Loenneke JP. Muscle Growth Does Not Contribute to the Increases in Strength that Occur after Resistance Training. Med Sci Sports Exerc. 2021 Sep 1;53(9):2011-2014. doi: 10.1249/MSS.0000000000002662. PMID: 34398064.
Folland JP, Balshaw TG. Muscle Growth Does Contribute to the Increases in Strength that Occur after Resistance Training. Med Sci Sports Exerc. 2021 Sep 1;53(9):2006-2010. doi: 10.1249/MSS.0000000000002732. PMID: 34398063.
Typically we associate increase in size with an increase in strength. Or this at least would be common sense thinking. But how much is this true? Turns out like most things to do with humans it can be complex.
Most strength adaptations appear to be related to our ability or recruit and contract muscles more easily. There are studies for example that show that when growth occurs in different training programs groups with superior gains in size don’t always show significantly more improvement in their strength. Meaning that they are sometimes related but not a requirement. It also seems that muscle size has some relationship with strength as seen in some studies on elite powerlifters but it may not be black and white.
For example, while training studies looking at high and low load training show similar results in terms of growth. Higher load training groups show significantly more improvements in strength. Which suggests that the load being used impacted the specific adaptation more than the growth of muscle.
There is some evidence that size can result in variations of strength expression up to 50-80% of variations. And in untrained individuals we can see most adaptations early in training are strength based and hypertrophy then follows. Which means we could see that strength improvements proceed size changes due to loads used and other common variables we manipulate. It also seems there is a lack of long term studies that look at how muscle mass contributes to strength gains. This is however hard to directly associate at this time. But as a rule of thumb for very simple exercises like a fixed position leg extension we might be able to use improvements in performance over time as well as circumference measurements as proxies for muscle growth. This is also where progress pictures would be important. This creates some redundancies but helps us have metrics to track overtime to gauge progress.
Bettariga, Francesco & Turner, Anthony & Maloney, Sean & Maestroni, Luca & Jarvis, Paul & Bishop, Chris. (2021). The Effects of Training Interventions on Interlimb Asymmetries: A Systematic Review With Meta-analysis. Strength and Conditioning Journal. 10.1519/SSC.0000000000000701.
Inter limb asymmetries refers to imbalances between sides. This can be normally be considered via many performance metrics. It is thought that these can reduce overall performance and increase risk of injury but this far is inconsistent in research. Normally, 10-15% differences side to side are considered significant. However, it seems that often asymmetrical performance might be task specific and sometimes within the norm. And it appears that one test is not sufficient to quantify asymmetry.
It seems that in the study training can have a moderating effect on asymmetry from one side to another but was specifically looked at here for jumping, counter movements, and changes in direction. One of the issues however is that there are large ranges of what migut be considered a normal side to side difference. And this calls into question many of the ways in which these differences are used for sporting performance. And remains unclear how these differences and training to reduce these actually impacts performance. It also seems that bilateral and unilateral training had an effect on the measures of asymmetry. Which goes against what most people think in regards to “needing” to train unilateral movements to reduce asymmetry in performance.
Overall this suggests that for performance in the contexts of powerlifting and bodybuilding we likely don’t need to worry that much about this. Except in bodybuilding having asymmetry in regards to physique development which is a key aspect of the sport.
Bernárdez-Vázquez R, Raya-González J, Castillo D, Beato M. Resistance Training Variables for Optimization of Muscle Hypertrophy: An Umbrella Review. Front Sports Act Living. 2022 Jul 4;4:949021. doi: 10.3389/fspor.2022.949021. PMID: 35873210; PMCID: PMC9302196.
We have seen and discussed in past newsletters that it seems mechanical tension, metabolic stress, and muscle damage are some of the largest factors that contribute to resistance training related hypertrophy. From a health and performance standpoint there are correlations between muscle mass and these outcomes. So beyond our pursuits of powerlifting and bodybuilding there are benefits to hypertrophy.
For example, hypertrophy adaptations are associated with a decreased risk for diabetes, high blood pressure, and general cardiovascular demands of exercise tend to be less. Further, there are improvements often seen in blood lipid profiles, glucose tolerance, insulin sensitivity, bone mass and many factors associated with quality of life.
