Kevin R. 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.

Resistance Exercise and Physical Performance in Adults Aged 60 to 83

OBJECTIVES: This investigation examined the effect of 6 months of high‐ or low‐intensity resistance exercise on muscular strength and endurance and stair climbing ability in adults aged 60 to 83.

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.

Resistance exercise and bone turnover in elderly men and women

PURPOSE This investigation examined the effect of 6 months of high- or low-intensity resistance exercise (REX) on bone mineral density (BMD) and biochemical markers of bone turnover in adults aged 60-83 yr. METHODS Sixty-two men and women (68.4 +/- 6 yr) were stratified for strength and randomly assigned to a control (CON, N = 16), low-intensity (LEX, N = 24), or high-intensity (HEX, N = 22) group. Subjects participated in 6 months of progressive REX training. Subjects trained at either 50% of their one repetition maximum (1-RM) for 13 repetitions (LEX) or 80% of 1-RM for 8 repetitions (HEX) 3 times x wk(-1) for 24 wk. One set each of 12 exercises was performed. 1-RM was measured for eight exercises. BMD was measured for total body, femoral neck, and lumbar spine by dual energy x-ray absorptiometry (DXA). Serum levels of bone-specific alkaline phosphatase (BAP), osteocalcin (OC), and pyridinoline cross-links (PYD) were measured. RESULTS 1-RM significantly increased for all exercises tested for both the HEX and LEX groups (P < and = 0.050). The percent increases in total strength (sum of all eight 1-RMs) were 17.2% and 17.8% for the LEX and HEX groups, respectively. Bone mineral density (BMD) of the femoral neck significantly (P < 0.05) increased by 1.96% for the HEX group. No other significant changes for BMD were found. OC increased by 25.1% and 39.0% for the LEX and HEX groups, respectively (P < 0.05). BAP significantly (P < 0.05) increased 7.1% for the HEX group. CONCLUSION These data indicate high-intensity REX training was successful for improving BMD of the femoral neck in healthy elderly subjects. Also, these data suggest REX increased bone turnover, which over time may lead to further changes in BMD.

Effects of resistance training on insulin-like growth factor-I and IGF binding proteins.

PURPOSE Our goal was to determine the effects resistance training on circulating IGF-I and on two of its major binding proteins, IGFBP-1 and IGFBP-3. Additional goals were to compare the time course of hormonal changes with the time course of strength changes and to determine the effect of training volume on the extent of hormonal changes. METHODS Thirty-one men and women (mean age = 37 +/- 7 yr) completed a 25-wk, 3 d x wk(-1) program in which they performed single-set resistance training (1-SET, N = 11), multiple-set resistance training (3-SET, N = 11), or no exercise (Control, N = 9). Before training, and after 13 and 25 wk of training, blood hormones were analyzed and strength was assessed as the sum of one-repetition maximum (1-RM) for leg extension and chest press exercises. RESULTS During the first 13 wk of resistance training, circulating IGF-I increased by approximately 20% in both the 1-SET and 3-SET groups (P = 0.041). No further increases occurred between 13 and 25 wk. In the 3-SET group, IGFBP-3 decreased 20% between 13 and 25 wk (P = 0.008). Training did not alter IGFBP-1. Increases in 1-RM strength occurred mainly during the first 13 wk of training and were significantly higher with 3-SET training compared to 1-SET. CONCLUSIONS These findings indicate that increased circulating IGF-I may, at least in part, mediate increases in strength that result from resistance training.

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).

