Lifting Tempo: How Fast Should You Do Each Rep?

"Time under tension" and 4-second negatives have a strong reputation in gym culture, so it is worth asking what the trials actually show. The honest answer is mostly reassuring: for muscle growth, a wide range of rep speeds works. The places where tempo does change the outcome are the extremes, and strength training.

How tempo notation works

Tempo is usually written as four numbers: seconds spent lowering the weight, any pause at the bottom (the stretched position for most lifts), seconds spent lifting it, and any pause at the top. So 3-1-1-0 means three seconds down, a one-second pause, one second up and no pause at the top. Add the four numbers to get the seconds per rep, and multiply by the reps to get the time the muscle is loaded in a set. The checker below does that arithmetic and tells you where the result falls relative to the research.

What the evidence says about muscle growth

A 2015 systematic review and meta-analysis in Sports Medicine pooled eight studies of at least six weeks in which sets were taken to muscular failure. Muscle growth was similar for repetition durations from 0.5 to 8 seconds, so the authors concluded that a fairly wide range can be used when growth is the goal. The same analysis suggested that volitionally very slow reps, over about 10 seconds each, were inferior, but the authors noted that the lack of controlled studies made this hard to establish [1].

That review has limits. It covered only eight studies, it reported whole-rep duration rather than isolating the lowering and lifting phases, and the trials it included were not designed solely around tempo, so differences in load or effort can leak into the comparison [1]. A 2021 narrative review in Sports Medicine addressed the phases directly. It concluded that neither isolated slow nor isolated fast movement tempos are more effective for hypertrophy, that a slower eccentric (lowering) combined with a faster concentric (lifting) phase appears most favourable, and that slower tempos require a lighter external load but can still produce an adequate stimulus when time under tension is high enough [2]. Note that this review is not a meta-analysis, so it is a weaker basis for numbers than [1].

A 2025 Bayesian meta-analysis in the Journal of Strength and Conditioning Research is the most direct update. It pooled 14 studies that compared a slower with a faster tempo, where the slower arm averaged about 3.5 seconds per repetition (range 1.7 to 4.5) and the faster arm about 1 second (range 0.3 to 2). Gains were similar, and the pairwise comparison trivially favoured faster tempos (0.09, 95% credible interval −0.04 to 0.22); the authors concluded that tempo has minimal overall effect on hypertrophy, with possible differences under specific conditions [5]. Notice that the interval includes zero and the range of tempos tested stops at 4.5 seconds, so it says little about very slow reps.

A single trial shows the same pattern. In a within-person study of 13 resistance-trained men, each leg trained for 8 weeks at a fast (1-0-1) or slow (1-0-3) tempo. Both legs gained strength by similar amounts (17.0% fast versus 22.1% slow), muscle thickness rose in both, and the authors saw a small possible hypertrophy advantage for the fast tempo at one site, the distal quadriceps. The slow tempo felt harder (RPE 8.59 versus 7.98) [7]. Slower reps cost effort without buying extra growth.

What the evidence says about strength

Strength is where the reviews disagree, and the disagreement is worth showing rather than smoothing over. A 2017 meta-analysis of 15 studies found that fast and moderate-slow training produced similar gains in dynamic strength, with a non-significant trend toward a small advantage for fast training at moderate loads (60 to 79% of one-rep max, effect size 0.31, p = 0.06) [4]. A 2023 meta-analysis pooled 24 studies with 625 participants and found gains favouring fast or traditional-velocity lifting over intentionally slow lifting phases (effect size 0.21, 95% CI 0.02 to 0.41, p = 0.03), but also found evidence of publication bias, so the true effect is uncertain [3].

A 2025 meta-analysis looked at the lowering phase separately, across nine studies with 166 participants. It found strength and hypertrophy estimates too uncertain to confirm or rule out a worthwhile effect of longer lowering phases, though longer lowering phases produced equal or greater strength gains in trained participants and in trials that matched volume-load, while shorter lowering phases improved countermovement jump height [6]. Put together: a slow lifting phase is unlikely to help and may cost a little, while a slower lowering phase is not shown to hurt.

What to do with this

• Choose a speed at which you can keep the same range and technique on every rep. A rep you cannot control is too fast for you; beyond that, speed is a preference.
• Lower the weight deliberately (a couple of seconds is a practical judgement, not a trial result) and lift it with intent to move fast. This matches the pairing the 2021 review called most favourable and sits comfortably inside the band that grew muscle equally [1][2].
• If you pause, pause where it adds something: at the stretched position it removes the bounce, and it works well with a deliberate range of motion.
• Do not slow reps to reach for an imagined "time under tension" target. If a slower tempo forces a lighter load, you are trading load for time, and the evidence does not say that trade is better [2][5][7].
• Keep sets honest about effort. The tempo trials in [1] were trained to failure, so judge each set by how close it was to failure using RPE and reps in reserve, not by the clock.

Tempo also interacts with the rest of your plan. A lighter load at a slower tempo changes the rep range you land in, the training to failure evidence behind the tempo findings assumes sets were taken close to failure, and holding tempo constant is what makes week-to-week progressive overload comparable. Slower sets also take longer, which changes how much rest between sets you need to keep performance up.

How Reppit uses this

Reppit logs the load, reps and RPE of every completed set [8]. Since the evidence says rep speed matters less than load, reps and effort, those three numbers are the ones worth tracking: keep your tempo steady from session to session, and let the logged weight and RPE show whether you are progressing.