Starting Strength, 3rd Edition - Mark Rippetoe [196]
Figure 8-4. The metabolic speedometer. How hard and how long we exercise directly affects which metabolic pathways our bodies primarily use to fuel the activity. All physical activity lies along a continuum, from rest to all-out maximal effort. All activities are powered by the ATP already present in the muscle, and all bioenergetic activity acts to replenish these stores. Low-intensity exercise depends on cardiopulmonary delivery and muscular uptake of oxygen, the ready availability of which enables the body to use aerobic pathways and fatty acids as substrate. These aerobic processes take place inside the mitochondria within the muscle cells. As activity levels and energy requirements increase, the ability of oxidative metabolism to meet the increased demand for ATP is exceeded. Weight training and other forms of high-intensity training exist at the anaerobic end of the continuum, using substrate that does not require added O2. The diagram above represents the relationships between the energy substrates and the metabolic pathways in which they are used in different types of exercise. With the exception of short-duration all-out maximal efforts, no activity uses only one metabolic pathway, so the illustration above represents a sliding scale of continually increasing intensity of activity.
It is essential to understand that the 1RM work does not produce the conditioning stress that the 20RM work does, and that the long set of 20 reps is not heavy in the same way that the 1RM is. They are both hard, but for different reasons. Because they are so completely different, they cause the body to adapt in two completely different ways. These extremes represent a continuum, with a heavy set of 3 more closely resembling 1RM in its adaptation, and a set of 10 sharing more of the characteristics of a 20RM. Sets of five reps are a very effective compromise for the novice, and even for the advanced lifter more interested in strength than in muscular endurance. They allow enough weight to be used that force production must increase, but they are not so heavy that the cardiovascular component is completely absent from the exercise. Sets of five may be the most useful rep range you will use over your entire training career, and as long as you lift weights, sets of five will be important.
Progression
The effective training of novices takes advantage of the fact that untrained people get strong very quickly at first, and this effect tapers off over time until advanced trainees, who are already strong, gain more strength only by carefully manipulating all training variables. Novices can and should increase the weight of the work sets every workout until this is no longer possible. In fact, novices get strong as fast as the workout makes them, and what was hard last time is not hard today. They can adapt so quickly that the concept of “maximum intensity” is hard to define. If a kid gets strong as fast as his work sets increase, a 10-pound jump is not really heavier relative to his improved strength. The key to maintaining this rate of improvement is the careful selection of the amount of weight that you increase each time.
Work-set weight increases will vary with the exercise, your age and sex, your experience, and the consistency of your adherence to the program. For most male trainees with good technique, the squat can be increased 10 pounds per workout, assuming three workouts per week for two to three weeks. When you miss the last rep or two of your last work set, the easy gains are beginning to wane, and