The role of exercise in type II diabetes mellitus

A number of studies have demonstrated a beneficial effect of regular physical activity on levels of HgbA₁C in patients with type II diabetes mellitus, largely due to an increase in insulin sensitivity. Benefits are related to short term improvements in insulin sensitivity following individual exercise bouts. Regular exercise can prevent or delay the onset of type II diabetes in high risk populations. The insulin resistant state is associated with a cluster of cardiovascular risk factors all of which improve with regular physical activity. Because of the high incidence of occult coronary disease, patients need a cardiovascular evaluation when initiating an exercise program. High intensity exercise may result in retinal hemorrhage and transient worsening of diabetic proteinuria. The most common complication is hypoglycemia. A combination of aerobic and light resistance exercise is appropriate. Patients should exercise a minimum of three times a week for 30–60 minutes at 50% to 75% of their Vo_2max.     

Efficiency of twice weekly concurrent training in trained elderly men

This study compared the effects of different weekly training frequencies on the cardiovascular and neuromuscular adaptations induced by concurrent training in previously trained elderly. After 20 weeks of combined strength and endurance training, twenty-four healthy elderly men (65 ± 4 years) were randomly placed into two frequency training groups: strength and endurance training performed twice a week (SE2, n = 12); or, strength and endurance training performed three times per week (SE3, n = 12). The interventions lasted 10 weeks and each group performed identical exercise intensity and volume per session. Before and after the exercise training, one maximum repetition test (1RM), isometric peak torque (PT), maximal surface electromyographic activity (EMG), as well as muscle thickness (MT) were examined. Additionally, peak oxygen uptake (VO_2peak), maximum aerobic workload (W_max), first and second ventilatory thresholds (VT₁ and VT₂) were evaluated. There were significant increases in upper and lower-body 1RM, MT, VO_2peak, VT₁ and VT₂, with no differences between groups. There were no changes after training in maximal EMG and isometric peak torque. W_max was improved only in SE3. After 10 weeks of training, twice weekly combined strength and endurance training leads to similar neuromuscular and cardiovascular adaptations as three times per week, demonstrating the efficiency of lower frequency of concurrent training in previously trained elderly men.     

A moderate intensity exercise program did not increase the oxidative stress in older adults

Oxidative damage to lipoproteins, in particular low density lipoprotein (LDL), is known to play a role in a number of diseases associated with aging such as cardiovascular disease (CVD) and dementia. Exercise can alter the balance of oxidative and anti-oxidative species within the human body and may cause oxidative damage to lipoproteins. The purpose of this study was to assess the effect of a moderate intensity exercise program on markers of oxidative stress in older age adults. Parameters of lipoprotein protein and lipid oxidation, and lipoprotein nitration were assessed in aged individuals who undertook a program of moderate physical activity for a period of 8 weeks. There were no significant changes in LDL protein oxidation or nitration which could be attributed to 8 weeks of walking exercise, however, LDL nitration was increased following acute steady state exercise (pre-: 0.34 ± 0.1 vs. post-: 0.44 ± 0.07 μm/mg LDL; p = 0.04). Walking at moderate intensity caused a significant weight decrease in the exercise group, but did not have any significant effect on VO₂max. Exercise at this intensity was not harmful and did not increase risk factors for diseases associated with oxidative stress in the participants of the study.     

The effect of an advanced glycation end-product crosslink breaker and exercise training on vascular function in older individuals: A randomized factorial design trial

