Heather K. Vincent

Oxidative stress and potential interventions to reduce oxidative stress in overweight and obesity

Purpose:  Obesity may be a state of chronic oxidative stress. Oxidative stress may be the mechanism underlying the development of co‐morbidities in obesity. This review provides a summary of the available evidence regarding systemic oxidative stress in young, older and clinical obese populations.

Exercise training improves myocardial tolerance to in vivo ischemia-reperfusion in the rat

Experimental studies examining the effects of regular exercise on cardiac responses to ischemia and reperfusion (I/R) are limited. Therefore, these experiments examined the effects of endurance exercise training on myocardial biochemical and physiological responses during in vivo I/R. Female Sprague-Dawley rats (4 mo old) were randomly assigned to either a sedentary control group or to an exercise training group. After a 10-wk endurance exercise training program, animals were anesthetized and mechanically ventilated, and the chest was opened by thoracotomy. Coronary occlusion was achieved by a ligature around the left coronary artery; occlusion was maintained for 20 min, followed by a 10-min period of reperfusion. Compared with untrained, exercise-trained animals maintained higher ( P < 0.05) peak systolic blood pressure throughout I/R. Training resulted in a significant ( P < 0.05) increase in ventricular nonprotein thiols, heat shock protein (HSP) 72, and the activities of superoxide dismutase (SOD), phosphofructokinase (PFK), and lactate dehydrogenase. Furthermore, compared with untrained controls, left ventricles from trained animals exhibited lower levels ( P < 0.05) of lipid peroxidation after I/R. These data demonstrate that endurance exercise training improves myocardial contractile performance and reduces lipid peroxidation during I/R in the rat in vivo. It appears likely that the improvement in the myocardial responses to I/R was related to training-induced increases in nonprotein thiols, HSP72, and the activities of SOD and PFK in the myocardium.Experimental studies examining the effects of regular exercise on cardiac responses to ischemia and reperfusion (I/R) are limited. Therefore, these experiments examined the effects of endurance exercise training on myocardial biochemical and physiological responses during in vivo I/R. Female Sprague-Dawley rats (4 mo old) were randomly assigned to either a sedentary control group or to an exercise training group. After a 10-wk endurance exercise training program, animals were anesthetized and mechanically ventilated, and the chest was opened by thoracotomy. Coronary occlusion was achieved by a ligature around the left coronary artery; occlusion was maintained for 20 min, followed by a 10-min period of reperfusion. Compared with untrained, exercise-trained animals maintained higher (P < 0.05) peak systolic blood pressure throughout I/R. Training resulted in a significant (P < 0.05) increase in ventricular nonprotein thiols, heat shock protein (HSP) 72, and the activities of superoxide dismutase (SOD), phosphofructokinase (PFK), and lactate dehydrogenase. Furthermore, compared with untrained controls, left ventricles from trained animals exhibited lower levels (P < 0. 05) of lipid peroxidation after I/R. These data demonstrate that endurance exercise training improves myocardial contractile performance and reduces lipid peroxidation during I/R in the rat in vivo. It appears likely that the improvement in the myocardial responses to I/R was related to training-induced increases in nonprotein thiols, HSP72, and the activities of SOD and PFK in the myocardium.

Obesity and mobility disability in the older adult

Mobility disability is becoming prevalent in the obese older population (≥60 years of age). We included a total of 13 cross‐sectional and 15 longitudinal studies based on actual physical assessments of mobility in the obese older population in this review. We systematically examined existing evidence of which adiposity estimate best predicted mobility disability. Cross‐sectional studies (82–4000 participants) showed poorer lower extremity mobility with increasing obesity severity in both men and women. All longitudinal studies (1–22 years) except for one, reported relationships between adiposity and declining mobility. While different physical tests made interpretation challenging, a consistent finding was that walking, stair climbing and chair rise ability were compromised with obesity, especially if the body mass index (BMI) exceeded 35 kg m−2. More studies found that obese women were at an increased risk for mobility impairment than men. Existing evidence suggests that BMI and waist circumference are emerging as the more consistent predictors of the onset or worsening of mobility disability. Limited interventional evidence shows that weight loss is related with increased mobility and lower extremity function. Additional longitudinal studies are warranted that address overall body composition fat and muscle mass or change on future disability.

