Exercise: A program you can live with

• Introduction
• How Exercise Affects Your Body
  • Energy Metabolism
  • Heart and Blood Vessels
  • Lungs
  • Muscles
  • Bones
  • Hormones
  • Immune System
• What Exercise Can Do for You
  • Cardiovascular Disease
  • Diabetes
  • Cancer
  • Osteoporosis
  • Depression and Anxiety
  • Gallstones
  • Arthritis
  • Weight Management
  • Longevity
  • Quality of Life
• Exercise Basics
  • Exercise and Physical Activity: The Partnership
  • What Does Fitness Mean?
  • How Much Exercise Do I Need?
  • How Hard Am I Working?
• Building Your Exercise Program
  • Components of a Balanced Program
  • Designing the Right Program
• Getting Started
  • Core Aerobic Program: Walking
  • Strengthening Program: Weight Training
  • Flexibility Program: Stretching
• Keeping At It
  • Sticking With Exercise
  • Getting Back on Track
• Exercising Safely
  • Risks of Exercise
  • Questions You Should Ask Yourself
  • Tips for Safe Exercise
  • Exercise for People With Chronic Conditions
• What You Should Know About Exercise Equipment
  • Types of Exercise Equipment
  • Tips for Being a Smart Consumer
  • Exercise: A Worthwhile Investment
• Glossary
• Resources
  • Organizations
  • Books

How Much Exercise Do I Need?
So how active do you have to be to reap health benefits? This is where things can get tricky. It's true that for completely sedentary people, any activity makes an impact. But it's also true that, up to certain limits, the more exercise you get, the better.

This principle was borne out in a 1986 study in the New England Journal of Medicine that analyzed research conducted on 17,000 Harvard alumni. It appears that the greatest gains, in terms of longer life and lowered risk for disease, come when you expend approximately 2,000 calories per week in some form of dynamic exercise, such as walking, gardening, or sports. Sedentary men were 64% more likely to suffer a heart attack than their counterparts who exercised up to the 2,000-calorie level. This translated into an average two-year gain in life span for the most active group. Since walking or jogging burns roughly 100 calories per mile, the 2,000 calorie threshold can be reached by walking 20 miles per week or its equivalent, an hour of moderate exercise five or six days a week.

The challenge is to figure out exactly what these parameters mean for you. For people who are mostly sedentary, walking or jogging 20 miles is a tall order. In fact, it's neither a practical nor advisable target for people who haven't been off the couch in years. The good news is that the health benefits begin kicking in at a much lower level - around 700 calories per week. This translates to logging 7 miles a week, roughly a brisk half-hour walk four times a week. For many people, this is a much more reasonable goal. Once you've reached this goal, you should aim to hit the 1,000-calorie-a-week mark (about 10 miles a week), since several studies have linked specific health benefits, such as greater longevity, to this target. If you'd rather not count calories, this translates into 30 minutes of moderate activity, 5-6 times a week.