Aging leads to accumulation of irreversible advanced glycation end-products (AGEs), contributing to vascular stiffening and endothelial dysfunction. When combined with the AGE-crosslink breaker Alagebrium, exercise training reverses cardiovascular aging in experimental animals. This study is the first to examine the effect of Alagebrium, with and without exercise training, on endothelial function, arterial stiffness and cardiovascular risk in older individuals. Forty-eight non-exercising individuals (mean age 70 ± 4 years) without manifest diseases or use of medication were allocated into 4 groups for a 1-year intervention: Exercise training & Alagebrium (200 mg/day); exercise training & placebo; no exercise training & Alagebrium (200 mg/day); and no exercise training & placebo. We performed a maximal exercise test (VO₂max) and measured endothelial function using venous occlusion plethysmography and intra-arterial infusion of acetylcholine, sodium nitroprusside and N^G-monomethyl-l-arginine. Arterial stiffness was measured using pulse wave velocity. Cardiovascular risk was calculated using the Lifetime Risk Score (LRS). In the exercise training groups, LRS and VO₂max improved significantly (23.9 ± 4.5 to 27.2 ± 4.6mLO₂/min/kg, p < 0.001). Endothelial response to the vasoactive substances did not change, nor did arterial stiffness in any of the four groups. In conclusion, one year of exercise training significantly improved physical fitness and lifetime risk for cardiovascular disease without affecting endothelial function or arterial stiffness. The use of the AGE-crosslink breaker Alagebrium had no independent effect on vascular function, nor did it potentiate the effect of exercise training. Despite the clinical benefits of exercise training for older individuals, neither exercise training nor Alagebrium (alone or in combination) was able to reverse the vascular effects of decades of sedentary aging.     

Exercise as the cornerstone of cardiovascular prevention

Lack of physical activity in the general population is a public health problem and is recognized as an independent risk factor for the development of coronary disease. The relative risk of inactivity is similar to that of hypertension, hypercholesterolemia and smoking. Consequently, a sedentary lifestyle is associated with a concurrent increase in cardiovascular disease. Engaging regularly in mild-to-moderate physical exercise results in a range of physiological adaptations that are beneficial for health. Various studies have demonstrated that there is an inverse relationship between regular exercise and the risk of coronary heart disease, cardiac events and death. Exercise improves the lipid profile and glycemic control, reduces or prevents hypertension, obesity and stress, and promotes fitness and longevity. However, most evidence for the benefits of exercise comes from observational studies and, although maximum oxygen uptake and the duration of exercise on an exercise stress test are powerful predictors of mortality, there is no agreement on the quantity or intensity of the physical activity needed for primary or secondary prevention. On the other hand, although there is a temporarily increased risk of acute myocardial infarction during exhaustive exercise, the balance of risks and benefits is strongly in favor of the benefits because there is a minimum threshold for the weekly energy expenditure required to reduce cardiovascular risk.     

The effects of improved metabolic risk factors on bone turnover markers after 12 weeks of simvastatin treatment with or without exercise

Objective

Emerging evidence supports an association between metabolic risk factors and bone turnover. Statins and exercise independently improve metabolic risk factors; however whether improvements in metabolic risk factor affects bone turnover is unknown. The purpose of the present study was to: 1) evaluate the relationship between metabolic risk factors and bone turnover; and 2) determine if improvements in metabolic risk factors after 12 weeks of statin treatment, exercise or the combination affect bone turnover.

Methods

Fifty participants with ≥ 2 metabolic syndrome defining characteristics were randomly assigned to one of three groups: statin (STAT: simvastatin, 40 mg/day), exercise (EX: brisk walking and/or slow jogging, 45 minutes/day, 5 days/week), or the combination (STAT + EX). Body composition and whole body bone mineral density were measured with dual energy X-ray absorptiometry. Serum markers of bone formation (bone specific alkaline phosphatase, BAP; osteocalcin, OC), resorption (C-terminal peptide of type I collagen, CTX) and metabolic risk factors were determined. Two-factor (time, group) repeated-measures ANCOVA was used to examine changes of metabolic risk factors and bone turnover. General linear models were used to determine the effect of pre-treatment metabolic risk factors on post-treatment bone turnover marker outcomes.

Results

Participants with ≥ 4 metabolic syndrome defining characteristics had lower pre-treatment OC than those with 3 or fewer. OC was negatively correlated with glucose, and CTX was positively correlated with cholesterol. STAT or STAT + EX lowered total and LDL cholesterol. The OC to CTX ratio decreased in all groups with no other significant changes in bone turnover. Higher pre-treatment insulin or body fat predicted a greater CTX reduction and a greater BAP/CTX increase.

Conclusion

Metabolic risk factors were negatively associated with bone turnover markers. Short-term statin treatment with or without exercise lowered cholesterol and all treatments had a small effect on bone turnover.     

