Progress 07/01/03 to 06/30/08
Outputs
OUTPUTS: Our research has been targeted at better understanding the role of specific dietary factors and their possible interaction with exercise in reducing risk for obesity, heart disease and diabetes. We have conducted a number of investigations during the life of this project including designing the studies, recruiting study participants, obtaining data in response to changes in diet and exercise, analyzing the data, and presenting the data at national meetings: Specifically we have conducted the following studies: 1A- an investigation designed to to understand the role of acute endurance exercise in improving the glycemic and insulinemic response to a high carbohydrate meal provided immediately post-exercise; Study 1B-designed to understand the effect of acute exercise on fat oxidation in response to a post-exercise carbohydrate-rich meal; Study 2.) designed to examine the role of carbohydrate supplementation during resistance exercise on hunger, satiety, post-exercise food intake, and circulating plasma ghrelin concentrations, an appetite-stimulating peptide; and Study 3.) a major undertaking to compare the effects of a diet-exercise intervention in sedentary Mexican Americans (high diabetes risk group) to that of sedentary nonHispanic whites (lower diabetes risk group) on insulin action, plasma lipids and lipoprotiens, and specific inflammatory markers. We have also engaged in proteomic analysis of skeletal muscle to determine possible differences in skeletal muscle proteins that are related to the lower insulin sensitivity seen in Mexican Americans. Our goal was to determine if Mexican-Americans who appear to be more susceptible to a sedentary lifestyle and a diet high in saturated fat and refined carbohydrates can improve their insulin sensitivity as much as non Hispanic whites who undergo the same diet-exercise intervention. We have presented the findings of these studies at national meetings and also to the leaders at El Centro, the Hispanic advocacy board at Colorado State University. Also, based on our preliminary findings, we have submitted NIH and USDA grant proposals to further study the impact of diet and exercise on chronic disease risk in Mexican Americans. Finally, we have presented our results in Brazil, Australia and New Zealand, countries which also have indigenous groups similar to Mexican Americans in regard to their higher risk for chronic disease, specifically the Aboriginals in Australia and the Maouri in New Zealand. PARTICIPANTS: Chris Melby, PI, professor and department head of Food Science and Human Nutrition at Colorado State University; Matthew Hickey, Co-PI, professor, Department of Health and Exercise Science; Stacy Schmidt, Graduate student, Department of Food Science and Human Nutrition; Virginia Englert, Graduate student, Department of Food Science and Human Nutrition; Katherine Wells, Graduate student, Department of Food Science and Human Nutrition; Katherine McCabe, Graduate student, Health and Exericse Science; Holly Klamer, Graduate student, Department of Food Science and Human Nutrition; Matthew Cianciulli, Graduate Student, Department of Health and Exercise Science; Julie Pitts, Graduate Student, Department of Health and Exercise Science; Maria Botero, Graduate Student, Department of Food Science and Human Nutrition; Kyle Pffaffenbach, Graduate Student, Department of Health and Exercise Sience and Department of Food Science and Human Nutrition; Tasha Ballard, Ph.D., Post-doctoral fellow; Partner Organizations- El Centro Hispanic Advocacy Organization, Colorado State University; Hartshorn Health Center, Colorado State University, Russel Risma, M.D., Medical Director; Gatorade Sports Science Institute provided additional funding to study the effects of carbohydrate supplementation during resistance exercise on hunger, satiety, and varous hormones related to muscle growth and appetite regulation; The Metabolomics AEP provided technical and monetary support for proteomic analysis of skeletal muscle in Mexican Americans and nonHispanic whites. Scott Summers was an original co-investigator on the project but left CSU for a position at another university and thus did not participate in the project. TARGET AUDIENCES: The main target audience for our research has been the Mexican American population, a group that exhibits high risk for type 2 diabetes. We have reported our results to El Centro, the Hispanic advisory organization on campus, and have also enlisted their help in conducting a large survey among CSU Hispanic students to identify willingness of Hispanic students to participate in a lengthy diet and physical activity intervention designed to arrest weight gain and lower risk for diabetes. PROJECT MODIFICATIONS: Our original project was to include a 28-day intervention to improve insulin sensitivity in Mexican Americans. However, after initiating the project, it quickly become evident that we could not recruit Mexican Americans who were willing to participate for 28 days. Thus we shortened the intervention to 7-days based on previous studies that have shown that a week-long intervention could induce improvements in insulin sensitivity. While we worked on shortening the protocol, we initiated several other studies that were pertinent to the project goals of understanding the interaction of diet and exercise on specific risk factors for chronic disease. Thus, the AES funds were augmented by other sources to conduct two additional studies beside the major study of comparing the effects of a diet-exercise intervention on diabetes risk in Mexican Americans and nonHispanic white adults. The first additional study focused on the effect of acute exercise on the glycemic and insulinemic indices in response to a carbohydrate rich meal, and the second study focused on the effect of a carbohydrate supplementation during resistance exercise on hunger, satiety, post-exercise food intake, and hormonal changes related to skeletal muscle growth and appetite regulation.
Impacts
Our research has been targeted at better understanding the role of specific dietary factors and their possible interaction with exercise in reducing risk for obesity, heart disease and diabetes. During the life of this Hatch project, which has been augmented by funds from other sources, we have accomplished the following: 1. Determined that a single bout of endurance exercise lowers the insulinemic index but not the glycemic index of a carbohydrate rich meal. This finding suggests that acute exercise can lower the amount of insulin required to dispose of dietary glucose, which has implications for individuals with insulin resistance. 2. Determined that an endurance bout of exercise significantly increases fat oxidation during the recovery period, but this increase is rapidly diminished in response to ingestion of a carbohydrate rich meal. 3. Determined that resistance exercise decreases plasma ghrelin (a gut peptide that increases appetite), which in turn is related to lower relative energy intake when subjects are presented with opportunity to eat ad libitum from a buffet 2 hours following exercise. 4. Determined that young, sedentary non-obese Mexican Americans exhibit lower insulin sensitivity (are at greater risk for future diabetes) than their nonHispanic white counterparts. When exercising daily and consuming a low saturated fat, low sugar diet Mexican Americans improve their insulin sensitivity by about 33%, but still do not narrow the gap with nonHispanic whites in insulin sensitivity owing to similar improvements in the latter group. These data suggest that Mexican Americans may need more aggressive interventions in order to lessen the disparity in their risk of diabetes compared to nonHispanic white adults.
Publications
- Long, W., Wells, K., Englert, V., Schmidt, S., Hickey, M.S., Melby, C.L. (2008) Does prior acute exercise affect postexercise substrate oxidation in response to a high carbohydrate meal Nutrition and Metabolism 5(1): 2 [Epub ahead of print]
- Englert, V., Wells, K., Long, W., Hickey, M.S., Melby, C.L. (2006) Effect of Acute Prior Exercise on Glycemic and Insulinemic Indices. Journal of the American College of Nutrition, 25: 195-202.
- Melby, C.L. and Hickey, M.S. (2005) Exercise and Body Weight Regulation. Sports Science Exchange 18 (4): 1-6.
- Ho, R,, Davy, K., Hickey, M., Melby, C.L. (2005) Circulating Tumor Necrosis Factor Alpha is Higher in Non-Obese, Non-Diabetic Mexican Americans Compared to Non-Hispanic White Adults. Cytokine 30: 14-21.
- Melby, C.L., Schmidt, S., Hickey, M.S. (2006) Functional Foods, Insulin Resistance, and Diabetes. In Nueza Brunoro Costa and Carla Barbosa Rosa (eds.) Alimentos Funcionais, chapter 8, pps. 159-184. (Portuguese)
- Schmidt, S., Klamer, H., McCabe, K., Botero, M., Hickey, M., Melby, C.L. (2008) Does the effect of a short-term diet and exercise intervention on insulin sensitivity differ between Mexican Americans and nonHispanic whites FASEB Journal. Presented at Experimental Biology 2008, San Diego, CA.
- Pfaffenbach, K. (2006) Skeletal muscle glut4 protein content: Ethnic differences in response to diet and exercise. Thesis, Colorado State University.
