Does tempo matter for muscle growth? • Stronger by Science

If you’ve consumed science-based lifting content before, you’ve probably heard quite a bit about lifting tempo. From old school proponents of super-slow training, to “milking the eccentric,” manipulating repetition tempo has been a relatively hot topic in science-based lifting. 

The popularization of slow eccentrics became synonymous with being a science-based lifter. The consensus, at least in some popular science-based circles, was that if you weren’t controlling the weight for 3-5 seconds, you were most likely definitely leaving gains on the table. 

This was mostly based on the hypothesis that eccentric contractions are more hypertrophic than concentric contractions, a notion that carries limited weight. Additionally, previous narrative reviews had concluded that a combination of slow eccentric and fast concentric movements was the most effective approach for maximizing gains. However, the main review that did allude to that also highlighted the lack of solid evidence and need for future research, while also suggesting that a variety of eccentric and concentric tempo combinations can be effectively used to maximize hypertrophy.

This is something that we also touched on when reviewing the literature in an attempt to understand the variables comprising an optimal technique for maximizing hypertrophy. In 2023, we had mentioned that “a repetition tempo of 2-8 s seems to be sufficient to maximize hypertrophy, and it is currently unclear whether extending the concentric or eccentric phase of a repetition will lead to greater hypertrophy.”

And this is where there was an issue with the tempo literature. Previous meta-analyses had not attempted to isolate the effects of tempo on the eccentric and concentric phases. Rather, they examined the effect of total repetition duration, which raised some minor, yet important, questions about whether a specific combination of eccentric and concentric tempos could influence long-term muscle gains.

This hot-off-the-press meta-analysis tackled this exact question by examining 14 studies that independently manipulated eccentric and concentric tempo.

Tempo speed was as follows:

• Fast reps: ~0.25-1 sec (for the concentric phase), ~0.25-2 sec (for the eccentric phase)
• Slow reps: ~2-4.5 sec (for the concentric phase), ~1.66-4.5 sec (for the eccentric phase)

The included studies had participants training at least 2x per week for 4+ weeks and used direct measurements of muscle growth (eg, ultrasound). Overall, 14 studies lasting ~8.5 weeks with ~280 participants were included.

So does tempo matter?

Not as much as some think.

On average, the meta-analysis findings indicated that both fast and slow tempos resulted in similar hypertrophy, observed in both eccentric and concentric phases. There was also no meaningful effect of tempo when looking at upper vs lower body training. That said, faster eccentric tempos had a slight edge over slower tempos when not training to failure, with slower eccentric tempos having a slight edge when training to failure, though the effects were small and uncertain.

So where does this leave us?

Pretty much where we were, just without the FOMO of optimization 😁

Overall, as long as you’re training close to failure and lift with a tempo that suits your preference, you’re fine. If purposefully slowing down the eccentric, or the concentric for that matter, feels better, then that’s totally fine. It’s likely that you’ll find tempo to be somewhat exercise-specific in terms of preference anyway. Some exercises may feel best performed a bit more explosively, while others may feel best when you control the weight a bit more (eg: on a Romanian deadlift).