Associations of sedentary behavior and screen time with biomarkers of inflammation and insulin resistance.

Sedentary behavior (SB) has been linked to risk factors of cardiometabolic disease, with inconsistent findings reported in the literature. We aimed to assess the associations of SB with multiple biomarkers of inflammation and insulin resistance in adults. Domain-specific SB, sitting time and moderate-to-vigorous physical activity (MVPA) were measured in 78 adults (mean ± SD 52.0 ± 10.8 y). Body fat percentage (BF%) was assessed using multi-frequency bioelectrical impedance. A blood draw assessed glucose, insulin, C-reactive protein (CRP), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), leptin, and adiponectin. Adiponectin-leptin ratio (ALR), homeostasis model assessment of insulin resistance (HOMA-IR) and beta-cell function (HOMA-ß) were calculated. Multivariable linear regression analyses, controlling for age, sex, MVPA, and BF%, were used to assess associations. After adjustment for age, sex and MVPA, total SB (7.5 ± 2.5 h/day) was positively associated with leptin, insulin, HOMA-IR, HOMA-ß (Standardized Beta (ß) range 0.21-0.32) and negatively associated with ALR (ß = -0.24, p < 0.05 for all). Similarly, total sitting time (7.2 ± 2.9 h/day) was associated with TNF-α (ß = 0.22) and ALR (ß = -0.26). These associations were attenuated to non-significance after adjustment for BF%. Leisure screen time was detrimentally associated with IL-6 (ß = 0.24), leptin (ß = 0.21), insulin (ß = 0.37), HOMA-IR (ß = 0.37), and HOMA-ß (ß = 0.34), independent of age, sex and MVPA (p < 0.05 for all). Only the associations with insulin (ß = 0.26), HOMA-IR (ß = 0.26), and HOMA-ß (ß = 0.23) remained significant after further controlling BF% (p < 0.05). Self-reported SB is associated with biomarkers of inflammation and insulin resistance, independent of MVPA, and in some cases BF%.

Associations of Sedentary Behavior and Screen Time with Human Gut Microbiome Composition and Diversity.

Human gut microbiome richness, diversity, and composition are associated with physical activity and impaired glycemic control; however, the associations with sedentary behavior and screen time are not as well-established. This study evaluated associations of sedentary behavior and screen time with the alpha diversity and composition of the human gut microbiome in adults with and without impaired glycemic control. Sedentary behavior and screen time data were collected via survey from 47 adults (38% with impaired glycemic control). Microbiome composition and alpha diversity were determined in fecal microbial DNA. Sedentary behavior was negatively associated with the number of observed operational taxonomic units (OTUs), Chao 1 Index, and Fisher's Alpha Index. These associations were slightly attenuated but remained significant when controlling for covariates. Screen time was negatively associated with the number of observed OTUs, Shannon Index, and Fisher's Alpha Index; however, only the association with observed OTUs was independent of all covariates. Our findings suggest sedentary behavior and screen time may be significant influencers of compositional changes in human gut microbiota. This may be a potential mechanism linking sedentary behavior and screen time to an increased risk of type 2 diabetes.

Sex Hormones and Abdominal Muscle Area and Radiodensity in Men: The Multi-Ethnic Study of Atherosclerosis.

Information on the associations of testosterone levels with abdominal muscle volume and quality in men is limited, while the role of estradiol and SHBG on these muscle characteristics are unclear. To investigate the association between fasting serum sex hormones and CT-derived abdominal muscle area and radiodensity in adult men. Cross sectional observational study using data from the Multi-Ethnic Study of Atherosclerosis. A community-based sample of 907 men aged 45-84 years; 878 men with complete data were included in the analysis. CT scans of the abdomen were interrogated for muscle characteristics. Multivariable linear regressions were used to test the associations. After adjustment, higher levels of both total testosterone and estradiol were associated with higher abdominal muscle area (1.79, 0.1-3.4, & 1.79, 0.4-3.2, respectively). In the final analyses, levels of total testosterone showed a positive association, while an inverse relationship was observed for SHBG with abdominal muscle radiodensity (0.3, 0.0-0.6, & -0.34, -0.6 - -0.1, respectively). Our results indicate a complex association between sex hormones and abdominal muscle characteristics in men. Specifically, total testosterone and estradiol were associated with abdominal muscle area, while only total testosterone was associated with muscle radiodensity and SHBG was inversely associated with muscle radiodensity.

