Muscle hypertrophy: Theory to application

Hypertrophy is defined as the increase in volume of an organ or tissue due to the growth of its component cells, and we’re primarily referencing skeletal muscle hypertrophy. Simply put, we’re talking about getting jacked...

By Travis Mash

Hypertrophy is defined as the increase in volume of an organ or tissue due to the growth of its component cells, and we’re primarily referencing skeletal muscle hypertrophy. Simply put, we’re talking about getting jacked. This is the aspect of exercise science that seems to have the most recent research, so this topic required the most amount of research which I truly enjoyed. My goal for this article is to lay out this complicated topic in a simple and digestible way, so you can discern the information and put it to use. Here’s what we are going to discuss:

  • ‘What’s taking place when we’re getting jacked?’ or what is skeletal muscle hypertrophy? (The physiology)
  • ‘How do we get Jacked?’ or what stimulates skeletal muscle hypertrophy? 
  • ‘Best way for me or my team to get jacked?’ or which stimuli makes the most sense for the Individual?
  • ‘Monitoring to make sure we’re getting jacked properly’ or monitoring to ensure desired adaptations.

Content menu:

What is Muscle Hypertrophy?

While writing this article, I asked myself the question, “who discovered skeletal muscle hypertrophy in the first place?” It turns out that Morpurgo B. (1897) was the first to document his research on work induced skeletal muscle hypertrophy by looking at the sartorius muscle of dogs during 2 months of run training. He documented an increase in muscle fiber diameter that he related to an increase in sarcoplasmic volume. Morpurgo’s work started a chain of research and led to alternative conclusions. For example, Helander E.A. (1961) noted increases in muscle weights and myofibrillar density in guinea pigs during four months of run training. He compared his guinea pigs performing the run training to a control group of guinea pigs that were restricted from exercise. He concluded that exercise enhanced the myofilamental density in the muscle cell, and inactivity decreased the myofilamental density and increased the nonfunctional sarcoplasmic content. Thanks to scientists like Brad Schoenfeld, Andy Galpin, and Cody Haun, we have a better understanding, but there is still room for improvement.

Check out Part 1 video presentation:


Hypertrophy vs hyperplasia:

Muscle hypertrophy refers to the increase in muscle fiber size. Muscle hyperplasia refers to an increase in the number of muscle fibers. Until recently, there was no evidence to conclusively determine the real cause of an increase in muscle size. There is one other possible explanation for muscle hypertrophy, and that’s muscle fiber splitting. That’s in reference to a muscle fiber splitting into two or more fibers, and then those fibers increase in size causing increased growth. This theory has actually been documented in research to conclusively happen. Murach, KA, et al., (2019) documented fiber splitting, but that was within a group of athletes taking exogenous steroids and lifting massive loads. For fiber splitting to occur, it takes extreme muscle loading and steroids, and yet it still isn’t the primary reason for muscle growth. 

Jorgenson, KW, et al., (2020) has shown fairly conclusively that hyperplasia probably doesn’t occur. If it does occur at all, it’s definitly not the primary cause of muscle growth. Fiber splitting happens, but primarily with steroid enhanced athletes lifting extremely heavy loads. The primary explanation for muscle growth is muscle fiber hypertrophy with individual fibers increasing in diameter. Now let’s take a closer look at the physiology linked to hypertrophy. 

Skeletal Muscle Hypertrophy, the Physiology:

Muscle grows 5-20% in the first few months of training, which is why you will hear the term “newbie gains”. After the first 3-4 months, it gets a lot harder. Something to think about is that muscle isn’t added to all sections of the muscle equally. Researchers have consistently measured differences in the distal, proximal, and medial sections of the muscle. As Dr. Andy Galpin has alluded to in many of his videos, this is probably a case for changing up the exercises used to target specific muscle groups. However, there is more research to be performed on this subject. 