The Influence of Yoga-Based Programs on Risk Profiles in Adults with Type 2 Diabetes Mellitus: A Systematic Review

There is growing evidence that yoga may offer a safe and cost-effective intervention for Type 2 Diabetes mellitus (DM 2). However, systematic reviews are lacking. This article critically reviews the published literature regarding the effects of yoga-based programs on physiologic and anthropometric risk profiles and related clinical outcomes in adults with DM 2. We performed a comprehensive literature search using four computerized English and Indian scientific databases. The search was restricted to original studies (1970–2006) that evaluated the metabolic and clinical effects of yoga in adults with DM 2. Studies targeting clinical populations with cardiovascular disorders that included adults with comorbid DM were also evaluated. Data were extracted regarding study design, setting, target population, intervention, comparison group or condition, outcome assessment, data analysis and presentation, follow-up, and key results, and the quality of each study was evaluated according to specific predetermined criteria. We identified 25 eligible studies, including 15 uncontrolled trials, 6 non-randomized controlled trials and 4 randomized controlled trials (RCTs). Overall, these studies suggest beneficial changes in several risk indices, including glucose tolerance and insulin sensitivity, lipid profiles, anthropometric characteristics, blood pressure, oxidative stress, coagulation profiles, sympathetic activation and pulmonary function, as well as improvement in specific clinical outcomes. Yoga may improve risk profiles in adults with DM 2, and may have promise for the prevention and management of cardiovascular complications in this population. However, the limitations characterizing most studies preclude drawing firm conclusions. Additional high-quality RCTs are needed to confirm and further elucidate the effects of standardized yoga programs in populations with DM 2.

Obesity exacerbates oxidative stress levels after acute exercise

INTRODUCTION/PURPOSE This study compared oxidative stress levels and antioxidant capacity in nonobese and obese participants after acute resistance (RX) and aerobic exercise (AX). METHODS Blood samples were collected from 28 nonobese (mean = 20.8% body fat) and obese (mean = 35.0% body fat) participants pre- and immediately post-RX and AX. Lipid hydroperoxides (PEROX), malondialdehyde (TBARS) and total antioxidant status (TAS) were measured. Oxygen consumption (VO2) and minute ventilation (VE) values were determined during each exercise session. RESULTS In both groups, PEROX and TBARS were elevated post-RX and AX, with the greater elevations occurring in the obese group in each case (P < 0.05). In the obese, TBARS increased by 42% and 41% post-RX and AX, respectively, compared with 7.1% and 26.9% in the nonobese group. PEROX increased by 100% and 70% post-RX and AX, respectively, in the obese, and by 85% and 62% in the nonobese. TAS was 17% higher (P < 0.05) post-RX in the nonobese compared with the obese, whereas TAS values were not different post-AX. Peak and average VE, and relative VO2). rates were higher in the obese post-AX compared with the nonobese (P < 0.05) Correlations existed between the exercise-induced change in PEROX and body fat, vitamin C and A intake, peak oxygen consumption, and exercise ventilation rates in the obese group (r = 0.784-0.776, P < 0.05). In both groups, the exercise-induced changes in PEROX were associated with vitamin C intake, exercise ventilation rates, VO2peak, and plasma triglycerides (r = 0.669-0.558, P < 0.05). CONCLUSION Lipid peroxidation is elevated in both RX and AX, and it is exacerbated in the obese. The mechanisms underlying this response in each exercise may be different but could involve plasma triglycerides, oxygen consumption, and antioxidant intake.

Resistance training lowers exercise-induced oxidative stress and homocysteine levels in overweight and obese older adults

Objective: To compare exercise‐induced oxidative stress and levels of homocysteine and cholesterol in normal‐weight and overweight older adults after resistance exercise (RX).

Obesity and Weight Loss in the Treatment and Prevention of Osteoarthritis

Obesity is associated with an increasing prevalence of musculoskeletal complaints and pain. Obesity is a major risk factor for osteoarthritis (OA), and pain can manifest in load‐bearing and nonload‐bearing joints. The lumbar spine and the knee are 2 primary sites for pain onset in the obese patient. Irrespective of the weight loss method, reduction of body fat can lower the mechanical and inflammatory stressors that contribute to OA. Single or combined methods of weight loss including exercise, dietary modification, medications, and bariatric surgery are associated with lower joint pain and increased physical function. Methods of weight loss or maintenance in early years may reduce the life exposure of joints to the obesity induced stressors on load bearing joints.

