For years, strength training has been surrounded by almost “sacred” rules:
3 sets, 8–12 repetitions, training to failure, periodisation…

As if there were only one correct way to do it.

But the new Position Stand from the American College of Sports Medicine (ACSM) — the first in 17 years — has just updated that view based on the largest synthesis of evidence to date.

This document is based on an umbrella review of 137 systematic reviews involving more than 30,000 participants, analysing how variables such as volume, load, frequency or type of training affect outcomes such as strength, hypertrophy and performance.

And what it shows is not a new formula.

It is something simpler: there are many ways to train that work.

Different training approaches can lead to improvements in strength, muscle mass and performance, provided certain basic principles are met. And, in many cases, variables that were considered critical have less impact than previously thought.

In this article, we will break down this paper, but you can consult the full document here:
https://journals.lww.com/acsm-sse/fulltext/2026/04000/american_college_of_sports_medicine_position.21.aspx

First things first: strength training is not optional

The document does not begin by proposing methods or training structures. It starts with something more fundamental: strength training should form part of any exercise programme. Not as a complement, but as a central element.

The evidence shows that, compared with inactivity, strength training consistently improves muscular strength, muscle mass, power, muscular endurance and the ability to perform basic functional tasks such as walking, standing up or maintaining balance.

This point is particularly relevant because it shifts the focus from “how to train” to “whether one is training at all”. In this sense, the main conclusion is clear: the absence of strength training has a greater impact than any error in its application.

The major shift: there is no single correct way to train

This is where the document introduces one of its most relevant nuances.

For years, the discourse around strength training has focused on identifying the most effective method: the optimal combination of exercises, loads, volume or structure. This search for a “correct” model has not only shaped practice, but also the way training has been communicated, creating the impression that progress depends on adhering to a single valid approach.

The ACSM’s approach moves away from this logic.

The evidence shows that different training configurations can produce significant improvements in strength, muscle mass and physical function, without depending on a single format or a specific structure. This includes not only traditional gym-based training, but also other modalities such as:

• home-based training
• the use of resistance bands
• circuit training
• or speed- and power-oriented work

All of them have proven capable of generating meaningful adaptations when the stimulus is appropriate.

This point is important because it expands the framework of what is considered effective training. It is not that all variables have the same impact, nor that any approach produces identical results, but rather that there is far greater flexibility than traditionally assumed.

In other words, the document does not eliminate the importance of variables, but it does question the need to fit into a single model.

The underlying idea is clear: training effectiveness does not depend on adhering to a specific structure, but on consistently applying a sufficient stimulus within multiple possible configurations.

Improving vs optimising: a key distinction

The document introduces a distinction that is rarely clearly addressed in training: improving and optimising are not the same.

In light of the evidence analysed, it is clear that a wide variety of programmes can generate significant improvements in strength, hypertrophy and physical performance. In other words, the threshold required for progress is not particularly restrictive: different combinations of exercises, loads or structures can be effective if the stimulus is appropriate.

Optimising, on the other hand, operates at another level. It involves more precisely adjusting variables such as volume, load or training organisation with the aim of maximising adaptations and extracting peak performance.

The problem is that, in practice, this distinction has become blurred.

Elements related to optimisation are often presented as basic requirements, as if they were essential to achieve any type of result. This has contributed to building an unnecessarily complex perception of training, where it seems that progress depends on getting multiple variables right from the start.

The consequences are clear:
on the one hand, the entry barrier for beginners increases;
on the other, a level of sophistication is introduced that does not always translate into additional benefits for those already training.

Against this trend, the ACSM document proposes a more evidence-aligned interpretation. It does not deny the usefulness of optimisation, but it does reposition its role.

The conclusion is clear: it is possible to achieve meaningful improvements without adhering to a theoretically optimal programme.

 

What does matter (and what matters less)

The study does not suggest that all training variables carry the same weight. What it does is better organise priorities: not everything influences results equally.

What does play a relevant role

First, the document highlights three elements that consistently influence adaptations.

• Effort

The evidence is quite clear on this point: it is not necessary to reach muscular failure to improve strength, hypertrophy or power.