- Ballard, T., Camus, H., Cianciulli, M., Pitts, J., Hickey, M.S., Melby, C.L. (2007) Resistance Exercise with or without supplemental carbohydrate lowers plasma ghrelin but does not reduce post-exercise hunger and energy intake. FASEB Journal 21:5, A691. Presented at Experimental Biology 2007, Washington, DC.
- Wells, K., Englert, V., Long, W., Hickey, M.S, Melby, C.L. (2005) Prior acute exercise lowers the insulinemic but not the glycemic index of ingested carbohydrate. FASEB Journal, 2005. Presented at Experimental Biology 2005, San Diego, CA.
- Ho RC, Davy KP, Hickey MS, and Melby CL. (2003) Circulating tumor necrosis factor-alpha is higher and soluble tumor necrosis factor receptor 2 is lower in nonobese, nondiabetic Mexican Americans compared to nonHispanic white men and women. FASEB Journal 17: A, 2003. Presented at Experimental Biology. San Diego, CA.
- McCabe, K. (2008) Tumor Necrosis Factor-alpha: Ethnic differences in response to diet and exercise. Thesis, Colorado State University
- Cianciulli, M. (2007) The influence of carbohydrate supplmentation during resistance exercise on systemic cortisol, insulin-like growth factor-1, and insulin. Thesis, Colorado State University.
- Englert, V. (2005) The effect of acute exercise on post-exercise glycemic index. Thesis, Colorado State University.
- Wells, K. (2006) The effect of acute exercise on post-exericse insulinemic index. Thesis, Colorado State University.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: We have previously shown that Mexican Americans (MA) exhibit lower insulin sensitivity (IS) compared to non-Hispanic whites (NHW), even when matched for physical fitness, total body fat, and regional fat distribution. This phenomenon is related to the higher risk for type 2 diabetes in MA compared to NHW adults living in the U.S. We have found that the lower insulin sensitivity in the MA adults is related to higher intakes of saturated fat and lower intakes of dietary fiber. Possibly ethnic differences also exist in the magnitude of the change in IS in response to a diet and exercise intervention. We therefore determined the combined effects of exercise and a low-saturated fat, low -sugar, high-fiber diet on estimates of IS in young, non-obese previously sedentary young MA adults (n=16, age=23 y, BMI=25.4 kg/m2) and NHW adults (n=19, age=23y, BMI =25.5 kg/m2). Upon enrollment in the study, subjects initially consumed their usual habitual diet and remained sedentary for 7
days, which was followed by measures of insulin sensitivity/resistance using two separate approaches: 1.) the intravenous glucose tolerance test (IVGTT) to determine the 3-h insulin area under the curve (IAUC); 2.) the homeostatic model for the assessment of insulin resistance (HOMA-IR) from fasting plasma samples. Immediately following this initial 7-day period, subjects completed a diet/exercise intervention in which subjects exercised for 6 out of the 7 days for 40/minutes per session at 65% of peak oxygen consumption. Subjects were fed all meals during this period, with the energy intake designed to maintain caloric balance, while providing low amounts of saturated fat and sugar, and liberal fruits, vegetables, legumes, and whole grains. Following the 7-day intervention subjects completed another round of tests to determine insulin sensitivity/resistance. Pre-test measures showed a non-significantly higher IAUC and HOMA-IR for the MA compared to NHW. There was a significant
treatment effect on IS but no group x treatment interaction indicating that the magnitude of the improvement was similar in both groups (IAUC micro Units*min/L: MA: pre=2162, post=1471, 32% improvement; NHW: pre=1787, post=1207, 34% improvement. HOMA-IR: MA: pre=1.18, post =0.783, 34% improvement; NHW: pre=0.975, post=0.729, 25% improvement). These data clearly show that MA, despite higher risk for insulin resistance and type 2 diabetes, can improve their insulin sensitivity in a similar fashion to NHW by regular exercise and a change in dietary intake patterned after the USDA Dietary Recommendations. With this AES project, we have also examined the interaction of acute exercise and carbohydrate intake on post-prandial, post-exercise rates of fat oxidation, ad libitum food intake and the orexigenic gastric peptide, ghrelin. We have shown that resistance exercise, with or without supplemental dietary carbohydrate, attenuates the natural rise in ghrelin concentrations, but does not
alter perceptions of hunger/satiety, and does not effect subsequent ad libitum food intake.
PARTICIPANTS: Chris Melby, Dr.P.H., PI of project, Professor and Department Head, Department of Food Science and Human Nutrition. Matt Hickey, Ph.D., Co-PI of project, Associate Professor, Department of Health and Exercise Science. Stacy Schmidt, Ph.D. student, Department of Food Science and Human Nutrition. Maria Botero, M.S. student, Department of Food Science and Human Nutrition. Kathryn McCabe, M.S. student, Department of Food Science and Human Nutrition. Holly Klamer, M.S. student, Department of Food Science and Human Nutrition. Heidi Camus, M.S. student, Department of Food Science and Human Nutrition. Tasha Ballard, Ph.D., post-doctoral fellow, Department of Food Science and Human Nutrition Heidi Camu These students are all part of the research team and have various responsibilities on the project. The M.S. students are using portions of this project to complete their M.S. theses, and the Ph.D. student has served as a project manager and her dissertation research will come from
this AES project. As students involved in the project, they have had opportunity to be trained in a wide array of experimental procedures including health screening, assessment of dietary intake, indirect calorimetry, anthropometry, venipuncture, measurement of insulin resistance by intravenous glucose tolerance tests, assays for various biomarkers of inflammation,and laboratory procedures for quantifying skeletal muscle signaling proteins. In addition, all of these students participate in our journal club and attend research team meetings. Finally, all students completed research ethics training through our University Institutional Review Board.
TARGET AUDIENCES: Young Hispanic Adults, a population at high risk for obesity, type 2 diabetes, and the cardiometabolic syndrome. All study participants have been informed of their test results and the importance of a food intake pattern in accordance with recent USDA recommendations has been the focus of classroom instruction and information conveyed to various Hispanic groups on campus.
PROJECT MODIFICATIONS: Scott Summers left CSU for a position at another university and is no longer a co-investigator on this AES project. His expertise was in ceramide metabolism and insulin sensitivity, so the effects of the diet/exercise intervention on skeletal muscle ceramide concentrations is no longer part of the project.
Impacts
With previous AES funding, we have shown that young Hispanic adults exhibit lower insulin sensitivity and greater sub-clinical markers of inflammation than age-matched non-Hispanic Whites (NHW). These findings suggest that young Latino/a adults compared to their NLW counterparts are at greater risk for type 2 diabetes at a relatively younger age. However, we have now demonstrated that young Hispanics adults who follow a diet rich in fruits and vegetables and low in saturated fat and sugar (sucrose and high fructose sweetener) and who exercise regularly experience a dramatic improvement in insulin sensitivity. Thus our previous and ongoing work suggests that MA are especially susceptible to the untoward consequences of physical inactivity and a high fat, high sugar, low fiber diet, but conversely are especially sensitive to the benefits of a healthy diet and increased physical activity. The results of this project to date have generated significant interest within the
Latino community in Northern Colorado. We have partnered with El Centro, the Hispanic Advocacy Organization to submit several grant proposals targeted at the development of an effective lifestyle intervention to attenuate weight gain and lower risk for diabetes and the cardiometabolic syndrome in Hispanic college students. The focus on preventing obesity-related chronic disease in future Hispanic leaders could have broad-reaching impacts on lowering the disproportionate burden of disease in this population.
Publications
- Ballard, T., Camus, H., Cianciulli, M., Pitts, J., Hickey, M.S., and Melby, C.L. 2007. Resistance Exercise with or without supplemental carbohydrate lowers plasma ghrelin but does not reduce post-exercise hunger and energy intake. FASEB Journal 21:5, A691.
