Publications by authors named "Richard Viskochil"

14 Publications

  • Page 1 of 1

Impact of the COVID-19 pandemic on exercise habits among cancer patients.

Res Sq 2021 Sep 21. Epub 2021 Sep 21.

Purpose There is limited information on how the COVID-19 pandemic has changed health behaviors among cancer patients. We examined the impact of the pandemic on changes in exercise behaviors and identified characteristics associated with these changes among cancer patients. Methods Cancer patients (n   1,361) completed a survey from August-September 2020 to assess COVID-19 pandemic-related changes in health behaviors and psychosocial factors. Patients were categorized into 3 groups: exercising less, exercising did not change, and exercising more. Patient characteristics were compared by exercise groups. Results One-third of the patients reported a decreased amount of regular exercise, while 11% reported exercising more during the pandemic. Patients who exercised less were more likely to be unemployed/retired, undergoing active treatment, and had increased pandemic-related alcohol consumption and psychosocial stressors such as loneliness and financial stress (all  < 0.05). In contrast, patients who exercised more were younger, female, full-time employed, did not consume alcohol, and had good health status and more social interactions (all  < 0.05). Patients who were living in rural areas and did not experience changes in daily life, were also more likely not to experience changes in exercise habits (all  < 0.05). Conclusion Our results indicate that a significant proportion of cancer patients experienced changes in exercise habits during the first 6 months of the COVID-19 pandemic. Age, sex, employment status, health status, alcohol consumption, and psychosocial factors were associated with changes in exercise behaviors. Providers should monitor for changes in health behaviors, such as exercise, because of their importance in improving cancer survivorship.
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http://dx.doi.org/10.21203/rs.3.rs-704646/v1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8475966PMC
September 2021

Understanding the Prevalence of Prediabetes and Diabetes in Patients With Cancer in Clinical Practice: A Real-World Cohort Study.

J Natl Compr Canc Netw 2021 Mar 10;19(6):709-718. Epub 2021 Mar 10.

2Huntsman Cancer Institute, and.

Background: This study aimed to understand the prevalence of prediabetes (preDM) and diabetes mellitus (DM) in patients with cancer overall and by tumor site, cancer treatment, and time point in the cancer continuum.

Methods: This cohort study was conducted at Huntsman Cancer Institute at the University of Utah. Patients with a first primary invasive cancer enrolled in the Total Cancer Care protocol between July 2016 and July 2018 were eligible. Prevalence of preDM and DM was based on ICD code, laboratory tests for hemoglobin A1c, fasting plasma glucose, nonfasting blood glucose, or insulin prescription.

Results: The final cohort comprised 3,512 patients with cancer, with a mean age of 57.8 years at cancer diagnosis. Of all patients, 49.1% (n=1,724) were female. At cancer diagnosis, the prevalence of preDM and DM was 6.0% (95% CI, 5.3%-6.8%) and 12.2% (95% CI, 11.2%-13.3%), respectively. One year after diagnosis the prevalence was 16.6% (95% CI, 15.4%-17.9%) and 25.0% (95% CI, 23.6%-26.4%), respectively. At the end of the observation period, the prevalence of preDM and DM was 21.2% (95% CI, 19.9%-22.6%) and 32.6% (95% CI, 31.1%-34.2%), respectively. Patients with myeloma (39.2%; 95% CI, 32.6%-46.2%) had the highest prevalence of preDM, and those with pancreatic cancer had the highest prevalence of DM (65.1%; 95% CI, 57.0%-72.3%). Patients who underwent chemotherapy, radiotherapy, or immunotherapy had a higher prevalence of preDM and DM compared with those who did not undergo these therapies.

Conclusions: Every second patient with cancer experiences preDM or DM. It is essential to foster interprofessional collaboration and to develop evidence-based practice guidelines. A better understanding of the impact of cancer treatment on the development of preDM and DM remains critical.
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http://dx.doi.org/10.6004/jnccn.2020.7653DOI Listing
March 2021

Fusobacterium nucleatum and Clinicopathologic Features of Colorectal Cancer: Results From the ColoCare Study.