Development of a Fitness Surveillance System to Track and Evaluate Obesity in North Idaho.

BACKGROUND: Internationally 18% of youth are obese. Fitness testing can be used to establish fitness surveillance, which can inform policy and targeted interventions aimed at addressing obesity. The purpose of this study was to estimate the prevalence of overweight, obesity, and low fitness in Idaho school-aged youth through a pilot study. METHODS: A convenience sample of 13 teachers from 11 north Idaho rural schools collected FitnessGram fitness data: body composition (body mass index [BMI]), aerobic capacity (Progressive Aerobic Cardiovascular Endurance Run [PACER] test), muscular endurance (curl up), strength (pushup), and flexibility (sit and reach). RESULTS: A total of 761 students (aged 9-18 years) from grades 3&5, 7, and 9 to 12 participated in the study. Approximately 24% of 3&5 and 22% of 7th, and 12% of 9 to 12th-grade students were categorized as Needs Improvement/Health Risk by FitnessGram standards for BMI. Similarly, approximately 25% of 3&5, and 22% of 7 and 9 to 12th-grade students were considered Needs Improvement/Health Risk for PACER. IMPLICATIONS FOR SCHOOL HEALTH POLICY, PRACTICE, AND EQUITY: Results from fitness testing can provide school and public health representatives with a "needs assessment" of student health that can be used to help develop policies and practices to improve student health and wellbeing. CONCLUSIONS: This study provides a model for statewide annual fitness testing surveillance and reporting within K-12 public school physical education classrooms.

Associations between muscle quality and N-terminal pro-B-type natriuretic peptide (NT-proBNP): The multi-ethnic study of atherosclerosis.

INTRODUCTION: N-terminal pro-B-type natriuretic peptide (NT-proBNP) is widely used in clinical settings to identify cardiac stress, diagnose, and manage heart failure (HF). We explored the associations between NT-proBNP and both muscle area and density. METHODS: A cross-sectional analysis including 1,489 participants from the MESA. Plasma NT-proBNP concentrations and inflammatory biomarkers and health history questionnaires were analyzed. Computed tomography quantified abdominal body composition. Separate multivariable linear regression models were used to assess the associations between both muscle (MA) area and density (MD) and NT-proBNP. RESULTS: In models adjusted for sociodemographic characteristics, risk factors for cardiovascular disease, anthropometric variables, and subcutaneous and visceral adiposity, NT-proBNP was inversely associated with total abdominal and psoas MAs. Adjustment for inflammatory markers and MD attenuated these associations to the null. Stabilization MA and NT-proBNP were not significantly associated. Analyses per quartiles of MA confirmed lack of a consistent association between stabilization and total abdominal MAs and NT-proBNP. While the third and fourth quartiles of psoas MA were inversely associated with NT-proBNP, adding inflammation biomarkers and MD to the model attenuated the association to the null. Conversely, after full adjustment, NT-proBNP was inversely and significantly associated with total abdominal, stabilization and psoas MDs. For psoas MD, but not the other muscle density variables, the addition of MA to the model attenuated the association to the null. The quartiles of MD were consistently inversely associated with NT-proBNP, where higher MDs showed larger estimates of the association compared to the lowest quartiles, for all muscle groups investigated. CONCLUSION: Muscle density is inversely associated with NT-proBNP, while muscle area is not after adjustment for inflammation and muscle density.

Patterns and correlates of sedentary behavior among university students.