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Progress 01/01/06 to 12/31/06
Outputs
We have shown in previous work supported by the Colorado AES, that young, nonobese, Mexican Americans (MA) have higher risk for diabetes than their nonHispanic white (NHW) counterparts, even when the groups are matched for physical fitness, and central and total body fatness. Based on this finding we are now seeking to determine if a combination of endurance exercise and prudent diet (low saturated fat, low sugar) can enable Mexican Americans to "catch up" to the NHW. In other words, given that MA start a lower level of insulin sensitivity with greater room for improvement, will the diet-exercise intervention improve insulin sensitivity in this group to a greater extent than seen in the NHW? This project is ongoing, with a total of 32 subjects studied to date, including 12 MA and 20 NHW participants. Preliminary analyses using only a portion of the enrolled subjects suggest that the MA show similar, but not greater, improvements in insulin sensitivity in response to
the diet and exercise changes. The MAs also appear to exhibit greater variability in response. That is, some individuals showed marked improvements and others very little. This research indicates that despite the high risk for diabetes in this minority population, nutrition and exercise can significantly lower their aggregate risk. However, it also points to the importance of future research to identify characteristics of those who are most sensitive to diet and exercise changes, as well as the characteristics of those who will need more aggressive approaches to lowering diabetes risk. A second investigation is designed to examine the interaction of acute exercise and macronutrient intake on substrate oxidation and insulin sensitivity. Ingestion of a mixed meal rapidly shifts fuel oxidation toward carbohydrates and away from fat, while exercise recovery is characterized by a shift toward fat oxidation, both of which have implications for fat balance and risk for body fat accumulation.
In a study of young men and women (n=8), we found that following cessation of exercise prior to meal ingestion, plasma insulin was low, non-esterified fatty acids (NEFAs) were increased two-fold, and fat oxidation was high. Upon ingestion of a mixed meal (50 g carbohydrate, 7 g fat, 19 g protein), the increase in insulin produced a rapid decrease in NEFA concentrations, which were only modestly higher than during the postprandial period without prior exercise. The rate of fat oxidation during the postexercise, postprandial period decreased to the same level as when subjects ate the same meal without prior exercise. These results suggest that ingesting a mixed meal immediately following exercise can significantly attenuate the high rate of fat oxidation that occurs during recovery from exercise, even in the face of modestly higher concentrations of circulating fatty acids. To improve fat oxidation, a delay in meal consumption following exercise may be of benefit.
Impacts
Our data to date, although limited by small numbers, suggest that despite lower levels of insulin sensitivity in Mexican Americans compared to nonHispanic whites, the former experience significant improvements in insulin action in response to a specific diet/exercise intervention. These data suggest that regular exercise and a low saturated fat diet may be especially important in reducing risk for type 2 diabetes in the Mexican American population. Also our research suggests that given the large variability in response to diet and exercise, future research will need to to identify characteristics of those Mexican Americans who are most sensitive to diet and exercise changes, as well as the characteristics of those who will need more aggressive approaches to lowering diabetes risk.
Publications
- Melby, C.L., Schmidt, S., Hickey, M.S. 2006 Functional foods, insulin resistance, and diabetes. In Nueza Brunoro Costa and Carla Barbosa Rosa (eds.) Functional Foods, chapter 8, pps. 159-184.
- Schmidt, S. 2005. Measures of insulin sensitivity following a one-week diet and exercise intervention. Masters Thesis, Department of Food Science and Human Nutrition, Colorado State University.
- Pfaffenbach, K. 2005 Skeletal muscle glut4 protein content: ethnic differences in response to diet and exercise. Masters Thesis, Department of Health and Exercise Science, Colorado State University.
- Englert, V., Wells, K., Long, W., Hickey, M.S., and Melby, C.L. 2006. Effect of Acute Prior Exercise on Glycemic and Insulinemic Indices. Journal of the American College of Nutrition, 25: 195-202.
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Progress 01/01/05 to 12/31/05
Outputs
The purpose of this study is to determine whether or not Mexican Americans (MA, a group at high risk for insulin resistance and type 2 diabetes) in comparison to nonHispanic whites (NHW, a group at lower risk) experience similar improvements in insulin sensitivity in response to regular endurance exercise. In a preliminary analysis of our first 10 subjects studied in 2005 (more to be studied in future years), we have examined the effect of lowering dietary saturated fat to less than 5% of total energy intake and high intensity exercise intervention (40 minutes per day @ 70% VO2 max for 5 sessions in 7 days) on insulin sensitivity (Si) in MA and NHW adults. Pre- and post-intervention Si was measured using the frequently sampled intravenous glucose tolerance test using minimal model analysis in previously sedentary MA and NHW. We controlled for diet by providing all study volunteers with the same low saturated fat, whole food, energy balanced diet during the 7-day
intervention. The diet/exercise-induced changes in Si were of similar magnitude in the MA than NHW (post-test Si, MA=11.8, NHW=12.2), with no post-test ethnic differences in Si following the short diet/exercise intervention. When examining another measure of insulin resistance, the homeostatic model for the assessment of insulin resistance (HOMA-IR), again the MA showed similar improvements to NHW in response to the diet/exercise intervention. The small sample size to date renders this study underpowered to definitively determine if the slope of improvement might actually be greater in MA than NHW.
Impacts
Our data to date, although limited by small numbers, suggest that despite lower levels of insulin sensitivity in Mexican Americans compared to nonHispanic whites, the former experience significant improvements in insulin action in response to a specific diet/exercise intervention. These data suggest that regular exercise and a low saturated fat diet may be especially important in reducing risk for type 2 diabetes in the Mexican American population.
Publications
- Ho,R., Davy,K., Hickey,M., and Melby,C.L. 2005 Circulating Tumor Necrosis Factor Alpha is Higher in Non-Obese, Non-Diabetic Mexican Americans Compared to Non-Hispanic White Adults. Cytokine 30: 14-21.
- Wells,K., Englert,V., Long, W., Hickey, M., and Melby, C.L. 2005. Prior acute exercise lowers the insulinemic but not the glycemic index of ingested carbohydrate. Abstract, FASEB Journal.
- Wells,K. 2005. Effect of acute exercise on post-exercise insulinemic index. Masters Thesis, Department of Food Science and Human Nutrition, Colorado State University
- Long,W. 2005. Do exercise-induced elevations of plasma non-esterified fatty acids attenuate the decrease in fat oxidation that normally occurs following carbohydrate ingestion? Masters Thesis, Department of Food Science and Human Nutrition, Colorado State University
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Progress 01/01/04 to 12/31/04
Outputs
Our study to examine the effect of a short-term diet/exercise program on insulin sensitivity in Mexican Americans and nonHispanic Whites is in the data collection phase. The following AES study has just been completed with the findings described in this report. Background: An elevation of blood insulin concentrations is associated with increased risk for various chronic diseases. Because low glycemic index (GI) foods generally stimulate less insulin secretion, much attention is being given to the use of these slowly absorbed carbohydrates in the prevention and treatment of obesity and type 2 diabetes. Because of the heightened insulin sensitivity associated with recovery from acute exercise, it is possible that prior exercise could favorably blunt the blood glucose and insulin responses to high GI carbohydrates. Therefore we tested the hypothesis that the glycemic and insulinemic responses to a moderately high glycemic index (GI) food consumed following an exercise
bout would be lower than when the same food is consumed without prior exercise. Methods: 4 lean males (age: 27+4 y) and 4 lean females (age: 23+3 y) completed 3 experimental conditions in random order: 1.) CHO/Ex)- Subjects exercised on a cycle ergometer at 70% VO2 max with a net energy cost of 400 kcal, which was immediately followed by consumption of high CHO energy bar; 2.) CHO/NoEx- Same as CHO/Ex except subjects sat quietly rather than exercised; and 3.) Glc/NoEx- Same as CHO/NoEx except subjects consumed a 50 g glucose drink as the reference CHO for GI and insulinemic index (II) determination. For each condition, following exercise or rest, baseline fasting venous blood samples were obtained, subjects were fed the CHO bar or the glc drink, and postprandial blood samples were obtained at 15 min intervals for 2 h. Results: The 2-h glucose area under the curve (AUC) for the CHO/Ex and CHO/NoEx did not differ, nor was there a significant difference in the GI between the CHO/Ex
(63.3) and CHO/NoEx (66.3). However, the insulin AUC for CHO/Ex was 28% lower than the insulin AUC for CHO/NoEx (p = 0.03), and the calculated insulinemic index for the CHO/Ex condition (73+12) was also lower than that of CHO/NoEx (104+10) (p=0.05) Conclusions: An acute bout of prior exercise had no effect on the glycemic index of a carbohydrate rich food (energy bar) compared to that of the same food determined under the standard no-exercise conditions. However, exercise resulted in a lower 2-h insulin response to the CHO bar.