Clin Colorectal Cancer 2021 09 27;20(3):e165-e172. Epub 2021 Feb 27.

Huntsman Cancer Institute, Salt Lake City, UT; Department of Population Health Sciences, University of Utah, Salt Lake City, UT.

Background: Fusobacterium nucleatum (Fn), a bacterium associated with a wide spectrum of infections, has emerged as a key microbe in colorectal carcinogenesis. However, the underlying mechanisms and clinical relevance of Fn in colorectal cancer (CRC) remain incompletely understood.

Patients And Methods: We examined associations between Fn abundance and clinicopathologic characteristics among 105 treatment-naïve CRC patients enrolled in the international, prospective ColoCare Study. Electronic medical charts, including pathological reports, were reviewed to document clinicopathologic features. Quantitative real-time polymerase chain reaction (PCR) was used to amplify/detect Fn DNA in preoperative fecal samples. Multinomial logistic regression was used to analyze associations between Fn abundance and patient sex, age, tumor stage, grade, site, microsatellite instability, body mass index (BMI), alcohol consumption, and smoking history. Cox proportional hazards models were used to investigate associations of Fn abundance with overall survival in adjusted models.

Results: Compared to patients with undetectable or low Fn abundance, patients with high Fn abundance (n = 22) were 3-fold more likely to be diagnosed with rectal versus colon cancer (odds ratio [OR] = 3.01; 95% confidence interval [CI], 1.06-8.57; P = .04) after adjustment for patient sex, age, BMI, and study site. Patients with high Fn abundance also had a 5-fold increased risk of being diagnosed with rectal cancer versus right-sided colon cancer (OR = 5.32; 95% CI, 1.23-22.98; P = .03). There was no statistically significant association between Fn abundance and overall survival.

Conclusion: Our findings suggest that Fn abundance in fecal samples collected prior to surgery varies by tumor site among treatment-naïve CRC patients. Overall, fecal Fn abundance may have diagnostic and prognostic significance in the clinical management of CRC.
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http://dx.doi.org/10.1016/j.clcc.2021.02.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8390557PMC
September 2021

Community Health Behaviors and Geographic Variation in Early-Onset Colorectal Cancer Survival Among Women.

Clin Transl Gastroenterol 2020 12;11(12):e00266

Division of Epidemiology, Augusta University at the Medical College of Georgia, Augusta, Georgia, USA.

Introduction: Despite overall reductions in colorectal cancer (CRC) morbidity and mortality, survival disparities by sex persist among young patients (age <50 years). Our study sought to quantify variance in early-onset CRC survival accounted for by individual/community-level characteristics among a population-based cohort of US women.

Methods: Geographic hot spots-counties with high early-onset CRC mortality rates among women-were derived using 3 geospatial autocorrelation approaches with Centers for Disease Control and Prevention national mortality data. We identified women (age: 15-49 years) diagnosed with CRC from 1999 to 2016 in the National Institutes of Health/National Cancer Institute's Surveillance, Epidemiology, and End Results program. Patterns of community health behaviors by hot spot classification were assessed by Spearman correlation (ρ). Generalized R values were used to evaluate variance in survival attributed to individual/community-level features.

Results: Approximately 1 in every 16 contiguous US counties identified as hot spots (191 of 3,108), and 52.9% of hot spot counties (n = 101) were located in the South. Among 28,790 women with early-onset CRC, 13.7% of cases (n = 3,954) resided in hot spot counties. Physical inactivity and fertility were community health behaviors that modestly correlated with hot spot residence among women with early-onset CRC (ρ = 0.21 and ρ = -0.23, respectively; P < 0.01). Together, individual/community-level features accounted for distinct variance patterns in early-onset CRC survival among women (hot spot counties: 33.8%; non-hot spot counties: 34.1%).

