to account for multiple comparisons. Results: Ten years after completing STRRIDE, there were a number of group-specific health and fitness legacy effects. Original participation in either the moderate intensity exercise or control group resulted in a 10.5% decrease in peak VO2 over the ensuing 10 years. Conversely, both vigorous intensity groups experienced only a 4.7% decrement in cardiorespiratory fitness over that time period. As compared to controls, all three exercise groups experienced smaller increases in waist circumference. Those who participated in moderate intensity exercise experienced the greatest 10-year reduction in fasting insulin. Compared to all other groups, the moderate intensity subjects had greater reductions in mean arterial pressure at the Reunion timepoint. Summary: Ten years after completing a randomized eight-month exercise training intervention, previously sedentary individuals exhibited group-specific differences consistent with an intervention-based legacy effect on cardiorespiratory fitness and cardiometabolic parameters. These findings highlight the critical need to better understand the sustained legacy health effects of exercise training interventions.

Effects of Exercise Training With and Without Ranolazine on Peak Oxygen Consumption, Daily Physical Activity, and Quality of Life in Patients With Chronic Stable Angina Pectoris.

Ranolazine reduces angina frequency and increases exercise capacity. We hypothesized that exercise training with ranolazine would allow subjects to train at greater intensities, resulting in greater improvements in exercise capacity, physical activity, and health-related quality of life (HRQOL). In a pilot study, subjects with chronic stable angina pectoris were randomized to ranolazine (n = 13) or placebo (n = 16). After a 2-week drug titration period, subjects participated in a 12-week exercise program. Peak VO2, physical activity (via accelerometer), and HRQOL were assessed before and after training. After exercise training, peak VO2increased twice as much with ranolazine (2.1 ± 3.4 ml/kg/min) as with placebo (0.9 ± 1.5) (both p <0.05). After exercise training, both groups significantly improved HRQOL score (p <0.05); however, the improvement with ranolazine (19 ± 21) was almost 50% greater than with placebo (13 ± 18). There was a significant decrease in maximal heart rate after training with ranolazine but not with placebo (group difference, p = 0.04). Oxygen pulse (peak VO2/peak HR) increased in both groups after training; but, the increase was 4 times greater with ranolazine - resulting in a significant difference between groups (p = 0.044). In conclusion, patients with angina, the addition of ranolazine to an exercise program may improve aerobic fitness, physical activity, and HRQOL beyond the results of an exercise training program alone. Exercise training with ranolazine led to significantly greater increases in oxygen pulse, which is significantly correlated with stroke volume and is an independent predictor of mortality.

Impact of hormone replacement therapy on exercise training-induced improvements in insulin action in sedentary overweight adults.

Exercise training (ET) and hormone replacement therapy (HRT) are both recognized influences on insulin action, but the influence of HRT on responses to ET has not been examined. To determine if HRT use provided additive benefits for the response of insulin action to ET, we evaluated the impact of HRT use on changes in insulin during the course of a randomized, controlled, aerobic ET intervention. Subjects at baseline were sedentary, dyslipidemic, and overweight. These individuals were randomized to 6 months of one of 3 aerobic ET interventions or continued physical inactivity. In 206 subjects, an insulin sensitivity index (S(I)) was obtained with a frequently sampled intravenous glucose tolerance test pre- and post-ET. Baseline and postintervention fitness, regional adiposity, general adiposity, skeletal muscle biochemistry and histology, and serum lipoproteins were measured as other putative mediators influencing insulin action. Two-way analyses of variance were used to determine if sex or HRT use influenced responses to exercise training. Linear modeling was used to determine if predictors for response in S(I) differed by sex or HRT use(.) Women who used HRT (HRT+) demonstrated significantly greater improvements in S(I) with ET than women not using HRT (HRT-). In those HRT+ women, plasma triglyceride change best correlated with change in S(I). For HRT- women, capillary density change and, for men, subcutaneous adiposity change best correlated with change in S(I). In summary, in an ET intervention, HRT use appears to be associated with more robust responses in insulin action. Furthermore, relationships between ET-induced changes in insulin action and potential mediators of change in insulin action are different for men, and for women on or off HRT. These findings have implications for the relative utility of ET for improving insulin action in middle-aged men and women, particularly in the setting of differences in HRT use.

Exercise training amount and intensity effects on metabolic syndrome (from Studies of a Targeted Risk Reduction Intervention through Defined Exercise).

