No pain, no gain, grandmother said wisely. Yet a set that you experience as heavy, is not automatically a set that leads to muscle growth.

CRITERIA OF A SET

If you’re training for muscle growth, a set should contain enough stimulating (or effective) reps. That’s roughly five reps right before muscle failure, the point where you can’t do a decent rep anymore.

You can recognize stimulating repetitions by the fact that they feel significantly heavier than the first reps of your set and because the performance is a lot stiffer, and therefore slower. After all, the more tired the muscle, the slower the contractions. And it is precisely those slow contractions that provide the most growth stimulus. The fatigue in a muscle is also called local (or peripheral) fatigue.

Yet, don’t tire a muscle too much in a set: depending on the type of exercise, leave one to three repetitions ‘in the tank’ (1-3 Reps In Reserve, RIR), so that on balance you get more qualitative sets and therefore more stimulating reps. So, usually train close to failure, but not completely.

NUMBER OF REPS

Whether you do a set with light weights (many reps) or heavy weights (few reps), it doesn’t matter much. Yet it’s best to train in the range of 6 to 20 repetitions.

If you train with very light weights (for example, with which you can do 30 repetitions) you will have to train to complete muscle failure to be sufficiently effective, while that is much more difficult in such a long set.

Training with very heavy weights (< 6 reps) is not recommended for muscle growth either, because they can deliver too few stimulating repetitions and because of a greater (and unnecessary) injury risk.

HEAVY, BUT NOT STIMULATING (ENOUGH)

Now, how come we sometimes do sets that feel heavy, but aren’t stimulating (enough) for significant muscle growth?

1. TOO MUCH CARDIOVASCULAR FATIGUE

Sometimes you have to stop a set early because the cardiovascular fatigue is too big. That is the fatigue related to the heart and blood vessels. This fatigue manifests itself very clearly in your breathing, just as it can during or after cardio exercise.

Some cardiovascular fatigue from regular (i.e. non-metabolic) strength training is unavoidable and okay, but be sure to limit the aerobic load as much as possible.

That strain is greatest when you do long sets of large compound exercises like the barbell squat. Therefore choose heavy weights – aim for 6 to 10 reps.

But even with smaller exercises a disproportionate amount of cardiovascular fatigue can arise, namely if you train in very high rep ranges (20-40 repetitions). There’s a good chance that your set will be stranded at 30 reps, when you could do 40 from a local fatigue perspective. That is a worthless set for muscle growth, because we already saw that with very light weights you should train all the way to muscle failure.

Lengthy sets are normally not necessary at all, unless you cannot do otherwise because of an injury or lack of training material with sufficient resistance.

Another cause of excessive cardiovascular fatigue is that you rest too short between sets. Rest 1-2 minutes between sets of isolation exercises, 2-3 for most compound exercises and 3-5 for squats and deadlifts.

Finally, the use of special training techniques such as supersets and dropsets can also cause unnecessary cardiovascular fatigue. Use these types of techniques only with a conscious goal, such as a metabolic training block.

2. TOO MUCH CENTRAL FATIGUE

Also central fatigue may be a spoilsport in your set. That is the fatigue in the central nervous system, that is, the brain and spinal cord. When this nervous system is fatigued, it has trouble activating your muscles. So even though the muscle itself is no longer fatigued, it no longer receives the correct instructions from the brain to use its full strength potential.

Central fatigue is somewhat abstract: where you perceive cardiovascular fatigue in your breathing and local fatigue due to loss of muscle strength, central fatigue cannot be felt in a specific place or way. It is more of an overall feeling of discomfort or tiredness that you experience.

Disproportionate central fatigue often goes hand in hand with cardiovascular fatigue. It therefore arises mainly with long sets, short rest times, and with special training techniques such as supersets. So see point 1.

Central fatigue also increases as your workout progresses. As a result, the quality of your sets later in your training will be lower than if you were doing those sets at the beginning. And that while the ‘late’ sets feel much heavier. For that reason, some coaches recommend programming each muscle group at least once a week at the beginning of the workout. In addition, do not train for too long: do 3-10 sets per muscle group per training and a maximum of 15 to 25 sets in total. At normal rest times, this equates to a maximum of 60 to 90 minutes of training.

Finally, the complexity of an exercise can also create additional central fatigue. If you have a lot of effort to do an exercise correctly, that in itself causes central fatigue. Normally, it decreases as you do an exercise more often (under the influence of neural adaptation). So don’t change exercises too often, but make an exercise your own, and then become stronger in it.

3. TOO MUCH LOCAL FATIGUE

A third possibility is that you start your sets with an unnecessarily large local fatigue, so that a muscle will tire unnecessarily quickly during the set. And that undermines muscle growth, even though such a set will undoubtedly feel heavy. Let’s take a closer look at this.

Yes, during a workout you have to tire your muscles, but local fatigue is not a goal in itself. Your goal is basically to create as many stimulating reps as possible with as few sets as possible. After all, the more sets you do, the more muscle damage you cause, the more that demands from your recovery capacity.

You therefore strive for the highest possible quality per set. And in principle, the ‘fresher’ the muscle is, the higher the quality of the set. Just think: in your first set for a certain muscle group you usually get the most (stimulating) repetitions. Although the quality may only be optimal in your second set, when your technique is optimized and you can achieve a better mind-muscle connection.