Discussion: Individual/community-level features accounted for approximately one-third of variation in early-onset CRC survival among women and differed between hot spot vs non-hot spot counties. Understanding the impact of community health behaviors-particularly in regions with high early-onset CRC mortality rates-is critical for tailoring strategies to reduce early-onset CRC disparities.
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http://dx.doi.org/10.14309/ctg.0000000000000266DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7678794PMC
December 2020

Diabetes, Body Fatness, and Insulin Prescription Among Adolescents and Young Adults with Cancer.

J Adolesc Young Adult Oncol 2021 04 29;10(2):217-225. Epub 2020 Jul 29.

Huntsman Cancer Institute, Salt Lake City, Utah, USA.

Rates of obesity and obesity-related health consequences, including type 2 diabetes (T2D) and cancer, continue to rise. While cancer patients are at an increased risk of developing T2D, the prevalence of T2D and insulin prescription among young patients with cancer remains unknown. Using the Total Cancer Care Study cohort at Huntsman Cancer Institute (Salt Lake City, UT), we identified individuals age 18-39 years at cancer diagnosis between 2009 and 2019. Multivariable logistic regression was used to investigate associations between body mass index (BMI) with insulin prescription within 1 year of cancer diagnosis. In total, 344 adolescents and young adults (AYAs) were diagnosed with primary invasive cancer. Within this cohort, 19 patients (5.5%) were ever diagnosed with T2D, 48 AYAs ever received an insulin prescription (14.0%), and 197 were overweight or obese (BMI: 25+ kg/m) at cancer diagnosis. Each kg/m unit increase in BMI was associated with 6% increased odds of first insulin prescription within 1 year of cancer diagnosis among AYAs, even after adjustment for age, sex, smoking history, marital status, glucocorticoid prescription, and cancer treatments (odds ratio = 1.06, 95% confidence interval 1.02-1.11;  = 0.005). One in every 18 AYAs with cancer ever had T2D, 1 in 7 AYA patients with cancer ever received an insulin prescription, and higher BMI was associated with increased risk of insulin prescription within a year of cancer diagnosis among AYAs. Understanding the incidence of T2D and insulin prescription/use is critical for short-term and long-term clinical management of AYAs with cancer.
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http://dx.doi.org/10.1089/jayao.2020.0071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8064923PMC
April 2021

Multi-omics Analysis Reveals Adipose-tumor Crosstalk in Patients with Colorectal Cancer.

Cancer Prev Res (Phila) 2020 10 12;13(10):817-828. Epub 2020 Jul 12.

International Agency for Research on Cancer (IARC), Lyon, France.

Obesity and obesity-driven cancer rates are continuing to rise worldwide. We hypothesize that adipocyte-colonocyte interactions are a key driver of obesity-associated cancers. To understand the clinical relevance of visceral adipose tissue in advancing tumor growth, we analyzed paired tumor-adjacent visceral adipose, normal mucosa, and colorectal tumor tissues as well as presurgery blood samples from patients with sporadic colorectal cancer. We report that high peroxisome proliferator-activated receptor gamma () visceral adipose tissue expression is associated with glycoprotein VI (GPVI) signaling-the major signaling receptor for collagen-as well as fibrosis and adipogenesis pathway signaling in colorectal tumors. These associations were supported by correlations between visceral adipose tissue expression and circulating levels of plasma 4-hydroxyproline and serum intercellular adhesion molecule 1 (ICAM1), as well as gene set enrichment analysis and joint gene-metabolite pathway results integration that yielded significant enrichment of genes defining epithelial-to-mesenchymal transition-as in fibrosis and metastasis-and genes involved in glycolytic metabolism, confirmed this association. We also reveal that elevated prostaglandin-endoperoxide synthase 2 () colorectal tumor expression is associated with a fibrotic signature in adipose-tumor crosstalk via GPVI signaling and dendritic cell maturation in visceral adipose tissue. Systemic metabolite and biomarker profiling confirmed that high expression in colorectal tumors is significantly associated with higher concentrations of serum amyloid A and glycine, and lower concentrations of sphingomyelin, in patients with colorectal cancer. This multi-omics study suggests that adipose-tumor crosstalk in patients with colorectal cancer is a critical microenvironment interaction that could be therapeutically targeted..
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http://dx.doi.org/10.1158/1940-6207.CAPR-19-0538DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7877796PMC
October 2020