Objective: To characterize the context, patterns, and correlates of sedentary behavior (SB) in university students. Participants: A total of 95 adults (41% men) enrolled in 34 different undergraduate majors. Methods: SB was assessed by questionnaire and accelerometer. Results: Objective SB and moderate-to-vigorous physical activity (MVPA) accounted for 8.4 ± 1.5 and 1.2 ± 0.5 h·day-1, respectively. Most SB was spent in occupational, leisure, and screen time behaviors, and was accumulated in short bouts of 10 min or longer. Women were more sedentary than men (522.0 ± 80.3 vs. 486.1 ± 91.3 min·day-1, p = 0.03) and engaged in more prolonged bouts of SB. Correlates of SB included female sex, smoking, light activity, MVPA, and markers of obesity, with higher levels of light activity and current smoking the strongest and most consistent correlates of reduced SB. Conclusions: University students engage in high amounts of SB and accumulate most of their SB in short bouts, with differences in patterns of SB between men and women.

High-Resolution Taxonomic Characterization Reveals Novel Human Microbial Strains with Potential as Risk Factors and Probiotics for Prediabetes and Type 2 Diabetes.

Alterations in the composition of the gut microbiota is thought to play a key role in causing type 2 diabetes, yet is not fully understood, especially at the strain level. Here, we used long-read DNA sequencing technology of 16S-ITS-23S rRNA genes for high-resolution characterization of gut microbiota in the development of type 2 diabetes. Gut microbiota composition was characterized from fecal DNA from 47 participants divided into 4 cohorts based on glycemic control: normal glycemic control (healthy; n = 21), reversed prediabetes (prediabetes/healthy; n = 8), prediabetes (n = 8), or type 2 diabetes (n = 10). A total of 46 taxa were found to be possibly related to progression from healthy state to type 2 diabetes. Bacteroides coprophilus DSM 18228, Bifidobacterium pseudocatenulatum DSM 20438, and Bifidobacterium adolescentis ATCC 15703 could confer resistance to glucose intolerance. On the other hand, Odoribacter laneus YIT 12061 may be pathogenic as it was found to be more abundant in type 2 diabetes participants than other cohorts. This research increases our understanding of the structural modulation of gut microbiota in the pathogenesis of type 2 diabetes and highlights gut microbiota strains, with the potential for targeted opportunistic pathogen control or consideration for probiotic prophylaxis and treatment.

Physical Activity Type and Intensity Are Associated With Abdominal Muscle Area and Density: The Multiethnic Study of Atherosclerosis.

BACKGROUND: Using data from a multiethnic cohort, the authors tested associations of multiple types and intensities of physical activity (PA) with abdominal muscle area and density. METHODS: 1895 Multiethnic Study of Atherosclerosis participants (mean age 64.6 [9.6] y) completed health history and PA questionnaires and computed tomography to quantify body composition and measurements of cardiovascular and inflammatory biomarkers. Analyses included multivariable regression. RESULTS: Compared with those not meeting PA guidelines for Americans, those meeting the guidelines had higher total abdominal muscle area (odds ratio, 95% confidence interval 1.60, 1.20 to 2.15), stability muscle area (1.68, 1.28 to 2.20), and stability muscle density (1.35, 1.03 to 1.76). After adjustment for relevant covariates, each SD increase in total moderate to vigorous PA was associated with a higher total abdominal (ß, 95% confidence interval = 0.068, 0.036 to 0.173), stability (0.063, 0.027 to 0.099), and locomotor (0.069, 0.039 to 0.099) muscle area and higher locomotor muscle density (0.065, 0.022 to 0.108, P < .01). Only intentional and conditioning exercise were associated with total abdominal and stability muscle density (P < .05). Light PA and walking were not associated with muscle area or density. CONCLUSIONS: Most types of PA are positively associated with abdominal muscle area and density across functional categories, independent of relevant covariates. These results provide additional evidence for promoting PA for healthy muscle aging.