For years, it has been assumed that training to fatigue was essential for progress, but the data do not support that idea. Taking every set to the limit does not consistently provide additional benefits, so it should not be considered a requirement within programming.

However, this does not mean that effort is no longer important. In fact, quite the opposite: what is essential is that the stimulus is sufficient.

This stimulus can be achieved in different ways, with different loads and training structures, as long as the level of demand is appropriate.

In this sense, the document introduces a key nuance: effort does not depend solely on reaching failure. It can be regulated through tools such as perceived exertion or proximity to failure.

As a practical reference, working close to failure — for example, leaving approximately 2–3 repetitions in reserve (RIR) — is sufficient to generate adaptations in most cases, without needing to take each set to the limit.

Moreover, the document notes that not all adaptations benefit from extreme effort. In the case of strength or power, systematically training to fatigue may even be counterproductive.

At its core, the idea is simple: you do not need to train to the limit, but you do need to train hard enough to give the body a reason to adapt.

 

• Volume

Volume is one of the variables most consistently identified by the document as relevant, especially in relation to hypertrophy, although it also influences strength.

In general terms, the relationship is quite intuitive: more work tends to translate into more adaptation, at least within certain ranges.

In fact, if simplified, the logic is clear:
one set is better than none,
two sets are better than one,
and adding more work can continue to provide benefits.

However, this does not mean that more is always better.

As volume increases, improvements tend to become progressively smaller. This is what is known as diminishing returns: each additional set contributes something, but less than the previous one. Moreover, there is no universal number of sets that works equally for everyone or in all contexts.

This is where the document introduces an important nuance that helps better understand how training actually works.

Beyond the specific number of repetitions or the weight used in each set, what determines adaptation is the total stimulus received by the muscle. And that stimulus does not depend on a single variable, but on how volume, load and effort are combined.

This explains why similar results can be achieved with different load ranges: it is not only the weight that makes the difference, but the total amount of work accumulated.

At its core, the idea is simple: there is no single “correct” way to combine repetitions and loads, but it is necessary to perform enough work for the muscle to have a reason to adapt.

 

• Load (depending on the goal)

Load remains a central variable within strength training, but its role makes sense primarily when interpreted through the principle of specificity.

In other words, not all adaptations respond in the same way to the same loads.

For strength development, the best adaptations are associated with high loads, typically expressed as high percentages of 1RM.

In the case of power, the approach changes: moderate loads combined with fast execution are prioritised, where movement velocity — especially in the concentric phase — becomes decisive.

For hypertrophy, however, the scenario is more flexible. The document states that there is a fairly wide range of effective loads, provided that the level of effort is sufficient. This means that it is not necessary to work within a specific repetition range to build muscle mass.

In addition, the paper highlights something important: load cannot be analysed in isolation. It is directly related to the number of repetitions performed and to the level of effort applied in each set.

Therefore, rather than focusing on finding a “perfect” intensity, the message is different: load matters, but its application depends on the goal and the context, and allows for more flexibility than traditionally assumed.

 

What matters less

Compared to the variables above, the document also introduces an important nuance: some elements traditionally considered key have less impact than previously thought.

Specifically, the evidence analysed allows us to put into perspective the role of several variables:

• Training to failure

Here, the message is quite clear: performing sets until momentary muscular failure does not consistently improve adaptations in strength, hypertrophy or power.

In other words, it is not a requirement for progress.

What remains necessary is reaching a sufficient level of effort that acts as a stimulus. And this can be achieved without taking each set to the limit, simply by training close to failure.

In this regard, the document introduces a useful idea: proximity to failure can be estimated using different tools, such as repetitions in reserve (RIR). As a practical reference, it mentions training while leaving approximately 2–3 repetitions in reserve, although without establishing it as a strict rule.

It also notes that in certain contexts — for example, in less experienced individuals or older populations — systematically training to fatigue may not be the most advisable approach, both for safety reasons and due to the potential loss of technical quality.

At its core, the idea is quite straightforward: you do not need to train to the limit to progress, but you do need to train enough to generate a stimulus.

 

• Exact training frequency

Frequency can influence results, but its impact decreases when total training volume is kept constant. In addition, the available evidence does not allow for establishing a clear dose–response relationship — that is, it cannot be stated that training more days per week systematically produces better results.