Associations between physical activity, sedentary behavior, and urinary oxidized guanine in colorectal cancer patients: results from the ColoCare Study.

Appl Physiol Nutr Metab 2020 Nov 22;45(11):1306-1309. Epub 2020 Jun 22.

Huntsman Cancer Institute, Salt Lake City, UT 84112, USA.

To determine associations between physical activity (PA), sedentary behavior (SB), and oxidative stress in colorectal cancer patients, ColoCare Study participants in Germany wore an accelerometer 6 and/or 12 months after surgery. Spearman partial correlations were used to assess associations between PA and urinary concentrations of oxidized guanine, a validated marker of oxidative stress. There were no significant associations between PA or SB and oxidized guanine in = 76 measurements (ng/mg creatinine; = 0.03, = 0.76 for PA, = -0.05, = 0.69 for SB). Objectively measured PA was not associated with a marker of oxidative stress in colorectal cancer patients.
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http://dx.doi.org/10.1139/apnm-2019-0836DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7609563PMC
November 2020

Metrics of Diabetes Risk Are Only Minimally Improved by Exercise Training in Postmenopausal Breast Cancer Survivors.

J Clin Endocrinol Metab 2020 05;105(5)

Department of Kinesiology, University of Massachusetts, Amherst, MA, US.

Context: Insulin resistance is a risk factor for breast cancer recurrence. How exercise training changes fasting and postglucose insulin resistance in breast cancer survivors is unknown.

Objective: To evaluate exercise-induced changes in postglucose ingestion insulin concentrations, insulin resistance, and their associations with cancer-relevant biomarkers in breast cancer survivors.

Setting: The University of Massachusetts Kinesiology Department.

Participants: 15 postmenopausal breast cancer survivors not meeting the physical activity guidelines (150 min/week of exercise).

Intervention: A supervised 12-week aerobic exercise program (60 min/day, 3-4 days/week).

Main Outcome Measures: Postglucose ingestion insulin was determined by peak insulin and area under the insulin curve (iAUC) during a 5-sample oral glucose tolerance test. Insulin sensitivity was estimated from the Matsuda composite insulin sensitivity index (C-ISI). Changes in fitness and body composition were determined from submaximal VO2peak and dual energy X-ray absorptiometry.

Results: Participants averaged 156.8 ± 16.6 min/week of supervised exercise. Estimated VO2peak significantly increased (+2.8 ± 1.4 mL/kg/min, P < .05) and body weight significantly decreased (-1.1 ± 0.8 kg, P < .05) following the intervention. There were no differences in fasting insulin, iAUC, C-ISI, or peak insulin following the intervention. Insulin was only significantly lower 120 min following glucose consumption (68.8 ± 34.5 vs 56.2 ± 31.9 uU/mL, P < .05), and there was a significant interaction with past/present aromatase inhibitor (AI) use for peak insulin (-11.99 non-AI vs +13.91 AI uU/mL) and iAUC (-24.03 non-AI vs +32.73 AI uU/mL).

Conclusions: Exercise training had limited overall benefits on insulin concentrations following glucose ingestion in breast cancer survivors but was strongly influenced by AI use.
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http://dx.doi.org/10.1210/clinem/dgz213DOI Listing
May 2020

Elevated insulin levels following 7 days of increased sedentary time are due to lower hepatic extraction and not higher insulin secretion.

Appl Physiol Nutr Metab 2019 Sep 10;44(9):1020-1023. Epub 2019 Apr 10.

