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This idea that increasing time under tension, with little regard for intensity, has to end!

Time Under Tension (TUT) refers to how long a muscle is under strain during a set. This has been said to be one of the most important variables of muscle growth—and for good reason. However, in more recent years, this theory of TUT has been bastardized and turned into a silly game of how-slow-can-you-move-the-weight.

Look at some training videos on YouTube of some of the most elite bodybuilders alive. You’re bound to come across keyboard warriors in the comment section criticizing the fact that they’re not training “slow and controlled.” They’re the same guys who’ve been benching 135 lbs for the last year and have made no noticeable improvements to their physique—yet, they’ve got it all figured out.

Give me a fucking break.

Although slowing down your reps in order to increase time under tension seems sound in theory, it’s a disaster in practice.

Why Slow Rep Tempos Suck for Muscle Growth

Bear with me as I take the gloves off for this one.

Alright, where shall I start? Ah yes…anyone who recommends that you purposely slow down the rep speed—whether on the eccentric or the concentric—is a fucking moron. I don’t care how slowly your bench pressing the bar, you’re not going to build a bigger chest until you’re loading that shit up. You see, it’s not about the time under tension, it’s about the magnitude of the tension we’re under.

Let’s look at it from a practical standpoint. As we know, the main goal in our training is to use a load heavy enough to maximize growth while gradually increasing volume over time. If we, however, begin to put more emphasis on the time we keep a muscle under tension than the actual magnitude of the tension itself, here’s how it would look:

Let’s say Gary’s max bench press was 225 pounds. That means that, if aiming for 8-10 repetitions, he’d have to lift about 70% of his 1RM or 165-170 pounds. But Gary read a few fitness magazines and has decided to focus more on time under tension so he’s going to slow down his reps in hopes to get bigger. Here’s the problem: if Gary—when using a normal, controlled tempo—pushes 170 pounds for 10 reps, maximum, he’s going to have to decrease that weight substantially if he wants to get the same amount of reps in with a slower rep tempo. In fact, if he were to attempt to use the same 170 pounds while slowing down the lifting tempo—say 4 seconds on the eccentric and 3 seconds on the concentric—Gary would be lucky to get half the reps he’s capable of when using a normal lifting speed.

So, since he doesn’t want to get less reps (because that just wouldn’t make any sense), he decreases the load to 135 pounds instead. There are a few issues with this, however. For starters, he’s dramatically decreased one of the most important variables for muscle growth: intensity. Secondly, despite performing the same 10 reps per set, he’s managed to decrease his total volume—another key factor for growth—substantially. And if that wasn’t enough, he’s completely defeated the purpose of the, arguably, most important portion of the lift: the eccentric. The biggest benefit of the negative is that we’re able to handle a heavier load when lowering the weight than we can lift—now that goes out the window.

Congrats, Gary—you’ve just managed to get smaller and weaker because you didn’t read my book.

The Perfect Lifting Speed

If you want to get big, you’ve got to get strong—no if, ands, or buts about it. And thanks to a 2014 study published in the European Journal of Sports Science, we know that lifting a weight as fast as possible (while maintaining control) produces greater gains than purposely slowing your lifting tempo. It’s going to require more power to push 225 pounds on the bench press in 1 second than it will to move it in 3—it’s basic physics.

You see, there’s a huge difference between slow reps and controlled reps. If you want to take full advantage of the negative portion of the lift, all you’ve got to do is ensure that you’re controlling the weight—not the other way around. If you slow down the eccentric too much, you’re going to sacrifice total volume. If you ignore it completely, however, you miss all of the benefits and, more importantly, risk serious injury. The goal when lowering the load is to ensure that you’re in control of it the entire time. At first, it may be a good idea to count 2 seconds as you lower it—this will ensure that you’re not just letting gravity take over. As you get gain experience, however, you’ll have a better idea of what it feels like to lower the weight under control without thinking about it or having to count.

As for the concentric, lifting as fast and explosive as possible—without sacrificing control—is the goal.  Too often, people associate “explosive reps” with “sloppy form”—that’s just not the case. Context is the key. If you’re using sloppy form, you’re not going to maximize force. Thus, if you’re going to lift a weight as fast and explosive as possible, you’re going to have to be in complete control; otherwise, you not only risk injury, but end up grinding out an ugly rep. That said, I recommend focusing on perfecting the lift first, and then—once the lift has become second nature—work on being faster and more explosive.

Simply put, if you want to maximize each rep, lifting speed matters. Make sure you’re controlling the weight throughout the entirety of the set—without overthinking it—and focus on getting stronger from there.

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