by Reed Humphrey, Ph.D., P.T.

Regular aerobic exercise, along with a sensible program of flexibility and resistance exercise, is valuable in reducing health risk, improving quality of life, prolonging functional independence and, possibly, increasing a person's life span. A variety of guidelines exist for individuals setting up exercise programs or modifying programs to maximize the physiological benefit. Among these guidelines, widespread agreement exists that the cardiovascular component of exercise should result in about 30 minutes of aerobic activity on most days of the week. To improve fitness, research suggests exercise on a minimum of three days per week; to manage weight, exercise on more days is necessary to increase the overall caloric effect, plus exercise duration should probably progress from 30 minutes to as much as one hour.

Most people can identify the quantity of aerobic exercise needed—at least in duration (minutes per session) and frequency (days per week). What is unclear to many people is the exercise intensity, or effort, needed to achieve the optimal health and fitness outcome.

Research seems to suggest a pattern that makes intuitively good sense: lower intensity effort results in important physical and mental health benefits, which can include weight loss if the individual exercises more. As the effort level gradually increases, the benefits of significantly improved fitness begin to materialize, i.e. independence and perhaps reduced mortality. So part of the intensity question is related to desired outcome(s).

All too often, health and wellness professionals will advise older adults that they need to exercise at a moderate to high level to maximize health benefits. But older exercisers can achieve critically important health benefits from lower intensity effort, such as walking at a comfortable, conversational pace. This fact is often overlooked by both health and wellness professionals and the public, which likely contributes to the high proportion of people who do not engage in any leisure time activity.

Data from recent years shows an alarming trend towards less activity, and the rates of diabetes and obesity have increased to levels certain to derail affordable healthcare unless these trends are reversed. As America ages, an emphasis on exercise even at the lowest effort level will be necessary to stem the economic and sociological burden of chronic illness that could largely be prevented by regular exercise.

Most individuals can achieve the benefits afforded by regular exercise by eventually setting the level of exercise close to their "conversational limit" during exercise, which is associated with more labored breathing. Breathing pattern is probably the simplest marker that divides lower and higher intensity exercise. Physiologically, the sharper increase in breathing that impairs the ability to converse during exercise is closely associated with fitness level.

Higher exercise levels challenge the body to deliver the energy necessary to sustain the effort, resulting in labored breathing. Effort at this level causes the body to adapt, which confers the benefits associated with higher intensity exercise. But exercise close to this level will also confer benefits greater than very easy exercise. In addition, as a person's fitness level improves, his/her conversational limit likewise will increase, permitting the exerciser to achieve higher levels of effort before being limited by labored breathing.

It's best to consider health benefits as a continuum. The key is to provide the highest, comfortable level of exercise that clients can tolerate for upwards of 30-60 minutes, depending on an individual's relative need for improved physical fitness (30 minutes) or weight loss (upwards of 60 minutes).

If exercise effort impedes an individual's willingness to continue a program, the health or wellness professional should slow down to ensure the person stays with the program. The client will still accrue significant health benefits at this lower intensity level. And there is plenty of time to increase effort level as the person's general health and fitness improves.

Reed Humphrey, Ph.D., P.T., is an associate professor in the Department of Physical & Occupational Therapy at Idaho State University. He is currently U.S. Delegate and Secretary-General, World Council for Cardiovascular and Pulmonary Rehabilitation, plus a fellow and past president (1995-96) of the American Association of Cardiovascular and Pulmonary Rehabilitation. Humphrey is also a fellow of the American College of Sports Medicine, and served as associate editor of ACSM's Guidelines for Graded Exercise Testing and Prescription, fifth edition, and the recently published ACSM's Resources for Clinical Exercise Physiology.

Relevant resources

American College of Sports Medicine. ACSM Position Stand on The Recommended Quantity and Quality of Exercise for Developing and Maintaining Cardiorespiratory and Muscular Fitness, and Flexibility in Adults. Medicine & Science in Sports & Exercise 1998;30:975-991

Howley, E.T. You Ask for It: Question Authority. The equation of 220-age. ACSM Health & Fitness Journal 2000;4:6

American College of Sports Medicine. ACSM's Guidelines for Graded Exercise Testing and Prescription, 6th ed. Baltimore MD: Lippincott, Williams & Wilkins, 2000

Disclaimer: This information is not intended to replace a one-on-one relationship with a qualified healthcare professional and is not intended as medical advice. It is intended as a sharing of knowledge and information from research. The ICAA encourages you to make your own health and business decisions based upon your research and in partnership with a qualified professional qualified professional.