Either way, all of this means getting a muscle to start a set as fresh as possible. You can achieve this in the following ways:

• have sufficient rest time between sets and exercises (see point 1);
• don’t do too many sets for one muscle group during the same workout.

For example, if you only rest for a minute after a set, the local fatigue in your muscle has not yet been completely ‘cleared’ and you will reach muscle failure much faster than if you had waited two or three minutes.

And if you start a few more sets after ten sets for a certain muscle group, the muscle is much too tired to get a decent potential of stimulating reps from it. It is much better to save those sets for the next workout, when your muscles are fresh and toned again. Hence the advice of most coaches to do a maximum of 10-12 per muscle group per training. This is independent of the fact that you have already reached your full growth potential for that muscle group around 10 sets. At least as a natural. Ideally you program for a muscle group 3 to 10 sets per training.

The irony: if you start your 15th set for your chest during a workout, it will undoubtedly feel very heavy. However, that set is anything but productive and will only cause unnecessary muscle damage that may cost you muscle gains rather than gain additional muscle gains. Hard work pays off ? Not in this case.

In short, in the words of multiple Mr. Olympia Lee Haney:

Stimulate, don’t annihilate.

4. TOO MUCH MENTAL FATIGUE

You don’t always think about it, but psychological ballast can also negatively affect your training performance. If you enter the gym with all kinds of daily worries still lingering in your head (work stress, an upcoming exam, relationship problems, and so on), you may be less focused in your training. Result: your sets feel heavier than they actually are, so they don’t yield the optimal return.

That may sound a bit vague, but it was recently proven in a study that coach Omar Isuf discusses in this video. In short, subjects who had taken a mentally strenuous test just before the training performed about 15% worse than subjects who had just relaxed just before the training. Of course, this is only one study, but it seems plausible to us in every way that mental baggage can shorten physical functioning.

Well, we have a life outside the gym and things don’t always run smoothly. That is not an issue, as long as psychological stress is not a dominant factor in your life. After all, that can also seriously undermine the recovery from strength training .

Fortunately, strength training in itself also has a positive influence on the mental condition. If you enter the gym with a ‘full’ head, after a number of firm sets of your favorite exercise it may already be a lot emptier.

5. WEAKER SYNERGIST

Finally, it can also happen that you have to stop a set because another muscle group fails than the target muscle you are training. So you ‘fail’ because not the agonist (the muscle that makes the head movement possible), but a synergist (a muscle that accompanies the head movement) appears to be the weakest link. As a result, you don’t stimulate the agonist enough.

Often the forearms are the culprit, as with dumbbell lunges, deadlifts, and shrugs. In that case, it is important to strengthen this by means of separate grip training. You can also use aids such as lifting straps.

With dumbbell lunges, your traps can also prove to be a nuisance, because they help to hold the dumbbells. That’s why it’s better to do a separate set for each leg with rest between sets, rather than alternating both legs in one set. Or use a barbell instead of dumbbells.

Finally, you should not unnecessarily ‘pre-fatigue’ synergists, which is why it is best to do your abdominal exercises at the end of your workout, for example. Or why you shouldn’t do isolating biceps exercises before major back exercises.

IN SUMMARY

Heavy training does not automatically mean that you train effectively with natural bodybuilding. Conversely, effective training is generally quite heavy, but you also manage to save your strength at the right moments. To do this, follow the advice below.

1.   Create enough effective reps by training your sets to near muscle failure. As a rule, you use 1-3 RIR.

2.   Choose adequate weights so that you don’t do unnecessarily long sets. After all, these cause a lot of cardiovascular and central fatigue, which may outweigh the local fatigue, leaving your set stranded well before muscle failure. Aim for 6-10 reps for compound exercises and 10-20 reps for isolation exercises.

3.   Take plenty of rest between sets and exercises. If you rest too short, the central and local fatigue of the previous set will not be completely resolved, which will affect the quality of your next set. Rest for 1-2 minutes for isolation exercises, 2-3 minutes for most compound exercises, and 3-5 minutes for squats and deadlifts. Don’t ‘just’ do special training techniques like supersets: only consciously as part of a metabolic training block.

4.   Don’t make your workouts too long, otherwise the central fatigue will become too great at the end of your workout. Do 3-10 sets per muscle group per workout and a maximum of 15 to 25 sets in total. At normal rest times, this equates to a maximum of 60 to 90 minutes of training.

5.   Do not do too many sets and exercises per muscle group in one workout. After all, the more sets you do, the more central and local fatigue there is, the more that affects the quality of the late sets. Do 3-10 sets per muscle group per workout, respecting the previous point.

6.   Try to relax before the training and in this way also prevent you from starting your training with too much mental ballast. Because mental fatigue can also have a negative influence on training performance.

7.   Your set should ‘fail’ due to fatigue of the target muscle, not a failure of an auxiliary muscle. Therefore make sure that the auxiliary muscles are not pre-tired. If an auxiliary muscle turns out to be the weak link, such as the forearm muscle in various exercises, try to make it stronger. You can also use aids such as lifting straps.

8.   Don’t change exercises too often, but make sure you familiarize yourself with an exercise. Once you’ve mastered the technique, you don’t have to waste energy on it anymore and you can fully focus on achieving progressive overload, the key to muscle growth.