Department of Kinesiology, University of Massachusetts, Amherst, MA 01003, USA.

Higher insulin following sedentary behavior may be due to increased insulin secretion (IS), decreased hepatic insulin extraction (HIE), or a combination of both. Ten healthy adults completed glucose tolerance tests following 7 days of normal activity and 7 days of increased sitting. There were no differences in IS; however, HIE at 120 min after ingestion (85.4% ± 7.2% vs. 74.6% ± 6.6%, < 0.05) and the area under the curve (73.6% ± 9.4% vs. 67.5% ± 11.3%, < 0.05) were reduced following 7 days of increased sedentary time.
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http://dx.doi.org/10.1139/apnm-2018-0802DOI Listing
September 2019

The ColoCare Study: A Paradigm of Transdisciplinary Science in Colorectal Cancer Outcomes.

Cancer Epidemiol Biomarkers Prev 2019 03 6;28(3):591-601. Epub 2018 Dec 6.

Department of General, Visceral and Transplantation Surgery, University Hospital of Heidelberg, Heidelberg, Germany.

Background: Colorectal cancer is a leading cause of cancer death. Biomarkers to predict treatment outcomes are needed, as is evidence whether postdiagnosis diet and lifestyle can affect well-being and clinical outcomes. The international ColoCare Consortium aims to identify new biologic markers (e.g., metabolomic, transcriptomic, metagenomic, genetic, epigenetic, proteomic markers) that predict clinical outcomes, and to characterize associations between modifiable risk factors (e.g., diet, supplement use, physical activity) with short-term and long-term patient-reported and clinical outcomes among patients with colorectal cancer. ColoCare is recruiting newly diagnosed patients with colorectal cancer across six sites in the United States and one site in Germany. As of April 2018, we have recruited >2,000 patients across all sites. Our projected enrollment is >4,000 multiethnic patients with colorectal cancer. The study includes uniformly collected, comprehensive sets of data and biospecimens at multiple time points up to 5 years after diagnosis. Treatment and clinical data are abstracted from medical records and centrally harmonized. Biospecimens are archived according to standardized procedures. Our initial studies demonstrated metabolic differences in adipose tissue types. We further reported on associations of biological factors (e.g., inflammation, DNA methylation, metabolomics) with lifestyle factors (e.g., adiposity, smoking, physical activity, dietary supplement use) or joint associations with clinical outcomes.

Conclusions: ColoCare is a consortium for the investigation of multilevel factors relevant to colorectal cancer survivorship.

Impact: The combination of a comprehensive set of biospecimens collected at multiple time points, jointly with detailed assessments of health behaviors and other prognostic factors, results in a unique resource that facilitates wide-ranging, innovative, and impactful research on colorectal cancer.
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http://dx.doi.org/10.1158/1055-9965.EPI-18-0773DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6420345PMC
March 2019

Pilot Study of Impact of a Pedal Desk on Postprandial Responses in Sedentary Workers.

Med Sci Sports Exerc 2018 Oct;50(10):2156-2163

Department of Kinesiology, University of Massachusetts Amherst, Amherst, MA.

Physical inactivity has been linked to rates of obesity, diabetes, and heart disease through insulin resistance and other mechanisms. Although sedentary workplace environments have unintentionally contributed to the risk for chronic diseases, innovations in the workplace environment could potentially rectify this public and occupational health problem.

Purpose: To evaluate the effects of light-intensity physical activity using a pedal desk (PD) compared with a standard desk (STD) in a pilot study on postprandial metabolic responses and work skills.

Methods: Twelve overweight/obese full-time sedentary office workers (six men and six women; body mass index, 28.7 ± 3.6 kg·m) were tested in two conditions: 1) PD, pedaling at self-selected light-intensity pace for 2 h and 2) STD, remaining seated for 2 h in a conventional workstation setup while performing scripted computer-based work tasks. Blood samples were analyzed for plasma glucose, insulin, and free-fatty acids in response to a standardized meal and work skills were evaluated. Paired samples t-tests were used to examine the differences in metabolic responses and work performance tasks between the conditions.