Aerobic physical training has little effect on cardiovascular autonomic control in aging rats subjected to early menopause

We investigated and compared the effects of physiological menopause (PM) and early menopause (EM) and the adaptations promoted by physical training on the cardiovascular autonomic control of aged rats. Female Wistar rats (N = 72) were assigned to 3 groups: control (22 weeks old rats, undergoing sham surgery in the 10th week of life), PM (82 weeks old rats, undergoing sham surgery in the 10th week of life) and EM (82 weeks old rats, undergoing ovariectomy in the 10th week of life). In each group, half of the rats were subjected to swimming training over a period of 10 weeks. Sedentary PM and EM groups had higher basal mean arterial pressure (MAP) and heart rate (HR) and lower intrinsic HR compared to the sedentary control group. Physical training reduced MAP in PM group. All trained groups had lower basal HR; however, only control and PM-trained groups showed decreased intrinsic HR. The assessment of cardiac autonomic balance showed that PM and EM sedentary groups exhibited sympathetic predominance compared to control group. After physical training, only EM group presented sympathetic predominance. HR variability (pulse interval) was similar among all sedentary groups. However, control and PM-trained groups showed lower power in low frequency band (LF; 0.2–0.75 Hz) and higher power in high frequency band (HF; 0.75–3.0 Hz). The analysis of systolic arterial pressure variability revealed that PM and EM sedentary groups had higher LF power. However, PM group showed lower LF power following physical training. Finally, PM and EM groups had a reduction in spontaneous baroreflex sensitivity, that was attenuated by physical training. The overall results suggest that PM or EM promotes similar negative effects on MAP, HR and cardiovascular autonomic control. However, unlike the PM group, physical training was not able to mitigate all negative effects of EM on cardiovascular autonomic control.     

Antiplatelet therapy in the perioperative period

The current practice of withdrawing aspirin 7-10 days preoperatively may be dangerous in certain groups of patients. The risk of cardiovascular events increases 3-fold after aspirin withdrawal. The average time between aspirin withdrawal and the manifestation of acute coronary syndrome is 8 to 11 days. The withdrawal of clopidogrel earlier than 4-6 weeks after bare metal stent implantation or less than 12 months after drug-eluting stent implantation is very risky and poses a high risk of stent thrombosis and high perioperative mortality. Continuing aspirin perioperatively leads to a 1.5-fold increase in perioperative bleeding complications but it does not lead to a higher severity of bleeding complications or higher mortality. The article analyzes current European and American guidelines for perioperative antiplatelet treatment and suggests an algorithm based on the guidelines to help make clinical decisions.     

What should the clinician tell patients with mild hypertension about physical activity?

Recent guidelines recommend lifestyle measures, with physical activity as an integral component, for all patients with hypertension or prehypertension to lower blood pressure and control other risk factors. This review discusses both acute and long-term effects of dynamic aerobic endurance exercise and resistance exercise as nonpharmacologic tools to reduce blood pressure, respectively. The optimal exercise characteristics to lower blood pressure need to be more precisely defined, especially with regard to resistance exercise; so far, these effects have been shown to be immediate and elicited by low-intensity short-duration exercise. Based on the current evidence, hypertensive patients should be recommended to exercise on most, preferably all, days of the week, with moderate intensity (40% to 60% of VO₂ reserve) for at least 30 minutes of continuous or accumulated physical activity per day, consisting primarily of endurance training but supplemented by resistance training.     

Physical activity and coronary heart disease: prevention and effect on risk factors

The general public recommendation to accumulate 30 minutes of daily physical activity on most, preferably all, days of the week was recently modified by the National Academy of Science Institute of Medicine to at least 60 minutes of cumulative daily physical activity to maintain cardiovascular health at a maximal level. Data suggest that regular physical activity, even as little as 30 minutes daily, can positively impact cardiovascular health by improving many of the major risk factors associated with coronary heart disease, including hypertension, dyslipidemia, obesity, insulin resistance, and endothelial function. With the recent and rapid rise in the rate of obesity in the United States, a doubling of the dose of physical activity daily may help offset the trend of increased caloric intake that has contributed to this epidemic. We briefly review the evidence regarding the amount and intensity of physical activity necessary to alter these cardiovascular risk factors with the goal of reducing coronary events.     

