Studies on Women and Exercise
For sometime now, most of the research on the health benefits of exercise included primarily male subjects. Luckily, times have changed, and during the past two decades, a good deal of research has found that women stand to gain just as much as men from an active lifestyle. Here are some of the most noteworthy findings.
Cardiovascular disease and associated risk factors
Exercise helps to prevent diseases of the cardiovascular system, which are the leading cause of death for both men and women. A strong body of research has suggested for years that exercise prevents, or at least significantly postpones, cardiovascular disease in men, and the few studies that have included women suggest this association holds for women as well. This makes biological sense since exercise helps to prevent or control a number of important factors that increase risk for cardiovascular disease in both men and women, including hypertension, non-insulin dependent diabetes mellitus, high-risk lipid profile (low HDL and high LDL cholesterol levels) and excess body fat.
Bone density and osteoporosis
Numerous studies substantiate the importance of physical activity for the development of maximal bone density in young adulthood and the delay of bone mineral loss during middle and old age. While even weight-supported activity such as cycling may confer some benefit in terms of osteoporosis prevention, bone density appears to adapt in a dose-response fashion to the mechanical stress exerted upon it, suggesting that activities that place more stress on the musculoskeletal system may lead to greater increases in bone density. It is for this reason that strength training may be especially beneficial. Strength training also increases muscle mass and improves strength and balance, all of which may prevent falls that lead to fracture.
Many researchers believe physical activity protects against breast, ovarian and endometrial cancer by decreasing a woman's lifetime exposure to estrogen. Lower levels of body fat may be the protective factor, since estrogen precursors are converted into active estrogens in adipose tissue. Physical activity seems to exert a particularly protective effect against breast cancer when performed during the decade following the beginning of menstruation.
Several studies have found that physical activity is associated with reduced risk of colon cancer for both men and women. Physical activity may exert its protective effect by decreasing transit time of digested food. Some investigators have also hypothesized that exercise helps prevent colon cancer by reducing estrogen levels through lower body fat levels and/or menstrual irregularity. Reducing estrogen decreases bile production; bile is suspected to act as a carcinogen in the colon.
Researchers have also hypothesized that physical activity may decrease cancer risk by increasing natural immunity, or indirectly by altering other lifestyle factors such as dietary fat intake.
Weight control is a complex issue for many women and goes far beyond concern for good health. The way a woman (and others important to her) perceives her physical self has a strong impact on her self-image and self-esteem. Since current fashion emphasizes an unrealistically lean appearance, many girls and women experience a great deal of frustration and dissatisfaction as they try unsuccessfully to achieve this extreme ideal.
In the past, women have been encouraged by both the popular press and the medical profession to follow very-low-calorie diets to lose body fat. These diets are harmful to our health, lead to food cravings and binges, encourage an unhealthy relationship with food and usually don't work. In extreme cases, such practices lead to eating disorders and other pathogenic weight-control measures.
Women cannot ignore the issue of weight control. For example, at least a third of North American women are overweight, and the definition of overweight has broadened to include more women than ever. Recently, the Nurses' Health study found an association between weight gain "within the normal weight range" allowed by standard weight-for-height charts and increased risk of heart disease. A gain in weight as few as 11 pounds since age 18 was associated with increased risk.
The answer? Women must cultivate habits that promote lifelong weight control, habits that are congruent with a balanced, joyful lifestyle, habits that reinforce purposeful self-care rather than self-punishment. Lifelong physical activity is essential for weight control. Daily aerobic exercise such as walking, dancing, swimming and cycling, which expends energy and confers the numerous health benefits discussed above, should be combined with strength training when feasible. Strength training increases muscle mass and raises metabolic rate, so women can eat more without gaining weight.
Functional independence in old age
Women make up a majority of the older population. Many older women live alone and are concerned about losing functional independence with advancing age. Women are often forced into institutional living because they no longer have the strength to perform daily tasks such as carrying groceries, going up stairs or even using the toilet. Recent studies suggest that high-intensity strength training can lead to significant increases in muscle mass and strength, even in the very old, and improve the quality of life. Lifelong strength training could conceivably delay loss of functional independence due to inadequate strength.
Perhaps most important of all exercise benefits are the psychological benefits that contribute to the quality of daily life. Regular physical activity has been shown to be as effective as psychotherapy in the treatment of depression, which occurs at a higher frequency in women than men. Aerobic exercise has been shown to improve the negative mood associated with premenstrual symptoms and menopause. The exact mechanisms by which exercise improves psychological function remain unclear, but several hypotheses have been put forth. Physical activity may improve mood and relieve depression by altering the concentration or function of central nervous system chemicals, including endorphins or neuro- transmitters, such as serotonin. A feeling of deep physical relaxation commonly follows vigorous activity, and physical relaxation is usually accompanied by mental relaxation as well. Physical activity may also provide a recreational diversion from bothersome problems and improve mood and outlook.
Physical educators have observed that involvement in physical activity and sport helps girls and women appreciate their bodies not just for how they look but for their strength, endurance, agility and ability to perform. Strength training has also proved to be especially beneficial for improving body image and psychological outlook in both young and middle-aged women.
Armando Mendoza Jr., PTRP
Weight Management Consultant
Fitness First Philippines