Although exercise improves individual risk factors for metabolic syndrome (MS), there is little research on the effect of exercise on MS as a whole. The objective of this study was to determine how much exercise is recommended to decrease the prevalence of MS. Of 334 subjects randomly assigned, 227 finished and 171 (80 women, 91 men) had complete data for all 5 Adult Treatment Panel III-defined MS risk factors and were included in this analysis. Subjects were randomly assigned to a 6-month control or 1 of 3 eight-month exercise training groups of (1) low amount/moderate intensity (equivalent to walking approximately 19 km/week), (2) low amount/vigorous intensity (equivalent to jogging approximately 19 km/week), or (3) high amount/vigorous intensity (equivalent to jogging approximately 32 km/week). The low-amount/moderate-intensity exercise prescription improved MS relative to inactive controls (p <0.05). However, the same amount of exercise at vigorous intensity was not significantly better than inactive controls, suggesting that lower-intensity exercise may be more effective in improving MS. The high-amount/vigorous-intensity group improved MS relative to controls (p <0.0001), the low-amount/vigorous-intensity group (p = 0.001), and the moderate-intensity group (p = 0.07), suggesting an exercise-dose effect. In conclusion, a modest amount of moderate-intensity exercise in the absence of dietary changes significantly improved MS and thus supported the recommendation that adults get 30 minutes of moderate-intensity exercise every day. A higher amount of vigorous exercise had greater and more widespread benefits. Finally, there was an indication that moderate-intensity may be better than vigorous-intensity exercise for improving MS.

Inactivity, exercise training and detraining, and plasma lipoproteins. STRRIDE: a randomized, controlled study of exercise intensity and amount.

Exercise has beneficial effects on lipoproteins. Little is known about how long the effects persist with detraining or whether the duration of benefit is effected by training intensity or amount. Sedentary, overweight subjects (n = 240) were randomized to 6-mo control or one of three exercise groups: 1) high-amount/vigorous-intensity exercise; 2) low-amount/vigorous-intensity exercise; or 3) low-amount/moderate-intensity exercise. Training consisted of a gradual increase in amount of exercise followed by 6 mo of exercise at the prescribed level. Exercise included treadmill, elliptical trainer, and stationary bicycle. The number of minutes necessary to expend the prescribed kilocalories per week (14 kcal x kg body wt(-1) x wk(-1) for both low-amount groups; 23 kcal x kg body wt(-1) x wk(-1) for high-amount group) was calculated for each subject. Average adherence was 83-92% for the three groups; minutes per week were 207, 125, and 203 and sessions per week were 3.6, 2.9, and 3.5 for high-amount/vigorous-intensity, low-amount/vigorous intensity, and low-amount/moderate-intensity groups, respectively. Plasma was obtained at baseline, 24 h, 5 days, and 15 days after exercise cessation. Continued inactivity resulted in significant increases in low-density lipoprotein (LDL) particle number, small dense LDL, and LDL-cholesterol. A modest amount of exercise training prevented this deterioration. Moderate-intensity but not vigorous-intensity exercise resulted in a sustained reduction in very-low-density lipoprotein (VLDL)-triglycerides over 15 days of detraining (P < 0.05). The high-amount group had significant improvements in high-density lipoprotein (HDL)-cholesterol, HDL particle size, and large HDL levels that were sustained for 15 days after exercise stopped. In conclusion, physical inactivity has profound negative effects on lipoprotein metabolism. Modest exercise prevented this. Moderate-intensity but not vigorous-intensity exercise resulted in sustained VLDL-triglyceride lowering. Thirty minutes per day of vigorous exercise, like jogging, has sustained beneficial effects on HDL metabolism.

Response of high-sensitivity C-reactive protein to exercise training in an at-risk population.

BACKGROUND: High-sensitivity C-reactive protein (hsCRP) is promoted as an independent predictor of atherosclerotic risk. In addition, cardiorespiratory fitness is inversely related to hsCRP in single-sex cross-sectional analyses. Our objective was to determine if modulating fitness with exercise training imposes changes in high-sensitivity C-reactive protein in a mixed-sex population at risk for cardiovascular disease. METHODS: We studied baseline and postintervention plasma hsCRP in 193 sedentary, overweight to mildly obese, dyslipidemic men and women who were randomized to 6 months of inactivity or 1 of 3 aerobic exercise groups: low amount-moderate intensity (energy equivalent of approximately 19.3 km/wk at 40%-55% peak VO2), low amount-high intensity (energy equivalent of approximately 19.3 km/wk at 65%-80% peak VO2), or high amount-high intensity (energy equivalent of approximately 32.2 km/wk at 65%-80% peak VO2). RESULTS: At baseline, the study population was at intermediate to high cardiovascular risk as defined by hsCRP. Cardiorespiratory fitness was inversely related to hsCRP (P < .001) even after adjusting for significant and expected sex differences. Fitness, hormone replacement therapy use, and high-density lipoprotein cholesterol accounted for the sex difference in baseline hsCRP. Fitness, high-density lipoprotein cholesterol, fasting insulin, hormone replacement therapy, and visceral adiposity were all independent predictors for baseline hsCRP (r2 = 0.34 for the entire model, P < .0001). However, despite significant improvements in fitness, visceral adiposity, subcutaneous adiposity, and insulin sensitivity, hsCRP did not change in response to exercise training (P > .20). CONCLUSIONS: Cardiorespiratory fitness is inversely related to hsCRP independent of sex and accounts for most of the large sex disparity in hsCRP. Nonetheless, in the absence of a significant change in diet, 6 months of aerobic exercise training does not produce a significant change in hsCRP in an at-risk population.