Your biceps and any muscle in your body is made up of millions of muscle fibers also known as muscle cells. There are three main types of muscle fibers: type I, type IIA, and type IIX. There are many combinations of these three types as each muscle fiber can be identified on a spectrum of each. Type I is considered slow twitch and rely mainly on oxygen for fuel earning them the title oxidative. Type IIA are muscle fibers that are fast oxidative glycolytic fibers, present higher twitch speeds than type I fibers but are less fatigue resistant. Type IIx fibers, or fast glycolytic fibers, possess the fastest twitch speeds but are highly fatigable. Fast twitch fibers tend to be bigger than the slower twitch fibers, and are the fibers recruited for explosive movements not lasting very long like a 100m sprint or a power clean. 

Skeletal Muscle Hypertrophy the Physiology-

Figure 1

In figure 2 below, you can see the anatomy of a muscle. The entire muscle is surrounded by the epimysium. You can also see that muscle fibers are arranged in bundles called fascicles. Each fascicle is surrounded by the perimysium, which is a sheath of connective tissue that aids in lateral force transmission. Each muscle fiber is surrounded by the endomysium, which is the connective tissue where lateral force originates. Costameres are sub-membranous, Z-line associated structures found in striated muscle. They help to transfer force from the contractile units to the extracellular matrix at the Z and M Lines specifically to the endomysium which transfers force to the adjoining muscle fibers eventually ending up at the tendon. You can get an idea how costameres transfer force laterally by taking a look at figure 1 above.

Hypertrophy: Figure 2 Anatomy of Skeletal Muscle

Figure 2

Each muscle fiber consists of hundreds to thousands of myofibrils, which are encircled by branches of T Tubules, the sarcoplasmic reticulum (SR), and expanded chambers of the SR called terminal cisternae that lie on each side of the T tubules forming what is known as the triad. The terminal cisternae of the SR contain calcium ions. A muscle contraction begins when these calcium ions are pumped into the cytosol of the sarcoplasm.

Myofibrils are bundles of myofilaments, which are protein filaments consisting primarily of actin, myosin, and titin proteins. Actin and myosin are the myofilaments responsible for contraction. The arrangement of actin and myosin into an organized functional unit is known as a sarcomere. Each myofibril consists of approximately 10,000 sarcomeres. Simply put, the T Tubules allow an action potential to spread throughout the muscle fiber causing the sarcoplasmic reticulum to release calcium ions. Calcium ions bind to the troponin located on the actin filaments weakening the bond between actin and the troponin-tropomyosin complex. This action leads to the exposure of the active sites on the actin filament, which is the very thing the myosin heads are attracted to. You probably know the rest of the story with the myosin head binding to the exposed active site on the actin filament. The myosin performs the power stroke creating movement. Before binding to actin, the myosin has to be activated by the hydrolysis of ATP located on the myosin head by the enzyme ATPase. This reactivation splits ATP into ADP and an inorganic phosphate. 

When scientists talk about fast twitch fibers, this is primarily determined by the amount of ATPase found on the myosin head. The greater the amount of myosin ATPase, the faster the contraction velocity. Now that you have a little idea of the form and function, let’s dive deeper into the aspects that pertain to hypertrophy.

Muscle fibers consist of 75% water and 25% protein filaments. Of that 25%, 15% is myofibrillar consisting of actin, myosin, titin, and a few other proteins responsible for structure. 5% of the proteins are found in the sarcoplasm. Also 40% of the proteins are for metabolism or energy production, and only 10% for contraction. Of the contractile proteins, 50% are from myosin filaments, 20% actin, 10% titin, 5% nebulin/troponin/tropomyosin, and 5% sarcoplasmic reticulum. Before we move on, I want you to understand a few things about the sarcomere. Titin is the protein filament responsible for elasticity and for keeping the myosin filaments in place. Nebulin is responsible for keeping the actin filaments in place, and is potentially also responsible for elasticity.

Muscle fibers grow in one of two ways: in series and in parallel. In series is in reference to muscle fibers growing by stacking sarcomeres end to end, and in parallel is stacking them side by side.  Before you think that growing in series would make the entire muscle longer, you have to understand pennation angle. Muscle fibers grow at an angle in relation to the longitudinal axis of the entire muscle. If the angle increases, the muscle fiber can grow in series without forcing the muscle as a whole to grow longer.

