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Chiao-Nan Chen, Lee-Ming Chuang, Mallikarjuna Korivi and Ying-Tai Wu

Background:

This study investigated the differences in exercise self-efficacy, compliance, and effectiveness of home-based exercise in individuals with and without metabolic syndrome (MetS).

Methods:

One hundred and ten individuals at risk for diabetes participated in this study. Subjects were categorized into individuals with MetS and individuals without MetS. Metabolic risk factors and exercise self-efficacy were evaluated for all subjects before and after 3 months of home-based exercise. Univariate analysis of variance was used to compare the effectiveness of a home-based exercise program between individuals with and without MetS.

Results:

The home-based exercise program improved body mass index and lipid profile in individuals at risk for diabetes, regardless of MetS status at baseline. Individuals without MetS had higher exercise self-efficacy at baseline and performed greater exercise volume compared with individuals with MetS during the intervention. The increased exercise volume in individuals without MetS may contribute to their better control of insulin resistance than individuals with MetS. Furthermore, baseline exercise self-efficacy was correlated with exercise volume executed by subjects at home.

Conclusions:

We conclude that home-based exercise programs are beneficial for individuals at risk for diabetes. However, more intensive and/or supervised exercise intervention may be needed for those with MetS.

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Meredith C. Peddie, Claire Cameron, Nancy Rehrer and Tracy Perry

Background:

Interrupting sedentary time induces improvements in glucose metabolism; however, it is unclear how much activity is required to reduce the negative effects of prolonged sitting.

Methods:

Sixty-six participants sat continuously for 9 hours except for required bathroom breaks. Participants were fed meal replacement beverages at 60, 240 and 420 min. Blood samples were obtained hourly for 9 hours, with additional samples collected 30 and 45 min after each feeding. Responses were calculated as incremental area under the curve (iAUC) for plasma glucose, insulin and triglyceride. Participants wore a triaxial accelerometer and a heart rate monitor. Energy expenditure was estimated using indirect calorimetry.

Results:

After controlling for age, sex and BMI, every 100 count increase in accelerometer derived total movement was associated with a 0.06 mmol·L-1·9 hours decrease in glucose iAUC (95% CI 0.004–0.1; P = .035), but not associated with changes in insulin or triglyceride iAUC. Every 1 bpm increase in mean heart rate was associated with a 0.76 mmol·L-1·9 hours increase in triglyceride iAUC (95% CI 0.13–1.38).

Conclusion:

Accelerometer measured movement during periods of prolonged sitting can result in minor improvements in postprandial glucose metabolism, but not lipid metabolism.

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Dinesh John, Dixie L. Thompson, Hollie Raynor, Kenneth Bielak, Bob Rider and David R. Bassett

Purpose:

To determine if a treadmill-workstation (TMWS) increases physical activity (PA) and influences anthropometric, body composition, cardiovascular, and metabolic variables in overweight and obese office-workers.

Methods:

Twelve (mean age= 46.2 ± 9.2 years) overweight/obese sedentary office-workers (mean BMI= 33.9 ± 5.0 kg·m-2) volunteered to participate in this 9-month study. After baseline measurements of postural allocation, steps per day, anthropometric variables, body composition, cardiovascular, and metabolic variables, TMWS were installed in the participants’ offices for their use. Baseline measurements were repeated after 3 and 9 months. Comparisons of the outcome variables were made using repeated-measures ANOVAs or nonparametric Friedman’s Rank Tests.

Results:

Between baseline and 9 months, significant increases were seen in the median standing (146−203 min·day-1) and stepping time (52−90 min·day-1) and total steps/day (4351−7080 steps/day; P < .05). Correspondingly, the median time spent sitting/lying decreased (1238−1150 min·day-1; P < .05). Using the TMWS significantly reduced waist (by 5.5 cm) and hip circumference (by 4.8 cm), low-density lipoproteins (LDL) (by 16 mg·dL-1), and total cholesterol (by 15 mg·dL-1) during the study (P < .05).

Conclusion:

The additional PA energy expenditure from using the TMWS favorably influenced waist and hip circumferences and lipid and metabolic profiles in overweight and obese office-workers.

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Laura Banks, Cedric Manlhiot, Stafford W. Dobbin, Don Gibson, Karen Stearne, Jolie Davies-Shaw, Nita Chahal, Amanda Fisher and Brian McCrindle

