Physical Activity Helps Prevent Vascular Atherosclerosis
Endothelium dysfunction has been proposed as a possible contributor to cardiovascular damage. Endothelium, the thin lining of arterial walls, plays a primary role in the modulation of vascular tone and structure through the production of nitric oxide.
Nitric oxide in turn acts to protect vessel walls from developing atherosclerosis and thrombosis.
Evidence that physical exercise can improve endothelium-dependent vasodilation led to the current investigation. The study population included 12 young and elderly sedentary subjects (average age: 26.9 and 62.9 years, respectively) and 11 young and 14 elderly matched athletes (average age: 27.5 and 66.4 years, respectively). Athletes included long-distance runners, triathletes and cyclists; sedentary subjects performed no regular exercise.
Apart from age, the four study groups were similar in terms of blood pressure, body mass index, and plasma total cholesterol and glucose levels. However, young and elderly athletes had decreased resting heart rate, increased high-density lipoprotein (HDL) and decreased low-density lipoprotein (LDL) levels compared with sedentary subjects. Results also showed that blood vessel function was also quite similar in elderly athletes compared with younger sedentary subjects, suggesting the value of physical activity in protecting the inner lining of the blood vessels. The authors speculated that the mechanism behind these results is most likely "the restoration of nitric oxide availability consequent to prevention of production of oxidative stress."
Evidence that physical exercise can improve endothelium-dependent vasodilation led to the current investigation. The study population included 12 young and elderly sedentary subjects (average age: 26.9 and 62.9 years, respectively) and 11 young and 14 elderly matched athletes (average age: 27.5 and 66.4 years, respectively). Athletes included long-distance runners, triathletes and cyclists; sedentary subjects performed no regular exercise.
Apart from age, the four study groups were similar in terms of blood pressure, body mass index, and plasma total cholesterol and glucose levels. However, young and elderly athletes had decreased resting heart rate, increased high-density lipoprotein (HDL) and decreased low-density lipoprotein (LDL) levels compared with sedentary subjects. Results also showed that blood vessel function was also quite similar in elderly athletes compared with younger sedentary subjects, suggesting the value of physical activity in protecting the inner lining of the blood vessels. The authors speculated that the mechanism behind these results is most likely "the restoration of nitric oxide availability consequent to prevention of production of oxidative stress."
Daily Walking Reduces Risk of Hypertension
Previous studies have shown an inverse relationship between physical activity and hypertension, especially with respect to consistent vigorous exercise. However, little research has thoroughly investigated the direct impact of walking on blood pressure, despite the fact that brisk walking is part of the recommended treatment protocol for patients with hypertension (especially in Japan, where walking to work constitutes a primary form of exercise).
The subject group for this study included 6,017 Japanese men (35-60 years of age) with blood pressure less than 140/90 and no history of hypertension or diabetes at baseline.
The subject group for this study included 6,017 Japanese men (35-60 years of age) with blood pressure less than 140/90 and no history of hypertension or diabetes at baseline.
Questionnaires were used to gather data on physical activity (work-related and leisure-time), the length of the walk to work, and other variables such as alcohol intake and smoking habits. Blood pressure was measured using a standard mercury sphygmomanometer, with pressure of at least 160/95 designating hypertension.
Results: Men whose walk to work lasted 21 minutes or more had a decreased risk of incident hypertension compared with those whose walk lasted 10 minutes or less. This association was maintained after adjusting for age, body mass, alcohol consumption, smoking status, blood pressure, fasting plasma glucose level, and other physical activity variables (i.e., frequency of leisure-time physical activity). The authors recommend walking to work as a means to reduce blood pressure, concluding that "even persons who drive to work or use public transportation may benefit from parking or leaving their transportation more than a 20-minute walk from the office."
Hayashi T, Tsumura K, Suematsu C, et al. Walking to work and the risk for hypertension in men: the Osaka Health Survey. Annals of Internal Medicine 1999:130, pp21-26.
