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Work to Rest Ratio

Dear Dr. Bell, How long should I rest between sets? Does it differ based on Rep Max:1-5RM, 8-12RM or 10-15RM? I just ordered the PFT classic option and looking forward to getting started. 

Welcome to the IFPA Team Jeff,

Rest Intervals (R.I.) are determined based on multiple goals: i.e.: athletes' goals, training level, competition schedule, sports need analyses, energy system utilization, S.A.I.D Principles, principle needs for hypertrophy, strength, speed, power, muscular or neuromuscular (CNS), adaptation goals, etc.

To answer your questions, I’m going to assume you are interested in bodybuilding. Powerlifters, Olympic Lifters, CrossFitters, and other athletes all have different goals. When you receive “The Book on Personal Training,” you can refer to the percent of 1RM & Reps allowed section.

In brief:

1RM = 100% of Maximum Strength (effort)

5RM = 87% of Maximum Strength (effort)

8 RM = 80% of Maximum Strength (effort)

12 RM = 67% of Maximum Strength (effort)

15 RM = 65% of Maximum Strength (effort)

In general. The closer you are to 100% effort, the longer your R.I. must be. For bodybuilders, your goal is to increase muscle hypertrophy (size). To do this, you need to work as deeply as possible into the Lactic Acid Energy System. The chronic build-up of acid in the muscle cells, causes the cells to continuously decrease pH. The cells will adapt by increasing the cytoplasm in the cell. This causes the majority of hypertrophy.

The heavy lifting strategies of Powerlifters and Olympic Lifters who typically maintain 1-5 RM sets cause greater hypertrophy to the contractile proteins: Actin & Myosin. This causes a much greater increase in strength, but less hypertrophy since the contractile proteins make up a relatively small volume of the cell.

You can review Chapter 9 for greater detail on the relationship between the percent of maximal effort – work intervals to rest intervals, particularly tables 9.2 & 9.3.

For the Rep Ranges you listed in your questions:

Rep Range     Rest Interval

1-5                   5-7 minutes

8-12                 3-5 minutes

10-15               2-3 minutes

Always keep in mind, that failure is defined as being unable to complete another Rep..WITH PROPER FORM! You are not just fatiguing a muscle or energy system, you are fatiguing the Central Nervous System (CNS). Continuing to work past a fatiguing CNS dramatically increases the risk of injury, even in very advanced lifters and athletes.

Staying safe and injury-free means you can continue to train with consistency for a life-time! You make the best gains with consistency. Train smart as well as hard!