Results: Pedal desk use required significantly less insulin to maintain glucose concentrations compared with STD condition (peak insulin concentration, 42.1 μU·mL vs 66.9 μU·mL; P = 0.03; and area under the curve, 302.6 vs 441.8 μU·min·mL; P < 0.001). No significant changes in plasma glucose and free-fatty acid concentrations were observed at any timepoints (all P > 0.05). In addition, pedaling at a self-paced rate caused no adverse effects on work skills (P > 0.05).

Conclusions: The PD resulted in lower postmeal insulin concentrations without an overall negative impact on work skills. Thus, the PD could have the potential to achieve public and occupational health goals in sedentary work environments.
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http://dx.doi.org/10.1249/MSS.0000000000001679DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6138546PMC
October 2018

Exercise training and metformin, but not exercise training alone, decreases insulin production and increases insulin clearance in adults with prediabetes.

J Appl Physiol (1985) 2017 Jul 4;123(1):243-248. Epub 2017 May 4.

Department of Kinesiology, University of Massachusetts, Amherst, Massachusetts;

Adding metformin to exercise does not augment the effect of training alone to boost whole body insulin sensitivity and lower circulating insulin concentrations. Although lower insulin concentrations (lower supply) following lifestyle and/or pharmacological interventions are primarily attributed to reductions in insulin secretion that match increases in peripheral insulin sensitivity (lower demand), it is unclear whether exercise and/or metformin exert direct effects on insulin production, extraction, or clearance. Thirty-six middle-aged, obese, sedentary adults with prediabetes were randomized to placebo (P), metformin (M), exercise and placebo (E+P), or exercise and metformin (E+M) for 12 wk. Fasting plasma proinsulin (an indicator of insulin production), C-peptide, insulin, and glucose were collected before and after the intervention. Peripheral insulin sensitivity (euglycemic clamp), hepatic insulin extraction, insulin clearance, body weight, and cardiorespiratory fitness were also measured. Fasting proinsulin was unchanged following P (19.4 ± 10.1 vs. 22.6 ± 15.0 pmol/l), E+P (15.1 ± 7.4 vs. 15.5 ± 7.4 pmol/l), or M (24.8 ± 18.9 vs. 16.7 ± 20.3 pmol/l) but was significantly reduced after E+M (18.6 ± 11.9 vs. 13.9 ± 6.7 pmol/l; = 0.04). Insulin clearance was significantly greater following M (384.6 ± 19.4 vs. 477.4 ± 49.9; = 0.03) and E+M (400.1 ± 32.0 vs. 482.9 ± 33.9; = 0.02) but was unchanged in P or E+P. In this study, metformin combined with exercise training reduced circulating proinsulin, and both groups taking metformin increased insulin clearance. This suggests that adding metformin to exercise may augment or attenuate training effects depending on the outcome or organ system being assessed. Exercise is increasingly viewed as medication, creating a need to understand its interactions with other common medications. Research suggests metformin, a widely prescribed diabetes medication, may diminish the benefits of exercise when used in combination. In this study, however, metformin combined with exercise training, but not exercise alone, lowered proinsulin concentrations and increased insulin clearance in adults with prediabetes. This may directly influence personalized prescriptions of lifestyle and/or pharmacology to reduce diabetes risk.
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http://dx.doi.org/10.1152/japplphysiol.00790.2016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5538813PMC
July 2017

The independent and combined effects of exercise training and reducing sedentary behavior on cardiometabolic risk factors.

Appl Physiol Nutr Metab 2014 Jul 7;39(7):770-80. Epub 2014 Jan 7.

a Department of Kinesiology, University of Massachusetts Amherst, Amherst, MA 01003, USA.