Background: Moderate-to-vigorous physical activity (MVPA) has been negatively associated with cardiometabolic risk. We sought to determine if MVPA interacts with body-mass index (BMI) and waist circumference (WC) in determining cardiometabolic risk in adolescents. Methods: This cross-sectional study included cardiometabolic risk (blood pressure [BP], nonfasting lipids) screening and a 7-day recall physical activity questionnaire in 4,104 adolescents (51% male; mean age: 14.6 ± 0.5 years old). WC- and BMI- percentiles were used to define anthropometric categories (including obese adolescents: 390th WC, 385th BMI). Results: Obesity in adolescents was associated with lower levels of high-density lipoprotein (HDL cholesterol (Estimate [EST]: -0.28(0.07) mmol/L, p < .001) and higher non-HDL cholesterol (EST: +0.38(0.14) mmol/L, p = .008). Each additional day with 320 min of MVPA was associated with lower non-HDL cholesterol (EST: −0.014(0.005) mmol/L/days/week, p = .003), independent of anthropometric category. Each additional day with 320 min of MVPA was associated with an increased odds ratio (OR) for higher BP category in obese adolescents (OR: 1.055, 95% CI: 1.028−1.084, p < .001) and a lower odds ratio for higher BP category in presumably-muscular adolescents (OR: 0.968, 95% CI: 0.934−0.989, p = .005). Conclusions: An increase in MVPA was associated with an increased likelihood for higher BP category in obese adolescents. The dose-response relationship between physical activity and cardiometabolic risk needs to be evaluated in adolescents of varying anthropometry categories.

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Roy J. Shephard

The pediatric sports physician faces an epidemic of obesity. A preliminary triage of individual patients can be based on the body mass index (BMI). The 80th and 95th percentiles of age-specific BMI suggest overweight and obesity, respectively; the diagnosis is confirmed by measurements of triceps and subscapular skinfolds. Over the last twenty years, the proportions of overweight and obese children have increased in both indigenous populations and most developed societies. The increase in body fat content seems to be associated with a decline in daily energy expenditure. Immediate health consequences include an increased prevalence of atherosclerotic plaques, hypertension, and an adverse lipid profile; in addition, the resulting poor self-image limits sport participation. Many obese children become obese adults, facing increased risks of cardiovascular and all-cause deaths. A combination of increased lifestyle activities, behavioral modification techniques to reduce sedentary behavior, and an appropriate diet seems to be the most effective approach to both prevention and treatment of obesity. Such initiatives should be supported by quality daily physical education and changes in the urban environment that encourage an active lifestyle.

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Paulo Farinatti, Silvio Rodrigues Marques Neto, Ingrid Dias, Felipe A. Cunha, Eliete Bouskela and Luiz G. Kraemer-Aguiar

Purpose:

Cardiac autonomic dysfunction (CADysf) in children is often associated to obesity and may be attenuated by physical activity. In this study, we investigated the effects of resistance training (RT) upon CADysf assessed by heart rate variability (HRV) in obese adolescents.

Method:

Volunteers were assigned into groups according to standard deviation scores for body mass index (z-BMI) and percentile for age and sex: obese (OB; z-BMI from 2 to 3 and ≥ 95th percentile, n = 24) and normal weight controls (CG; z-BMI from -2–1 and < 85th percentile, n = 20). OB performed isolated RT during 12 weeks [3 sets of 6–10reps with 70–85% 10RM]. Waist circumference, systolic/diastolic blood pressures (SBP/DBP), lipids, and HRV were assessed at baseline. Only OB underwent postintervention assessments.

Results:

At baseline, SBP (122.4 ± 9.1 vs. 109.7 ± 11.5 mmHg, p < .001) and DBP (76.1 ± 7.1 vs. 65.3 ± 5.9 mmHg, p < .001) were higher, while parasympathetic HRV indexes were lower (p < .05) in OB compared with CG. After RT, waist circumference (3%, p < .001) and SBP (10%, p < .001) reduced in OB. Parasympathetic indexes of HRV increased in OB (SDNN: 25%, p = .03; rMSSD: 48%, p = .0006; pNN50: 67%, p = .001; total power: 54%, p = .01; HF: 101%, p = .001) and baseline differences between groups for sympathetic and parasympathetic activities were no longer observed after RT.

Conclusion:

RT attenuated CAdyfs and BP in obese adolescents, by increasing parasympathetic activity and decreasing sympatho-vagal balance.

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Ya-Wen Hsu, Chih-Ping Chou, Britni R. Belcher, Selena T. Nguyen-Rodriguez, Marc J. Weigensberg, Arianna D. McClain and Donna Spruijt-Metz

While most studies have focused on investigating the preventive effects of physical activity on metabolic risk, the longitudinal impacts of metabolic syndrome (MetS) on activity levels is poorly understood. This study aims to examine the influence of MetS on initial activity levels and the trajectory of activity levels in Latina and African American female children over 12 months (n = 55, 9 ± 1 years). Metabolic measures, including fat and lean tissue mass by BodPod, fasting glucose, lipids, blood pressure, and waist circumference, were collected at baseline. Moderate-to-vigorous physical activity and sedentary behavior by accelerometry were collected on a quarterly basis. There were no significant differences in either initial activity levels by MetS status (Moderate-to-vigorous physical activity: 33 ± 12 mins/day for MetS, 48 ± 28 mins/day for Non-MetS, p = .12; sedentary behavior: 408 ± 57 mins/day for MetS, 421 ± 72 mins/day for Non-MetS, p = .67). Longitudinal declines in moderate-to-vigorous physical activity (p = .038) and increases in sedentary behavior (p = .003) were found. Daily sedentary behavior increased by 82.64 more minutes in youth with MetS than in those without over one year (p = .015). This study yields the first evidence of the adverse effect of MetS on sedentary behavior. Targeted intervention strategies to reduce progressive sedentariness evident in minority youth with MetS are warranted.

