Weeks Of Moderate Exercise Training Research Articles

Moderate Exercise and Immune Response in Rats: A Model for Cancer Prevention / Exercício Moderado e Resposta Imune em Ratos: Um Modelo para a Prevenção do Câncer

Exercise is believed to cause changes in population and/or activity of immunocompetent cells. Study of this relationship is difficult in humans because of the multifactorial nature of human physiology and concomitant problems in controlling extraneous variables. We have investigated the effects of 4 weeks of moderate exercise training on percentage of NK cells and Lymphocyte activity in Wistar male rats under tightly controlled laboratory conditions. The animals were randomized into two groups: exercise and control. Exercised rats ran at a treadmill speed of 20 m/min (moderate exercise intensity), for 20 minutes, 6 days/week. Laboratory and handling conditions were matched, and food was controlled for both groups. Twenty-four hours after the exercise training program, lymphocyte response did not change significantly (p>0.05). Exercised rats demonstrated a significant increase in the percentage of circulating NK cell population (p<0.05). Exercise training demonstrated a significantly lower body weight for the exercised rats (p<0.05). With this simple model, this study supports the concept that regular moderate exercise leads to beneficial changes in the immunological response that may prevent cancer.

Exercise Mediated Nrf2 Signaling Protects the Myocardium From Isoproterenol-Induced Pathological Remodeling.

Although exercise derived activation of Nrf2 signaling augments myocardial antioxidant signaling, the molecular mechanisms underlying the benefits of moderate exercise training (MET) in the heart remain elusive. Here we hypothesized that exercise training stabilizes Nrf2-dependent antioxidant signaling, which then protects the myocardium from isoproterenol-induced damage. The present study assessed the effects of 6 weeks of MET on the Nrf2/antioxidant function, glutathione redox state, and injury in the myocardium of C57/BL6J mice that received isoproterenol (ISO; 50 mg/kg/day for 7 days). ISO administration significantly reduced the Nrf2 promoter activity (p < 0.05) and downregulated the expression of cardiac antioxidant genes (Gclc, Nqo1, Cat, Gsr, and Gst-μ) in the untrained (UNT) mice. Furthermore, increased oxidative stress with severe myocardial injury was evident in UNT+ISO when compared to UNT mice receiving PBS under basal condition. Of note, MET stabilized the Nrf2-promoter activity and upheld the expression of Nrf2-dependent antioxidant genes in animals receiving ISO, and attenuated the oxidative stress-induced myocardial damage. Echocardiography analysis revealed impaired diastolic ventricular function in UNT+ISO mice, but this was partially normalized in the MET animals. Interestingly, while there was a marginal reduction in ubiquitinated proteins in MET mice that received ISO, the pathological signs were attenuated along with near normal cardiac function in response to exercise training. Thus, moderate intensity exercise training conferred protection against ISO-induced myocardial injury by augmentation of Nrf2-antioxidant signaling and attenuation of isoproterenol-induced oxidative stress.

Lipids and insulin regulate mitochondrial-derived peptide (MOTS-c) in PCOS and healthy subjects.

Polycystic ovarian syndrome (PCOS) is a heterogeneous endocrine disorder associated with mitochondrial dysfunction and insulin resistance (IR). MOTS-c, a mitochondrial peptide, promotes insulin sensitivity (IS) through activating AKT and AMPK-dependent pathways. The current study was designed to examine the response of MOTS-c to lipids (intralipid) followed by insulin in PCOS and healthy subjects. All subjects underwent 5-hour intralipid/saline infusion with a hyperinsulinemic-euglycaemic clamp in the final 2hours. Plasma samples were collected to measure circulating MOTS-c using a commercial ELISA kit. Subsequently, this was repeated following an eight-week exercise intervention. Intralipid significantly increased plasma MOTS-c both in controls and PCOS subjects, whilst the insulin infusion blunted the intralipid-induced response seen for both lipids and MOT-c. Intralipid elevated plasma MOTS-c to 232±124% of basal in control (P<0.01) and to 349±206% of basal in PCOS (P<0.001) subjects. Administration of insulin suppressed intralipid-induced MOTS-c from 232±124% to 165±97% (NS) in control and from 349±206% to 183±177% (P<0.05) in PCOS subjects, respectively. Following exercise, intralipid elevated plasma MOTS-c to 305±153% of basal in control (P<0.01) and to 215±103% of basal in PCOS (P<0.01) subjects; insulin suppressed intralipid-induced MOTS-c only in controls. In conclusion, this is the first study to show increased lipid enhanced circulating MOTS-c whilst insulin attenuated the MOTS-c response in human. Further, eight weeks of moderate exercise training did not show any changes in circulating MOTS-c levels in healthy controls and in women with PCOS.