Contracted plasma and blood volume in chronic heart failure

OBJECTIVES The purpose of this study was to determine if long-term pharmacotherapy mediated changes in intravascular plasma and blood volumes in patients with chronic heart failure (CHF). BACKGROUND Intravascular fluid volume expansion is an acute compensatory adaptation to ventricular dysfunction in patients with CHF. To our knowledge there are no reports on plasma and blood volume measures in clinically stable patients with CHF receiving standard pharmacotherapy. Such information may provide a better understanding of the clinical hallmarks of heart failure. METHODS Plasma volume (PV) and blood volume (BV) were measured in 12 patients (62.8 +/- 8.2 years old, 175.2 +/- 6.8 cm, 96.2 +/- 18.2 kg, peak oxygen consumption (VO2max) 15.2 +/- 3.3 ml/kg per min) with CHF secondary to coronary artery disease (left ventricular ejection fraction 31.2 +/- 9.7, New York Heart Association functional class 2.5 +/- 0.5) and seven healthy subjects (71.7 +/- 5.3 years old, 177.1 +/- 10.8 cm, 84.4 +/- 11.7 kg, VO2max 26.0 +/- 6.5 ml/kg per min) 3 to 4 h after eating and after supine rest using the Evans blue dye dilution technique. Venous blood samples were collected before blue dye infusion and analyzed for hematocrit (corrected 4% for trapped plasma and venous to whole body hematocrit ratio) and hemoglobin. RESULTS Hematocrit was 36.6 +/- 3.5% and 37.4 +/- 1.1%, and hemoglobin was 15.4 +/- 1.9 and 16.2 +/- 1.4 g/dl for patients with CHF and control subjects, respectively. Absolute PV was 3489.3 +/- 655.0 and 3728.7 +/- 813.2 ml, and absolute BV was 5,496.8 +/- 1,025.4 and 5,942.4 +/- 1,182.2 ml in patients with CHF and control subjects, respectively. Relative PV was 34.1 +/- 12.9 versus 44.5 +/- 9.0 ml/kg (p < or = 0.05), and relative BV was 58.5 +/- 12.3 versus 70.8 +/- 12.6 ml/kg (p < or = 0.05) in patients with CHF and control subjects, respectively. CONCLUSIONS Our data indicate significantly lower intravascular volumes in patients with CHF than in control subjects, indicating a deconditioned state or excessive diuresis, or both. The contracted PV and BV may contribute to exercise intolerance, shortness of breath and chronic fatigue, secondary to reduced cardiac output or regional blood flow, or both.

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.

A Randomized Sham-Controlled Trial of a Neurodynamic Technique in the Treatment of Carpal Tunnel Syndrome

STUDY DESIGN Randomized, controlled trial. OBJECTIVES To assess the believability of a novel sham intervention for a neurodynamic technique (NDT) in participants with signs and symptoms of carpal tunnel syndrome (CTS). Additionally, we wished to assess a potential mechanism of NDT (hypoalgesia) and to compare outcomes related to clinical pain and upper extremity disability between NDT and a sham intervention. BACKGROUND Preliminary evidence suggests that NDT is effective in the treatment of CTS. A sham-controlled study is lacking from the literature and could provide insight to the efficacy of NDT, as well as the corresponding mechanisms. METHODS Participants with signs and symptoms consistent with CTS provided baseline measures of expectation, clinical pain intensity, upper extremity disability, and experimental pain sensitivity. Participants were then randomly assigned to receive either a NDT known to anatomically stress the median nerve or a sham technique intended to minimize stress to the median nerve. Following brief exposure to the assigned technique, expectation was reassessed to observe for group-dependent changes. Participants received the assigned intervention over 3 weeks. Additionally, all participants received a prefabricated wrist splint for their involved hands, with instructions to sleep in the splint and to wear it during painful activities when awake. Following 3 weeks of the assigned intervention and splint wear, baseline measures were reassessed and participants were asked which intervention they believed they had received. RESULTS Forty females agreed to participate. Expectations for pain relief and perceived group assignment were similar between the groups. Within-session decreases in clinical pain intensity and pressure pain sensitivity were observed independent of group assignment. Reduction of temporal summation was observed only in participants receiving NDT. Significant improvements in clinical pain intensity and upper extremity disability were observed at 3 weeks, independent of group assignment. CONCLUSION The sham intervention was successful in blinding the participants. Immediate changes in pain sensitivity and intensity and 3-week changes in clinical pain intensity and upper extremity disability associated with NDT were equivalent to a sham intervention to which the participants were adequately blinded. Conversely, reduction of temporal summation was only observed in participants receiving the NDT, suggesting the potential of a favorable neurophysiological effect.