Much has been written about nutritional and training strategies that optimise hypertrophy. However, if we include a desire to age gracefully, there is another a consideration that needs to be made. Functional strength coach Paul Ehren explains.
According to Brad Schoenfeld, arguably the world’s foremost researcher into hypertrophy and resistance training, hypertrophy is: “An increase in the size of muscle tissue. During the hypertrophy process contractile elements enlarge and the extracellular matrix expands to support growth. Growth occurs by adding sarcomeres, increasing non-contractile elements and sarcoplasmic fluid, and bolstering satellite cell activity.”
This one paragraph covers an enormous amount of ground and leads us into an in-depth discussion, not only of the anatomy and biochemistry involved, but also the drivers of any hypertrophy response and the resistance training fundamentals that are seen to trigger it. Bear in mind too that the word hypertrophy breaks down into two distinct elements: hyper (meaning ‘beyond or exceeding’), which is the training element, and trophia (meaning ‘nourishment’), which relates to the nutritional aspects.
Types of hypertrophy and strength
When we initially think of hypertrophy and hypertrophy training, we may associate these terms with strength and physique athletes. However, there are currently very few athletes of any discipline who do not incorporate hypertrophy or strength training into their regular off-season programmes.
This observation may, in turn, lead us into a discussion of functional (myofibrillar) hypertrophy, non-functional (sarcoplasmic) hypertrophy, and some of the different definitions of strength. These include ‘maximal’, ‘relative’, ‘functional’, ‘speed strength’, ‘strength endurance’ etc. Each of these forms of training have particular relevance to different sporting modalities, where the requirements of the activity are so varied. The powerlifter, triple jumper, martial artist, gymnast, bodybuilder, and track cyclist are all different in their appearance, and the demands of their sports are very diverse. However, without exception they all would have utilised strength/hypertrophy protocols within their training blocks.
Functional hypertrophy
It then becomes the job of the coach to ensure that the training undertaken by the athlete meets the requirements of their sport – this has been termed ‘functional hypertrophy’. It would, for example, be completely counterproductive to achieve strength gains in a gymnast, but accompany that with an increase in muscle bulk. This may destroy their power-to-weight ratio and make them less able to perform explosive movements. Conversely, the additional size, combined with bolstered strength, might be exactly what the front row rugby forward or the American football defensive lineman is looking for. In reality, for each athlete there will be a huge range of both acute and chronic adaptations to strength and hypertrophy training in addition to muscle size/strength, some of which we will touch upon later.
However, let’s pause for a minute to consider just one – neural adaptation. The neural learning process will almost certainly precede any muscular growth by some weeks, if not months (1) and involves, inter alia, muscle activation, motor unit synchronisation, antagonist co-activation, and doublets. It’s easiest to think of these adaptations as ‘motor learning’. If we take a complex skill, such as a golf swing or a tennis stroke, the initial performance of the movement will probably be somewhat jerky and uncoordinated, improving with the correct practice and coaching. The same is true for strength-based moves, such the bench press or a squat. Neural adaptation to these will lead to an improvement in strength before a change in muscle size is noted. Please retain this concept of neural adaptation in mind when we start to consider other aspects, such as general health and ageing.
Drivers of hypertrophy
The three main training-induced drivers of the hypertrophy response are: mechanical tension (2), metabolic stress (3), and muscle damage (4). I use the word “driver” to mean an event which triggers a cellular response, leading to increased skeletal muscle synthesis.
Looking at each of these in turn:
Mechanical tension
Mechanical tension would involve putting a muscle under load, thereby triggering a process known as mechanotransduction, in which the loading process is translated to molecular events, which mediate intercellular anabolic and catabolic pathways.
Metabolic stress
Metabolic stress can be defined as the accumulation of muscle metabolites that result from resistance training, including lactate, inorganic phosphate and hydrogen ions, which, as well as contributing to fatigue, again mediate the pathways mentioned above. You will recognise this as the ‘muscle burn’ you feel after completing a high number of repetitions of an exercise.
Muscle damage
Muscle damage describes the physical disruption to the contractile elements of skeletal muscle tissue (4), leading to that unpleasant phenomenon known as DOMS – delayed onset muscle soreness. The repair of this damage, and the satellite cell activation it promotes, is seen to contribute to the growth of the muscle(s) concerned.
The exact contribution that each of these drivers plays to the process of hypertrophy is much debated, and to my mind everyone probably has their own ‘sweet spot’, where each element contributes to their maximum potential. Aiming for this sweet spot involves the athlete and coach in the manipulation of the training variables, which would make up a strength/hypertrophy-based programme. The choices made would have a fundamental effect on the results expected for the athlete, and would therefore vary depending upon the needs of a particular sport.