Effects of exercise training amount and intensity on peak oxygen consumption in middle-age men and women at risk for cardiovascular disease.

STUDY OBJECTIVES: Although increasing aerobic fitness by exercise training is advocated as part of a healthy lifestyle, studies examining the different effects of intensity and amount on peak consumption (V(O2)) remain sparse. DESIGN: This randomized controlled trial compared the effects of three different exercise regimens differing in amount and intensity on fitness improvements. PARTICIPANTS: Overweight men and women with mild-to-moderate dyslipidemia were recruited. INTERVENTIONS: The exercise groups were as follows: (1) low amount/ moderate intensity (LAMI, n = 25), the caloric equivalent of walking 19 kilometers (km)/wk at 40 to 55% of peak V(O2); (2) low amount/high intensity (LAHI, n = 36), the equivalent of jogging 19 km/wk at 65 to 80% of peak V(O2); (3) high amount/high intensity (HAHI, n = 35), the equivalent of jogging 32 km/wk at 65 to 80% of peak V(O2); and (4) a control group (n = 37). MEASUREMENTS AND RESULTS: Peak V(O2) and time to exhaustion (TTE) were tested before and after 7 to 9 months of training. All exercise groups increased peak V(O2) and TTE compared to baseline (p < or = 0.001). Improvements in peak V(O2) were greater in the LAHI and HAHI groups compared to the control group (p < 0.02); HAHI group improvements were greater than the LAMI group (p < 0.02) and the LAHI group (p < 0.02). Increased TTE for all exercise groups was higher compared to the control group (p < 0.001) CONCLUSIONS: Exercising at a level of 19 km/wk at 40 to 55% of peak V(O2) is sufficient to increase aerobic fitness levels, and increasing either exercise intensity or the amount beyond these parameters will yield additional separate and combined effects on markers of aerobic fitness. Therefore, it is appropriate to recommend mild exercise to improve fitness and reduce cardiovascular risk yet encourage higher intensities and amounts for additional benefit.

Inactivity, exercise, and visceral fat. STRRIDE: a randomized, controlled study of exercise intensity and amount.

Despite the importance of randomized, dose-response studies for proper evaluation of effective clinical interventions, there have been no dose-response studies on the effects of exercise amount on abdominal obesity, a major risk factor for metabolic syndrome, diabetes, and cardiovascular disease. One hundred seventy-five sedentary, overweight men and women with mild to moderate dyslipidemia were randomly assigned to participate for 6 mo in a control group or for approximately 8 mo in one of three exercise groups: 1) low amount, moderate intensity, equivalent to walking 12 miles/wk (19.2 km) at 40-55% of peak oxygen consumption; 2) low amount, vigorous intensity, equivalent to jogging 12 miles/wk at 65-80% of peak oxygen consumption; or 3) high amount, vigorous intensity, equivalent to jogging 20 miles/wk (32.0 km). Computed tomography scans were analyzed for abdominal fat. Controls gained visceral fat (8.6 +/- 17.2%; P = 0.001). The equivalent of 11 miles of exercise per week, at either intensity, prevented significant accumulation of visceral fat. The highest amount of exercise resulted in decreased visceral (-6.9 +/- 20.8%; P = 0.038) and subcutaneous (-7.0 +/- 10.8%; P < 0.001) abdominal fat. Significant gains in visceral fat over only 6 mo emphasize the high cost of continued inactivity. A modest exercise program, consistent with recommendations from the Centers for Disease Control/American College of Sports Medicine (CDC/ACSM), prevented significant increases in visceral fat. Importantly, a modest increase over the CDC/ACSM exercise recommendations resulted in significant decreases in visceral, subcutaneous, and total abdominal fat without changes in caloric intake.

Effects of the amount of exercise on body weight, body composition, and measures of central obesity: STRRIDE--a randomized controlled study.