Volume is most often defined as the total number of sets performed of an exercise or for a group of body parts per week. Traditionally, we see that higher volume programs result in more hypertrophy. Of course, this needs to be within reason because the definition of high volume and response, and or ability to recover can vary person to person. Volume within session can have a cap but varies person to person and is seen to range to as low as 1 set for elderly untrained individuals, and in trained people can cap as low as 6 sets. Often in people ages 18-65 multiple sets result in better results than singular sets. Some research shows 4 or less sets per week can be beneficial, but most suggests that more close to “optimal” results are seen with 10-20 sets per week. But this doesnt mean that someone might do better with less, or even more sets. As often in people who do not see a response when more sets are added we see improvement in growth.
Frequency is also one of the main variables that we can manipulate to have a large effect on hypertrophy. This would be how often within a week we train a muscle/group. If volume is equated frequency seems to not matter much, so often frequency is used to manipulate volume across a week to allow for better recovery from that volume. This also might make it easier to perform more volume within a week as well. For example, an athlete might find it difficult to recover from 1 day with 12 sets of quad focused exercises, so might feel they can tolerate more volume with 2 days of 6 sets or even 4 days with 3 sets. And we can refer back to a prior newsletter for a deeper understanding of frequency.
Intensity is the load that we utilize or percentage of 1RM, we can also in some cases use RPE and RIR as a proxy for this to just understand we are in the right ball park. As training with lighter loads under 60% 1RM can produce similar results in muscle size but often is seen needing to be taken closer to momentary failure to achieve similar results. And to a point heavier loads do result in better improvements in strength due to specificity. But these choices can be used individually as well, as since high loads and lighter loads result in similar growth, we could manipulate this depending on an individuals response. For example, some people feel they can recover better with less exposure to loads over 80% ish + 5-10% so it may be easier to complete a program using lighter weights if youre hoping to achieve growth. This is messier when it comes to powerlifting and maybe better saved for discussion in our podcast.
Now we are getting more into the weeds, so we will look at contraction type and rep duration. What is typically seen is that with the eccentric portion of lifting we can utilize more weight and produce more tension on a muscle. While this is the case and you can see good growth with only eccentrics for many exercises they become inconvenient or more time consuming. Also with eccentric contractions we tend to see more growth at the distal portion of a muscle, versus when concentric only is performed, in the mid portion of the muscle belly. So it seems more appropriate to utilize both most of the time. For rep duration, it seems there are similar results between .5-8 seconds, and we previously reviewed an article exclusively looking at this. And rep duration with longer time tends to result in ability to perform overall less volume and possibly mechanical tension as there may be a need for a certain velocity to help stimulate enough mechanical tension.
As far as exercise selection, it seems that multi joint exercises result in the most benefit for the overall time performing exercises. However, single joint exercises in combination with multi joint, result in superior growth. This might be because with single joint exercises we can achieve certain length tension relationships. Further we might think of this as refining specific areas more with single joint exercises. Also, the order doesnt seem to make a huge difference but has less evidence to make a strong conclusion here. It may be prudent for example then with particular lagging body parts to do the isolation exercises for those at the beginning of a workout or when more fresh to allow more energy to be put into that training. And as with exercise order the time of day we train doesnt seem to make a huge difference so it might be best to train when it is most convenient for you or when you feel best fits your life.
Periodization which is the logical and systemic process of sequencing training also seems to make little difference in hypertrophy. While it likely helps to have an idea and overall plan so you can make adjustments our traditional thoughts of what periodization is not needed for growth. Which is discussed in greater detail in a past newsletter.
Lastly, blood flow restriction training can be used as a modality and results in similar hypertrophy often with lesser training loads. However, it is not superior than traditional training. This doesnt mean we shouldnt ever use it, you could utilize this if you enjoy it or find you are limited with loading for example when injured.
Overall, I think many of us knew most of this information but it is always good to refresh and discuss, especially as we can often get lost in finer details.