In this context, the number of weekly sessions loses importance as an isolated variable. Its relevance depends, to a large extent, on how the total volume of work is distributed.

In practical terms, this means that different distributions of training across the week can be equally effective, provided that the total stimulus applied to the muscle is adequate.

 

• Periodisation

Although periodisation remains a valid tool within training programming, the document introduces an important nuance.

The evidence suggests that, in healthy adults, it is not significantly superior to non-periodised programmes when the stimulus is properly designed.

This does not eliminate its usefulness — especially in specific contexts or with particular objectives — but it does reduce its role as an essential element for improving strength or hypertrophy in the general population.

In this sense, periodisation shifts from being a central requirement to being one more tool within a broader set of options.

 

• Type of training or equipment

The document also states that there is no clearly superior training modality.

Different approaches — from machine-based or free-weight training to resistance bands, home-based training or circuit formats — can generate similar adaptations when applied with an appropriate stimulus.

This reinforces an important idea within the document: context or equipment are not limiting factors in themselves, provided that the basic principles of training are respected.

As a result, the focus shifts from “where” or “with what” one trains, to “how” the stimulus is applied.

 

Overall, the document does not eliminate the importance of these variables, but it does adjust their relevance.

The conclusion that emerges is clear: fewer factors are decisive than traditionally assumed, and there is greater flexibility in how to structure an effective programme.

 

Progression: important, but not essential

Progressive overload has traditionally been one of the central principles of strength training.

The ACSM document does not question it, but it does introduce an important nuance: it is not necessary to obtain benefits.

In other words, it is possible to improve strength, hypertrophy and performance without the need to constantly increase load, volume or other training variables.

Progression becomes more important when the goal is to continue progressing in the long term, especially in more experienced individuals. However, it should not be understood as an essential condition for training to be effective.

This allows us to rethink a widely held idea in the field, according to which progress necessarily depends on continuous improvements in training variables. The evidence suggests a more nuanced interpretation: progress can occur without constant progression, although progression is useful for sustaining it over time.

In other words, progression helps you keep improving, but it is not what determines whether training works from the beginning.

 

Adherence as the cornerstone of training

Beyond specific variables, the document introduces a deeper shift in perspective. If multiple forms of strength training can generate similar adaptations, then the choice of programme no longer depends solely on its theoretical design.

It depends, to a large extent, on its sustainability.

For this reason, the document places clear emphasis on the individualisation of training, not only as a tool to optimise results, but as a key factor for:

• improving adherence
• increasing enjoyment
• ensuring safety
• and adapting training to each individual’s context and characteristics

In this sense, individualisation shifts from being a secondary element to becoming a central condition. Because, ultimately, the effectiveness of training does not depend only on how it is designed, but on whether it is maintained over time.

And this is the key idea running throughout the document:
without adherence, there is no training; and without training, there are no results.

This has a direct implication: in practice, doing less but consistently is often more effective than trying to optimise without continuity.

 

And also: it is safe

The document also addresses an aspect that, in many cases, still raises doubts: strength training is safe for healthy adults of all ages.

The evidence analysed shows that:

• it does not increase the risk of serious adverse events
• the incidence of non-serious events (such as discomfort or fatigue) is similar to that of aerobic exercise
• and cardiovascular complications are even less frequent

This point is not minor, especially in the general population or among individuals less familiar with strength training, where certain perceptions of risk still persist that are not supported by the evidence.

So, what really changes?

The ACSM does not introduce a new method or completely redefine strength training.

What it does is something more relevant: it aligns the message with the available evidence.

Until now, much of the discourse has been focused on:

• finding the correct programme
• following specific structures
• optimising every training variable

The document proposes a shift in approach.

The focus moves towards:

• training strength regularly
• applying a sufficient level of effort
• sustaining training over time
• and adapting it to each individual

If the document had to be summarised in a single idea, it would be this:
strength training is effective in multiple forms, and its impact depends more on consistency than on perfection in its design.

And that, more than changing how we train, changes how training should be understood.

This shift in perspective, although subtle in appearance, has important implications both for those who train and for those who design and communicate training programmes.