Should I be doing my reps fast or slow?

Are slow reps or fast reps better for you when it comes to weightlifting? Well, it all depends on your fitness goals!

Train Heroic explains that there are three types of rep speeds: slow, normal, and fast. Going slow emphasizes good form and helps control the movement better. A normal speed might look like what you’re already doing. Alternatively, going fast — like you typically would see in CrossFit classes — can improve force. Let's dive deeper into the concept of rep speed and understand which works best for your goals.

Slower reps can build more muscle thanks to increased time under tension (via Muscle & Fitness). A 2021 review in Sports Medicine suggested using slower eccentric movements together with faster concentric lifts for increased muscle mass. However, a 2015 review in Sports Medicine recommends not overdoing it with slow reps. Take no longer than 10 seconds per lift if you want to build muscle. Slower reps--particularly focusing on the slower eccentric movement--can also improve impulse, which is the amount of force in a short time.

If increasing strength is what you’re after, then try faster reps. A 2020 study in the Journal of Sports Science & Medicine tested different rep speeds on the eccentric part of the movement and found that two-second lifts were able to improve strength better than four or six second lifts. Similarly, a 2011 study in the Journal of Strength and Conditioning Research showed that male weight lifters also improved their one-rep max (1RM) by using shorter reps. However, a 2022 study in Journal of Strength and Conditioning Research found similar gains regardless of how quickly reps were done - so why not mix both slow and fast tempo into your workouts?