A rest period or interest rest is the amount of time spent recovering between sets and exercises. A rest period can be active rest (such as jogging in place, doing pushups, or jumping jacks) or a passive rest where you just stand, sit down or lightly walk around. The length of rest between sets depends on your training goal, the amount of weight (if any) that you’re moving, and your fitness level. In general, people with less training experience will require longer rest periods compared to more advanced trainees. As a trainer, one of the most frequent questions I receive from clients is, “How much time do I rest between sets?”
The answer requires me to explain that it depends on the goal. I’ve had different clients training for absolute strength, aesthetics, weight loss, and improving muscular endurance. Those clients’ workouts (or at least part of them) required different rest intervals. Take a look at the between-set rest intervals suggested by the National Strength & Conditioning Association Essentials of Strength Training & Conditioning.
Strength: 2-5 min
Power: 2-5 min
Hypertrophy (muscle building): 30 seconds to 1.5 min
Muscular endurance: 30 seconds or less
These rest periods are based on how the body produces the energy to perform work during training. Specifically, the body will use three different energy systems at all times but the amount of each energy system’s contribution depends on the intensity and the duration of the event.
ENERGY SYSTEMS ALLOW US TO WORKOUT
For strength activities such as a one-rep-max deadlift or bench press, the phosphagen system contributes most of the energy. The phosphagen system provides ATP (adenosine triphosphate, used to power muscular activity) for short-duration activities lasting up to 30 seconds. A phosphagen is an energy-storing compound like creatine phosphate or ATP. Phosphagens get depleted during high intensity exercise like weightlifting and sprinting. Complete ATP re-synthesis occurs with 3-5 minutes, hence why it’s suggested to that strength/power athletes rest this much between sets. Building more muscle may result in more phosphagens, thus allowing for more intensity or a longer duration of previous intensity in more lean individuals.
Work past 30 seconds and up to 2 minutes and you’re using the glycolysis energy system which is the breakdown of stored glucose (glycogen) or glucose in the blood to resynthesize ATP. There’s about 300-400 grams of glycogen in the body’s total muscle and 70-100 grams in the liver but these numbers can be increased with strength training, aerobic training and a good diet. If you’re exercising very hard, say at 100% of your maximal oxygen uptake (VO2max), you can burn through the entire glycogen stores of some muscles. Eating plenty of carbohydrates every two hours after a hard workout ensures you’ll refill your glycogen stores. A full refill can happen within 24 hours.
Bodybuilders typically train in a rep range and intensity that enlists the phoshagen and glycolysis systems. At 8-12 reps of 60-85% 1RM, bodybuilders look to deplete their glycogen, stimulate growth, and re-feed their muscles immediately. This is also why people take BCAAs during the workout, in case all glycogen has been depleted from several sessions of hard training and the body starts to use amino acids for energy. Adding more amino acids to the protein pool by supplementation can spare some of body’s natural amino acids from being broken down. In the case of a ketogenic trainee, their abundance of fat stores would be depleted prior to using protein.
Glycolysis and Oxidative Systems
At 2-3 minutes of work, you’ll still use the glycolysis system but start to ask more of the oxidative or aerobic system. The aerobic system uses carbohydrates, fats and as a last resort, protein for energy. Muscular endurance training can involve sets that last 2-3 minutes, for example, a set of 30 bodyweight squats or lunges may take 2 minutes to complete. Three sets of an exercise done for 20-30 reps will tap both the glycolysis and oxidative systems. It’s during muscular endurance training with weights or just bodyweight that you’ll rest 30 seconds or less between sets.
Activities over 3 minutes, like going for a 1-mile run, primarily use the oxidative system. While training in this low-intensity form, you’ll need to make sure electrolyte, hydration and food intake are on point because it’s literally a race against time before you get completely fatigued. Rest periods during long, steady state cardio workouts at low intensity are typically taken as needed.
Interval training involves exercise intensity close to VO2max. It’s typically used for aerobic endurance training so activities like running, biking, stair climbing, and swimming. Use work periods of 3-5 minutes and after that work period, you rest. The work to rest ratio during interval training should be 1:1, meaning you’ll rest just as much as you work. Interval training should result in increased VO2max and improved power production.
HIGH INTENSITY INTERVAL TRAINING
High intensity interval training (HIIT) uses repeated hard bouts of work interspersed with short rest periods. Again, you will be exercising near your maximum heart rate or VO2x max. You may even exceed these limits for a few seconds. HIIT training can be short (under 45 seconds of work) or long (2-4 minutes). I like to use shorter work durations with a 1:1 or 1:2 work to rest ratio for starters. I typically add 30-60 seconds on top of the inter-set rest interval for the between-round rest period. A sample HIIT workout I would give a beginner to intermediate client is:
Complete 3 Rounds of:
- Work: 40 seconds
- Rest: 40 seconds between exercises, 1 minute 40 seconds between rounds.
- Dumbbell Squat and Press
- Medicine Ball Russian Twist
- Dead Hang
- Wall Sit
- Bear Crawl
- Treadmill Run
In this example, the phosphagen system won’t be able to handle the load, the glycolytic and aerobic energy systems will come into play too. Although the phoshagen system will start to be used at the top of each round since 1 minute and 40 seconds is enough time for the body to replenish some phosphagens, eventually the body will need to break down glucose for energy.
SPECIFIC SCENARIOS RESEARCH
Recent research has been done on the effect of rest interval length on strength and muscle recovery. In these very specific situations, it’s generally suggested that more rest is better.
A 2017 PLOS ONE study examined muscle fatigue after three different CrossFit workouts: “Cindy” (as many rounds as possible of 5 pushups, 10 pullups, and 15 air squats in 20 minutes), a HIIT jump rope “double under” workout which called for 8 rounds of 20 seconds work and 10 seconds rest, and a weightlifting workout consisting of as many reps of possible of a barbell power clean (40% 1RM) in five minutes. The only workout with rest intervals was the jump rope workout. Before, during and 3 minutes after each workout the study subjects were tested on their jumping height. The result was that the double under group was able to regain their jump ability 3 minutes post-workout, unlike the other no rest groups. The recovered jump ability observed 3 minutes after the entire workout was likely explained by recovered creatine phosphate levels. The short duration of the workout and short rest periods were enough to allow the body to recreate more energy.
According to a 2011 Kinesiology study, resting 3 minutes results in more volume (sets x reps) performed compared to 2 minutes during two different leg workouts that you and I have probably done before. On one day, study subjects did 3 sets of 4 common leg exercises at 80% 1RM until voluntary exhaustion: leg press, leg extension, leg curl and barbell squat using a 1-minute rest interval between sets. Two or three days later, the lifters did the same workout but using a 3-minute rest period and were able to do more sets and reps.
Resting 2 minutes is more beneficial for maintaining power output across sets compared 1 minute rest, says a Journal of Sports Science & Medicine study. The study participants did 6 sets of 6 reps of the Smith Machine squat at 60% 1RM resting either 1, 2, or 3 minutes between sets. Although power output decreased as the lifters went on through the workout, there was a lower decrease of average power when lifters rested 2 minutes (2.6% decrease) compared with (10.5% decrease) using a 1-minute rest period.
There are numerous other studies on rest intervals during weight lifting and the general trend is that more rest equals better results. To time your rest periods, use a wrist watch that you can set a vibrating timer on, your cell phone or locate the nearest clock. A good interval training app is Intervals on iOS but any app that allows for you create custom work and rest periods will suffice. Rest periods do matter and they can make the difference when trying to improve performance or prevent injury.