Who doesn’t want to be stronger – to be able to lift more weight AND have the functional strength to do the things you enjoy? You build strength by forcing your muscles to bear more force than they’re accustomed to. When your main goal is to build strength, using a heavy resistance (80 to 90% of your one-rep max) maximizes strength gains. Using a weight this heavy means you’ll only be able to do between 2 to 5 reps.
On the other hand, you might be trying to build muscle size. Yet, you would still like to increase strength as well. In that case, you might do rep work in the 6 to 10 rep range to maximize hypertrophy while still gaining strength. The number of reps you do and the resistance you use is dependent on your goal.
How Rest Periods Influence Strength and Hypertrophy Gains
While resistance and number of reps are two variables that impact strength gains, the length of time you rest between sets is another consideration. Typically, the rest period between sets is longer when you’re trying to build strength as opposed to muscle size. A longer rest period gives your muscles more time to recover. This allows you to lift heavier weight on the next set or do more volume.
Does resting longer really make a difference in terms of strength gains? A study published in the Journal of Strength and Conditioning Research, suggests that it does. In this study, researchers assigned two groups of men, all of whom resistance trained regularly, to one of two groups. Before the study, they underwent testing of muscle strength and endurance. In addition, researchers measured their muscle thickness using ultrasound.
Each group performed the same exercises. The only difference was the length of the rest period between sets. Group one rested only one minute while the second group rested for a full 3 minutes. Each group did 7 different exercises per workout and completed 3 sets of 8 to 12 reps until they reached failure. The participants followed this workout schedule for 8 weeks.
At the end of the study, researchers used ultrasound imaging to again measure muscle thickness and repeated the strength tests. The results? Strength and hypertrophy gains were greater in the group that rested for 3 minutes as opposed to only one. Both groups also showed gains in muscle endurance that were similar between the two groups.
Mind you, the difference was fairly small, about 1.2 to 3.5 millimeters of extra muscle thickness in the group that rested 3 minutes. However, there WAS a difference and the difference was apparent in all the muscles they tested – quadriceps, triceps, and biceps. Strength gains were significant as well. The group that rested 3 minutes increased their bench press one-rep max by 12.7% over the 1-minute rest group and their one-rep max on the squat improved by 15.2%. It may be modest but you don’t have to drastically change your workout to get greater benefits. Simply increase the rest period between sets.
What a Meta-Analysis Showed
Of course, this is only one study. What do other studies say about the issue? A meta-analysis of 35 studies published in Sports Medicine found that extending the rest period between sets to 3 to 5 minutes allowed a greater volume to be completed over multiple sets. This, in turn, led to larger increases in strength. It makes sense since you’re giving your muscles more time to recover between sets.
More recovery time means you can potentially do more reps on the next set. It takes at least 3 minutes for your phosphagen energy system, also known as the ATP-CP system, to fully recover. This is the energy system you use for intense activities where you have to generate lots of force quickly like lifting a heavy weight. It provides short-term energy from stored creatine phosphate. When this energy system completely recovers, you can maximize force generation.
What about hypertrophy? With a rest period of 3 minutes as opposed to 1 minute, your muscles have more time to recover so you can theoretically do more volume. However, the longer rest period, based on some studies, may reduce growth hormone release. Growth hormone is an anabolic hormone that boosts muscle protein synthesis – a good thing if you’re trying to build muscle size.
Plus, when you have a shorter rest period, you don’t flush all of the lactate out of your muscles. As a result, your body, over time, improves its ability to buffer lactate. The enhanced ability means your muscles can hold a contraction longer before fatiguing. Yet, at least in this study, the longer rest period led to greater gains in muscle thickness. So, there may be some benefit to extending the rest period even if you’re focusing on hypertrophy.
What about a rest period right in the middle – 2 minutes? Unfortunately, the study didn’t look at that, although it would have been interesting. A 2-minute rest period could save time and, possibly, offer the same benefits. Moderate rest periods of around 2 minutes could be the “sweet spot” that allows you to lift heavy enough to maximize growth and strength gains yet still get the metabolic benefits of a shorter rest period between sets.
Rest Periods Depend Upon Your Goals
All in all, how long you rest between sets depends upon your goals and how heavy you’re lifting. If you’re lifting at a higher percentage of your one-rep max, 80% or greater, your rest period will, by necessity, be longer. It has to be so you can lift heavy on the next set. Your rest period might be as long as 3 or 4 minutes. If your main goal is to increase muscle size, a shorter rest period of 1 to 3 minutes would be appropriate. If you’re doing a circuit workout for general fitness, a rest period of 30 seconds suffices. The short rest period increases the calorie burn and your heart rate for aerobic benefits as well.
What can you take away from this study? Experiment with extending the rest period to 3 minutes, especially if you’re trying to build strength. You could also periodize the rest periods between sets so that one week you keep the rest period long and shorten it another week. That way you stress your muscles a little differently.
Journal of Strength & Conditioning Research: November 20, 2015 doi: 10.1519/JSC.0000000000001272.
J Sports Sci Med. 2013 Mar; 12(1): 138–143.Published online 2013 Mar 1.
Men’s Health. “You’re Probably Not Resting Enough Between Sets For Maximum Gains”
Sports Med. 2009;39(9):765-77. doi: 10.2165/11315230-000000000-00000.
IDEA Health and Fitness Association. “The Three Metabolic Energy Systems”
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