Bodybuilding coaches like to talk about training pace. A common advice for optimal muscle growth is to do slow reps, especially in the eccentric phase of an exercise. New research (once again) undermines this advice.
Key points:
1. Pace, the length of time a repetition, is a training variable that should not be given too much importance.
2. For muscle growth, it is normally sufficient to perform the concentric phase of an exercise relatively quickly (1 or 2 seconds, or possibly explosively) and the eccentric phase controlled (1-3 seconds).
3. If you want to increase the time under tension of a set, it’s better to do it by adding reps than by doing reps slower.
4. Mind-muscle connection is more important than training pace. But slow reps can help you learn to achieve that mind-muscle connection.
‘CONTROLLED’ VS ‘SLOW’
Yes, in most cases it is advisable to carry out the eccentric phase in a controlled manner. When doing the bench press, for example, you let the bar come down in about 2 seconds and not ‘fall’. After all, there must be eccentric muscle tension. But braking the weight is different from lowering it excessively slowly, in 6 seconds, for example. The latter is also known as ‘super slow eccentrics’. ‘Slow eccentrics’ could then be synonymous with ‘controlled’, but often this also means deliberately slow repetitions, which can sometimes be confusing.
It is often preached that you trigger extra muscle growth with super slow reps or eccentrics, because you increase the time under tension (TUT), and because you activate the type II muscle fibers relatively more in the eccentric phase. But there is insufficient scientific evidence for this assumption. In fact, more recent studies show the contrary.
NEW RESEARCH
The most recent research on reptempo comes from Nóbrega ea (2018). A group of twelve male subjects, each of whom had three-and-a-half years of training experience, was split into two: one group of men was allowed to choose for themselves during training which rep tempo they used: fast or slow, according to what they themselves felt was best. The other group was prescribed a pace: two seconds in the concentric (positive) phase and two seconds in the eccentric (negative) phase (2-2). Each group did three sets to muscle failure on the leg press, at a training intensity of 80%/1RM. The researchers measured muscle activity (by means of EMG, electromyography), TUT per repetition and per session, and session volume (the total number of repetitions).
The results? The group that was allowed to determine the rep tempo themselves noted higher EMG values and more training volume than the group with the prescribed rep tempos. The TUT of the session was about the same in both groups. Also interesting: the self-selected rep tempos were faster than the 2-2 protocol for all participants.
You can conclude from this that slowing down rep tempo leads to less muscle activation and less training volume. The latter seems logical: the slower you do the reps, the fewer reps you can complete per set. The TUT of the set may be about the same, but for muscle growth, more reps seems better than slower reps – at the same weight, of course.
The results and conclusion are in line with those of another, similar study, by Lacerda et al. (2016). In the bench press, rep tempos of 3 and 6 seconds were compared. And again, EMG measurements showed that the muscle activation was greater with the short repetitions, as well as the lactate values. This despite an approximately equal TUT per set. The researchers concluded that more reps causes more metabolic stress than fewer, but longer reps. If you want to make progress and you can’t do that immediately by increasing the weight, it is better to opt for more repetitions than slower repetitions.
A logical explanation for the above seems to be that giving up concentric TUT in favor of eccentric TUT is unfavorable for muscle growth. A meta-analysis by hypertrophy expert Brad Schoenfeld and colleague Dan Ogborn showed that the eccentric and concentric phase of an exercise are equally important for muscle growth. And if you do fewer reps, you can do the concentric phase of an exercise less often.
SO SLOW REPS AMORTIZED?
It comes as no surprise that slow repetitions in principle offer no added value for muscle growth and may even have the opposite effect. In a 2015 meta-analysis, Brad Schoenfeld and Dan Ogborn again concluded that a wide range of rep tempos is suitable for muscle growth, as long as you stay under 10 seconds per rep. 2 to 6 seconds for the entire rep seems like a good starting point.
Also dr. Jacob Wilson, aka ‘The Muscle PhD’, has come to the conclusion after analyzing several studies that excessively slow repetitions are probably counterproductive for muscle growth. But, he believes, you can use them to teach mind-muscle connection. Slow repetitions make you more aware of the muscles that are working and that is beneficial for muscle growth.
Once you’ve mastered the mind muscle connection, release the slow reps. Think about the muscle, not the tilt rate. Brad Schoenfeld:
Instead of worrying about a specific tempo, simply focus on the muscle being trained and visualize it working throughout the full range of motion.
CONCLUSIONS AND ADVICE
1. Pace, the length of time a repetition, is a training variable that you should not lift too much weight on.
2. For muscle growth, it is normally sufficient to perform the concentric phase of an exercise relatively quickly (1 or 2 seconds, or possibly explosively) and the eccentric phase controlled (1-3 seconds).
3. If you want to increase the time under tension of a set, it’s better to do it by adding reps than by doing reps slower.
4. Mind-muscle connection is more important than training pace. But slow reps can help you learn that mind-muscle connection.