Associations between Weight-Adjusted Waist Index and Abdominal Fat and Muscle Mass: Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: The weight-adjusted waist index (WWI) reflected body compositional changes with aging. This study was to investigate the association of WWI with abdominal fat and muscle mass in a diverse race/ethnic population. METHODS: Computed tomography (CT) data from 1,946 participants for abdominal fat and muscle areas from the Multi-Ethnic Study of Atherosclerosis (785 Whites, 252 Asians, 406 African American, and 503 Hispanics) were used. Among them, 595 participants underwent repeated CT. The WWI was calculated as waist circumference (cm) divided by the square root of body weight (kg). The associations of WWI with abdominal fat and muscle measures were examined, and longitudinal changes in abdominal composition measures were compared. RESULTS: In all race/ethnic groups, WWI was positively correlated with total abdominal fat area (TFA), subcutaneous fat area, and visceral fat area, but negatively correlated with total abdominal muscle area (TMA) and abdominal muscle radiodensity (P<0.001 for all). WWI showed a linear increase with aging regardless of race and there were no significant differences in the WWI distribution between Whites, Asians, and African Americans. In longitudinal analyses, over 38.6 months of follow-up, all abdominal fat measures increased but muscle measures decreased, along with increase in WWI. The more the WWI increased, the more the TFA increased and the more the TMA decreased. CONCLUSION: WWI showed positive associations with abdominal fat mass and negative associations with abdominal muscle mass, which likely reflects the abdominal compositional changes with aging in a multi-ethnic population.

Computed Tomography-Derived Myosteatosis and Metabolic Disorders.

The role of ectopic adipose tissue infiltration into skeletal muscle (i.e., myosteatosis) for metabolic disorders has received considerable and increasing attention in the last 10 years. The purpose of this review was to evaluate and summarize existing studies focusing on computed tomography (CT)-derived measures of myosteatosis and metabolic disorders. There is consistent evidence that CT-derived myosteatosis contributes to dysglycemia, insulin resistance, type 2 diabetes mellitus, and inflammation, and, to some extent, dyslipidemia, independent of general obesity, visceral fat, and other relevant risk factors, suggesting that it may serve as a tool for metabolic risk prediction. Identification of which muscles should be examined, and the standardized CT protocols to be employed, are necessary to enhance the applicability of findings from epidemiologic studies of myosteatosis. Additional and longer longitudinal studies are necessary to confirm a role of myosteatosis in the development of type 2 diabetes mellitus, and examine these associations in a variety of muscles across multiple race/ethnic populations. Given the emerging role of myosteatosis in metabolic health, well-designed intervention studies are needed to investigate relevant lifestyle and pharmaceutical approaches.

Perceived Risk and Intentions to Practice Health Protective Behaviors in a Mining-Impacted Region.

Effective risk communication strategies are critical to reducing lead exposure in mining-impacted communities. Understanding the strength of the associations between perceived risk and individuals' behavioral intentions to protect their health is important for developing these strategies. We conducted a survey within three communities of northern Idaho, USA (n = 306) in or near a Superfund Megasite with legacy mining contamination. Survey data were used to test a theoretical model based on the Health Belief Model. Respondents had higher intentions to practice health protective behaviors when they perceived the risk of lead contamination as severe and recognized the benefits of practicing health protective behaviors. Women reported higher behavioral intentions than men, but age and mining affiliation were not significantly associated with behavioral intentions. Although managing lead hazards in communities impacted by mining is challenging due to widely distributed contamination, effective health risk messages, paired with remediation, are powerful tools to protect the health and safety of residents.

Muscle area and density and risk of all-cause mortality: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Lean muscle plays critical roles in physical functioning and metabolism. However, little is known regarding associations between muscle and mortality in adults. OBJECTIVE: The purpose was to evaluate associations between abdominal muscle quantity (area) and quality (density) with risk of all-cause mortality in a diverse cohort free of cardiovascular disease. DESIGN: Data were taken from the Abdominal Body Composition, Inflammation, and Cardiovascular Disease ancillary study of the Multi-Ethnic Study of Atherosclerosis prospective cohort study. Participants were adults (45-85 years) free of extant cardiovascular disease, and of Hispanic, African American, Chinese, or Caucasian descent. Of the original 6814 MESA participants, a random, representative sample (n = 1974) participated in the ancillary body composition study. Abdominal muscle area and density were measured from computed tomography scans spanning L2-L4. Muscle density was measured as attenuation in Hounsfield units, and area was quantified as cm2. Gender-stratified cox proportional hazard models assessed the risk of all-cause mortality across gender-specific quartiles of muscle area and density adjusting for confounders, with area and density entered simultaneously. RESULTS: At baseline, the mean age for men (n = 946) and women (n = 955) was 61.5 and 62.5 years and median follow-up time was 10.6 and 10.9 years, respectively. Muscle density was inversely associated with mortality, with the highest quartile of density showing a 73% reduction in risk for men (HR = 0.27, 95% CI = 0.14-0.51; p-trend<0.001) and 57% reduction for women (HR = 0.43, 95% CI = 0.18-1.01; p-trend = 0.04) compared to the lowest quartile when adjusting for mortality risk factors, lifestyle, BMI and visceral fat. There was no association between muscle area and all-cause mortality for men (p-trend = 0.58) or women (p-trend = 0.47). CONCLUSIONS: Greater abdominal muscle density, but not muscle area, is associated with markedly lower risk of all-cause mortality across a decade of follow up. Muscle quality may be a powerful predictor of mortality in community dwelling adults.