Impacts
Elevated blood insulin concentrations have been linked to increased risk for pro-inflammatory diseases such as obesity, diabetes, cardiovascular disease, and cancer. Individuals with insulin resistance, who exhibit higher risk for these chronic diseases, are often encouraged to consume slowly absorbed carbohydrates that lower the requirements for insulin. We have shown here that engaging in aerobic exercise prior to ingestion of a rapidly available carbohydrate reduces the insulin requirement by 30% compared to when the carbohydrate is consumed without exercise. These findings suggest that exercise is benificial in reducing the insulin response to carbohydrate ingestion, which could potentially reduce chronic disease risk in insulin resistant individuals.
Publications
- Bell,C., Petitt,D., Osterberg,K., Melby,C.L, and Seals,D. 2004. Higher energy flux mediates the tonically augmented beta-adrenergic support of resting metabolic rate in habitually exercising older adults. Journal of Clinical Endocrinology and Metabolism 89:3573-3578.
- Englert, V. Effect of acute exercise on post-exercise glycemic index. M.S. Thesis, 2004. Department of Food Science and Human Nutrition, Colorado State University.
- Stob, N. Post-exercise protein feeding does not alter molecular markers of translation initiation or measures of skeletal muscle function. Ph.D. Dissertation, 2004. Department of Food Science and Human Nutrition, Colorado State University.
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Progress 01/01/03 to 12/31/03
Outputs
We have used cross-sectional data to examine the interaction of cardiorespiratory fitness and nutritional status in attempting to understand reasons for the higher rate of diabetes and insulin resistance in Mexican Americans (MA) compared to nonHispanic Whites (NHW). We measured cardiorespiratory fitness (VO2 max) using a graded exercise test on a motorized treadmill, and insulin sensitivity was estimated from fasting blood glucose and insulin concentrations (HOMA-IR, homeostatic model for measurement of insulin resistance) in 13 MA and 13 NHW across a fairly wide range of cardiorespiratory fitness levels. We previously reported (Am J Physiol, 2002) that the MA were less insulin sensitive despite similar levels of CRF compared to NHW, which might suggest that fitness has little effect on insulin sensitivity in MA. Within the MA group, we found a weak and statistically insignificant association between cardiorespiratory fitness and HOMA-IR (r= -0.386, p= 0.19).
However, when controlling for the dietary intake of palmitate relative to total energy intake, the magnitude of the relation between fitness and estimates of insulin sensitivity increased substantially (HOMA-IR and fitness, r= -0.76, p=0.03). The addition of percent plasma palmitate to the model did not add to this already strong association between fitness and insulin sensitivity. Interestingly, when MA were divided into two groups based on higher and lower VO2 max values, we found a significantly lower plasma percent palmitate in the high compared to low fit group. Taken together, these data suggest that the strength of the relation between cardiorespiratory fitness and insulin sensitivity is likely affected by saturated fatty acid intake, with the possibility that higher dietary saturated fat attenuates the benefits of higher cardiorespiratory fitness on insulin sensitivity. Higher intakes of saturated fatty acids (especially palmitic acid) by Mexican Americans may contribute to
their lower insulin sensitivity compared to nonHispanic Whites, even at similar levels of cardiorespiratory fitness.
Impacts
It is possible that a diet high in saturated fat could attenuate the benefit of regular exercise on insulin action in Mexican Americans. If confirmed experimentally, these data will have important implications for lifestyle interventions targeted at reducing type 2 diabetes in Mexican Americans.
Publications
- Davy, B.M. and Melby, C.L. (2003) The Effect of Fiber-Rich Carbohydrates on Features of Syndrome X: A Review. Journal of the American Dietetic Association. 103:86-96.
- Ho, R.C., Davy, K.P., Hickey, M.S., and Melby, C.L. (2003) Circulating tumor necrosis factor-alpha is higher and soluble tumor necrosis factor receptor 2 is lower in nonobese, nondiabetic Mexican Americans compared to nonHispanic white men and women. FASEB Journal abstract.
- Heinisch H. (2003) Skeletal Muscle Abundance of Glycogen Synthase Kinase 3-B in Mexican Americans and nonHispanic Whites. M.S. Thesis, Colorado State University.
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Progress 01/01/02 to 12/31/02
Outputs
We found that Mexican Americans compared to nonHispanic Whites exhibit lower insulin sensitivity, based on the homeostatic model for assessment of insulin resistance (HOMA-IR), even after controlling for total body fat, visceral fat, acute exercise, and cardiorespiratory fitness. We sought to determine if this phenomenon was related to ethnic differences in plasma free fatty acid concentrations and/or dietary fat intake. We obtained meticulously recorded 4-day dietary records from the study subjects. The intake of total fat and saturated fat was higher in the MA (n=13) compared to NHW (n=13), with the 16:0 fatty acid, palmitate ingested in significantly higher amounts in the MA. Within the entire sample (both groups combined), we found that palmitate was significantly positively related to HOMA-IR (r=0.47, p<0.05). When the group differences in HOMA-IR were analyzed using dietary palmitate as a covariate, the ethnic differences in insulin sensitivity were attenuated
to the point of no longer being statistically significant. Within the MA group, dietary palmitate (g/day) was significantly related to HOMA-IR after partialling out total energy intake and cardiorespiratory fitness (partial r= 0.72, p<0.05). Possibly the higher saturated fat diet in MA is related to lower insulin sensitivity, via increased plasma nonesterified fatty acids (NEFA) and skeletal muscle triglyceride accumulation. Along these lines, we found a significant correlation among the MA between fasting plasma NEFA and both saturated fat (rho= 0.63, p<0.05) and palmitate intake (rho= 0.66, p<0.05). These data suggest that the lower insulin sensitivity in MA compared to NHW may be at least partially due to their higher palmitate intake and higher circulating NEFAs.
Impacts
Our findings that higher palmitate intake and higher circulating plasma fatty acids in Mexican Americans compared to nonHispanic Whites may contribute to their lower insulin sensitivity, will lead to further research to better understand the best dietary approaches to prevent type 2 diabetes in this high risk population. The results of our study, published in the American Journal of Physiology, will be disseminated to clinicians working among Latino populations, through a commentary article to be published in Medicina y Cultura.
Publications
- Yu L, Perret J, Davy B, Wilson J, Melby, CL. 2002. Antioxidant Properties of Cereal Products. Journal of Food Science 67:2600-2603.
- Ho R, Davy K, Davy B, Melby CL. 2002. Whole Body Insulin Sensitivity, LDL Particle Size and Oxidized LDL in Overweight, Nondiabetic Men. Metabolism 51:1478-1483.
- Melby CL, Osterberg KL, Resch A, Davy B, Johnson S, and Davy K. 2002. Effect of Carbohydrate Ingestion During Exercise on Post-exercise Substrate Oxidation and Energy Intake. International Journal of Sport Nutrition and Exercise Metabolism 12:294-309.
- Ho RC, Davy KP, Hickey MS, Melby CL. 2002. Behavioral, Metabolic and Molecular Correlates of Lower Insulin Sensitivity in Mexican Americans. 2002. American Journal of Physiology: Endocrinol Metab 283:E799-E808.
- Davy BM, Ho RC, Beske SD, Davrath LR, Davy KP, Melby CL. 2002. High-fiber oat ceral compared with wheat cereal consumption favorably alters LDL-cholesterol subclass and particle number in middle-aged and older men. American Journal of Clinical Nutrition 76:351-358.
