Physical activity and exercise: How much is enough?

by Jeff Godin

     In a conversation with a prospective client, I came to the realization that there is tremendous confusion regarding the recommended amount of exercise. She had asked an Ironman triathlete, a fitness enthusiast, and an average middle aged adult how much exercise one should do.
The triathlete told her that she needed to train vigorously 2-3 hours a day. The fitness enthusiast stated that she needed to be in her target heart rate zone for twenty to thirty minutes at least three times per week. The healthy adult told her to not worry about exercise, but just be active, move as much you can throughout the day.
     "Who is right?" she asked. The problem is that there isn't one over-arching answer to this question. Compounding this dilemma are the seemingly conflicting statements from professional organizations and institutions about the recommended quantity and quality of activity. This article will help to to clarify the existing guidelines for physical activity and health and how they might relate to you and your personal goals.
First, a few definitions are in order. Physical activity is any bodily movement that involves the activation of skeletal muscle and the expenditure of energy. Sometimes exercise and physical activity are used synonymously, but exercise is a subset of physical activity that is structured and planned. Exercise is used to improve one or more of the components of physical fitness.
Physical fitness is an attribute that we all possess to a greater or lesser extent. Health related physical fitness is made up of five dimensions: cardiorespiratory endurance, muscle strength, muscle endurance, flexibility, and body composition. Each of these dimensions is in some way connected to our health. There is also performance related fitness which includes those aforementioned dimensions - plus speed, power, agility, skill, and balance. These dimensions are related to our capacity to perform athletically. The focus here will be on the health related aspects of fitness.

     In 1995, the Journal of the American Medical Association published a joint report from the Centers for Disease Control and American College of Sports Medicine. The report surmised that people of all ages could gain significant health benefits by including moderate amounts of physical activity at least five days per week. Research clearly shows that the greatest health benefits are achieved when someone moves from a sedentary lifestyle to become moderately active. To achieve this benefit the activity can be accumulated throughout the day. Moderate activity includes a brisk walk, household chores, yard work and the like.
     However, the CDC and ACSM guidelines are not alone. The nation is in the midst of an obesity epidemic. The prevalence of obesity is alarmingly high and shows no signs of abatement, with expectations that it will soon surpass smoking as the leading preventable cause of death in the United States. This has lead to the development of an additional set of guidelines for physical activity. In 2002, the National Academies Institute For Medicine published a report that recommended 60 minutes of moderate intensity physical activity on most days of the week to prevent unhealthful weight gain. This has caused a lot of confusion. Is it thirty or is it 60 minutes?
     Both sets of physical activity guidelines are a significant diversion from guidelines that have existed for a number years. Basically, the older guidelines stated that we had to exercise for 20 minutes or more, three or more times per week within our target heart rate range in order to improve our cardiorespiratory endurance. The guidelines from 1995 and 2004 aren't meant to replace the existing guidelines; they complement them. Since most Americans can't seem to find the time or just simply don't care to exercise, the newer physical activity guidelines represent a minimum everyone should achieve to promote good health.

     Let's put these guidelines in perspective. First, since 60% of the American population doesn't achieve the minimum 30 minutes of day of moderate activity five or more days per week, it seems logical to start here. For people who are trying to reach a healthy weight, greater amounts of physical activity may be necessary. These individuals should build up to 60 minutes of daily activity. Even greater health benefits can be realized if a person chooses to engage in more vigorous types of activity or perform them for a longer period of time. This will improve health and increase physical fitness. People who are physically fit have some protection against chronic disease and a capacity to withstand the rigors of daily life without undue fatigue.
     So how much exercise/physical activity do we need to do? The recommendations made by the individuals were all correct. It depends on the person and their goals. Most people just need to become more active. Once a person incorporates moderate amounts of physical activity into his/her life, then he/she can move to the next level. Exercising to improve one’s physical fitness provides noticeable benefits. Many people find they enjoy exercise and the benefits that come with their new found fitness. Some choose to engage in athletics like a triathlon. At this point, they are no longer exercising for good health alone; they are trying to improve their physical performance.
One final thought: physical activity is for everyone. There is some level of activity that is appropriate for every individual. Physical activity does not need to be strenuous to be enjoyable or to provide some type of health benefit. Choose activities that you enjoy and can continue throughout your lifespan. Buildup gradually, periodically challenge yourself, you may be surprised at what you are capable of achieving thorough physical activity, exercise, and fitness.
Tammy and Jeff Godin are proprietors of Blackstone Valley Human Performance. We help people reach their physical activity and fitness goals, whether it is for good health or physical performance.