How long you rest between sets is one of the training variables you can manipulate to get different results from a resistance training program. When your main goal is to get stronger, rest periods between 2 and 5 minutes give your muscles enough recovery time to maximize the amount you lift on the next set.
In contrast, when your focus is on building muscle endurance and burning calories and you are using lighter weights, you need little or no rest period between sets. Hypertrophy training falls somewhere between with rest periods of one to two minutes being optimal.
You might think rest literally means rest – doing nothing between sets. For many people, that’s exactly what they do. They relax between sets and mentally prepare for the set to follow – but there’s another alternative – active rest. An active rest is doing something other than sitting or standing around passively between sets. Some people use the time between sets to stretch, which is a form of active recovery since you’re still moving, but you can also do something a bit more demanding, like light cardio.
Active versus Passive Recovery
Are there advantages to doing a little cardio between weight training sets? According to some research, there is. In one study, participants who did light cycling on a stationary bike between sets of parallel squats were able to do an additional 5 reps on the following set on average. The same was true for upper body training. Participants who did 2 minutes of light cardio, around 45% of their V02 max, between sets were able to generate greater force afterward as compared to when they rested passively.
You might think you should conserve energy between sets to perform your best on the subsequent set. So how the heck could an active rest be better? After a set, assuming you’re using a challenging resistance, lactic acid builds up in your muscles and the pH drops as your muscles fatigue. The rest period between sets is when your muscles partially recover by clearing away some of the lactic acid and partially restoring physiological pH. As a result, your muscles recuperate enough to do another set. The reason an active recovery may be better is that light cardio increases blood and oxygen delivery to the muscles you’re just worked, thereby aiding in lactic acid clearance.
Why is lactic acid such a problem? When lactic acid builds up and pH drops, it reduces the activity of key enzymes involved in energy use – like the enzyme glycogen phosphorylase that breaks down glycogen to glucose. It also impacts enzymes that enhance your body’s ability to use fatty acids as fuel. As a result, your muscles have a harder time producing ATP to fuel muscle contraction when there’s too much lactic acid around. A low pH also interferes with a muscle’s ability to take up calcium, which is what signals the muscle to contract. So, you would expect better muscle performance if you remove lactic acid and raise the pH. An active recovery helps you do this by delivering more oxygen to muscle tissue.
Other Benefits of Active Rest between Sets
Staying active between sets also keeps your muscles warm, and muscles perform better when they’re warm. Think about how stiff your muscles feel when they’re cold and you haven’t warmed them up properly. Warm muscles simply function better.
Another advantage of staying active between sets – you’re burning a few more calories per workout. If your objective is to maximize the calorie burn, an active rest helps. Plus, it keeps your heart rate up, which enhances the cardiovascular benefits of your workout. What you DON’T want to do is exercise hard enough to build up MORE lactic acid, so keep the intensity light.
What Type of Active Recovery?
If you want to try an active recovery between resistance training sets, what are your options? Jogging in place, lightly jumping rope, jumping jacks, or cycling are all options. The key is to keep the exercise relatively light – light to moderate.
Active Recovery after a Workout
Another time low-intensity activity works in your favorite is during the post-workout recovery period. After a tough workout, it’s tempting to drop the weight after the last set and plop down on an exercise mat but resist the urge. Just as light activity, helps recovery BETWEEN sets, it aids in recovery after exercise. Again, you’re using light activity to flush lactic acid out of your muscles and return the pH closer to normal. Five minutes of light exercise is enough to offer some benefit.
Another reason to do light activity after a workout – if you stop suddenly, blood pools in your calves and feet, a process called venous pooling. This leaves less oxygenated blood to be carried back to your heart. An active recovery where you’re contracting the muscles in your legs pushes blood back to your heart. One reason you feel lightheaded or dizzy when you stop exercising suddenly is due to venous pooling, and in some cases, dehydration.
The Bottom Line
If you’re taking it easy between resistance training sets, you might want to rethink this practice. Light cardio may actually help your performance by clearing lactic acid out of your fatigued muscles more quickly. You’ll also burn a few more calories and get more cardiovascular benefits. Also, try doing light cardio at the completion of a resistance training workout as a form of active recovery. So, keep moving!
BreakingMuscle.com. “Use Active Rest to Build More Muscle”
Journal of Strength & Conditioning Research: January 2012 – Volume 26 – Issue 1 – pp 73-79. doi: 10.1519/JSC.0b013e31821bf1f5.
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ABC Bodybuilding. “Active Recovery–A Three Fold Break Down”
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