Lifting tempo refers to the speed at which the individual intentionally lifts and lowers a weight, which is only under control to a certain extent, as the speed of the concentric portion (i.e., the active lifting of the weight, as opposed to the lowering or eccentric portion) will inevitably be slow when lifting a maximal load (e.g., a 1-repetition maximum) or squeezing out the last couple of repetitions during a high-repetition set to failure.
There is evidence to suggest that lifting with a very slow tempo on the concentric portion (10 seconds) can impair muscle gain.[1] Another study found that lifting with a faster tempo on the concentric portion (1 second vs. 3 seconds) was better for muscle gain.[2]
With respect to the eccentric portion of a repetition, there is evidence to suggest that slower (4 seconds vs. 1 second) is better.[3]
The limited evidence available indicates that a slower tempo during the eccentric phase and a faster tempo during the concentric phase is probably beneficial for muscle hypertrophy,[4] but there aren’t strict guidelines that should be adhered to, with the exception of avoiding repetition durations that are intentionally very slow (> 10 seconds per repetition).[5]
For the purpose of muscle gain, the individual should strive for a relatively-explosive lifting motion, then lower under control. Further evidence for the lack of a need to focus on a specific lifting tempo stems from a 2020 study that found that lifting with a strict tempo of 2 seconds on the concentric portion and 2 seconds on the eccentric portion was no better than a self-selected lifting tempo for muscle gain.[6]
The same recommendation more or less applies for increasing strength: the concentric portion of the repetition should be explosive,[7] and there aren’t strict guidelines that should be adhered to for the eccentric portion, with the exception of avoiding very slow eccentric motions.
In two studies that examined the effects of different tempos on the eccentric during a 1-repetition maximum bench press test, slower tempos (4–10 seconds) decreased the amount of load lifted compared to faster tempos (either self-selected or 2 seconds).[8][9] Considering the importance of lifting heavy loads for increasing strength (see “What type of exercise is best for muscle size and strength?”), it’s prudent that those with serious strength goals utilize relatively fast tempos on the eccentric phase to maximize the amount of load they are able to lift.