Hypertrophy : theory to application - Figure 3 Andy Galpin’s YouTube Video on Muscle Physiology

Figure 3 from Andy Galpin’s YouTube video on Muscle Physiology

The truth is that scientists still don’t know exactly how the muscle fibers grow. The hypothesis that makes the most sense is that sarcomeres are stacked parallel causing the myofibrils to grow in thickness leading to the muscle fiber to also grow. Sarcoplasmic hypertrophy is also a part of the muscle growth process. Get ready for some more theories!

Sarcoplasmic Hypertrophy is in reference to the mitochondria, sarcoplasmic reticulum, fluid in the cell, connective tissue, and all the other noncontractile elements. Dr. Andy Galpin’s theory is that maybe bodybuilding with light weight for high reps to failure might add more sarcoplasmic hypertrophy, which is why bodybuilders get so huge without a functional increase in strength. The other side of the coin is powerlifters and weightlifters probably experience more myofibrillar hypertrophy, which is hypertrophy of the contractile units leading to more strength. (Roberts MD, et al., 2020) discovered that an increase in the noncontractile elements, especially fluid, probably happens first allowing for the myofibrillar hypertrophy to happen later. Regardless no matter how you train both sarcoplasmic and myofibrillar hypertrophy are taking place. However, it appears that going heavy probably leads to more myofibrillar hypertrophy.

All abiut Hypertrophy: Figure 4 Andy Galpin’s YouTube on Muscle Physiology

Figure 4: Andy Galpin’s YouTube video on Muscle Physiology

Why is Muscle Hypertrophy Important?

Skeletal muscle does a whole lot more than just pumping iron. The main purpose of skeletal muscle is movement. Skeletal muscle shortens, pulling on the tendon attached to the connected bone, and that creates torque which is rotation about an axis in this case the joint. Skeletal muscle is also responsible for:

  • Posture
  • Joint stability
  • Heat
  • Allow us to speak and chew
  • Storage of nutrients
  • Movement of blood throughout the body
  • Movement

Without muscle, we couldn’t move, talk, chew, or even stand. Without skeletal muscle, blood would just pool in the veins. Venous return relies on skeletal muscle to increase pressure driving the blood back to the heart. Muscle stores valuable nutrients like carbohydrates in the form of glycogen and amino acids; both are detrimental to the very existence of the human organism. Plus, you will rely on the homeostatic response of skeletal muscles when you find yourself stranded in the cold. The shivering that you will experience is your body’s way of producing extra heat to keep you warm. Yet, it’s probably movement that interests most of you athletes. 

When a skeletal muscle grows larger, it then produces a greater capacity to produce force. If you want to be stronger, more powerful, or faster, it’s the specific way that you add that muscle that makes it functional in a particular way. We will go into the specificity of muscle hypertrophy a little later. However, it’s critical that you understand the equation for force (force= mass x acceleration) because most of all the parameters for biomechanics stem from that one equation. For example, if you understand that acceleration is equal to the change in velocity divided by the time interval, you will then understand the need to measure velocity and time. Also, if you can measure distance, velocity, mass, and distance, you can figure out

  • Power (force x velocity)
  • Work (force x distance)
  • Rate of Force Development i.e RFD
  • Force
  • RSI (height/ contact time)
  • Eccentric (force, velocity, and power)
  • So much more!

That’s why having a GymAware RS or FLEX unit is so helpful. The era of believing that increased force production leads to all the other adaptations you are after is over. We understand the importance of specificity. We will look at this concept closer a bit later in the article. However, I am assuming that most of you are reading this to figure out how to add muscle to your athletes or to yourself. If that’s the case, you’re in the right place. Let’s dive in.

How does Muscle Hypertrophy Work?

What Stimulates Muscle Hypertrophy?