- Davy BM, Melby CL, Beske SD, Ho RC, Davrath LR, Davy KP. 2002. Oat Consumption does not affect resting casual and ambulatory 24-h arterial blood pressure in men with high-normal blood pressure to stage 1 hypertension. Journal of Nutrition 132: 394-398.
- Bubert, A. 2002. Circulating plasma leptin concentration does not differ between nonHispanic whites and Mexican Americans despite ethnic differences in insulin sensitivity. M.S. Thesis. Department of Food Science and Human Nutrition. Colorado State University. Fort Collins, CO 80523.
- Heald, L. 2002. Circulating estradiol concentrations do not correlate with differences in insulin sensitivity between Mexican Americans and nonHispanic whites. Plan B M.S. Thesis. Department of Food Science and Human Nutrition. Colorado State University. Fort Collins, CO 80523.
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Progress 01/01/01 to 12/31/01
Outputs
Mexican Americans (MA) exhibit lower insulin sensitivity compared with non-Hispanic white (NHW) adults. The reasons for this phenomenon remain obscure. Because tumor necrosis factor-alpha (TNFalpha) is associated with insulin resistance in various models of obesity and diabetes, we sought to determine whether this cytokine and its soluble receptors could account, at least in part, for any differences in insulin sensitivity between these groups. Fasting blood samples were used to determine concentrations of TNFalpha, soluble TNF receptors 1 (sTNFR1) and 2 (sTNFR2) in thirteen nonobese, nondiabetic MA (7 women, 6 men, age = 27.0 y, BMI = 23.0) and 13 NHW (7 women, 6 men, age = 24.8 y, BMI = 22.8) matched for cardiorespiratory fitness (VO2 max). Insulin sensitivity was estimated with the Homeostatic Model of Insulin Resistance (HOMA-IR). MA were significantly less insulin sensitive compared with their NHW counterparts (HOMA-IR, 1.53 vs. 0.87, p less than 0.05).
Circulating TNFalpha was significantly higher (3.11 vs. 2.10 pg/ml, p less than 0.05) and sTNFR2 was significantly lower (1323 vs. 1924 pg/ml, p less than 0.05) among MA compared with NHW subjects. The soluble TNFR1 was higher among NHW subjects, but this difference did not reach significance. (1218 vs. 970 pg/ml, p = 0.07). TNFalpha, sTNFR1 and sTNFR2 were not associated with HOMA-IR when the two groups were analyzed in aggregate. These data indicate that circulating levels of TNFa and sTNFR2 are different between nonobese, nondiabetic MA and NHW, but they do not appear to account for the observed group differences in estimated insulin sensitivity.
Impacts
Reasons for the higher circulating TNFalpha concentrations in Mexican Americans compared to nonHispanic Whites are unclear, but could possibly be related to diet and adiposity. This finding will stimulate research to uncover reasons for, and untoward consequences of, the higher TNF alpha concentrations in Mexican Americans, with the goal of reducing insulin resistance and type 2 diabetes in this population.
Publications
- Commerford SR, Pagliassotti MJ, Melby CL, Wei Y, Hill JO: Inherent capacity for lipogenesis or dietary fat retention is not increased in obesity prone rats. 2001. American Journal of Physiology. 280(6):R1680-7.
- Benezra, LM, Nieman, DC, Nieman CN, Melby CL, Cureton K, Schmidt D, Howley E, Costello C, Hill JO, Alexander H. 2001. Intakes of most nutrients remain at acceptable levels during a weight management program using the food exchange system. Journal of the American Dietetic's Association 101:554-558.
- Powell LA, Nieman DC, Melby CL, Cureton K, Schmidt D, Howley E, Hill JO, Alexander H. 2001. Assessment of Body Composition Change in a Community-Based Weight Management Program. Journal of the American College of Nutrition 20(1):26-31.
- Davy BM, Melby CL, Beske SD, Ho RC, Davrath LR, Davy KP. 2001. Influence of fiber consumption on blood pressure in men with high normal blood pressure and stage I hypertension. FASEB Journal 15:A275.
- Davy BM, Davy KP, Ho RC, Beske SD, Melby CL. 2001. The effect of oat compared to wheat cereal consumption on plasma lipoproteins in LDL subclass phenotype A vs B. FASEB Journal 15:A639.
- Melby CL, Osterberg KL, Resch A, Davy BM, Johnson S, Davy KP. 2001. Effect of carbohydrate consumption during exercise on postexercise substrate oxidation and energy intake. FASEB Journal 15:A990.
- Bell C, Day DS, Christou DD, Osterberg K, Melby CL, Seals DR, Jones PP. 2001. Influence of energy flux on resting metabolic rate in habitually exercising older adults. FASEB Journal 15:A990.
- Christou DD, Bell C, Day DS, Osterberg K, Melby CL, Seals DR, Jones PP. 2001. Relation of muscle sympathetic nerve activity to energy flux in habitually exercising older adults. FASEB Journal 15:A990.
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Progress 01/01/00 to 12/31/00
Outputs
Insulin resistance and type 2 diabetes are proportionately higher in Mexican Americans in Colorado compared to their nonHispanic white counterparts. Using data from our previously studied sample of Mexican American Coloradoans (J Am Coll Nutr.1999,18:127-134) we recently found a significant inverse relationship between insulin sensitivity (quantitative insulin sensitivity check index= 1/(log insulin+ log glucose)) and estimates of central adiposity, saturated fat and meat intake. Based on these recently analyzed data, we then renewed our Colorado AES funding to conduct a study of Mexican Americans and nonHispanic whites with the following aims: 1.) To determine the possible contribution of ethnic differences in plasma nonesterified fatty acids, ceramide production, and skeletal muscle insulin-signaling pathway intermediates to the greater insulin resistance seen in Mexican American compared to nonHispanic white adults; and 2.) To determine the possible contribution of
dietary fat intake and cardiorespiratory fitness to differences in insulin resistance between MA and NHW adults. We are presently recruiting subjects and collecting data to address these specific aims.
Impacts
If a lower intake of saturated fat and increased cardiorespiratory fitness and/or usual physical activity are confirmed to have beneficial associations with insulin sensitivity in Mexican Americans, these findings will have important implications for the primary prevention of type 2 diabetes, and its related clinical manifestations. There is the possibility that findings from this project will contribute toward the development of public health initiatives aimed at reducing the substantial burden imposed by the insulin resistance syndrome in this population.
Publications
- Commerford SR, Pagliasotti MJ, Melby CL, Wei Y, Gayles EC, Hill JO. 2000. Fat Oxidation, Lipolysis, and Free Fatty Acid Cycling in Obesity Prone and Obesity Resistant Rats. American Journal of Physiology: Endocrinology and Metabolism 279:E875-885.
- Melby CL, Ho RC, Jeckel K, Beal LD, Goran MI, Donahoo WT. 2000. Comparison of Risk Factors for Obesity in Young, Nonobese African American and Caucasian Women. International Journal of Obesity 24:1514-1522, 2000.
- Cordain L, Melby CL, Hamamoto AE, O'Neill DS, Cornier MA, Barakat HA, Israel RG, Hill JO. 2000. Influence of Moderate Chronic Wine Consumption on Insulin Sensitivity and other Correlates of Syndrome X in Moderately Obese Women. Metabolism 49: 1473-1478
- Osterberg KL, Melby CL. 2000. Effect of Acute Resistance Exercise on Postexercise Metabolic Rate in Young Women. International Journal of Sport Nutrition and Exercise Metabolism 10:71-81.
- Davy B, Ho R, Beske S, Davrath L, Davy K, Melby C. 2000. Oat compared to wheat fiber consumption favorably alters LDL-C subclass and particle number. FASEB Journal 14:A488.
- Cordain L, Melby CL, Hamamoto A, O'Neil S, Cornier M, Barakat H, Israel RG, Hill JO. 2000. Influence of moderate wine consumption on insulin sensitivity. FASEB Journal 14:A751.
