Does Tempo Impact Strength and Muscle Gains?

Dissecting an old idea to see how much it matters
7 min read
By: Dylan Dacosta

“If you want to build muscle, you have to focus on getting a lot of time under tension.”

This is something I used to believe and tell people. If someone wanted to build muscle, I’d have them go much slower during their lifts, especially during the eccentric phase of the lift. That’s just the part where your working muscle is lengthening under the load. Think of the way down on a bench press. 

Now, this is not bad advice. It’s just not entirely true, either. Like many other ideas that become pervasive in the gym, there is some truth to this, but the idea takes on a life of its own and becomes rigid dogma. 

I speak for myself here, but I think this is also common: the people who trope these beliefs the hardest are probably the ones who’ve read no real literature on the topic. 

Leading to why I wanted to write this article. To add nuance and practical considerations to this idea.

What Does the Science Say?

There isn’t a tonne of research on this topic, but we do have some data to pull from. As I like to do, looking at a meta-analysis when available is a great place to start. 

A meta-analysis is just a study of relevant studies on a topic. This allows for a larger sample size to be pooled and analyzed for a larger and hopefully clearer picture of any general findings. 

Schoenfeld et al. 2015 (1) did a meta-analysis on 8 studies. These were all untrained folks and were mixed sex and ranging from young to old. 

The general findings for building muscle were that a wide range of tempos can be used to build muscle. In this paper, the studies using a range of 0.5–8 seconds per rep yielded similar amounts of muscle growth. 

The groups were pooled into one of 4 categories:

• Fast/heavy (sets of 6–12 with 0.5–4 sec per rep)

• Fast/light (sets of 20–30 with 0.5–4 sec per rep)

• Medium (sets of 6–12 with 4–8 sec per rep)

• Slow (sets of 6–12 with greater than 8 sec per rep)

Above, you’ll see the effect sizes for each group. Technically, they favoured the fast group, but there was a non-significant difference between all the groups. This could be partially due to a sample size that was too small and that the confidence intervals were quite large (those are the lines spanning from the dots in the middle that mark the mean findings.)

Of the 8 studies, only one individual study (2) showed the fast-tempo group to yield better muscle growth than the slow-tempo group. Other than that, all the studies showed no difference between fast and slow.

A more recent study by Martins Costa et al. 2022 (3) showed a similar trend. 33 untrained young men were split into three groups. 2 groups trained the bench press three times a week with 50–55% for 3–4 sets, and one group was a control group (meaning they did nothing.)

The two benching groups were divided into doing either 1.5 seconds up and 1.5 seconds down per rep (fast) or 3 seconds up and 3 seconds down per rep (slow).

Hypertrophy tended to lean in favour of the fast group, but there were no statistically significant differences between the two. This is similar to the Schoenfeld meta mentioned above. A non-significant difference did favour faster reps, but similar to here, the variance of the data was quite large. 

On the other hand, when it comes to maximizing strength, a faster tempo does tend to yield greater gains. A meta-analysis by Davies et al. 2017 (4) showed a small effect favouring faster tempos over slower tempos. 

How to Apply This to Your Training

The good news is that if you’re trying to build muscle, you likely don’t have to get too bogged down on having the perfect tempo. 

The best data we have gives you a pretty wide range. As long as each rep isn’t taking 10 seconds or more, you should be fine. The obvious elephant in the room is that almost nobody trains like that. So, let’s get more granular. 

In my experience in the gym and even when looking at this data, I’m inclined to give the practical nudge toward a faster tempo than a slower one. 

This is especially true for the concentric phase of your lifts. The concentric is just the part where you’re actually exerting force against the load. This is also generally harder than the eccentric part. 

There really is just no reason to intentionally use slow tempos for the concentric phase if you’re trying to maximize strength or muscle growth. 

If you’re doing rehab and your physical therapist tells you to do so, that’s different. But if we assume you’re not injured, a faster concentric is probably the best way to go. 

The eccentric is likely the one you want to play around with without leaving gains on the table. This can look like playing around with different eccentric tempos or even adding pauses. 

I do these often, and they can be quite helpful if you’re stuck in a plateau for strength or even just for variety. Again, all of this data is based on average findings. You may personally find the slower eccentrics help you train more effectively.

When it comes to my clients, the most common tempo suggestion I give is as follows:

“Controlled through the eccentric and try to explode during the concentric.”

For the bench press, this would look like bringing the barbell down with control until it touches your chest (this usually takes 1.5–3 seconds) and then trying to drive that bar up as fast as you can. 

With light loads, that bar can absolutely cook, but with heavier loads, it will just never move that fast. That doesn’t matter because your intent is to still move it as fast as possible. 

This strategy also helps with gauging how close you are training to failure. If every rep you’re trying to move as fast as you can on the concentric phase, this will start to slow down as you get closer to failure, even though your intent is still to move it fast. 

Alternatively, if you’re intentionally going slow on the concentric, it’ll be harder to gauge how close to failure you were since each rep will be moving slowly — even the first ones where you’re nowhere near failure. 

Below, I’ve made a simple table you can use as a guide. Remember, this is not a rigid manual to follow. Instead, it’s a guide you can experiment with and see what works best for you.

Takeaways

• Tempos are not the key to building muscle. A wide range of between 0.5–8 seconds per rep can yield similar muscle growth.

• For maximizing strength, aiming to move the load as fast as you can through the concentric part of the movement is going to be your best bet.

• Although a wide tempo range can be used for building muscle, aiming for a controlled tempo during the eccentric and then again trying to move the load faster through the concentric is likely the most practical approach.

• The tempo you’d most likely want to play around with is slowing down the eccentric or even adding pauses. It’s hard to say it will improve gains, but it can be worth experimenting with to see what works best for you.

References:

1.Effect of repetition duration during resistance training on muscle hypertrophy: a systematic review and meta-analysis
https://pubmed.ncbi.nlm.nih.gov/25601394/

2. Early-phase muscular adaptations in response to slow-speed versus traditional resistance-training regimens
https://pubmed.ncbi.nlm.nih.gov/22328004/

3. Equalization of Training Protocols by Time Under Tension Determines the Magnitude of Changes in Strength and Muscular Hypertrophy
https://pubmed.ncbi.nlm.nih.gov/34932279/

4. Effect of Movement Velocity During Resistance Training on Dynamic Muscular Strength: A Systematic Review and Meta-Analysis
https://pubmed.ncbi.nlm.nih.gov/28105573/