The effects of exercise training on insulin resistance in patients with coronary artery disease

It is unclear whether the beneficial effects of habitual exercise on insulin resistance are due to concomitant weight loss, changes in diet or whether they are simply related to the transient effects of the last bout of exercise. Moreover, patients with coronary artery disease (CAD) have not been studied. Randomized controlled trial. To determine the effects of exercise training on insulin resistance (i.e. low insulin sensitivity) in CAD patients without diabetes independent of changes in weight, diet or the effect of acute exercise, 29 patients were randomized to 12 weeks of supervised exercise training and 26 to usual activity. Insulin sensitivity was determined at 72 h following their last bout of exercise using the minimal model technique. Weight was held constant by adjusting caloric intake. Following the intervention, peak oxygen uptake increased by 0.18+/-0.14 l/min in the exercise training group, which was significantly higher (P<0.0001) than that in the usual activity group (0.02+/-0.14 l/min). Insulin sensitivity did not change significantly within or between groups during the study [exercise training -0.24+/-1.15 x 10(4)/min and usual activity 0.06+/-0.67 x 10(4)/min/(microU/ml)]. Twelve weeks of moderate exercise training in the absence of weight loss did not result in significant change in insulin resistance in patients with CAD.

ATTENUATION OF CHEMOTHERAPY-INDUCED VASCULAR DYSFUNCTION BY EXERCISE TRAINING

We have previously shown that exercise training enhances endothelium-dependent vasodilation in a rat mammary tumor model, and that these changes resulted in an attenuation of vasoconstriction caused by the chemotherapeutic agent 5-fluororuacil (5-FU). We hypothesized that this was the result of increased nitric oxide (NO) production by the vasculature. In order to investigate possible mechanisms involved with the exercise-induced attenuation of vascular dysfunction, we determined endothelial nitric oxide synthase (eNOS) protein content in the aorta of N-methyl-N-nitrosourea (MNU)-treated rats following eight weeks of moderate exercise training. Virgin female Sprague Dawley rats were injected with MNU (25 mg/kg, i.p.) at 21 days of age, and at 28 days assigned to either sedentary or exercise groups. The exercise regimen consisted of treadmill running at 20–25 m/min, +15% grade, 30 min/d, 5 d/wk for 8 weeks. Our results show no significant differences in aortic eNOS protein content between sedentary and exercise groups following 2 or 4 weeks of exercise training. However, after 6 weeks of exercise training, significant (p < 0.05) increases in aortic eNOS protein content were observed in exercise trained rats when compared to sedentary animals. Following 8 weeks of exercise training, increases in eNOS protein content were sustained, however differences between sedentary and exercise trained animals were not statistically significant. These data demonstrate that moderate exercise training increases aortic eNOS protein content in a rat mammary tumor model. This suggests that the attenuation of 5-FU-induced vasoconstriction may be due, at least in part, to an increase in aortic eNOS protein content.

Free living energy expenditure in post menopausal women before and after exercise training.

The aim of the study was to determine the effects of 8 weeks of moderate exercise training, on 24-hour free living energy expenditure in previously sedentary post-menopausal women. The experimental group (EX) included 9 women. Ten non-exercising control subjects (CON) were recruited to undergo pre- and post-testing. Estimated total daily energy expenditure (TDEE), total 24-hour heart beats (HB), total energy intake (TEI), resting metabolic rate, maximal oxygen consumption (VáO2max), body composition, and submaximal heart rate were measured before and after the exercise intervention. Body composition did not change (body fat % in CON 34.0 +/- 4.0% vs. 33.9 +/- 3.6% and EX 34.1 +/- 4.0% vs. 34.0 +/- 3.4%). Mean submaximal heart rate during steady-state exercise in EX was lower after training compared to CON (p < .05); however, VáO2max did not increase significantly (CON 1.96 +/- 0.23 vs. 1.99 +/- 0.24 l L O2/min and EX 1.86 +/- 0.39 vs. 1.94 +/- 0.30 L O2/min). Neither estimated TDEE (CON, 11.6 +/- 2.0 vs. 11.4 +/- 2.78 MJ; and EX 11.4 +/- 3.3 vs. 11.5 +/- 2.5 MJ, pre vs. post, respectively), RMR (CON 134.2 +/- 9.4 vs. 136.9 +/- 15.0 KJ/kgFFM/day, and EX 138.4 +/- 6.4 vs. 140.7 +/- 14.2 KJ/kgFFM/day, pre vs. post, respectively), TEI (CON 7.9 +/- 2.2 vs. 8.2 +/- 2.5 MJ, and EX 9.4 +/-1.6 vs. 8.3 +/- 2.8 MJ), nor HB (CON 110,808 +/- 12,574 vs. 107,366 +/- 12,864 beats, and EX 110,188 +/- 9,219 vs. 114,590 +/- 12,750 beats) change over 8 weeks in either group. These data suggest that a moderate exercise program may not impact on TDEE, RMR, TEI, or HB in previously sedentary, older women.