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Jamie Zoellner, Carol Connell, Alicia Powers, Amanda Avis-Williams, Kathy Yadrick and Margaret L. Bogle

Background:

Race/ethnic-specific physical activity patterns and biological responses to physical activity is one of the most understudied, yet critical aspects related to the development and adoption of physical activity recommendations.

Methods:

In this 6-month community walking intervention targeting African Americans, participants wore a pedometer and maintained a pedometer diary for the study duration. Outcome measures included height, weight, percent body fat, waist circumference, blood pressure, lipids and glucose. ANOVA, Pearson Correlations, and Kruskal-Wallis tests were used to examine changes in steps/day over each month of the intervention and explore associations among pedometer-determined physical activity and anthropometric/biological change scores from month 1 to 6.

Results:

The 83 participants were primarily African American (98%) women (94%). There was a significant increase in the average step/day beginning with 6665 (SD = 3,396) during month 1 and increasing to 9232 (SD = 3670) steps/day during month 6 (F = 4.5, P < .0001). Associations among step counts and anthropometric/biological change scores were not significant.

Conclusions:

While this intervention resulted in significant increases in steps/day; it exemplifies that physical activity standards may be unachievable for some vulnerable, minority communities. Methodological considerations for exploring associations between changes in pedometer-determined step counts and anthropometric/biological outcomes are emphasized through this study.

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Mathieu L. Maltais, Karine Perreault, Alexandre Courchesne-Loyer, Jean-Christophe Lagacé, Razieh Barsalani and Isabelle J. Dionne

The decrease in resting energy expenditure (REE) and fat oxidation with aging is associated with an increase in fat mass (FM), and both could be prevented by exercise such as resistance training. Dairy consumption has also been shown to promote FM loss in different subpopulations and to be positively associated with fat oxidation. Therefore, we sought to determine whether resistance exercise combined with dairy supplementation could have an additive impact on FM and energy metabolism, especially in individuals with a deficit in muscle mass. Twenty-six older overweight sarcopenic men (65 ± 5 years old) were recruited for the study. They participated in 4 months of resistance exercise and were randomized into three groups for postexercise shakes (control, dairy, and nondairy isocaloric and isoprotein supplement with 375 ml and ~280 calories per shake). Body composition was measured by dual X-ray absorptiometry and REE by indirect calorimetry. Fasting glucose, insulin, leptin, inflammatory profile, and blood lipid profile were also measured. Significant decreases were observed with FM only in the dairy supplement group; no changes were observed for any other variables. To conclude, FM may decrease without changes in metabolic parameters during resistance training and dairy supplementation with no caloric restriction without having any impact on metabolic properties. More studies are warranted to explain this significant decrease in FM.

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Anna Skarpañska-Stejnborn, Lucia Pilaczynska-Szczesniak, Piotr Basta, Ewa Deskur-Smielecka and Magorzata Horoszkiewicz-Hassan

High-intensity physical exercise decreases intracellular antioxidant potential. An enhanced antioxidant defense system is desirable in people subjected to exhaustive exercise. The aim of this study was to investigate the influence of supplementation with artichoke-leaf extract on parameters describing balance between oxidants and antioxidants in competitive rowers. This double-blinded study was carried out in 22 members of the Polish rowing team who were randomly assigned to a supplemented group (n = 12), receiving 1 gelatin capsule containing 400 mg of artichoke-leaf extract 3 times a day for 5 wk, or a placebo group (n = 10). At the beginning and end of the study participants performed a 2,000-m maximal test on a rowing ergometer. Before each exercise test, 1 min after the test completion, and after a 24-hr restitution period blood samples were taken from antecubital vein. The following redox parameters were assessed in red blood cells: superoxide dismutase activity, glutathione peroxidase activity, glutathione reductase activity, reduced glutathione levels, and thiobarbituric-acid-reactive-substances concentrations. Creatine kinase activity and total antioxidant capacity (TAC) were measured in plasma samples, lactate levels were determined in capillary blood samples, and serum lipid profiles were assessed. During restitution, plasma TAC was significantly higher (p < .05) in the supplemented group than in the placebo group. Serum total cholesterol levels at the end of the study were significantly (p < .05) lower in the supplemented group than in the placebo group. In conclusion, consuming artichoke-leaf extract, a natural vegetable preparation of high antioxidant potential, resulted in higher plasma TAC than placebo but did not limit oxidative damage to erythrocytes in competitive rowers subjected to strenuous training.