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Progress 01/01/99 to 12/31/99
Outputs
Because insulin resistance (low insulin sensitivity) is related to the disproportionately higher prevalence of cardiovascular disease and type 2 diabetes in middle-aged and older African American (AA) compared to Caucasian (CA) women, we sought to determine if lower insulin sensitivity is also characteristic of younger AA women. Using the same subjects reported in our 1998 CRIS document, we measured dietary intake, physical fitness, and insulin sensitivity using the insulin-augmented frequently sampled glucose tolerance test in young (18-28 years) AA and CA women. We also sought to determine what characteristics might account for this difference. Our findings indicate that young, non-obese African-American women exhibit lower insulin sensitivity than their Caucasian counterparts (insulin sensitivity index was 3.26 for AA, 4.61 for CA). The lower insulin sensitivity in the AA women was related to higher fat and lower fiber intake. Also, the AA women were found to
exhibit lower aerobic fitness levels, which may also contribute to their lower insulin sensitivity. Skeletal muscle biopsy data showed no group differences in the activities of the enzymes phosphofructokinase (PFK), and 3-hydroxy-acyl-CoA dehydrogenase (HADH), which represent glycolytic and fatty acid oxidative enzyme activity, respectively. The acute insulin response to glucose which may be related to greater risk of type 2 diabetes, was two-fold higher in the AA compared to CA women. These data suggest that lower insulin sensitivity which may contribute to greater risk for heart disease and diabetes, occurs early in AA women and is related to both diet and low physical activity levels. These data suggest that increased physical activity and diets higher in fiber and lower fat may be beneficial in improving the health of AA women.
Impacts
Our findings suggest that the optimal diet for improving the health of many African American women will include more dietary fiber and less saturated fat. Our findings also point to the importance of more exercise energy expenditure in improving their health status.
Publications
- Alexander H, Lockwood L, Harris MA, Melby CL. 1999. Risk Factors for Cardiovascular Disease and Diabetes in Two Hispanic Populations with Different Dietary Patterns. Journal of the American College of Nutrition 18:127-134.
- Melby CL, Hill JO. 1999. Exercise, Macronutrient Balance, and Body Weight Regulation, Sports Science Exchange 12:1-6.
- Melby CL, Beal LD, Ho RC, Jeckel KM, Donahoo WT, Goran MI. 1999. Energy expenditure in young, sedentary nonobese African-American and Caucasian women. FASEB Journal. 13:A926 (abstract).
- Osterberg KL, Melby CL. 1999. Effect of strenuous resistance exercise on metabolic rate and resting fat oxidation in young women. Medicine and Science in Sports and Exercise. 31:S311 (abstract).
- Ho RC, Jeckel KM, Beal LD, Donahoo WT, Melby CL. 1999. Resting and submaximal exercise fat oxidation in young African American and Caucasian women. Medicine and Science in Sports and Exercise. 31:S371 (abstract).
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Progress 01/01/98 to 12/31/98
Outputs
Based on our previous studies that clearly show a higher prevalence of obesity among African-American (AA) women compared to their Caucasian (CA) counterparts, we sought to determine if young AA (n=10) compared to CA women (n=10) exhibit greater metabolic and behavioral propensity for obesity. We examined the following characteristics in each group: aerobic physical fitness, resting energy expenditure (REE), resting and submaximal exercise fat oxidation rates, total daily energy expenditure (TDEE) by the doubly-labeled water method (stable isotopes); physical activity energy expenditure (PAEE), and insulin sensitivity estimated by a frequently sampled intravenous glucose tolerance test. TDEE in the AA women was almost 700 kcal per day lower than that of the CA women. The mean REE for the AA women was 70 kcal/day lower than that of the CA women, which indicates that the lower energy expenditure of the AA compared to the CA women, was primarily a function of lower
physical activity energy expenditure. The mean PAEE in AA women was significantly lower in the AA group (x=304 + 55 kcal/day) compared to the CA group (x=805 + 131 kcal/day. Interestingly, the lower PAEE in the AA women was associated with lower maximal aerobic capacity (VO2 max). There were no racial differences in the rates of resting and submaximal exercise fat oxidation. Data from this study suggest that the energy intake requirements of young AA women are lower than their CA counterparts, primarily because of lower energy expended in physical activity. In a separate study in Hispanic-Americans we found that the presence of excess abdominal body fat was a greater risk factor for dyslipidemia and hyperinsulinemia, than any dietary constituents including high saturated fat and low fiber intake.
Impacts
(N/A)
Publications
- Toohey, M., Harris, M., Williams, D., Foster, G., Schmidt, W., and Melby, C. 1998. Cardiovascular disease risk factors in African-American vegans compared to lacto-ovovegetarians. J. Amer. Col. Nutr. 17:425-434.
- Cordain, L., and Melby, C. 1998. Alcohol, Wine, and Obesity. Bulletin de l'O.V.I.V (French ). 71:854-867.
- Melby, C., Commerford, S., and Hill, J. 1998. Exercise, macronutrient balance, and weight control in R. Murray and D. Lamb (eds), Perspectives in exercise science and sports medicine, Vol. 11: Exer. Nutr. and Weight Con., pps. 3-58, Cooper Publishing Co., Carmel, IN.
- Cline, A., Jansen, G., and Melby, C. 1998. Stress fractures in female army recruits: implications of bone density, calcium intake, and exercise. J. Amer. Col. Nutr. 17:128-135.
- Poehlman, E., and Melby, C. 1998. Resistance training and energy balance. Inter. J. Sport Nutr. 8:143-159.
- The Role of Lipid Metabolism in the Development of Obesity. Ph.D. Thesis, Susan Commerford, 1998.
- Physiological and Behavioral Characteristics of Hispanics with High and Low Fasting Plasma Insulin Concentrations. M.S. Thesis, Laura Lockwood, 1998.
- Risk Factors for Cardiovascular Disease and Diabetes in Hispanic Coloradoans. M.S. Thesis, Heather Alexander, 1998.
- Total and Physical Activity Energy Expenditure in African American and Caucasian Women. M.S. Thesis, Lena D. Beal, 1998.
- Estimates of Insulin Sensitivity in Young African-American and Caucasian Women. M.S. Thesis, Kimberly M. Jeckel, 1998.
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Progress 01/01/97 to 12/31/97
Outputs
We have previously shown that a plant-based, low saturated fat diet is associated with lower cardiovascular disease (CVD) risk in African-Americans. We now have extended these findings to Hispanic adults residing in urban Colorado. In a recent study, Hispanic semi- vegetarians (n=74) compared to Hispanic omnivores (n=45) exhibited lower body mass index, systolic blood pressure, and fasting plasma insulin, glucose, triglyceride, total cholesterol (TC) concentrations. These data indicate that a plant-based diet, low in saturated fatty acids is associated with lower risk for cardiovascular disease and Type 2 diabetes in Hispanic adults. This is an especially important finding because of the significant risk for heart disease and diabetes in Hispanic adults in Colorado. In our energy balance laboratory, we have found that resistance exercise is capable of producing prolonged postexercise elevations of both metabolic rate and fat oxidation in young women. When measured 15
hours following a strenuous bout of weight lifting, both resting metabolic rate and resting fat oxidation were higher than when measured prior to exercise. These data have implications for body weight regulation, suggesting that resistance exercise can contribute substantially to daily energy expenditure and fat oxidation. Finally, in an ongoing study, to date, we have found no racial differences in metabolic susceptibility to obesity in a small sample of African-American and Caucasian women. Additional subjects will be recruited and data collected in effort to understand the high prevalence of obesity and its sequelae in African-American women.
Impacts
(N/A)
Publications
- MELBY, C.L., FINNESTEAD, B., SCHMIDT, W.D., TOOHEY, M.L., and HARRIS, M.A. 1997. Exercise versus body mass index as predictors of CVD risk factors in African- American women. Med. and Sci. in Sports and Exer. 29:S87, (Abst. 501).