Hypertrophy and health
Leaving the whole question of elite sporting performance to one side for the moment, let us consider some other aspects of hypertrophy and resistance training, and the subsequent adaptations, that arguably are far more important, and may add significantly to the long term quality of our lives and that of our clients.
Resistance training is finally being seen as far more than simply a way of producing bigger and/or stronger muscles. Skeletal muscle contraction, and the methods of achieving this, are demonstrating a positive interaction with just about every bodily system to the benefit of our physical and mental health. Ruegsegger and Booth stated: “It is clear that physical training is complex biology, invoking polygenic interactions within cells, tissues/organs and systems, with remarkable cross talk occurring (5)”. This statement fits perfectly within the integrative approach that many of us are now applying to both our sporting and non-sporting clients.
Considerable research now exists to show the dangers of a sedentary lifestyle and how general exercise and activity can help alleviate these problems.
Some powerful sedentary lifestyle quotes:
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- “Sedentarism and physical inactivity are highly prevalent globally and are associated with a wide range of chronic disease and premature death (6).”
- “Adequate muscle mass and strength are not only important for sport performance, but these attributes are also associated with good health and longevity (7).”
- “Current theories and research (on ageing) is wide ranging, but exercise remains a constant (8).”
- “Exercise is the one true poly pill (9).”
- “All aspects of training are key to health and ageing (9).”
If we can therefore take it as read that exercise is fundamental to our long-term health and successful ageing, can we then apply the factors I have already discussed to both older athletes and the non-athletic population? The answer I believe is a resounding “yes”; it is simply a matter of redefining the loads and intensity levels to a point that are safe and relevant to the client in question. In doing this we also need to consider other areas, in addition to resistance training, which I tend to group as ‘functional athletic training’, taking account of such things as movement in various planes, flexibility, cardiovascular fitness, reaction time, hand-eye coordination, and posture etc.
If you are remembering the point I made earlier about neural adaptations, hopefully you can see that muscular coordination, stability, and increased reaction time become increasingly important to our overall health as we age, with falls being among the biggest contributors to mortality/morbidity in older individuals. When dealing with individuals who have been non-athletic for many years, possibly a lifetime, we need to be aware that the term ‘activity’ should potentially be substituted for ‘exercise’, which can involve many non-gym/track/pool-based methods of movement.
Downsides to hypertrophy?
It is at this point that we need to pause for a second and consider if there any downsides to what we are suggesting? Strangely, if we deep dive into the hypertrophy literature, there is a potential dilemma which presents itself.
Looking into the biochemistry of hypertrophy, the principal master network, accepted by researchers in the field, is thought to be the Phosphatidylinositol 3 Kinase (PI3K/AKT) mTOR pathway (10). Interesting, intermittent fasting research recognises that protein restriction, which leads to the lowering of intracellular amino acid levels, reduces mammalian target of rapamycin (mTOR) activity, and stimulates autophagy (a favourable process for ageing and cancer avoidance) (11). Other research papers concur with this connection between lowered mTOR activities and health ageing (12-15). So, on one hand the stimulation of mTOR is seen to be fundamental in the hypertrophy process, whilst on the other hand, it has been linked to chronic disease and accelerated ageing.
Does mTOR have negative consequences towards ageing?
If we delve into this quandary from a nutritional perspective, the descriptors ‘protein restriction’ and ‘caloric restriction’ (also well discussed in the fasting literature) are nebulous terms that can be extremely misleading when considering actual food consumption. For instance; is the restriction of free range, grass fed, organic meat the same as restricting a similar number of kilocalories and grams of protein in a processed, manufactured product? I think not, but the research to-date unfortunately does not differentiate food quality, only quantities.
Having identified a potential problematic duality of purpose for these particular pathways, we need to ask ourselves if this potential conflict exists for both sportsmen and non-athletes?
Research that directly compares and contrasts these two distinct mTOR roles seems very thin on the ground, so by extrapolating from the papers I have seen, and from my own sporting/coaching experience, I would like to suggest the following: The health benefits of exercise, including resistance training, is one of the few things that has universal acceptance across science and medicine, and together with the appropriate nutrition, is considered fundamental in helping us achieve our sporting goals, as well as continued good health and longevity.
We can then argue about the level of training undertaken: the famous J-shaped curve indicates that no exercise is extremely unwise, a moderate amount will help solve the majority of problems brought about by a sedentary existence, but excessive exercise may well be counter-productive, particularly if placed on top of a chronic stress-filled lifestyle.
