Tempo is one of those training variables that often gets mentioned but rarely gets much focus. Ask most gym-goers what tempo they’re lifting at and you’ll probably get a shrug. Even among personal trainers, tempo is more likely to be used as a cue for control than as a planned variable with specific outcomes in mind. But there’s growing evidence that the eccentric phase, that’s the lowering part of a lift, deserves more attention than it usually gets.
For those enrolled in personal trainer courses or delivering PT sessions, the question is: does changing how long your client takes to lower the weight actually make a difference? According to a systematic review and meta-analysis published in the Journal of Sports Sciences (Amdi & King, 2025), the answer is a bit of a mixed bag, but there are some very useful takeaways for anyone designing training programmes.
What Tempo Really Means
Tempo refers to the speed at which each phase of a rep is performed. A typical 2-0-1-0 tempo, for example, means a 2-second eccentric (lowering) phase, no pause, a 1-second concentric (lifting) phase follow by no pause. Most people naturally lift faster than that unless told otherwise. The eccentric phase, in particular, can be slowed down deliberately to increase time under tension, make a set more challenging or cue better technique.
What the Researchers Looked At
Amdi and King reviewed nine studies with a total of 166 participants, comparing shorter eccentric durations (≤2 seconds) with longer ones (3 to 6 seconds). They looked at three key outcomes: maximal strength, muscle hypertrophy and countermovement jump (CMJ) performance. The results are worth considering, especially if you’re on a PT course and learning about tempo, or your already qualified and need to help clients get stronger, build muscle or move better.
Power & Shorter Eccentric Phase
When it came to jump performance, shorter eccentric durations led to greater improvements in CMJ height. The effect size was considered large (g = -0.73), with a high level of certainty. In other words, keeping the eccentric phase brief seems to be more effective for improving explosive movements like jumping. The likely reason is that shorter eccentrics allow the stretch-shortening cycle to work more efficiently. When the muscle lengthens quickly under load and rebounds into a concentric action, more force can be produced in less time. This is especially important for athletes or clients training for speed and power.
Strength & Longer Eccentric Phase
For maximal strength, the results were less clear. Across all participants, there was a small effect favouring longer eccentric durations, but the confidence intervals were wide and the overall certainty was low. However, when the researchers looked at subgroups, some interesting patterns emerged. In trained individuals, longer eccentric phases appeared to lead to better strength gains. The same was true in studies where training volume (load × sets × reps) was matched between groups. In these cases, longer eccentrics may have created a more effective training stimulus due to increased time under tension and neuromuscular challenge, even if fewer reps were completed overall.
This finding matches other research suggesting that slower eccentrics can promote strength adaptations through enhanced neural drive and muscle control (Siddique et al., 2020). For more advanced clients, tweaking tempo to include longer eccentrics could be a way to progress training without increasing load or volume. It might also help break plateaus or improve movement quality in complex lifts.
Hypertrophy & the Eccentric Phase
Muscle hypertrophy results were even murkier. The average effect of eccentric duration on muscle growth was basically neutral (g = 0.05), with very low certainty of evidence. The data didn’t show consistent advantages for short or long eccentrics when it came to increasing muscle size. Some studies leaned slightly in favour of longer durations due to the increase in time under tension, but overall the impact was minimal. If the goal is hypertrophy, then other variables like proximity to failure, exercise selection and progressive overload are probably more important than how long a client spends lowering the weight.
Applying This in Real Life Coaching
So how can we put this into practice?
For clients training for explosive power or athletic performance, keep the eccentric phase short, between 1 to 2 seconds, to take full advantage of the stretch-shortening cycle. This will also help with rate of force development and reinforce fast, reactive movement patterns.
For clients focused on strength, particularly those with training experience, incorporating slower eccentrics (3 to 4 seconds) may improve outcomes without needing to increase load. These longer tempos might also be useful during specific strength blocks or when technique needs refining.
If hypertrophy is the goal, tempo can still be useful, but more as a tool for control, variety and fatigue management rather than a key driver of growth. Consistency, effort and load progression still reign supreme.
Tempo can also play a role in coaching quality and injury prevention. Slower eccentrics can help clients stay more connected to the movement, reduce momentum and control the range of motion. This is particularly helpful for beginners or during rehab phases.
Practical Cautions and Guidelines
The trick is to avoid extremes. Eccentric durations beyond 5 or 6 seconds may increase cardiovascular and neuromuscular fatigue without delivering much additional benefit. They can also reduce the number of reps a client can perform in a set, potentially limiting training volume or intensity.
Ultimately, tempo is a coaching tool. It shouldn’t be used in isolation but can be layered into a well-rounded programme to support specific goals. We don’t need to obsess over every second, but having a clear reason for choosing a certain tempo makes coaching more purposeful.
As with most things in training, the context matters. The more advanced the client, the more these details can be used to fine-tune results. For those early in their career or studying PT courses, understanding tempo is a solid foundation for better programming and client outcomes.
Reference
- Amdi, C.H. & King, A. (2025). The effect of eccentric phase duration on maximal strength, muscle hypertrophy and countermovement jump height: A systematic review and meta-analysis. Journal of Sports Sciences. Click here to review the full research article.
- Siddique, U. et al. (2020). Task-dependent modulation of corticospinal excitability and inhibition following strength training. Journal of Electromyography and Kinesiology, 52, 102411. Click here to review the full research article.
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