The Surgeon General has determined that lack of physical activity is detrimental to your health. Surgeon General recommends moderate activity: 150 calories per day or 1000 calories per week. American College of Sports Medicine suggest all adults should engage in 30 minutes or more of moderately intense physical activity daily. This level of activity corresponds to 200 kcals a day (Pate RR, Pratt M, Blair SN, et al 1995). See Calorie Expenditure Calculator.
Other authorities suggest the least amount of activity for optimal physical health is about 1500-2000 kcals a week of light and moderate intense activities. Additional physical health benefits come with increased intensity and eventually level off at around 3500 kcals per week (Peterson & Bryant 1995).
The ACSM recommends to target a weekly exercise expenditure of approximately 1000 kcals a week (e.g. 3 sessions of 300 Calories or 4 sessions of 200 Calories) (ACSM 1995). See Calorie Expenditure Calculator.
Review of the scientific literature suggests moderate intense aerobic activity needs to be performed most days of the week to bring about significant fat loss. Some sources recommend brisk walking progressing to 45 minutes or more daily. Other authorities recommend working up to 60-90 minutes of daily physical activity for weight loss.
A variety of exercises may be recommended to minimize repetitive orthopedic stresses of exercising daily. See Overtraining. The combination of aerobic and anaerobic exercise can utilize more fat than either type of exercise alone. See Fat Loss.
Cardiovascular fitness can be expresses as maximum oxygen uptake (VO2 max). This is the amount of oxygen the body can utilize per unit weight per unit time [ml / (kg x min)]. Since measuring oxygen consumption directly is not feasible, many methods of measuring VO2 max have been developed. These cardiovascular tests have been validated by measuring the direct correlation of VO2 max and estimates by the following (ACSM 1995).
Activities that involve large muscle groups over prolonged period of time offer the greatest improvement in VO2 max. These activities are rhythmic and aerobic in nature (e.g. walking, running, hiking, stair climbing, swimming cycling, rowing, dancing, skating, cross country skiing, rope jumping, etc.). An individuals skill and enjoyment toward an activity are factors that will influence compliance and ultimately the desired outcomes (ACSM 1995).
Cardiovascular fitness improvement is dependent upon frequency, duration, intensity of exercise. An increase of VO2 max may range from 5 to 30% depending on the interaction of these prescriptive components and an individuals fitness level. Those with low initial levels of fitness and those exhibiting large losses of body weight will exhibit the greatest relative increase in VO2 max. Similarly, only modest improvements may be expected from individuals with high initial levels of fitness or those who exhibit little change in body weight (ACSM 1995).
When a program has been established, intensity is the least forgiving component for cardiovascular fitness. Intensity, duration, and frequency are nearly inversely proportional. If one component increases, the others may be decreased, except intensity. An increase of duration or frequency can not make up for a moderate decrease of intensity without a decrease of cardiovascular fitness.
The inclusion or resistance training is important for a sound overall exercise program but will not significantly increase VO2 max. Weight training circuit weight training (e.g. 10 to 15 repetitions with 15 to 30 seconds between weight stations) improves VO2 max an average of about 5%. For this reason circuit training is not generally recommended as an activity to improve cardiovascular fitness. (ACSM 1995).
In general, the best exercise for a specific sport is the sport itself. Additional exercises should condition the particular components of fitness specific to the sport. The specific muscles involved, type of muscular contraction, intensity, duration, recovery time, and motor skill must be considered. Specific components of the sport may need to be trained separately. See Sports Conditioning Program. Periodization may be implemented for continued progress and specialization on particular components. For periodization examples, see Marathon Training , Cycling, Triathlon, and weight training periodization.
American College of Sports Medicine, (1995) Principles of Exercise Prescription, William & Wilkins, 5.
Peterson, P.A., Bryant, C.X. (1995) The StairMaster Fitness Handbook, 2, pp. 5-7.