Associations of leisure screen time with cardiometabolic biomarkers in college-aged adults.

We examined whether screen time was associated with cardiometabolic disease (CMD) risk factors in young adults. Ninety-five adults (19.9 ± 11.4 years) self-reported medical and health behavior history, screen time (television viewing, video games and computer games), and dietary intake. Waist circumference, blood pressure, fasting glucose and lipid levels, cardiorespiratory fitness (VO2peak), and body composition were measured. Total sedentary behavior and moderate-to-vigorous physical activity (MVPA) were measured by accelerometer. On average, leisure screen time (2.0 ± 1.6 h day-1) accounted for 24% of total sedentary time (8.4 ± 1.5 h day-1). After adjustment for demographics, smoking, sleep duration, total energy intake, total sedentary time and MVPA, a 1-standard deviation increase in leisure screen time was associated with a 26% higher BMI, 29% higher waist circumference, 25% higher fat mass, 23% higher triglyceride, and 24% lower VO2peak (p < 0.05). Our findings suggest that screen time may contribute to the risk of obesity and CMD in young adults.

Skeletal muscle area and density are associated with lipid and lipoprotein cholesterol levels: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Loss of muscle mass with age may be a key player in metabolic dysregulation. We examined the associations between abdominal muscle area and density with lipids and lipoproteins. METHODS: One thousand eight hundred and sixty eight adults completed health history and physical activity questionnaires, provided venous blood samples for lipids and inflammatory biomarkers, and underwent computed tomography to quantify body composition. Associations between muscle area and density with multiple lipid measures were assessed with multivariable linear and logistic regression. RESULTS: The mean age and body mass index of participants was 65 years and 28 kg/m2, respectively, and 50% were female. After adjustment for demographics, cardiovascular disease risk factors, lipid-lowering medications, physical activity, sedentary behavior, inflammatory biomarkers, and central obesity, a 1-standard deviation increase in total abdominal, stability, and locomotor muscle areas was associated with a 13%, 11%, and 8% lower high-density lipoprotein cholesterol level, respectively (P < .05). With similar adjustment, a 1-standard deviation increase in total abdominal and stability muscle area was associated with a 13% and 12% lower total cholesterol level, respectively (P < .01). Compared to the lowest quartiles of total, stability, and locomotor muscle area, those in the higher quartiles of muscle area had over a 40% reduction in the odds of triglyceride levels greater than 150 mg/dL (P < .05). Total abdominal muscle density was positively associated with total cholesterol (P < .05) but was not associated with the other lipid outcomes. CONCLUSION: Maintaining adequate skeletal muscle mass with age may decrease specific lipid levels related to hyperlipidemia and development of cardiometabolic disease.

Regulation of metabolism during hibernation in brown bears (Ursus arctos): Involvement of cortisol, PGC-1α and AMPK in adipose tissue and skeletal muscle.