BACKGROUND: Obesity is a major health problem due, in part, to physical inactivity. The amount of activity needed to prevent weight gain is unknown. OBJECTIVE: To determine the effects of different amounts and intensities of exercise training. DESIGN: Randomized controlled trial (February 1999-July 2002). SETTING AND PARTICIPANTS: Sedentary, overweight men and women (aged 40-65 years) with mild to moderate dyslipidemia were recruited from Durham, NC, and surrounding communities. INTERVENTIONS: Eight-month exercise program with 3 groups: (1) high amount/vigorous intensity (calorically equivalent to approximately 20 miles [32.0 km] of jogging per week at 65%-80% peak oxygen consumption); (2) low amount/vigorous intensity (equivalent to approximately 12 miles [19.2 km] of jogging per week at 65%-80%), and (3) low amount/moderate intensity (equivalent to approximately 12 miles [19.2 km] of walking per week at 40%-55%). Subjects were counseled not to change their diet and were encouraged to maintain body weight. MAIN OUTCOME MEASURES: Body weight, body composition (via skinfolds), and waist circumference. RESULTS: Of 302 subjects screened, 182 met criteria and were randomized and 120 completed the study. There was a significant (P<.05) dose-response relationship between amount of exercise and amount of weight loss and fat mass loss. The high-amount/vigorous-intensity group lost significantly more body mass (in mean [SD] kilograms) and fat mass (in mean [SD] kilograms) (-2.9 [2.8] and -4.8 [3.0], respectively) than the low-amount/moderate-intensity group (-0.9 [1.8] and -2.0 [2.6], respectively), the low-amount/vigorous-intensity group (-0.6 [2.0] and -2.5 [3.4], respectively), and the controls (+1.0 [2.1] and +0.4 [3.0], respectively). Both low-amount groups had significantly greater improvements than controls but were not different from each other. Compared with controls, all exercise groups significantly decreased abdominal, minimal waist, and hip circumference measurements. There were no significant changes in dietary intake for any group. CONCLUSIONS: In nondieting, overweight subjects, the controls gained weight, both low-amount exercise groups lost weight and fat, and the high-amount group lost more of each in a dose-response manner. These findings strongly suggest that, absent changes in diet, a higher amount of activity is necessary for weight maintenance and that the positive caloric imbalance observed in the overweight controls is small and can be reversed by a modest amount of exercise. Most individuals can accomplish this by walking 30 minutes every day.

Gender and racial differences in lipoprotein subclass distributions: the STRRIDE study.

Recent research has focused on the potential atherogenicity of various lipoprotein subclasses and their link to coronary heart disease (CHD) risk. This investigation seeks to identify differences in lipoprotein subclass distributions among a biracial, middle-aged population, while controlling for a number of confounding risk factors. Fasting plasma samples were analyzed in 285 sedentary, mildly dyslipidemic, overweight individuals between 40 and 65 years with no known history of CHD or diabetes. Women had lower levels of small and medium LDL, medium VLDL, large VLDL, and small HDL with a much higher concentration of large HDL than men. Whites had significantly more IDL, small LDL, medium VLDL, and large VLDL with lower levels of large LDL than blacks. HDL and LDL size were larger among blacks and women; VLDL size was greater among whites and men. There was also a trend for men to have more LDL particles than women and whites to have a higher LDL particle concentration than blacks. Within this homogenous population, there were distinct differences between gender and racial groups. Blacks and women had less atherogenic profiles than whites and men, which was not evident from the standard lipid panel.

Earbud-based sensor for the assessment of energy expenditure, HR, and VO2max.

INTRODUCTION/PURPOSE: The goal of this program was to determine the feasibility of a novel noninvasive, highly miniaturized optomechanical earbud sensor for accurately estimating total energy expenditure (TEE) and maximum oxygen consumption (VO2max). The optomechanical sensor module, small enough to fit inside commercial audio earbuds, was previously developed to provide a seamless way to measure blood flow information during daily life activities. The sensor module was configured to continuously measure physiological information via photoplethysmography and physical activity information via accelerometry. This information was digitized and sent to a microprocessor where digital signal-processing algorithms extract physiological metrics in real time. These metrics were streamed wirelessly from the earbud to a computer. METHODS: In this study, 23 subjects of multiple physical habitus were divided into a training group of 14 subjects and a validation group of 9 subjects. Each subject underwent the same exercise measurement protocol consisting of treadmill-based cardiopulmonary exercise testing to reach VO2max. Benchmark sensors included a 12-lead ECG sensor for measuring HR, a calibrated treadmill for measuring distance and speed, and a gas-exchange analysis instrument for measuring TEE and VO2max. The earbud sensor was the device under test. Benchmark and device under test data collected from the 14-person training data set study were integrated into a preconceived statistical model for correlating benchmark data with earbud sensor data. Coefficients were optimized, and the optimized model was validated in the 9-person validation data set. RESULTS: It was observed that the earbud sensor estimated TEE and VO2max with mean ± SD percent estimation errors of -0.7 ± 7.4% and -3.2 ± 7.3%, respectively. CONCLUSION: The earbud sensor can accurately estimate TEE and VO2max during cardiopulmonary exercise testing.