This pilot study examined if the combination of exercise training and reducing sedentary time (ST) results in greater changes to health markers than either intervention alone. Fifty-seven overweight/obese participants (19 males/39 females) (mean ± SD; age, 43.6 ± 9.9 years; body mass index (BMI), 35.1 ± 4.6 kg·m(-2)) completed the 12-week study and were randomly assigned to (i) EX: exercise 5 days·week(-1) for 40 min·session(-1) at moderate intensity; (ii) rST: reduce ST and increase nonexercise physical activity; (iii) EX-rST: combination of EX and rST; and (iv) CON: maintain behavior. Fasting lipids, blood pressure (BP), peak oxygen uptake, BMI, and 2-h oral glucose tolerance tests were completed pre- and post-intervention. EX and EX-rST increased peak oxygen uptake by ∼10% and decreased systolic BP (both p < 0.001). BMI decreased by -3.3% (95% confidence interval: -4.6% to -1.9%) for EX-rST and -2.2% (-3.5% to 0.0%) for EX. EX-rST significantly increased composite insulin-sensitivity index by 17.8% (2.8% to 32.8%) and decreased insulin area under the curve by 19.4% (-31.4% to -7.3%). No other groups improved in insulin action variables. rST group decreased ST by 7% (∼50 min·day(-1)); however, BP was the only health-related outcome that improved. EX and EX-rST improved peak oxygen uptake and BMI, providing further evidence that moderate-intensity exercise is beneficial. The within-group analysis provides preliminary evidence that exercising and reducing ST may result in improvements in metabolic biomarkers that are not seen with exercise alone, though between-group differences did not reach statistical significance. Future studies, with larger samples, should examine health-related outcomes resulting from greater reductions in ST over longer intervention periods.
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http://dx.doi.org/10.1139/apnm-2013-0379DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4075057PMC
July 2014

Mild fasting hyperglycemia shifts fuel reliance toward fat during exercise in adults with impaired glucose tolerance.

J Appl Physiol (1985) 2013 Jul 18;115(1):78-83. Epub 2013 Apr 18.

Energy Metabolism Laboratory, Department of Kinesiology, University of Massachusetts, Amherst, MA 01003, USA.

Impaired glucose tolerance (IGT) is characterized by decreased oxidative capacity and reduced carbohydrate utilization during exercise. However, it is unclear if the presence of impaired fasting glucose (IFG) affects fuel utilization during exercise in adults with IGT. We tested the hypothesis that the presence of IFG in adults with IGT decreases reliance on carbohydrate during exercise. Middle-aged, obese, sedentary individuals (n = 6, IGT and n = 6, IFG+IGT) were compared during exercise at 60% peak O2 consumption for 45 min on a cycle ergometer. Glucose rates of appearance and disposal and muscle glycogen were assessed by stable isotope dilution methods, and fat utilization was estimated via indirect calorimetry. A 75-g oral glucose tolerance test was used to determine fasting and 2-h glucose concentrations. A glucose intolerance severity z-score was calculated from the oral glucose tolerance test. Glucose flux (i.e., rates of appearance and disposal) was not different between groups. However, individuals with IFG+IGT had lower muscle glycogen use (P < 0.05) and elevated fat oxidation (P < 0.01) during exercise compared with those with isolated IGT. Plasma nonesterified fatty acids and glucose were significantly higher during exercise in subjects with IFG+IGT vs. IGT alone (P < 0.05). Fat utilization during exercise correlated with fasting glucose (r = 0.57, P = 0.05), glucose intolerance severity z-score (r = 0.66, P = 0.01), and nonesterified fatty acids (trend; r = 0.55, P = 0.08). The presence of IFG shifts fuel selection toward increased fat oxidation and decreased muscle glycogen utilization during exercise in adults with IGT. Whether these differences in substrate use contribute to, or are the result of, movement along the continuum from prediabetes to type 2 diabetes awaits further work.
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http://dx.doi.org/10.1152/japplphysiol.00084.2013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3727012PMC
July 2013
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