Whether you want to be toned, improve metabolic health, look better naked, or build strength, muscle growth is likely part of your goal. But even if your nutrition, sleep, recovery, and programming are dialed in, you may still be missing the piece to your muscle gains that really matters. And that’s what we’re diving into today.

I’m Annie Miller, certified strength and conditioning specialist. I help you learn as you train without having to figure it out for yourself. If you’re working to build muscle or even maintain what you’ve already built, two things need your attention: mechanical tension and appropriately challenging working sets.

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What Is Mechanical Tension?

You’ve likely heard of it before. Research tells us there are three possible drivers of hypertrophy: muscle damage, metabolic stress, and mechanical tension. Of the three, mechanical tension is the biggest player.

Mechanical tension is the demand placed on a muscle during resistance training. That can come from load, range of motion, time under tension, or contraction speed. It’s about how hard your muscle is being challenged. That’s what you need to care about.

How to Increase Mechanical Tension

You’re likely following a program already. Your sets, reps, and exercises are probably written out for you. But mechanical tension comes down to how you perform those movements — specifically in three areas: tempo, integrity, and range of motion.

Tempo

Tempo refers to the speed of each portion of your lift — the lowering (eccentric), the pause, and the lift (concentric). Many people rush through reps without realizing it. If your program includes tempo prescriptions, follow them closely. If it doesn’t, consider switching to one that does.

Slow down your eccentrics. If a program calls for a three- or four-second lowering phase, actually take that full time. That extra time under tension creates more demand on the muscle. When you cut corners on tempo, you could be missing 10+ seconds of muscle-building work in every set.

Integrity

Integrity means sticking to the tempo and rep quality. If the program calls for a pause at the bottom of a squat or a squeeze at the top of a row, actually do it. Don’t rush or cheat the movement. Keep the effort and intention high.

Range of Motion

This is another way to create more tension. Look at your form and ask if you’re cutting reps short. Can you go deeper in your squat? Are you getting full extension in your pull-down? Use tempo and control to find where you might be leaving tension — and muscle — on the table.

For more help dialing in your lifts, check out:
How to Achieve Progressive Overload

Are Your Working Sets Actually Working?

The second key piece is separating warm-up sets from your actual working sets — and making sure your working sets are truly challenging. This matters a lot more than people think.

Let’s say your program lists 3 sets of 8 reps. That doesn’t automatically mean all three are hard sets. If your first set was way too light and only the last two were tough, you really only did two working sets. That first one? It was a warm-up, even if it’s not labeled that way in the program.

Your working sets should have only 1–2 reps left in the tank, and the last reps should move slower than the first ones. That’s how you know it’s heavy enough. This is true whether you’re doing your main lifts or accessory work.

Use Rate of Perceived Exertion (RPE) as a guide. If the set feels like a 6 or 7 out of 10, it’s probably not a working set. You should be hitting 8 or 9, consistently, for growth.

Put It into Practice

Let’s recap what you can actually do:

• Focus on tempo — especially the lowering phase
• Stick to the prescribed tempo with full integrity
• Check your range of motion and aim to deepen it if possible
• Separate warm-ups from working sets
• Make sure your working sets are at a high enough effort level

These are small changes that make a big difference.

You don’t need to overhaul your training program. You don’t need to be perfect. But if you focus on these two elements — mechanical tension and challenging working sets — you’ll start getting more out of the work you’re already doing.

Final Thoughts

The missing piece to your muscle gains might not be a new program, new split, or even more weight. It could be the effort and execution in what you’re already doing. Dial in tempo. Push for full range. Separate warm-up from work. When you train like that consistently, the results will follow.

Want to take it further? Read: Best Training Split for Muscle Growth