Coronary risk related to sport

Regular physical activity is beneficial because it is associated with a 40% reduction in the risk of death or myocardial infarction. However, sport momentarily increases the risk of adverse cardiovascular events during the sporting activity. This increased risk is higher in the less accomplished sportsmen and in those with cardiovascular risk factors. Regular weekly exercise, even of mild to moderate intensity, has a protective effect. An adverse coronary event on exercise is observed in 1200 to 1500 patients per year in France. It results from underlying coronary artery disease which is often occult. In the under 35 year age group, although atherosclerotic plaque is already present, the possibility of a congenital anomalous coronary arterial anatomy should be considered. This can sometimes be detected by transoesophageal echocardiography. After 35 years of age, coronary arteriosclerosis is almost the only pathology observed. The probability of a coronary event is higher in under trained "veteran" with known classical cardiovascular risk factors, often occurring by "error" in the practice of an activity too intense for the level of physical fitness. It should be remembered that 50% of these complications occur in people who have experienced symptoms on exercise in the days or weeks before the event. This article also discusses which risk factors aggravate the risk in known coronary patients and what advice should be given to coronary patients who want to benefit from the effects of regular physical exercise.     

Exercise as a Treatment for the Risk of Cardiovascular Disease

Regular physical activity decreases the risk of cardiovascular disease and modifies multiple cardiovascular risk factors. The optimum amount of exercise continues to generate debate; however, the general recommendation is that all adults should engage in 30 min of moderate-intensity physical activity on five, and preferably all, days of the week. Despite extensive data and recommendations, a significant proportion of the US adult population remains sedentary. Promoting physical activity at a public level remains a major challenge because of the presence of multiple behavioral, physical, and environmental barriers. Health care providers have an opportunity and a responsibility to include exercise counseling in routine office visits.     

Risk factors for pulmonary complications, including pulmonary embolism, after total knee arthroplasty (TKA) in elderly Koreans

There has been a steady increase in elective TKA in elderly Koreans. However, there are few reports about the incidence of and risk factors for pulmonary complications, including pulmonary thromboembolism in these patients. We evaluated retrospectively 338 patients aged 60 years and over (290 females, median age 69 years) to assess the incidence and predictive factors for pulmonary complications, including pulmonary thromboembolism after TKA. Of these patients, 264 underwent simultaneous bilateral TKA (78%) by two surgeons and 56 (17%) had general anesthesia. No patient received thromboprophylaxis. There were 49 postoperative pulmonary complications in the 338 patients (14.2%, 49/338). Of the 49 patients, 27 developed atelectasis (27/49), six developed pneumonia (6/49), and four had pleural effusions (4/49) within 7 days of the surgery; 12 patients had a pulmonary thromboembolism (12/49) during their hospitalization. No pulmonary complication was fatal. Multivariate analysis revealed that pulmonary hypertension (right ventricular systolic pressure ≥ 35 mmHg on transthoracic echocardiography; odds ratio (OR) = 3.0, p = 0.016) was independently associated with pulmonary complications. A resting PaCO₂ ≥ 45 mmHg (OR = 22.9, p = 0.004) was the only independent predictor of the development of a pulmonary thromboembolism. Pulmonary hypertension may thus predict pulmonary complications and a PaCO₂ greater than 45 mmHg may be a risk factor for pulmonary thromboembolism following TKA. Preoperative blood gas analysis and transthoracic echocardiography can identify those patients at high risk for pulmonary complications, including pulmonary thromboembolism, after TKA in elderly Korean patients.     

Exercise and heart disease in women: why, how, and how much?

