When performing strength training exercises there are two questions that are often asked. How many sets am I doing and what weight should I use? What is often over looked is the amount of rest between sets. Moving back and forth between exercise with no rest can cause you to get out of breath and may not be the desired adaptation of the strength program.
Strength training has become one of the most popular physical activities for increasing absolute strength, endurance, hypertrophy and muscular power. Rest periods between sets is an integral and often overlooked contributor to the success of any strength training program. Optimal rest periods between sets can vary from 30 seconds or less, up to 5 minutes. Research has indicated that the rest interval between sets is an important variable that affects both acute responses and chronic adaptations to resistance exercise programs.
There are two different primary energy systems that your body uses during strength training to produce ATP, which is the primary fuel your muscles use for exercise. ATP-PC System (Phosphagen System) is used only for very short durations of up to 10 seconds. This system is training for explosive, high intensity with low weight, short repetition activities such as power weightlifters, football players and movements like a golf swing or 100m sprint.
All muscles are not created equal. When you lift heavy weights, you recruit your type II, or fast-twitch, muscle fibers. These fibers have the greatest potential for growth, and kick in when a task utilizes more than 25 percent of your maximum strength. However, these fibers also fatigue the fastest. With heavier weights, you target your nervous system more than with lighter weights. Optimal rest period range between sets is going to be 3 to 5 minutes. This will allow full phosphagen recovery before you begin the next set. Full recovery allows you to produce the greatest muscular force possible for each set performed, and thus receive the greatest absolute strength gains from your training.
In terms of acute responses, a key finding was that when training with loads between 50% and 90% of one repetition maximum, 3-5 minutes rest between sets allowed for greater repetitions over multiple sets and produced greater increases in absolute strength due to higher intensities and volumes of training. Similarly, higher levels of muscular power were demonstrated over multiple sets with 3-5 minutes versus 1 minute of rest between sets.
The Anaerobic System (Lactic Acid System) predominates in supplying energy for exercises lasting less than 2 minutes such as a 400m sprint and bodybuilding to create muscle mass and size. The higher repetitions and the lighter the weights, the shorter your rest.
Type I muscle fibers, also known as slow-twitch, offer endurance. They come into play during aerobic activities in this system. These fibers do not require as much energy to contract as type II, so you want to limit how much time you spend between sets. With higher reps, you rev your metabolism. If you wait too long, you will undo this effect.
Bodybuilders, long-sprint runners/swimmers and soccer players are examples of training for muscular size and or to increase your ability to apply near maximal muscular force over a time period within this energy system.
Optimal rest period range between sets is going to be 30 to 60 seconds. Using this rest interval between sets creates lactate levels in the exercising muscles. This forces the body to improve its ability to buffer the accumulating lactate, thereby improving your ability to sustain moderate, near maximal or maximal contractions over a given time period. High volume, short rest period training has also been found to increase human growth hormone levels when compared to training with longer rest periods. In addition, muscular hypertrophy (growth in size) will be maximized using the 1:1 work-rest ratio in conjunction with high training volume and a weight load between 8 and 12 repetitions maximum.
Training with short rest intervals (e.g. 20 seconds to 1 minute) resulted in higher repetition velocities during repeated submaximal muscle actions and also greater total torque during a high-intensity cycle test.
Here is what is recommended:
1 to 3 reps: Rest for 3 to 5 minutes
4 to 7 reps: Rest for 2 to 5 minutes
8 to 12 reps: Rest for 1 to 2 minutes
13 reps or more: Rest for 1 minute
Remember, these numbers are just guidelines for resting a muscle group before you work it again. The right amount of rest for you will depend on your goals. The rest interval between sets is an important variable that should receive more attention in resistance exercise prescription. When prescribed appropriately with other important prescriptive variables (i.e. volume and intensity), the amount of rest between sets can influence the efficiency, safety and ultimate effectiveness of a strength training program. So don’t always equate a good workout with how out of breath you may become. Know the goal of the exercise routine is to be sure you get maximum results.