Rep speed doesn't significantly affect muscle growth when training close to failure, but super-slow protocols may reduce gains.
Original: The BEST Rep Speed For Size (New Study)
Muscle growth is similar across a wide range of rep speeds when training to failure, but extremely slow tempos with light weights appear less effective.
Quick Answer
The new meta-analysis of 14 studies found no clear advantage for either faster or slower rep tempos in maximizing muscle hypertrophy. The overall effect size favored faster tempos by only 0.9% (equivalent to a 18% multiplicative difference), but the 95% credible interval included zero, meaning the difference is statistically negligible. Subgroup analyses showed no consistent benefit, and typical muscle growth from any tempo aligns with the standard 5% increase seen in the literature.
Claims (10)
1. You can build muscle just as well lifting light weights as heavy ones — as long as you push yourself until you can’t do another rep.
2. How fast or slow you lift and lower weights doesn’t matter as much for building muscle as how much weight you lift, how many reps you do, or how close you push yourself to failure.
3. To figure out whether speeding up or slowing down the lifting vs. lowering part of a weight workout makes your muscles grow more, scientists need to test each part separately—not at the same time.
4. When people lift weights regularly, their muscles usually get about 5% bigger on average, no matter what kind of weight routine they follow.
5. If you lift and lower weights quickly or slowly, as long as you do both phases the same way, your muscles grow about the same amount—speed doesn’t make a big difference.
6. Lifting weights fast or slow doesn’t make much difference in how much your muscles grow — the extra gain from going slow is practically nothing.
7. If you lift weights until you're really tired, it doesn't matter if you lift slowly or quickly—you'll still build about the same amount of muscle.
8. When you first start lifting weights, you get stronger not because your muscles grow bigger right away, but because your brain gets better at telling your muscles when and how to contract.
9. When people lift weights without going all the way to exhaustion, using machines that force a set speed might make fast lifting look better—but that’s because those machines don’t act like real free weights or gym machines we usually use.
10. Lifting weights really slowly with lighter weights doesn’t build as much muscle as lifting heavier weights at a normal speed—even if you push yourself to the limit in both cases.
Key Takeaways
- •Problem: People think slowing down reps makes muscles grow bigger, but it’s unclear if speed actually matters.
- •Core methods: Faster eccentric tempo, slower eccentric tempo, faster concentric tempo, slower concentric tempo, super-slow training (10s concentric, 4s eccentric), training to failure.
- •How methods work: Faster tempos reduce time under tension per rep; slower tempos increase it; super-slow uses very long durations with lighter weights; training to failure means pushing until you can’t do another rep, which stresses muscles enough to grow regardless of speed.
- •Expected outcomes: Muscle growth is about 5% on average, whether using fast or slow tempos; super-slow training led to less muscle fiber growth in one study.
- •Implementation timeframe: Muscle growth occurs over weeks to months; no specific timeframe is given, but results are similar regardless of tempo as long as training is intense enough.
Overview
The problem is determining whether specific rep tempos (eccentric or concentric speed) significantly enhance muscle hypertrophy compared to others. The solution preview is that a new meta-analysis of 14 studies shows no meaningful advantage for any tempo range, with typical muscle growth occurring regardless of speed when training to or near failure, and super-slow tempos potentially being less effective.
Key Terms
How to Apply
- 1.Perform resistance exercises using either a 1–2 second concentric and 1–2 second eccentric tempo (normal speed) or a slower tempo (e.g., 3–4 seconds eccentric, 1–2 seconds concentric), ensuring you train each set to or near muscular failure.
- 2.Avoid super-slow training protocols that use 10-second concentric and 4-second eccentric tempos, as one study showed reduced muscle fiber growth with this method even when using lighter loads.
- 3.Use loads between 70–85% of your one-rep max for optimal hypertrophy, or as low as 30% if training to failure, since light loads can be equally effective when intensity is high.
- 4.Focus on completing all sets with maximal effort, ensuring the last 1–2 reps are extremely challenging, as this is more important than rep speed for muscle growth.
- 5.Track your progress over time by increasing weight, reps, or sets weekly to ensure progressive overload, regardless of the tempo you choose.
You will achieve approximately 5% muscle growth over time, matching typical results in the literature, with no meaningful difference between faster or slower tempos — as long as you train to or near failure and avoid super-slow protocols.
Studies from Description (6)
Additional Links (8)
Claims (10)
1. You can build muscle just as well lifting light weights as heavy ones — as long as you push yourself until you can’t do another rep.
2. How fast or slow you lift and lower weights doesn’t matter as much for building muscle as how much weight you lift, how many reps you do, or how close you push yourself to failure.
3. To figure out whether speeding up or slowing down the lifting vs. lowering part of a weight workout makes your muscles grow more, scientists need to test each part separately—not at the same time.
4. When people lift weights regularly, their muscles usually get about 5% bigger on average, no matter what kind of weight routine they follow.
5. If you lift and lower weights quickly or slowly, as long as you do both phases the same way, your muscles grow about the same amount—speed doesn’t make a big difference.
6. Lifting weights fast or slow doesn’t make much difference in how much your muscles grow — the extra gain from going slow is practically nothing.
7. If you lift weights until you're really tired, it doesn't matter if you lift slowly or quickly—you'll still build about the same amount of muscle.
8. When you first start lifting weights, you get stronger not because your muscles grow bigger right away, but because your brain gets better at telling your muscles when and how to contract.
9. When people lift weights without going all the way to exhaustion, using machines that force a set speed might make fast lifting look better—but that’s because those machines don’t act like real free weights or gym machines we usually use.
10. Lifting weights really slowly with lighter weights doesn’t build as much muscle as lifting heavier weights at a normal speed—even if you push yourself to the limit in both cases.
Related Content
Claims (10)
How fast or slow you lift and lower weights doesn’t matter as much for building muscle as how much weight you lift, how many reps you do, or how close you push yourself to failure.
Lifting weights fast or slow doesn’t make much difference in how much your muscles grow — the extra gain from going slow is practically nothing.
If you lift and lower weights quickly or slowly, as long as you do both phases the same way, your muscles grow about the same amount—speed doesn’t make a big difference.
If you lift weights until you're really tired, it doesn't matter if you lift slowly or quickly—you'll still build about the same amount of muscle.
Lifting weights really slowly with lighter weights doesn’t build as much muscle as lifting heavier weights at a normal speed—even if you push yourself to the limit in both cases.