Despite a traditional view that cardiovascular disease primarily affects men, a growing body of information now recognizes that it is a disease that equally affects women and is the leading cause of morbidity and mortality in women in the United States. Both physical activity and physical fitness have been shown to have an inverse association with coronary heart disease and cardiovascular risk factors. Furthermore, physical inactivity is now recognized by the American Heart Association as an independent risk factor for coronary heart disease. However, national surveillance programs have reported that 1/4 of adults are currently sedentary, and 1/3 of women do not engage in any leisure-time physical activity. Regular exercise may significantly impact coronary heart disease in women, as some coronary risk factors have a stronger predictive value for coronary heart disease in women as compared with men. Recent studies have shown that women who exercise regularly are less likely to develop diabetes mellitus; exercise may reduce blood pressure and produce improvements in lipid profiles. Conflicting data exist regarding the dose and intensity of exercise necessary to achieve significant health benefits; however, many reports demonstrate a reduced risk of mortality from cardiovascular diseases and from all causes with only moderate intensity physical activity. The Centers for Disease Control, American Heart Association, and American College of Sports Medicine recommend a regular pattern of physical activity of moderate intensity, which can be accumulated throughout the day and should be performed at least 3 to 5 days per week. In addition, the benefit of weight-bearing exercise should be underscored in women, because it plays an important role in the prevention and treatment of osteoporosis. Continued efforts are necessary to encourage the many American women who are currently inactive to make even modest increases in levels of physical activity to achieve substantial cardiovascular, as well as other, health benefits.     

The physical activity patterns of cardiac rehabilitation program participants

PURPOSE: This investigation aimed to examine the physical activity patterns of cardiac rehabilitation program (CRP) participants. METHODS: The investigation enrolled 53 male and 24 female CRP participants between 46 and 88 years of age. By means of a uniaxial accelerometer (Life-Corder), the amount of physical activity (in kilocalories) and the time spent in physical activity at light (<3 metabolic equivalents [METs]), moderate (3 to 6 METs), and vigorous (>6 METs) intensity were evaluated. In addition to these variables, the MET levels for the CRP and non-CRP periods were calculated. RESULTS: The weekly amount of physical activity energy expenditure averaged 1597 +/- 846 kcal/week, and the time spent in light, moderate, and vigorous physical activity averaged, respectively, 375.5 +/- 124.5 minutes, 125.2 +/- 109.4 minutes, and 5.7 +/- 12.8 minutes per week. These levels were significantly lower on non-CRP days than on CRP days: 177 +/- 113 versus 299 +/- 161 kcal/day and, respectively, 49.3 +/- 19.3 versus 59.7 +/- 19.8 minutes, 10.5 +/- 14.6 versus 26.4 +/- 20.4 minutes, and 0.4 +/- 1.7 versus 1.4 +/- 3.0 minutes per day. CONCLUSIONS: These results indicate that the amount of physical activity was generally adequate on CRP days, but failed to reach target levels on non-CRP days. Thus CRP participants, when it is medically appropriate, should be encouraged to incorporate lifestyle physical activity, additional exercise, or both on non-CRP days to supplement their caloric expenditure from CRP exercise sessions.     

Diet and exercise in type 2 diabetes mellitus.

The question is no longer whether diet and exercise can benefit the individual with type 2 diabetes. Rather, the type and duration of exercise the magnitude of the effects on glycemic control, insulin sensitivity, and on risk factors for cardiovascular disease must be considered in determining the feasibility and acceptability of an intervention program. It is now clear that regular physical exercise is important in both the prevention and treatment of type 2 diabetes. The benefits of exercise are many and include increased energy expenditure, which, combined with dietary restriction, leads to decreased body fat, increased insulin sensitivity, improved long-term glycemic control, improved lipid profiles, lower blood pressure, and increased cardiovascular fitness. Persons with type 2 diabetes often find it difficult to exercise and are at increased risk for injury or exacerbation of underlying diseases or diabetic complications. Therefore, before starting an exercise program, all patients with type 2 diabetes should have a complete history and physical examination, with particular attention to evaluation of cardiovascular disease, medications that may affect glycemic control during or after exercise, and diabetic complications including retinopathy, nephropathy, and neuropathy. Exercise programs should be designed to start slowly, build up gradually, and emphasize moderately intense exercise performed at least three times a week and preferably five to seven times a week for best results.     

A single weekly bout of exercise may reduce cardiovascular mortality: how little pain for cardiac gain? 'The HUNT study, Norway'.