EFFECTS OF EXERCISE ON ENDOTHELIAL FUNCTION IN AN MNU-INDUCED RAT MAMMARY TUMOR MODEL

The purpose of this study was to assess endothelial function in N-methyl-N-nitrosourea (MNU)-treated rats following eight weeks of moderate exercise training. A secondary purpose was to determine if exercise training altered vascular responsiveness to the chemotherapeutic agent 5-fluorouracil (5-FU). Virgin female Sprague Dawley rats were injected with MNU (50 mg/kg, i.p.) at 21 days of age, and at 28 days assigned to one of four groups: 1) non MNU + no exercise (NM+NE), 2) non MNU + exercise (NM+E), 3) MNU + no exercise (M+NE), 4) MNU + exercise (M+E). The exercise regimen consisted of treadmill running at 20–25 m/min, 15% grade, 30 min/d, 5 d/wk for 8 weeks. Vascular reactivity was evaluated in isolated aortic rings following 0, 4, and 8 weeks of exercise training. No significant differences in vascular responsiveness were noted between M+E and NM+E, or between M+NE and NM+NE animals at 0, 4, or 8 weeks. In addition, four weeks of exercise training resulted in no significant changes in vasoactivity for any group. However, 8 weeks of exercise training resulted in increased maximal endothelium-dependent vasorelaxation to acetylcholine (ACh, 1x10-5 M) (M+NE, 56 +/− 7%; M+E, 69 +/− 8%; p < 0.05) following norepinephrine-induced (1x10-7 M) vasoconstriction. Exposure of aortic rings from each group to 5-FU (7x10-3 M) resulted in vasoconstriction. Rings obtained from exercise trained animals demonstrated enhanced vasorelaxation to ACh (1x10-5 M) following 5-FU-induced vasoconstriction compared to rings obtained from untrained animals (p < 0.05). The results demonstrate that exercise training can enhance endothelium-dependent vasodilation in an MNU-induced rat mammary tumor model and that these changes may serve to counteract the vasoconstrictive properties of 5-FU. Supported by NIH KO7 CA79554

THE EFFECTS OF EXERCISE TRAINING ON GALLBLADDER FUNCTION IN AN OBESE FEMALE POPULATION.

2064 Aerobic exercise may influence gallstone disease pathogenesis through its effect on gallbladder motility. The purpose of this investigation was to examine the effects of exercise training on gallbladder emptying in obese women. Twenty-seven obese subjects were randomized into one of two groups: exercise (E) (five 45 minute brisk walking sessions per week at 75.2±0.5% of maximum heart rate) and controls (C). Gallbladder function via cholescintigraphy, cardiorespiratory fitness, and body composition were measured in all subjects before and after a 12-week intervention period. In each cholescintigraphy trial subjects ingested an 8 oz liquid meal 45 min after injection of 99mTc disofenin to promote gallbladder emptying. Gallbladder areas were then scanned for 60 s and then every 5 min for 60 min. VO2max increased significantly by 9% for E when compared to C (P<0.001). Within E postprandial gallbladder ejection fraction (EF) increased significantly after training (39.5±4.9% to 54.7±6.5%, P<0.05), however this 15.2% increase in EF was not significantly greater than the change reported in the controls. Results indicate that 12 weeks of moderate exercise training does improve cardiorespiratory fitness but does not significantly effect gallbladder emptying in obese women. Supported by: The American College of Sports Medicine Foundation: Nordic Track Research Grant Initiative.

The effects of exercise on iron status and aerobic capacity in moderately exercising adult women

The purpose of this study was to examine the effects of a 10-week moderate exercise on iron status and aerobic capacity of adult women. Seventeen women, 56- to 67-years, served either as controls (no exercise, n = 9) or participated in a supervised exercise program (n = 8). Women in the exercise group cycled on an ergometer three days per week, for 40 minutes at 70 to 75% maximal heart rate for 10 weeks. Pre- and post- (weeks 0 and 11) submaximal treadmill stress tests were obtained. Aerobic capacity was evaluated by heart rate per grade, maximum oxygen capacity, and time to reach 70% maximum heart rate. The results indicated that average heart rate per grade decreased and time to reach 70% max heart rate increased in the exercise group (p < .05) after 10 weeks of moderate exercise training. Iron status as determined by serum ferritin, transferrin saturation, serum iron, total iron binding capacity, hemoglobin and hematocrit was normal and comparable between both groups. Hemoglobin increased (p < .05) after 10 weeks of supervised moderate exercise. The results suggest that 10 weeks of moderate exercise enhances aerobic capacity of older women but does not compromise iron status.