The purpose of this study was to investigate changes in expression of known cellular regulators of metabolism during hyperphagia (Sept) and hibernation (Jan) in skeletal muscle and adipose tissue of brown bears and determine whether signaling molecules and transcription factors known to respond to changes in cellular energy state are involved in the regulation of these metabolic adaptations. During hibernation, serum levels of cortisol, glycerol, and triglycerides were elevated, and protein expression and activation of AMPK in skeletal muscle and adipose tissue were reduced. mRNA expression of the co-activator PGC-1α was reduced in all tissues in hibernation whereas mRNA expression of the transcription factor PPAR-α was reduced in the vastus lateralis muscle and adipose tissue only. During hibernation, gene expression of ATGL and CD36 was not altered; however, HSL gene expression was reduced in adipose tissue. During hibernation gene expression of the lipogenic enzyme DGAT in all tissues and the expression of the FA oxidative enzyme LCAD in the vastus lateralis muscle were reduced. Gene and protein expression of the glucose transporter GLUT4 was decreased in adipose tissue in hibernation. Our data suggest that high cortisol levels are a key adaptation during hibernation and link cortisol to a reduced activation of the AMPK/PGC-1α/PPAR-α axis in the regulation of metabolism in skeletal muscle and adipose tissue. Moreover, our results indicate that during this phase of hibernation at a time when metabolic rate is significantly reduced metabolic adaptations in peripheral tissues seek to limit the detrimental effects of unduly large energy dissipation.

Comparison of Self-Reported and Objectively Measured Sedentary Behavior and Physical Activity in Undergraduate Students.

OBJECTIVE: To investigate differences between estimates of sedentary behavior and physical activity (PA) from the International Physical Activity Questionnaire (IPAQ) and accelerometry in undergraduate students. PARTICIPANTS: 91 students participated in the study. METHODS: Sedentary behavior and PA were objectively measured by an accelerometer for 7 days and then self-reported with the IPAQ. Partial correlations were used to assess associations among PA variables and participant characteristics between the methods. Agreement was assessed via the Bland-Altman method. RESULTS: Correlation coefficients between self-reported and objectively measured PA ranged from 0.21 to 0.38 (p≤0.05 for all). A higher proportion of students were classified as meeting PA guidelines via self-report compared to objective measurements. Bland-Altman plots revealed acceptable agreement between methods, however, bias was evident for all PA intensities. Sex and lean body mass impacted these differences. CONCLUSIONS: Researchers should exercise caution when interpreting PA assessed via the IPAQ in undergraduate students.

Associations of Sedentary Behavior and Abdominal Muscle Density: The Multi-Ethnic Study of Atherosclerosis.

BACKGROUND: Sedentary behaviors (SB) may exacerbate loss of muscle mass and function, independent of physical activity levels. This study examined the associations of SB with abdominal muscle area and density, a marker of muscle quality, in adults. METHODS: A total of 1895 participants from the Multi-Ethnic Study of Atherosclerosis completed detailed health history, physical activity and SB questionnaires, computed tomography to quantify body composition, and measurements of inflammatory markers. Analyses included linear and nonlinear regression. RESULTS: The mean age and body mass index were 64.6 years and 28 kg·m-2, respectively, and 50% were women. On average, participants engaged in 28 metabolic equivalent hours·week-1 of SB. With adjustment for age, sex, race/ethnicity, physical activity, cardiovascular disease risk factors, and inflammation, multivariable regression modeling revealed a nonlinear (quadratic) relationship between SB and locomotor, stability, and total abdominal muscle density (P < .01) but not muscle area. The SB inflection point at which locomotor, stability, and total abdominal muscle density began to decrease was 38.2, 39.6, and 39.2 metabolic equivalent hours·week-1 of SB, respectively. CONCLUSIONS: SB is associated with reduced muscle density when practiced as little as 5.5 metabolic equivalent hours·day-1. These findings may have important implications for SB guidelines for targeting skeletal muscle health in older adults.

Associations of abdominal intermuscular adipose tissue and inflammation: The Multi-Ethnic Study of Atherosclerosis.