Coronary Heart Disease and Physical Activity in Women
Heart disease is the leading cause of death among women in the United States. A decrease in physical activity is one of the risk factors for this disease. Women who are physically active have been shown to have lower coronary heart disease (CHD) rates than inactive women.
However, it is uncertain as to whether the association differs by intensity of activity or in women at high risk for CHD. This study examines the relationship between CHD and physical activity in women, specifically related to light-to-moderate walking activity and varying pace. A group of 39,372 healthy female health professionals aged 45 years or older enrolled throughout the United States for a three-year period, with a four-year follow-up period. Recreational activities, such as walking and stair climbing, were reported at study entry. Correlation of CHD with energy expended on all activities, vigorous activities, and walking, was measured.
The study participants were observed for an average of 5 years and within that time 244 confirmed incidents of CHD occurred. The findings of this study showed that:
* Active women had a lower body mass index than inactive women.
* Active women showed healthier behavior patterns (e.g., lass likely to smoke, consumed a healthier diet).
* Women with higher levels of activity were less likely to have hypertension, diabetes mellitus and elevated cholesterol.
* Active women were less likely to develop CHD.
* Women who walked at least one hour per week at a 'usual' pace experienced half the CHD risk of women who did not walk regularly.
* Walking pace or intensity was not considered as important as the amount of walking per week (i.e. walk at least 1 hour per week at a light to moderate pace produced protective effects).
Conclusion: This study shows that light-to-moderate activity may be associated with lower CHD rates in women. At least one hour of walking per week predicted lower risk. These findings also held true even for those patients who were overweight, had increased cholesterol levels, or were smokers.
The study participants were observed for an average of 5 years and within that time 244 confirmed incidents of CHD occurred. The findings of this study showed that:
* Active women had a lower body mass index than inactive women.
* Active women showed healthier behavior patterns (e.g., lass likely to smoke, consumed a healthier diet).
* Women with higher levels of activity were less likely to have hypertension, diabetes mellitus and elevated cholesterol.
* Active women were less likely to develop CHD.
* Women who walked at least one hour per week at a 'usual' pace experienced half the CHD risk of women who did not walk regularly.
* Walking pace or intensity was not considered as important as the amount of walking per week (i.e. walk at least 1 hour per week at a light to moderate pace produced protective effects).
Conclusion: This study shows that light-to-moderate activity may be associated with lower CHD rates in women. At least one hour of walking per week predicted lower risk. These findings also held true even for those patients who were overweight, had increased cholesterol levels, or were smokers.
How Physical Activity Helps Prevent Cancer
Previous studies provide evidence that exercise can help prevent a variety of cancers; data suggests that the link between exercise and colon cancer may be particularly strong.
A study involving 63 men and women (42-78 years of age) with a history of colonic polyps (a potential precursor to colon cancer) investigated the potential influence of leisure-time physical activity and low body mass index (BMI) on levels of prostaglandin E2 in rectal mucosa.
A study involving 63 men and women (42-78 years of age) with a history of colonic polyps (a potential precursor to colon cancer) investigated the potential influence of leisure-time physical activity and low body mass index (BMI) on levels of prostaglandin E2 in rectal mucosa.
High prostaglandin levels have been shown to be associated with the development of colon cancer.
Self-administered questionnaires assessed leisure-time physical activity per week, and levels of prostaglandin E2 were measured by examining rectal biopsy tissue samples taken eight weeks apart.
Prostaglandin levels increased with higher weight, higher BMI, and lower levels of leisure-time physical activity. An increase in BMI from 24.2 to 28.8 kg/m2 resulted in a 27% increase in prostaglandin levels, whereas an increase in physical activity from 5.2 to 27.7 MET-hours per week (one MET-hour being roughly equivalent to an oxygen uptake of 3.5ml/kg of body weight per minute) decreased prostaglandin levels by 28%.
Conclusion: Increasing physical activity and reducing body mass index may decrease the risk of colon cancer. These findings add support to previous evidence suggesting the protective value of physical activity against cancer and other chronic diseases.
