As a coach and trainer, I spend a lot of time watching people work out. Over the last 20 years or so, I've probably witnessed more than 100,000 workouts. I see the good, the bad and the ugly.
But one workout mistake stands out as probably the most common, especially with younger guys looking to build muscle: They don't manage their rest periods.
Thumb through your training log (if it's not handy, a mental snapshot will do just fine). As you do, pay attention to the information you decided to log. Odds are pretty good that you've got exercise names, sets, reps, weights—maybe even a note about how you felt or whether you'd tried a new pre-workout. Maybe it looks something like this:
- Back Squat: 315x10, 315x10, 330x10, 345x10, 355x10
- Safety Squat: 205x12, 205x12, 205x12
- Front Rack Reverse Lunge: 28kg x12, 28kg x12, 28kg x12
- Hip Thrust: 365x8, 365x8, 365x8
- RDL: 315x10, 315x10, 315x10, 315x10
- GHR: x10, x10, x10, x10
Looks good, right? That's a pretty tough workout for most people. But looking at it, I have no idea what kind of rest periods were used. What if this were an EMOM (Every Minute On the Minute) kind of workout? I'm not sure that's possible, but if so, it would be flat-out murderous.
Take your time, upload a few glory shots to Instagram and Facebook, futz around with your playlist, wait for the "good part" of the song to come on before getting back under the bar . . . suddenly that monster workout isn't so bad.
If you've been ignoring your rest periods—and you are ignoring them if you aren't using a stopwatch or at least the second hand on your watch—then you've been missing one of the most crucial drivers of strength, hypertrophy and muscular endurance.
Rest periods influence the hormones your body releases in response to exercise, the fiber types targeted in the muscle, and the different energy systems of the body, among other things. Don't worry, though. Everything you need to know to build muscle, increase strength or improve endurance is coming.
How we get stronger: A combination of factors drive gains in strength, the first being hypertrophy. As a muscle's cross-sectional area increases, it contracts with greater force.
Bigger muscle, bigger weight—enough said. In addition to hypertrophy, something known as neuromuscular coordination also plays a huge role in strength, and this one's a little more involved, as it has a few sub-components.
Rather than getting too lost in the details, let's look at a specific movement and see how the body adapts. Because it's relatively simple, let's use a Bicep Curl. As the body is forced to move heavier weights, it gets better and faster at sending signals to the biceps. In addition, it stops sending signals to the triceps (automatically activated to help control the joint and protect the body), which means there's less internal resistance to deal with. As it sends stronger and more frequent signals to the biceps, recruiting more muscle fibers, you move heavier weights. And, voila: you just got stronger.
Sets and reps recap: Heavy weight means low reps, and low reps mean you typically add a set or two to keep the total volume (number of reps performed) from dropping too low. Typical rep ranges vary from 1 to 6, with 3 to 6 sets being typical.
What this means for rest: Because you're training your nervous system as much as your muscles, and because you're working with near-maximal loads, rest can run from 2 to 5 minutes, with the higher end typically reserved for your biggest lifts (Squats and Deadlifts) and heaviest weights.
How we gain muscle: Hypertrophy is an uncomfortable process, as it requires you to stress the physical capacities of your body in a number of ways. Your ultimate aim is to help spur a shift in anabolic and catabolic hormones to encourage your body to build new muscle tissue. Anabolic hormones—which include growth hormone, testosterone, and IGF-1—encourage the body to take small molecules and build bigger ones. If we're building muscle, that means that proteins and fats combine to build new muscle cells and ultimately new muscle tissue. Catabolic hormones, which include cortisol and adrenaline, help the body break larger molecules down into smaller ones. This process can include digestion, releasing stored sugars into the bloodstream, or breaking down existing cells. If you want to build muscle, you need to keep these in check—not out of the picture, but in balance.
Sets and reps recap: In order to build muscle, you want to work with moderate weights and high volume. You've probably seen ranges from 6-12 reps and 3-5 sets, and these are a solid place for most movements to live.
What this means for rest: To help maximize the release of those anabolic hormones, rest periods are kept fairly short—between 30 and 90 seconds—and you get back to work before your muscle has had a chance to fully recover.
Since hypertrophy is not a performance-driven goal, the concern is not about how much weight you lift, but about how hard it is to lift that weight. You'll get stronger, and cycling through strength-driven periods can be helpful, but an honest-to-goodness muscle-building workout is fast-paced. My rule of thumb: If you're trying to impress a buddy or a girl across the gym with how much you can bench, you're probably resting too long.
How we build endurance: Local muscular endurance is largely determined by how well your muscles can deliver substrates to the working tissues, remove waste products and turn glucose or fat into usable energy. The first two are accomplished via the circulatory system. As the muscle is made to work longer, the body increases capillary density in those tissues. More capillaries mean more oxygen, sugar and fat can be delivered to working cells, and more carbon dioxide, lactate and other waste can be taken away. Additionally, special organelles (cell structures) called mitochondria are responsible for the aerobic breakdown of sugar, and an increase in the mitochondrial density of a muscle cell means it can produce more usable energy in less time.
Set and reps recap: Endurance work means high reps and moderate sets, typically 15-20+ on the rep front and 2 or more sets per exercise.
What this means for rest: If you allow muscles to rest and recharge, you haven't created much of a need for more efficient energy production. Following this logic, limit rest to about 30 seconds for endurance work—just enough to keep going while still signaling the body to make changes and help you do this more efficiently the next time out.
- Learn When and How to Take a Rest Day
- You Need Rest Intervals. Here's Why
- Flexibility Fillers: 3 Exercises to Make the Most of Your Rest Periods
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