Protein requirements as we age
BUT (isn’t there always a but…), it appears well established, in literature, that our protein requirements increase as we age, and in particular, our leucine threshold goes up. The general anabolic response to resistance training also blunts as we put more personal ‘miles on the clock’, so would that call for more training, or for smarter training?
Pausing for breath again here, and analysing our use of language, we do need to be careful that phrases used often enough can tend to become taken as truth; however, a pile of facts is no more good science than a pile of bricks is a house. Protein requirements may well increase with age, but does this simply mean that we need to increase our consumption?
What if I said that the instances of hypochlorhydria (low stomach acid) and pancreatic enzyme insufficiency increase substantially with age? This would tend to indicate that we should not simply add more whey protein to the diet. Similarly, should we not be looking at the absorption and utilisation of the protein/amino acids after the digestion process, and the various cofactors which aid these processes?
Conclusions
Having been a competitive athlete and a coach for some 25 years, and now being in my seventh decade, I think I can provide some perspective between published research and that of personal experience.
I am firmly in favour of leading a balanced and healthy life. Hypertrophy, and the resistance training which enables it, is seen as a vital part of most, if not all, athletes’ training regimes. In the non-athletic world, I would suggest that this modality of exercise should be part of everyone’s health and fitness routine.
The issues highlighted with mTOR and other pathways is certainly a point of academic interest, and worthy of further research, but to my mind it is the control of outside influences, including stress, poor lifestyle choices, health issues and medication, pollution and other toxins, continued extremes of exercise, or radical nutrition protocols, etc. that require most of our attention.
- Moritani T and deVries HA (1979). Neural factors versus hypertrophy in the time course of muscle strength gain. Am J Phys Med. 58:115-130.
- Hornberger TA et al (2006). The role of phospholipase D and phosphatidic acid in the mechanical activation of mTOR signaling in skeletal muscle. Proc Natl Acad Sci USA. 103:4741-4746.
- Rooney KJ et al (1994). Fatigue contributes to the strength training stimulus. Med Sci Sports Exerc. 26:1160-1164.
- Clarkson PM and Hubal MJ (2002). Exercise induced muscle damage in humans. Am J Phys Med Rehabil. 81:52-69.
- Ruegsegger GN and Booth FW (2018). Health benefits of exercise. Cold Spring Harb Perspect Med. 8(7):a029694.
- Arocha Rodulfo JL (2019). Sedentary lifestyle a disease from xxi century. Clin investing Arterioscler. 31(5):233-240.
- Wackerhage H et al (2018). Stimuli and sensors that initiate skeletal muscle hypertrophy following resistance exercise. J Appl Physiol (1985). 126(1):30-43.
- Fan X et al (2017). Mechanisms of hippocampal ageing and the potential for rejuvenation. Ann Review of Neuroscience. 40:251-272.
- Pete Williams. Functional medicine practitioner – direct communication.
- Bodine SC et al (2001). Akt/mTOR pathway is a crucial regulator of skeletal muscle hypertrophy and can prevent muscle atrophy in vivo. Nat Cell Biol. 3: 1014-1019.
- Abbasi J (2017). Can a diet that mimics fasting turn back the clock? JAMA. 318:227-229.
- Guertin DA and Sabatini DM (2007). Defining the role of mTOR in cancer. Cancer Cell. 12(1):9-22.
- Heras-Sandoval D et al (2009). The Phosphatidylinositol 3 Kinase mTOR pathway as a therapeutic target for brain ageing and neurodegeneration. Pharmaceuticals (Basel). 4(8):1070-1087.
- Johnson SC et al (2013). mTOR is a key modulator of ageing and age related disease. Nature. 493(7432):338-345.
- Liu GY and Sabatini DM (2020). mTOR at the nexus of nutrition, growth, ageing and disease. Nat Rev Mol Cell Biol. 21(4):183–203.
Paul Ehren is a former national and international competitive bodybuilder. For the last 15 years, he has run his own health, exercise and nutrition consultancy, with clients ranging from elite sportsmen and successful business people, to regular recreational sportspeople and those interested in simply improving their health.
Alongside his sporting connections, Paul is using the basic principles learned from years of participation in and coaching of elite sport to target successful ageing and population health, as some of the biggest challenges facing the country today.
Further details are available from www.paulkehren.co.uk
If you would like to learn more about hypertrophy from Paul Ehren and other hypertrophy specialists, we run a specialist short module called Hypertrophy for Sport and Exercise. It can be studied for CPD/CEU purposes, or as part of our Certificate of Integrative Sports Nutrition.
