What is most important for strength: frequency or volume?

Question

One popular fullbody barbell strength training program prescribes 3 set (x 5 reps) 3 times a week. Another one prescribes 5 set (x 5 reps) 3 times a week.

In order to save time, thinking that volume was the important factor, I have trained 5 sets twice a week.

I was surprised to find this study that found that performing only 1 set each workout resulted in less hypertrophy but equal or greater strength than performing 3 or 5 sets. The increases in strength are large for a 8 weeks study, especially for the squat. This seem to indicate that they were not trained in the squat before the study. The change in strength does not increase with volume as one would expect. On the other hand it does not decrease with volume either. This seems to indicate that overtraining was not the cause for this curious result. One possible explanation I can come up with is this: benchpress and squat has a large component of skill. The increases we see in strength in this study is mainly due to improvement in this skill. It is limited how much the brain can improve in this skill per workout. If this is the case the whole study becomes pretty worthless with respect to strength.

Also note that 8-12 reps was used. They mention that "it seems likely that training in more of a powerlifting range (3-5 reps) would necessitate the performance of more sets to maximize strength". Sadly this was not tested.

Another possible more general explanation is that hypertrophy is dependent on total volume, whereas strength is dependent on the total number of workouts per week once a minimum effective dosage (volume) is met.

Is this correct? Are there other studies that collaborate or contradict this?

If so I am thinking I am better off doing 2-3 sets 3 times a week than doing 5 sets twice a week.

The forementioned study seem to collaborate the old notion that bodybuilders are weak but "bloated". Greg Nuckols seem to disagree with this: Powerlifters Should Train More Like Bodybuilders.

In another article he mentions that "Early on in training, there’s a very weak relationship between gains in muscle and gains in strength". This confirms what we see in the study above.

Furthermore: "For more experienced lifters, gains in muscle mass may explain up to 65%+ of the variability in strength gains, highlighting hypertrophy as a key factor for strength gains in trained lifters".

Answer 1

There are a number of considerations that we should make when evaluating a study like this one. The first, and perhaps the most obvious, is that it represents just one tiny part of the body of research that has been conducted. It must be balanced and considered against all other research of its type. That said, and in the words of the key author himself, this study was designed to fill a gap in the existing research.

Equally importantly though, we must consider the study's protocol itself, since there are invariably a host of underlying assumptions being made within its definition. And we should examine the conclusions of the authors, and consider whether those conclusions are aligned with their findings.

Few of us should be surprised by the claim that "Marked increases in strength and endurance can be attained by resistance-trained individuals with just three, 13-minute weekly sessions over an 8-week period..." But given that the same study "showed significant pre-to-post intervention increases in strength and endurance in all groups," (emphasis added) by itself, this statement is not very meaningful.

However, "these gains are similar to that achieved with a substantially greater time commitment." Whom are the authors referring to? With what training protocol? Against what is this being measured? This is a broad and subjective statement, which although surely not untrue, is meaningless without a clearly defined datum.

The abstract of the study goes on to say that "muscle hypertrophy follows a dose-response relationship, with increasingly greater gains achieved with higher training volumes," which is entirely consistent with standard training theory.

It is to the authors' credit that they did not try to draw any further conclusions about strength development outside of their discussion: "it seems likely that training in more of a powerlifting range (3-5 reps) would necessitate the performance of more sets to maximize strength." The study was not designed to compare strength-training protocol, and no meaningful conclusion can be drawn from it.

So yes, hypertrophy is a function of total volume, provided that volume is performed with a load that is adequate to induce muscle damage. Strength, however, is primarily a function of load and frequency, not volume—the distinction being that it is about training with near-maximal loads as often as possible without overtaxing the Central Nervous System. That last point is undoubtedly why the subjects in this study found greater strength gains with less training.

The article by Greg Nuckols requires a significant response in itself, but suffice to say that he presents a lot of excellent information, but then draws questionable conclusions. The simple fact is that hypertrophy training necessarily develops poor relative strength, since a significant portion of the muscle mass developed is non-contractile. And this is where he makes one fundamentally misleading claim that "A bigger muscle, all other things being equal... is a stronger muscle." This is only true if we concede that a bigger muscle developed through bodybuilding protocol is not going to be equal in composition or innervation to one developed through strength training, and is hence going to be weaker than one trained in the manner which he is not advocating.

I hope this perspective proves useful.