Self-administered questionnaires assessed leisure-time physical activity per week, and levels of prostaglandin E2 were measured by examining rectal biopsy tissue samples taken eight weeks apart.
Prostaglandin levels increased with higher weight, higher BMI, and lower levels of leisure-time physical activity. An increase in BMI from 24.2 to 28.8 kg/m2 resulted in a 27% increase in prostaglandin levels, whereas an increase in physical activity from 5.2 to 27.7 MET-hours per week (one MET-hour being roughly equivalent to an oxygen uptake of 3.5ml/kg of body weight per minute) decreased prostaglandin levels by 28%.
Conclusion: Increasing physical activity and reducing body mass index may decrease the risk of colon cancer. These findings add support to previous evidence suggesting the protective value of physical activity against cancer and other chronic diseases.
Frequent, Vigorous Exercise Reduces Accumulation of Visceral Fat
Visceral fat, or fat that surrounds the abdomen and other internal organs, is considered a significant contributor to a variety of weight-related health problems, including heart disease, type 2 diabetes, and metabolic syndrome.
Regular exercise is known to provide a wide range of health benefits, including weight loss and reduction of total body fat. Despite this evidence, few studies have examined the direct effects of exercise programs on changes in visceral fat levels.
In this randomized, controlled study, 175 sedentary adults ages 40 to 65, all considered overweight or mildly obese, and all with mild to moderate dyslipidemia, were assigned to participate in a control group for 6 months, or to one of three exercise groups (low amount/moderate intensity, equivalent to walking 12 miles per week; low amount/vigorous intensity, equivalent to jogging 12 miles per week; or high amount/vigorous intensity, equivalent to jogging 20 miles per week). Computed tomography scans were performed pre- and post-study to analyze changes in visceral fat, subcutaneous abdominal fat, and total abdominal fat.
Results: "In the control group, visceral fat levels increased by 8.6%, which was statistically significant. Visceral fat levels did not change significantly in either of the low-amount exercise groups. The high-amount exercise group experienced an average decrease in visceral fat of 6.9%, which was significant. Only the high-amount exercise had any change in subcutaneous abdominal fat amount, which decreased in this group by 7.0%."
"Taken together, the data suggest a clear dose-response relationship between exercise amount and changes in visceral fat," the authors concluded. The authors also emphasized that "even a relatively modest exercise program, consistent with the activity recommendations from the Centers for Disease Control and American College of Sports Medicine, prevented significant increased in visceral fat," and recommended that "until we are able to prevent weight regain after short-term dieting success, a greater emphasis toward prevention should be a major goal in the U.S."
In this randomized, controlled study, 175 sedentary adults ages 40 to 65, all considered overweight or mildly obese, and all with mild to moderate dyslipidemia, were assigned to participate in a control group for 6 months, or to one of three exercise groups (low amount/moderate intensity, equivalent to walking 12 miles per week; low amount/vigorous intensity, equivalent to jogging 12 miles per week; or high amount/vigorous intensity, equivalent to jogging 20 miles per week). Computed tomography scans were performed pre- and post-study to analyze changes in visceral fat, subcutaneous abdominal fat, and total abdominal fat.
Results: "In the control group, visceral fat levels increased by 8.6%, which was statistically significant. Visceral fat levels did not change significantly in either of the low-amount exercise groups. The high-amount exercise group experienced an average decrease in visceral fat of 6.9%, which was significant. Only the high-amount exercise had any change in subcutaneous abdominal fat amount, which decreased in this group by 7.0%."
"Taken together, the data suggest a clear dose-response relationship between exercise amount and changes in visceral fat," the authors concluded. The authors also emphasized that "even a relatively modest exercise program, consistent with the activity recommendations from the Centers for Disease Control and American College of Sports Medicine, prevented significant increased in visceral fat," and recommended that "until we are able to prevent weight regain after short-term dieting success, a greater emphasis toward prevention should be a major goal in the U.S."
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