BACKGROUND: The observation that exercise training reduces cardiovascular mortality is robust and consistent, but the amount and intensity of exercise that is required for risk reduction is not yet resolved. METHODS: We studied the association between the amount and intensity of exercise and cardiovascular mortality in 27 143 men and 28 929 women who were free from known cardiovascular disease at the beginning of follow-up between 1984 and 1986. The relative risk of death was calculated as the rate of death among participants within a given physical activity category compared with the rate of death in the reference category (no physical activity). We used Cox regression analysis to adjust for age and other potentially confounding factors. RESULTS: After 16 years (SD 4 years) of follow-up, 2946 men (10.8%) and 2486 women (8.6%) had died from ischaemic heart disease or stroke. A single weekly bout of exercise of high intensity reduced the risk of cardiovascular death, both in men [relative risk (RR) 0.61, 95% confidence interval (CI) 0.49-0.75], and women (RR 0.49, 95% CI 0.27-0.89), compared with those who reported no activity. There was no additional benefit from increasing the duration or the number of exercise sessions per week. The risk reduction related to exercise increased with increasing age in men, but not in women. CONCLUSION: These results challenge the current recommendation that expenditure of at least 1000 kcal per week is required to achieve exercise-induced protection against premature cardiovascular mortality.     

Comparison of cardioprotective benefits of vigorous versus moderate intensity aerobic exercise

Aerobic fitness, not merely physical activity, is associated with a reduced risk of cardiovascular disease. Vigorous intensity exercise has been shown to increase aerobic fitness more effectively than moderate intensity exercise, suggesting that the former may confer greater cardioprotective benefits. An electronic search of published studies using PubMed was conducted for 2 types of investigations, epidemiologic studies that evaluated the benefits of physical activity of varying intensity levels and clinical trials that trained individuals at different intensities of exercise while controlling for the total energy expenditure. A secondary search was conducted using the references from these studies. The epidemiologic studies consistently found a greater reduction in risk of cardiovascular disease with vigorous (typically > or =6 METs) than with moderate intensity physical activity and reported more favorable risk profiles for individuals engaged in vigorous, as opposed to moderate, intensity physical activity. Clinical trials generally reported greater improvements after vigorous (typically > or =60% aerobic capacity) compared with moderate intensity exercise for diastolic blood pressure, glucose control, and aerobic capacity, but reported no intensity effect on improvements in systolic blood pressure, lipid profile, or body fat loss. In conclusion, if the total energy expenditure of exercise is held constant, exercise performed at a vigorous intensity appears to convey greater cardioprotective benefits than exercise of a moderate intensity.     

Physical activity is associated with improved aerobic exercise capacity over time in adults with congenital heart disease

Background

Impaired exercise capacity is common in adults with congenital heart disease (ACHD). This impairment is progressive and is associated with increased morbidity and mortality. We studied the influence of the frequency of at least moderately strenuous physical activity (PhysAct) on changes in exercise capacity of ACHD patients over time.

Methods

We studied ACHD patients ≥ 21 years old who had repeated maximal (RER ≥ 1.09) cardiopulmonary exercise tests within 6 to 24 months. On the basis of data extracted from each patient's clinical records, PhysAct frequency was classified as (1) Low: minimal PhysAct, (2) Occasional: moderate PhysAct < 2 times/week, or (3) Frequent: moderate PhysAct ≥ 2 times/week.

Results

PhysAct frequency could be classified for 146 patients. Those who participated in frequent exercise tended to have improved pVO₂ (?pVO₂ = + 1.63 ± 2.67 ml/kg/min) compared to those who had low or occasional activity frequency (?pVO₂ = + 0.06 ± 2.13 ml/kg/min, p = 0.003) over a median follow-up of 13.2 months. This difference was independent of baseline clinical characteristics, time between tests, medication changes, or weight change. Those who engaged in frequent PhysAct were more likely to have an increase of pVO₂ of ≥ 1SD between tests as compared with sedentary patients (multivariable OR = 7.4, 95%CI 1.5–35.7). Aerobic exercise capacity also increased for patients who increased activity frequency from baseline to follow-up; 27.3% of those who increased their frequency of moderately strenuous physical activity had a clinically significant (at least + 1SD) increase in pVO₂ compared to only 11% of those who maintained or decreased activity frequency.

Conclusions

ACHD patients who engage in frequent physical activity tend to have improved exercise capacity over time.