- GILLETTE, C.A., ZHU, Z., WESTERLIND, K.C., MELBY, C.L., WOLFE, P., and THOMPSON, H.J.. 1997. Energy availability and mammary carcinogenesis: Effects of calorie restriction and exercise. Carcinogenesis 18:1183-1188.
- PHELAN-FRAGAPANE, J., REINKE, E., HARRIS, M.A., and MELBY, C.L. 1997. Postexercise energy expenditure and substrate oxidation in young women resulting from exercise bouts of different intensity. Jrl. Amer. College of Nutr. 16:140-146.
- CORDAIN, L., BRYAN, E.D., MELBY, C.L., and SMITH, M.J. 1997. Influence of moderate daily wine consumption upon body weight regulation and metabolism in healthy free-living males. Jrl. Amer. College of Nutr. 16:135-139.
- COMMERFORD, S.R., CORDAIN, L., and MELBY, C.L. 1997. Reliability of the measurement of excess post-exercise oxygen consumption following two identically controlled cycling bouts. Med. and Sci. in Sports and Exer. 29:S195 (Abst. 1108).
- TOOHEY, M.L. 1997. Diet, Ascorbic Acid, and Cardiovascular Disease Risk Factors in African-Americans. Ph.D. Dissertation. Colorado State University.
- OSTERBERG, K. 1997. Effect of Acute Resistance Exercise on Postexercise Oxygen Consumption and resting Metabolic Rate in Women. M.S. Thesis. Colorado State University.
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Progress 01/01/96 to 12/30/96
Outputs
In our epidemiological pursuits, we have focused on understanding the lifestyle (diet and exercise) factors which mayprotect against hypertension and other cardiovascular disease (CVD) risk factors in African-American and Hispanic adults. We have shown that African-Americans vegetarians have less obesity, hypertension and a more favorable lipid profile than nonvegetarians. We have also found that plasma vitamin C concentrations are inversely related to blood pressure. In a recent analysis of a sample of 188 study participants from three northeastern US cities, subjects in the lowest terile of plasma vitamin C concentrations had an average systolic blood pressure that was 20mm Hg higher than the average blood pressure of subjects in the highest vitamin C tertile. This year, we examined in these same subjects the impact of regular exercise on CVD risk factors. We found that among the women, regular exercise attenuates the adverse effects of overweight on several, but
not all of the measured CVD risk factors. In unfinished studies, we collected dietary and exercise data on approximately 60 Hispanic adultsto examine the interaction of these variables on CVD risk.This year, in our energy balance laboratory, we are studying the relationships among skeletal muscle characteristics and resting and exercise substrate oxidation rates in youngAfrican-American and Caucasian women.
Impacts
(N/A)
Publications
- FRAGAPANE,J., REINKE,E., HARRIS,M. A., MELBY,C.L. 1996. Exercise and postexercisesubstrate oxidation in young women resulting from exercise bouts of different entensities. Med. & Sci. in Sports & Exercise 28:S43 (Abs. #255).
- TOOHEY,L, HARRIS,M.A., ALLEN,K.G. D., MELBY,C.L. 1996. Plasma ascorbic acid concentrations are related to cardiovascularrisk factors in African-Americans. J. of Nutrition 126:121-126.
- TOOHEY,M.L., HARRIS,M. A., WILLIAMS,D., FOSTER,G., MELBY,C.L. 1996. Cardiovascular disease risk factors in African-American vegans compared to lacto-ovovegetarians. FASEB J 10:A485(Abs. #2794).
- GILLETTE,C.A., WESTERLIND,K.C., THOMPSON,H. J., MELBY,C.L. 1996. Effects of feeding pattern and exercise on mammary gland weight and carcass energy. Med. & Sci. in Sports & Exercise 28:S31 (Abs.#185).
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Progress 01/01/95 to 12/30/95
Outputs
In our most recent study to examine lifestyle factors and cardiovascular disease(CVD) risk, we found that among subjects (n=188) recruited from Seventh-Day Adventist Churches in the Washington, D.C. area, serum total cholesterol (STC: x=144.9 vs 174.4 mg/dl), LDL-C (x=79.7 vs 102.3 mg/dl), and triglycerides (x=83.1 vs 103.5 mg/dl) were significantly (p<0.05) lower in vegans compared to LOVs. In the entire sample, plasma AA was inversely related to blood pressure which confirms our previous finding in another sample of Black Americans. In our energy balance laboratory this year, we studied the effects of low and high intensity exercise of similar energy output, on exercise and post-exercise energy expenditure and substrate oxidation in eight active, eumenorrheic females. Metabolic rate following high intensity, but not low intensity exercise remained elevated at the end of the 3-h post-exercise period. Total carbohydrate oxidation (exercise plus post-exercise period)
was significantly high for high compared to low intensity exercise. The rate of fat oxidation at the end of the measured 3-h recovery period remained higher for HIE compared to LIE. These data indicate that the recovery period should also be considered when determining the impact of different exercise intensities on total energy expenditure and fat and carbohydrate utilization.
Impacts
(N/A)
Publications
- HILL, J.O., MELBY, C.L., JOHNSON, S.L. AND PETERS, J.C. 1995. Physical Activity and Energy Requirements. Am. J. of Clinical Nutr. 62:1059s-1066s.
- BULLOUGH, R.D., GILLETTE, C.A., HARRIS, M.A. AND MELBY, C.L. 1995. Interaction of acute changes in exercise energy expenditure and energy intake on resting metabolic rate. Am. J. of Clinical Nutr. 61:473-481.
- TOOHEY, M.L., MELBY, C.L. AND HARRIS, M.A. 1995. Plasma ascorbic acid concentrations and cardiovascular risk factors in African Americans. FASEB J. 9:A177.
- WENZEL, D. 1995. Effect of a 20-week endurance exercise intervention on resting metabolic rate in middle-aged adults. Master's Thesis, Colo. State Univ., Fort Collins.
- FRAGAPANE, J. 1995. Carbohydrate and fat oxidation during and after exercise of different intensity and duration. Master's Thesis, Colo. State Univ., Fort Collins.
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Progress 01/01/94 to 12/30/94
Outputs
We have been interested in understanding the lifestyle (diet and exercise) factors which may protect against hypertension and other coronary heart disease risk factors in Black Americans. In a recent epidemiological analysis (not yet published) we have found that plasma ascorbic acid concentrations were inversely correlated with blood pressure (BP), serum total cholesterol (STC), low density lipoprotein-cholesterol (LDL-C), and plasma malondialdehyde equivalents (MDA, a marker for lipid peroxidation) concentrations. The plasma concentration of MDA equivalents was positively correlated with BP, STC, and LDL-C. Using the same data set, we found that Black women participating in regular exercise at least 4 times per week compared to those who exercise less, had a more favorable lipid profiles, primarily the result of higher high density lipoprotein-cholesterol (HDL-C) levels. We have recently obtained data on 220 Black vegetarians to determine if plasma ascorbate, and
level of exercise participation can predict BP and blood lipid levels within this group. In our energy laboratory we found that a bout of weight lifting exercise produced a greater elevation of post-exercise metabolic rate than did a bout of aerobic exercise of similar estimated caloric expenditure.
Impacts
(N/A)
Publications
- GILLETTE, C.A., BULLOUGH, R.C., AND MELBY, C.L. 1994. Postexercise energy expenditure in response to acute aerobic or resistive exercise. Inter. Journal of Sport Nutr. 4:347-360.
- MELBY, C.L., TOOHEY, M.L., AND CEBRICK, J. 1994. Blood Pressure and Blood Lipids Among Vegetarian, Semivegetarian, and Nonvegetarian African-Americans. Amer. Journal of Clin. Nutr. 59:103-109.
- MELBY, C.L., TOOHEY, M.L., AND CEBRICK, J. 1994. Blood pressure and blood lipids by level of exercise in African-American women. Med. and Sci. in Sports and Exercise 26:S159 (Abstract).
- BULLOUGH, R.C., SCHOLL, C.G., AND MELBY, C.L. 1994. Effects of acute exercise and energy balance on resting respiratory exchange ratio. Med. and Sci. in Sports and Exercise 26:S216 (Abstract).
