The Institute of Medicine of the National Academies, at the request of various U.S. agencies and Health Canada, released a report in 2002 which recommended doubling the amount of physical activity previously advised – from a minimum of 30 minutes per day to 60 minutes per day – balancing energy intake and expenditure, and minimizing intake of saturated fats, cholesterol and trans fatty acids.
The American College of Sports Medicine and the American Heart Association just updated their recommendations. They recommend 30 minutes of exercise 5 times a week. Vigorous intensity workouts only need three 20-minute workouts a week.
They use a system called Metabolic Equivalents minutes (METs) to calculate energy expenditure. The new guidelines suggest accumulating 450 to 750 METs per week.
Just one ride on my bike generates 750 METs. Another reason to keep riding.