Single-set or multi-set training – a frequently asked question
Intuitively, you might think that the more advanced the trainees are (the longer they have been doing strength training), the more effort seems necessary to trigger the training stimulus (hypertrophy stimulus). In this case, however, intuition does not match the scientific evidence (Burd et al, 2010).
Firstly, someone who has been doing strength training for a long time is not automatically "advanced". Just because someone has been doing something for a long time unfortunately does not mean that this person is doing it correctly and successfully.
Myths and science: why the number of sets is often overestimated
From a scientific point of view, there is no clear proof that single-set or multi-set training is clearly superior to the other. This, provided that the muscle was worked in one set to exhaustion and with the effective time under tension necessary for maximum muscle growth. In fact, many studies show that performing multiple sets is more effective than performing just one set. In such studies, however, the effective time under tension is not taken into account; a set of X repetitions is thus compared with the result of several sets of the same number of repetitions, without matching the total time under tension of the two protocols, which does not correspond to the logic on which modern single-set training is based. This also means that, in the case described, the required time under tension to muscle exhaustion is reached in multi-set training (60-120 seconds), but not in single-set training, since the time under tension is 2, 3 or even 4 times lower than in the multi-set protocol. In such comparisons, multi-set training can be expected to prove more efficient. If, on the other hand, the same effective time under tension were achieved in single-set training as in the multi-set protocol, the results of the two protocols would hardly differ.
As mentioned earlier, the muscle does not adapt to single-set or multi-set training, but rather due to intracellularly activated signalling cascades (which in turn depend on genetic and epigenetic factors, etc.). In terms of time, however, the total time expenditure (training effort) is considerably lower with single-set training. With similar or identical training success, the training thus becomes more efficient, since the breaks between sets are eliminated.
This is also why people no longer speak of single-set or multi-set training, because the quality of exercise execution and not the quantity is at the centre. Thus, the trigger for the adaptation of the muscle is exceeding a certain stimulus threshold. This is reached through the effective time under tension up to muscle exhaustion. It therefore makes no difference whether this time under tension is reached through single-set or multi-set training, provided that training is carried out with the same time under tension up to muscle exhaustion and the breaks in between are not too long.
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An illustrative example:
Triggering a growth stimulus for the muscle is comparable to flipping a light switch. A press of the button (1 set, until no further complete repetition over the individually possible range of motion is possible) switches the light (growth stimulus) on immediately, not gradually. It is the same with training: either the growth stimulus is triggered or it is not. Once the switch has been flipped and the stimulus for muscle growth thus set, no further "sets" are necessary. Pressing the light switch several times does not make the room any brighter either. Exceeding the stimulus threshold several times (multi-set training) does not lead to a greater training effect. On the contrary, the nervous system is unnecessarily burdened ("overdose"). In this context, it is important to emphasise that one set is enough only if the stimulus threshold has actually been reached through the required time under tension up to muscle exhaustion. Repeating the sets can, in this context, only make sense if the single set did not meet the described requirements; that is, either the effective time under tension was too short or training was not carried out to muscle exhaustion.
Single-set training does not mean just one exercise per muscle group
It should not be confused: in the case of the single-set training described, this does not rule out performing several exercises for the same muscle group. Since different movement patterns are executed here, different muscle fibres are also worked and the corresponding signalling cascades are thus triggered for more muscle fibres, which, for the goal of "muscle growth" is extremely important – especially when maximum results are to be achieved.
Conclusion: focus on effectiveness instead of the number of sets
The training log ultimately serves to document progress. Since we achieve progress, we are interested in training slightly above the stimulus threshold. It follows that in every training session with maximum goals – except in targeted relaxation or periodisation phases – you should try, under standardised conditions, to train up to the point at which no complete movement over the individually possible range of motion is possible any more. Only then can training progress be documented meaningfully (standardisation enables comparability).
So do not concern yourself with the pointless question of whether single-set or multi-set training is better, but make sure that you perform the exercises each time to complete exhaustion, and this for an effective time under tension of 60 to 120 seconds – regardless of whether in one go or spread over 2-3 sets with short breaks in between.