Short-term exercise training improves diaphragm antioxidant capacity and endurance

Abstract These experiments tested the hypothesis that short-term endurance exercise training would rapidly improve (within 5 days) the diaphragm oxidative/antioxidant capacity and protect the diaphragm against contraction-induced oxidative stress. To test this postulate, male Sprague-Dawley rats (6 weeks old) ran on a motorized treadmill for 5 consecutive days (40–60 min · day−1) at approximately 65% maximal oxygen uptake. Costal diaphragm strips were excised from both sedentary control (CON, n=14) and trained (TR, n=13) animals 24 h after the last exercise session, for measurement of in vitro contraction properties and selected biochemical parameters of oxidative/antioxidant capacity. Training did not alter diaphragm force-frequency characteristics over a full range of submaximal and maximal stimulation frequencies (P > 0.05). In contrast, training improved diaphragm resistance to fatigue as contraction forces were better-maintained by the diaphragms of the TR animals during a submaximal 60-min fatigue protocol (P < 0.05). Following the fatigue protocol, diaphragm strips from the TR animals contained 30% lower concentrations of lipid hydroperoxides compared to CON (P < 0.05). Biochemical analysis revealed that exercise training increased diaphragm oxidative and antioxidant capacity (citrate synthase activity +18%, catalase activity +24%, total superoxide dismutase activity +20%, glutathione concentration +10%) (P < 0.05). These data indicate that short-term exercise training can rapidly elevate oxidative capacity as well as enzymatic and non-enzymatic antioxidant defenses in the diaphragm. Furthermore, this up-regulation in antioxidant defenses would be accompanied by a reduction in contraction-induced lipid peroxidation and an increased fatigue resistance.

The aging musculoskeletal system and obesity-related considerations with exercise

Advancing age and adiposity contribute to musculoskeletal degenerative diseases and the development of sarcopenic obesity. The etiology of muscle loss is multifactorial, and includes inflammation, oxidative stress and hormonal changes, and is worsened by activity avoidance due to fear of pain. The risk for mobility disability and functional impairment rises with severity of obesity in the older adult. Performance measures of walking distance, walking speed, chair rise, stair climb, body transfers and ability to navigate obstacles on a course are adversely affected in this population, and this reflects decline in daily physical functioning. Exercise training is an ideal intervention to counteract the effects of aging and obesity. The 18 randomized controlled trials of exercise studies with or without diet components reviewed here indicate that 3-18 month programs that included aerobic and strengthening exercise (2-3 days per week) with caloric restriction (typically 750 kcal deficit/day), induced the greatest change in functional performance measures compared with exercise or diet alone. Importantly, resistance exercise attenuates muscle mass loss with the interventions. These interventions can also combat factors that invoke sarcopenia, including inflammation, oxidative stress and insulin resistance. Therefore, regular multimodal exercise coupled with diet appears to be very effective for counteracting sarocpenic obesity and improving mobility and function in the older, obese adult.

Rapid changes in gait, musculoskeletal pain, and quality of life after bariatric surgery

BACKGROUND Joint pain is a common musculoskeletal complaint of morbidly obese patients that can result in gait abnormalities, perceived mobility limitations, and declining quality of life (QOL). It is not yet known whether weight loss 3 months after bariatric surgery can induce favorable changes in joint pain, gait, perceived mobility, and QOL. Our objectives were to examine whether participants who had undergone bariatric surgery (n = 25; laparoscopic Roux-en-Y gastric bypass or laparoscopic adjustable gastric banding) demonstrate improvements in joint pain, gait (speed, stride/step length, width of base of support, toe angles, single/double support, swing and stance time, functional ambulatory profile), mobility, and QOL by 3 months compared with nonsurgical controls (n = 20). The setting was an orthopedics laboratory at a university hospital in the United States. METHODS The present study was a prospective, comparative study. Numeric pain scales (indicating the presence and severity of pain), mobility-related surveys, and the Medical Outcomes Study short-form 36-item questionnaire (SF-36) were completed, and gait and walking speed were assessed at baseline and at month 3. RESULTS The bariatric group lost an average of 21.6 ± 7.7 kg. Significant differences existed between the 2 groups at month 3 in step length, heel to heel base of support, and the percentage of time spent in single and double support during the gait cycle (all P <.05). The severity of low back pain and knee pain decreased by 54% and 34%, respectively, with no changes in the control group (P = .05). The walking speed increased by 15% in the bariatric group (108-123 cm/s; P <.05) but not in the control group. Compared with the control group, fewer bariatric patients perceived limitations with walking and stair climbing by month 3. The bariatric group had a 4.8-cm increase in step length, 2.6% increase in single support time during the gait cycle, and 2.5-cm reduction in the base of support (all P <.05). The SF-36 physical component scores increased 11.8 points in the bariatric group compared with the control group, which showed no improvement by month 3 (P <.0001). CONCLUSIONS Improvements in some, but not all, gait parameters, walking speed, and QOL and of perceived functional limitations occur by 3 months after a bariatric procedure.