Walking the Road to Fitness and Health.
Adam deJong, M.A., FACSM, is the assistant director of Preventive Cardiology and Rehabilitation at William Beaumont Hospital in Royal Oak, MI. He is also a faculty lecturer in the School of Health Sciences at Oakland University in Rochester, MI. He earned his Bachelor of Applied Arts and Master of Art degrees in Exercise Science from Central Michigan University. He currently serves on the American College of Sports Medicine's Committee on Certification and Registry Boards as chair for the Continuing Professional Education and International Certification subcommittees.
Physical inactivity continues to negatively affect the cardiovascular health of Americans, yet recent findings suggest that improvements in health and fitness could be just steps away. For years, the perception among sedentary individuals was that to become physically fit, the exercise had to involve tortuous machines and expensive equipment. Although it is well established that exercise is an important component to improving fitness and health, the idea of sore muscles and trips to a crowded gym discourages many individuals from starting an exercise program. The phrase "no pain, no gain" was born of this philosophy and could not have been farther from the truth. Research, however, has demonstrated that structured exercise programs are not always needed and that significant health and fitness benefits can be gained simply by walking.
THE BENEFITS OF WALKING
Participation in a regular endurance exercise program has been identified as a core component to maintain and improve cardiovascular health. Epidemiological research confirms that physical activity reduces age-related morbidity and all-cause mortality, yet to most sedentary individuals, walking is thought to be a daily activity rather than a means for exercise. It is the relative simplicity and daily use of walking, however, that makes it such an ideal exercise for a large percentage of individuals.
The current recommendation from the U.S. Centers for Disease Control and Prevention (CDC) and the American College of Sports Medicine (ACSM) (13) include a minimum of 30 minutes per day of moderate-intensity exercise. As most Americans do not achieve the recommended levels of physical activity, the institution of a walking program could have profound impact on public health, including a reduced risk of premature mortality and many other chronic diseases (12). In addition, as part of the CDC/ACSM recommendations, activities that accumulate 30 minutes in multiple bouts throughout the day provide similar benefits as one sustained bout, as long as each bout is 10 minutes or longer in duration (13). In fact, brisk walking is suggested in the CDC/ACSM recommendations as a favorable mode of exercise to meet these guidelines. The advantages of walking over other forms of exercise can be found in the Table.
WALKING BENEFITS FOR CLINICAL POPULATIONS
The benefits of walking are not only seen in the primary prevention of cardiovascular disease but also provide significant benefit to those individuals with established cardiovascular disease. Walking currently serves as the most common aerobic training modality in cardiac rehabilitation programs, and such programs have been shown to facilitate cardiovascular risk reduction in that patient population (19). In fact, the commonality of walking and the potential for underlying musculoskeletal limitations in this patient population make it an appropriate activity in early unsupervised rehabilitative programs (8). Walking also has been shown to favorably increase the ventilatory threshold in cardiac patients (5), as well as reduce oxygen uptake and heart rate during submaximal physical workloads (6). In addition, as in healthy individuals, walking has been shown to provide adequate aerobic training stimulus for the cardiac patient (15). Thus, a moderate-intensity walking program will typically play a large role in the rehabilitation of the cardiac patient because it can be sustained for an extended duration at an intensity adequate to achieve desired outcomes.
Walking also can have positive impact on obesity by providing significant caloric deficit when combined with therapeutic lifestyle modification. When compared with the current CDC/ACSM guidelines (13), recent guidelines demonstrate the need to exercise for considerably longer durations (60-90 minutes) to halt the onset of obesity, affect weight loss, or prevent weight regain (1,10,17). Because the gross caloric expenditure of walking is approximately 1.15 kcal/kg per mile, is relatively independent of speed, and increases linearly as a function of body weight, morbidly obese individuals can achieve substantial energy expenditure when walking covers considerable distances over time (8). In addition, it seems that multiple shorter bouts of walking may provide similar, or even greater, reductions in body weight as compared with a single bout of the same duration (11).
ADDING VARIETY TO THE WALKING PROGRAM
Although the popularity of walking cannot be ignored, improvements in fitness and the potential for monotony may require some modifications to the walking program. As with any well-designed exercise program, adding variety to the walking program may aid in activity retention while also providing a mechanism for additional fitness gains. The addition of light handheld weights and/or vigorous arm movements are beneficial adaptations to a walking program and have been associated with an enhanced oxygen consumption and concomitant increase in caloric expenditure (3,9). The addition of walking poles (Nordic walking) also has become increasingly popular. Nordic walking has been found to enhance oxygen consumption and increase caloric expenditure (4,14,16). In fact, Nordic walking elicits oxygen consumption values that rival jogging (18) and may allow for additional training benefits in those individuals (elderly, overweight/obese) who may be unable to maintain a jog.
IMPLICATIONS FOR THE EXERCISE PROFESSIONAL
For most individuals, walking on level ground approximates 2 to 3 METS. When walking on a treadmill, additional energy expenditure can be estimated using the "rule of 2 and 3 mph"(8). This rule is particularly helpful when additional energy expenditure is desired but faster walking speeds are not an option because of physical limitations or fitness levels. With this rule, energy expenditure in METS can be simply estimated by adding a grade to the walking speed. For example, when walking at 2 mph, each 3.5% increase in treadmill grade approximates a 1-MET increase to the gross energy expenditure (8). In addition, for individuals who are able to negotiate a faster walking pace (3 mph), each 2.5% increase in grade approximates a 1-MET increase to the gross energy expenditure (8). This information is particularly helpful to physicians and allied health professionals in determining safe training workloads without the need for consulting tables or nomograms (8).
Structured exercise programs are no longer the exclusive recommendation when incorporating activity into one's life. Randomized clinical trials have shown that increasing physical activity throughout the day can achieve similar health and fitness benefits as a structured exercise program (2,7). Whether you park farther away from the store and walk, take the stairs instead of the elevator, or even take the dog for a walk more often, the health improvements can be substantial. In many populations, including sedentary individuals, elderly, and the obese, walking should be a primary recommendation when designing an exercise program. So the next time you are working with a new client or patient, do them a favor and tell them to "take a hike." It may be the best advice you ever give them.
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