OBJECTIVE: This study examined the associations between abdominal IMAT area and density with inflammatory markers associated with cardiometabolic disease. METHODS: 1897 participants enrolled in the Multi-Ethnic Study of Atherosclerosis underwent computed tomography to quantify body composition and measurements of adiponectin, leptin, interleukin-6 (IL-6), C-reactive protein (CRP), and resistin. RESULTS: The mean age and body mass index of participants was 65years and 28kg/m2, respectively, and 50% were female. After adjustment for age, sex, and race/ethnicity, as IMAT area increased and density decreased from the first to fourth quartile, markers of inflammation increased linearly (p<0.01). Using linear regression, and with adjustment for demographics, cardiovascular disease risk factors, and abdominal muscle area and density, a 1-standard deviation (SD) increase in total abdominal IMAT area was associated with a 21%, 36% and 20% higher IL-6, leptin, and CRP, respectively, and 19% lower adiponectin (p<0.001). With similar adjustment, a 1-SD decrease in total abdominal IMAT density was associated with a 14%, 32%, and 15% higher IL-6, leptin, and CRP, respectively, and 22% lower adiponectin (p<0.001). These associations were attenuated with the addition of visceral fat (p>0.05). CONCLUSIONS: Abdominal IMAT area and density are associated with inflammatory markers, with these associations attenuated by central adiposity.

Predictors of change in affect in response to high intensity interval exercise (HIIE) and sprint interval exercise (SIE).

Affect is typically positive at intensities below the lactate or ventilatory threshold, yet more aversive responses occur at supra-threshold intensities which may reduce positive perceptions of exercise. Completion of high intensity interval exercise (HIIE) typically elicits a reduction in affect, yet greater post-exercise enjoyment has been reported in response to HIIE versus moderate intensity continuous exercise (MICE). This study examined affectual responses to HIIE and sprint interval exercise (SIE) in 71 active men and women (age = 24.0 ±â€¯4.8 year). Participants performed various HIIE and SIE regimes on the cycle ergometer during which affect (+5 - -5 scale), rating of perceived exertion (RPE, Borg 1-10 scale), and blood lactate concentration (BLa) were determined. Enjoyment was measured post-exercise using the PACES scale. Predictors of change in these variables in response to exercise were identified using multiple regression. Results showed a significant reduction in affect (p = .001) which was greater (p = .03) with SIE (-5.7 ±â€¯2.7) compared to HIIE (-4.3 ±â€¯2.4). Nevertheless, there was marked variability in the affect response across participants, as its change ranged from -1 to -7 units from pre- to post-exercise in 85% of all sessions. Sixty two percent of the change in affect seen across regimes was explained by baseline affect, BLa, and enjoyment. Significant associations were shown between the change in affect and baseline affect (r = -0.46, p < .001) and change in RPE (r = -0.59, p < .001). In addition, RPE significantly increased in response to HIIE (6.1 ±â€¯1.7) and SIE (6.9 ±â€¯2.0) but was not different (p = .050) between regimes. Our findings document an intensity-dependent relationship between affect and intensity during interval training, as supramaximal intensities elicit a larger decline in affect compared to submaximal intensities. In addition, pre-exercise affect is associated with the magnitude of change in affect reported in response to interval exercise.

Associations of Abdominal Muscle Area and Radiodensity with Adiponectin and Leptin: The Multiethnic Study of Atherosclerosis.

OBJECTIVE: This study examined the associations of muscle area and radiodensity with adiponectin and leptin. METHODS: A total of 1,944 participants who enrolled in the Multi-Ethnic Study of Atherosclerosis underwent computed tomography to quantify body composition and measurements of adiponectin, leptin, interleukin-6, C-reactive protein, and resistin. RESULTS: The mean age and BMI of participants were 64.7 years and 28.1 kg/m2 and 49% were female. With adjustment for age, gender, race/ethnicity, traditional cardiovascular disease risk factors, inflammatory biomarkers, physical activity, and sedentary behavior, a 1-SD increment in total abdominal, stability, and locomotor muscle area was associated with a 19%, 17%, and 12% lower adiponectin level, respectively (P < 0.01 for all) but not leptin (P > 0.05). Muscle radiodensity was more robustly associated with adiponectin and leptin in the multivariable linear regression models. That is, with full adjustment for all covariates, a 1-SD increment in total abdominal, stability, and locomotor muscle radiodensity was associated with a 31%, 31%, and 18% lower adiponectin level (P < 0.01 for all) and a 6.7%, 4.6%, and 8.1% higher leptin level (P < 0.05 for all), respectively. CONCLUSIONS: The data suggest that increases in muscle area and radiodensity may have positive impacts on chronic inflammation and, in turn, reduce the risk of cardiometabolic disease.