In order to determine how much rest you should take between sets, you should first define your fitness goal. Do you want to develop strength, bigger muscles, or endurance? Each one of these goals requires separate strategies for achieving maximum results and therefore must be approached differently.

Three Types of Systems

Before you dive into a training program, you should first understand the three types of systems and how they function. Each of these body system types corresponds with the three goals mentioned above and has a direct impact on how you meet your specific fitness goals.

ATP-PC (Adenosine Triphosphate Phosphocreatine)/Phosphogen System – This system doesn’t use your body’s oxygen and it doesn’t produce lactic acid. The ATP-PC/Phosphogen system is utilized when you make short and powerful movements like what are used for rapid, intense lifts that last 10 seconds or less.

Anaerobic/Gylcolytic System – You tap into this system when you tackle activities which last 2 minutes or less. This is the main system used by bodybuilders for building muscle mass and it draws most of its energy from carbohydrates.

Aerobic System – As its name implies, this is the predominant system used when practicing aerobic exercises that last 5 minutes or longer. Your aerobic system consumes your body’s stores of carbs and fats through the utilization of oxygen.

Three Types of Training

Now, let’s take a look at the three types of training and how they effectively tap into the correct corresponding body system.

Strength Training – If your goal is to build strength then your rest period between sets should be from 3 to 5 minutes with 3 minutes being optimal. To build strength, you lift 1 to 6 reps of heavy weight. The fuel needed to make these rapid, heavy lifts comes from the ATP-PC system which supplies rapid bursts of energy by using phosphagens, but without utilizing oxygen.

Because the body has a relatively small reserve of phosphagens, it requires approximately 3 minutes to fully recover before it’s ready for the next lift. Resting longer than 5 minutes will cause you to cool down too much and increase your risk for injury.

Hypertrophy Training – Hypertrophy is the term given to enlarging muscle mass and the best rest period to use between sets for this goal is 1 and 2 minutes. For muscle building, you should lift between 6 and 12 reps of moderate weight. Such a weight training program taps into both the ATP-PC and glycolytic systems. The ATP-PC system provides rapid movements while the glycolytic system allows for faster recovery and, therefore, shorter rest periods.

Also, shorter rest periods trigger the release of anabolic hormones which the body uses to increase muscle mass. These muscle-building hormones (such as testosterone) are released in greater amounts when rest periods are shorter. Short rest periods also increase blood flow to muscles, which helps deliver greater amounts of oxygen, protein and other vital nutrients for maximized growth as well as greater lactate production that leads to muscle fatigue, a necessity for short-term muscle mass gains.

Endurance Training – Endurance training garners its energy from your aerobic system that draws off of your body’s supply of carbs and fat for its energy. The rest period between sets is dependent on the activity and should range between 45 seconds to 2 minutes. Weight training for endurance requires more reps (15-20) of light to moderate weight, which increases the resistance of the muscles to fatigue. Aerobic exercise accomplishes the same goal.

This type of long term exercise causes your body to better boost hormones, improve the vascular system and more efficiently rid itself of lactic acid. Bodybuilders are more fatigue resistant than powerlifters because they use higher reps and take shorter breaks, helping the body clear out lactic acid buildup.