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Progress 01/01/93 to 12/30/93
Outputs
In several epidemiologic studies, we have examined the influence of diet and exercise on cardiovascular disease (CVD) risk. We have found the vegetarian (VEG) diet to be associated with a protective effect against hypertension (HT) in both middle-aged and elderly African-Americans. Data from these studies suggest that although the VEG diet attenuates risk for HT in Black Americans, it does not completely offset their higher risk compared to white adults. In a separate study of African-Americans, we found the VEG and semivegetarian diets to be associated with significantly less HT and lower total and LDL-cholesterol levels than a less prudent omnivorous diet. The lower LDL-cholesterol level of the vegetarians was associated with lower body mass index, less central body adiposity, and lower intakes of saturated fat and protein. In our laboratory-based studies, we have found RMR and the rate of fat oxidation to be significantly elevated 15h following a strenuous bout of
resistive exercise. We have also found that the level of acute exercise and energy intake, can affect resting energy expenditure, even when subjects are weight stable and kept in approximate energy balance. The higher RMR values observed when individuals were subjected to a condition of high exercise energy expenditure and high energy intake, were associated with higher resting plasma norepinephrine levels.
Impacts
(N/A)
Publications
- BULLOUGH R.C., AND MELBY, C.L. 1993. Effect of inpatient versus outpatient measurement protocol on resting metabolic rate and respiratory exchange ratio. Annals of Nutr. and Metabol. 37:24-32.
- SCHMIDT, W.D., CORRIGAN, D., AND MELBY, C.L. 1993. Two seasons of weight-cycling does not lower resting metabolic rate in collegiate wrestlers. Medicine and Sci. in Sports and Exerc. 25:613-619.
- MELBY, C.L., GOLDFLIES, D.G., AND TOOHEY, M.L. 1993. Blood pressure differences in older black and white long-term vegetarians and nonvegetarians. J. Amer. College of Nutr. 12:262-269.
- SCHOLL, C.G. 1993. Effect of resistance and cycling exercise on recovery energy expenditure and substrate utilization. 53 p., M.S. Thesis, Colorado State University.
- BULLOUGH, R.C. 1993. Effects of exercise, energy intake, and energy flux on resting energy metabolism and thermogenic hormones. 240 p., Ph.D. Dissertation,.
- MELBY, C.L., SCHOLL, C., EDWARDS, G., AND BULLOUGH, R.C. 1993. Effect of acute p resistance exercise on postexercise energy expenditure and resting metabolic rate. J. Applied Physiology 75:1847-1853.
- BURKE, C.M., BULLOUGH, R.C., AND MELBY, C.L. 1993. Resting metabolic rate and postprandial thermogenesis by level of aerobic fitness in young women. European J. Clinical Nutr. 47:575-585.
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Progress 01/01/92 to 12/30/92
Outputs
In several epidemiologic studies, we have examined the influence of diet and exercise on cardiovascular disease risk. In elderly African-Americans and Caucasians, we found that the Black long-term vegetarians (VEG) exhibited lower blood pressure (BP) and had less hypertension (HT) than their omnivorous (OM) counterparts, but higher BP than either group of elderly white VEG and OM. Data from this study suggest that the VEG diet may attenuate risk for HT in older Black Americans, but that it does not completely offset their higher risk compared to White adults. In a separate study of African-Americans, we found the VEG and prudent OM diet to be associated with significantly less HT and lower total and and LDL-cholesterol levels than a less prudent OM diet. A prudent plant-based diet appears to afford some protection against the potent CVD risk factors of HT and hyperlipidemia in Black adults. In our laboratory-based studies, we are examining the impact of diet and
different types of exercise on resting metabolic rate (RMR) and substrate utilization. In young men, we have found RMR and the rate of fat oxidation to be significantly elevated 15 hours following a strenuous bout of resistive exercise. We are currently examining the impact of energy flux (high and low caloric intake matched to high and low expenditure) on RMR, substrate utilization, and various thermogenic hormones.
Impacts
(N/A)
Publications
- MELBY, C., TINCKNELL, T. AND SCHMIDT, W. 1992. Energy Expenditure Following a Bout of Non-steady State Resistance Exercise. J Sports Med. Phys. Fit. 32:128-135.
- LYLE, R., WEAVER, C., SEDLOCK, D., RAJARAM, S., MARTINE, B. AND MELBY, C. 1992. Iron Status in Exercising Women: The Effect of Oral Iron Therapy vs Increased Consumption of Muscle Foods. Am. J. Clin. Nutr. 56:1049-55.
- SCHMIDT, W., MELBY, C., AND CORRIGAN, D. 1992. Resting Metabolic Rate in Weight Cycling Wrestlers Compared With Noncycling Wrestlers & Noncycling Controls. (Abstract) Med. Sci. Sport Exerc. 24:S51.
- SOCKLER, J. SMITH, C. AND MELBY, C. 1992. Postexercise Metabolism in Lean and Nonlean Males of Matched Lean Mass. (Abstract) Med. Sci. Sport Exerc. 24:S52.
- BURKE, C. AND MELBY, C. 1992. Resting Metabolic Rate and Postprandial Thermogenesis by Level of Aerobic Fitness in Young Women. (Abstract) Med. Sci. Sport Exerc. 24:S77.
- MELBY, C. AND EDWARDS, G. 1992. Effects of a Bout of Resistance Exercise on Postexercise Oxygen Consumption and Resting Metabolic Rate. (Abstract) Med. Sci. Sport Exerc. 24:S175.
- BULLOUGH, R. AND MELBY, C. 1992. Effect of Inpatient vs Outpatient Protocol on Resting Metabolic Rate and Respiratory Exchange Ratio. (Abstract) FASEB J. 6:A1117.
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Progress 07/01/91 to 12/30/91
Outputs
We have undertaken several initiatives to examine the influence of diet and exercise on cardiovascular disease risk in African-Americans. In the first study using data we had previously gathered, we found that only 20% of regularly exercising Black adults were hypertensive compared to 42% of the nonexercisers. Age and gender-adjusted blood pressure (BP) was significantly lower in the exercisers (BP=124/73 mm Hg) compared to the sedentary adults (BP=134/77). Black adults who adhered to a vegetarian diet and who engaged in exercise at least two times per week, exhibited one-third the hypertension of the sedentary nonvegetarians (18% versus 55%), and their average systolic BP was 14 mm Hg lower. We are currently collecting data on Black vegetarians and nonvegetarians to examine blood lipids by diet and exercise patterns. We are also conducting studies to examine the impact of diet and exercise on energy expenditure. The first study was undertaken to establish the
reliability of resting metabolic rate (RMR) measurements in our energy metabolism laboratory. We found RMR values of young men to be highly reproducible and similar under either inpatient or outpatient conditions. In another study, we are currently examining RMR and postprandial thermogenesis by level of exercise and dietary intake in young women. Preliminary results using the data obtained to date, suggest that women who engage in high levels of exercise may be less thermogenically efficient at rest than less active women.
Impacts
(N/A)
Publications
- MELBY, C.L., SYLLIAASEN, S., AND RHODES, T. 1991. Diet-induced Weight Loss and Metabolic Changes in Obese Women With High Versus Low Prior Weight Loss/Regain. Nutrition Research 11:971-978.
- MELBY, C.L., GOLDFLIES, D.G., AND HYNER, G.C. 1991. Blood Pressure and Anthropometric Differences in Regularly Exercising and Nonexercising Black Adults. Clinical & Experimental Hypertension 13:1233-1248.
- POEHLMAN, E.T., MELBY, C.L., AND BADYLAK, S.F. 1991. Relation of Age and Physical Exercise Status to Metabolic Rate in Younger and Older Health Men. J. of Gerontology: Biological Sciences 46:B54-58.
- POEHLMAN, E.T., MELBY, C.L., AND GORAN, M.I. 1991. The Impact of Exercise and Diet Restriction on Daily Energy Expenditure. Sports Medicine 11:78-101.
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