Kiely, J. Periodization Theory: Confronting an Inconvenient Truth. Sports Med 48, 753–764 (2018). https://doi.org/10.1007/s40279-017-0823-y
Periodization has been a mainstay in most introductions to resistance training regardless of the goals. However, some issues arise with the foundations of periodization as a theory. Largely this theory has gone unchallenged and unchanged over the last 70 years since its inception. Yes we have new models within the frame work, for example undulating periodization, block, linear, non linear, but the foundation itself has not been as questioned.
Primarily, periodization is also based on assumptions that adaptation can be reliably predicted, and adaptation is a purely biological process. But since the first theory emerged our understanding of how we react to stress has changed. While we can still appreciate the people who contributed to the theories creation we can and should move past outdated concepts and assumptions. For example, how often do we hear that strength training stunts children's growth? This has continued to persist in culture despite the base of this claim being from a 1960 report from Japan where malnourished children were performing hard manual labor daily. And this has persisted despite good evidence to the contrary, and common sense telling us that in this report there was a lot going on that likely contributed to those children having stunted growth.
Periodization is a planned practice of stress management, but we continue to recycle interpretations that largely only focus on the training stress itself. For example, we assume that there is a generalized adaptation that occurs in predictable manner, known as generalized adaptation syndrome (GAS). This comes from study on rats and utilizing understanding of homeostasis. Or an organism will revert back to a tightly controlled range of responses to stress. However, we now know that this isnt the case except in very specific situations or extreme circumstances. Currently stress research has adapted the term allostasis. Which is a less tightly and ridged controlled way we respond to stress. This also accounts for multiple processes changing simultaneously, as well as accounting for social and personal feeling or emotions surrounding stress. As we are not passive recipients of stress, we have feelings about how that stress effects us. So due to these other factors influencing our adaptation and reaction to stress, the responses are not always predictable and linear. As an example, our blood pressure and heart rate can vary greatly through the day, as is now mostly common sense that non physical stressors can significantly influence both.
Largely our body also adapts to stressors in a way that is to mitigate future issues based on past experiences and “threats”. Our body wants to know what is going to happen and have clear predictions and plans about how to respond (this is a reduced understanding of a concept called predictive processing). So we can see a collaborative process occur where we either preserve or deploy resources to adapt to an otherwise unpredictable and changing environment. We over time gain stability through change and more experience. Think of learning a new language for example in spanish the word for left is izquierda and the word right is Derecha, when pronounced to an untrained ear the R sound in Derecha is more pronounced, so I related that to the english word right and is a way I remembered which one was which. An example, of cognitive allostasis.
What we see overtime is that with allostasis as we respond to stress there will be positive adaptations to the overall “load” or stressors that we face, but overtime if that stress is significantly overwhelming, or hard to cope with we will see the penalties of that. For example, worse training when we have worse sleep, increased life stressors, etc etc. There is a blend of psycho-emotional, physiological, biological, neural, immune and behavioral responses.
So our expectations surrounding training also influence the adaptations. If we feel a training session is going to be hard and grueling it likely will be and be harder to recover from. Versus if we enjoy training and feel it will be beneficial it will more likely be beneficial. And evidence exists that general life stress seems to impact injury rates in sports, as elevated psycho-emotional stress seems to be related to injury, as well as personality traits like self blame and perfectionism being related to increased injury probability. We often see things like increased daily hassles, periods of increased academic and work stress, are related to injury as well. These would demonstrate the concept of allostatic load being too high. We also see these can impact our immune system, mood, and cognitive function.
While gym training provides a stimulus to adapt to, the results and extent of adaptation is filtered by multiple interacting filters before we see changes in outcomes. We can see this as even with the same training program individuals can have a huge variance of responses, and while between group differences may vary, within group responses are similar. So claims that one best way of doing thing exists is false, unless we could prove there is a direct dose/response relationship that is predictable over given timeframes.
We have a natural tendency to seek order as humans, thus more easily measured metrics get taken more into account, but measurability does not directly reflect importance. So while we can use a frame work to help us make decisions, we need to be flexible taking into account individual preferences, history, personality, and expectations to help us.