The answer wholly depends on your time constraints and specific goals. In fitness there exists a principle of Specific Adaptation to Imposed Demands (SAID). In other words, this principle asserts that the human body will adapt to the physical stress, whether biomechanical or neurological, that is placed upon it. Fortunately, a qualified Personal Trainer can assist you in determining what exercises to employ and how much is required to meet your fitness goals whether they be to improve muscular balance and coordination, increase cardiovascular function, enhance strength, or other needs. However, from a general conditioning standpoint the AmericanCollege of Sports Medicine in conjunction with the American Heart Association provide the following exercise recommendations for healthy adults under the age of 65:
moderately intense cardio 30 minutes a day, five days a week
vigorously intense cardio 20 minutes a day, 3 days a week
eight to 10 strength-training exercises, eight to 12 repetitions of each exercise twice a week.
For those that want to just “feel good” and work toward a healthy body weight, these recommendations will work well. Visit the ACSM site for
Physical Activity and Public Health Guidelines for more info.