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Duncan and his colleagues3 concluded that exercise does not have to be vigorous to reduce cardiovascular risk factors. In other words, people who choose to stroll rather than walk briskly can reduce their risk for cardiovascular disease. After studying the physical activity patterns of 17,000 Harvard alumni over a 20-year period, Paffenbarger and his colleagues4 concluded that walking as little as five city blocks per day can reduce the risk of cardiovascular disease, and walking 2 miles per day can reduce the risk of a heart attack by 28% or more. Therefore, while walking at a fast pace will improve aerobic fitness, walking at any speed (slow or fast) can reduce a person’s risk for heart disease. WALKING AND WEIGHT REDUCTION Walking is an excellent activity for burning calories. The steeper the incline and/or the faster the speed, the more calories are burned. For example, a 150-pound person walking at 3.5 miles per hour on flat ground will burn about 300 calories per hour. This same person will burn 400 calories per hour on a gentle 4% incline and 500 calories per hour on a steeper 10% incline. If this person speeds the pace up to 4 miles per hour on level ground, 350 calories will be burned in one hour.5 It should be noted that participants who do not wish to walk at faster speeds can burn a comparable number of calories by walking for longer periods of time. WALKING AND BONE DENSITY Osteoporosis is a major health problem in the United States, affecting an estimated 15 to 30 million people. An age-related disorder, osteoporosis reduces the density of bones. This disease can be life-threatening since many older people die as a result of complications suffered from broken bones. Adequate calcium in the diet and weight-bearing exercises seem to reduce the risk of osteoporosis. 25 Several studies have reported that regular walking at moderate to brisk speeds appears to increase bone density. Specifically, Fradin and his colleagues6 found that 70-year-old subjects who walked at least 30 minutes per day had higher bone mineral content than subjects who walked less than 30 minutes per day. Jones and his colleagues7 reported that sedentary women (aged 30 to 61 years old) who began a regular walking program and continued for one year increased their bone density. Since walking can be comfortably performed by people of any age, walking appears to be practical and effective in reducing a person’s risk for developing osteoporosis. WALKING AND STRESS REDUCTION There are many stressors in today’s society, including economic concerns, work-related pressures and the need to balance career goals with home responsibilities. People who are unable to cope with these types of stressors are often tense and anxious, and may even become physically or psychologically ill. Researchers have found that exercise is one way to help people reduce stress. For example, subjects who engaged in a regular aerobic conditioning program and who altered their diets experienced significant gains in self-concept, feelings of well-being and reduced depression.8 Cramer and his colleagues9 specifically examined the effect of brisk walking on mildly obese sedentary women and found that walking improved general psychological well-being. Walking therefore appears to be an effective tool for improving psychological well-being. WALKING AND INJURIES Walking is often associated with a low injury rate. Walking is considered to be a "low impact" activity because one foot remains in contact with the ground at all times. Walking at speeds of 3 miles per hour produces vertical impact forces that are around 1.25 times body weight, whereas running at 7 miles per hour increases vertical impact forces to more than 2.5 times body weight. During a 24-week study, not one of 59 participants who walked five days a week at speeds between 3 and 5 miles per hour sustained a walking-related injury that necessitated consulting with a physician. Carroll and his colleagues10 reported that 14% of the elderly subjects participating in a walking study suffered training- related orthopedic injuries, mostly to the lower leg and foot. The majority of injuries occurred in the group assigned to "fast walking." It is important to note that all forms of exercise have some degree of risk associated with the activity. Generally, the less mechanical stress on the musculoskeletal system, the less risk of becoming injured. Because of the low-impact nature of walking, the incidence of injury appears to be low when compared to other high-impact activities. REFERENCES 1. Rippe, J., Ross, J., et. al. OCardiovascular effects of walking.O (Abstract), Proceedings of the Second International Conference on Physical Activity, Aging and Sports, July, 1985, p. 47. 2. Pollock, M., Miller, H. Jr., et. al. OEffects of walking on body composition and cardiovascular function of middle-aged men.O Journal of Applied Physiology, 1971, 30:126.130. 3. Duncan, J., Gordon, N., et. al. OWomen walking for health and...