Most of you probably want the answer to this question. Only my fellow nerds out there care about the anatomy and physiology of skeletal muscle. Yet, all my fellow meatheads want to know how this is accomplished. In 2017, I wrote my e-book “Mash Jacked”, and it was all about this topic. Back then, there were three main ways to stimulate hypertrophy: mechanical tension, muscle damage (that terrible soreness we all experience after sets of 10 with back squats and  associated with muscle protein breakdown sparking subsequent protein synthesis), and metabolic stress (the pump). Turns out, that mechanical tension is the primary way to stimulate muscle growth. Muscle damage and metabolic stress can be associated sometimes with mechanical loading, but neither one is a requirement for growth. 


Mechanical Tension:

What is mechanical tension? When an athlete is lifting a weight, the muscles are experiencing a stretching imposed by the external force which is the mass of the barbell being acted upon by gravity. When back squatting, the quads and hip extensors (hamstrings, adductor magnus, and glutes) work together to stand you up by shortening while the weight on the bar and gravity are trying to lengthen the muscles. It’s that tension or stretching effect that begins the signal to the muscle to grow. 

Here are four major components to consider when hypertrophy is the goal:

  1. Getting as close to failure as possible as many times as possible, and as often as possible due to the size principle
  2. The bar speed has to slow down (force-velocity relationship)
  3. Maximum Effort
  4. Maximum Velocity

Going to Failure:

Going to failure has nothing to do with getting a pump, but it has everything to do with motor unit recruitment and force production. When I apply a maximum effort into a barbell, I in turn recruit maximum motor units. A motor unit is the way the brain communicates with muscles. A motor unit consists of an alpha motor neuron and all the muscle fibers it innervates. The good thing is that once a motor unit is recruited, all the muscle fibers it innervates is recruited. That’s the all or none principle. 

If the weight is light, the body will activate just the number of motor units required to perform a specific task. As the fatigue builds, the body calls on more and more of the larger high threshold motor units to help perform the task. Once the maximum amount of motor units are recruited, it’s the amount of force experienced by the muscle fibers that leads to growth. 

Bar Speed has to Slow Down:

As I explained earlier, muscle fibers are bundles of myofibrils containing the smallest functional units of a muscle fiber, the sarcomere. I briefly explained the sliding filament theory earlier in this article, but simply put, it’s when the myosin head grabs the actin filaments, performs a power stroke, and in turn causes a shortening of the sarcomere. The more cross-bridges that can take place is directly proportional to the amount of hypertrophy one can expect. These cross-bridges require a slower bar velocity for making the maximum amount of cross-bridges. There are a few other factors that you should consider, but I will add those in just a bit. This slowing effect is the reason we use the GymAware RS and FLEX to monitor velocity loss.

Maximum Effort:

You have probably heard the term, compensatory acceleration, thrown around in a lot of different strength and conditioning circles. Yet, why is compensatory acceleration important? To recruit the maximum number of high threshold motor units(HTMUs), a maximum effort is required. This is why athletes have been shown to recruit maximum amounts of HTMUs at multiple velocities with the only common theme being, effort. Recruiting HTMUs is only the first step in hypertrophy. Like I explained earlier, the bar has to slow down for the muscle fibers to experience the greatest amount of muscle tension.

Maximum Velocity:

This one goes hand in hand with maximum effort. If the athlete is expressing a maximum effort, then a maximum velocity should also be present. Once again, I use my GymAware devices to ensure the athlete is performing each repetition with maximum effort and velocity. Anyone that has ever performed a back squat knows exactly what I am talking about. There is a big difference in squatting 184kg/405lb for 5 repetitions versus 184kg/405lb for 5 repetitions with maximum effort and velocity. There will be so many other adaptations like improved rate coding and synchronization leading to an improved rate of force development when the athlete is expressing a maximum effort and velocity. This is the main reason we squat, pull, and press with a velocity prescription.

Signalling process in very simple terms:

So what happens when the muscle experiences mechanical tension? There are mechanosensors on the cell wall, possibly the costameres that pick up on mechanical tension or the stretching of the cell wall. I’ve already explained the needed stimulus, so now we’re going to talk about the signaling process. 

The mechanical tension experienced by the cell wall causes a cascade of signaling proteins to communicate within the cytoplasm. This cascade ends up in the nucleus leading to gene expression and eventually protein synthesis. There are three main signaling pathways to be aware of: the anabolic pathway, catabolic pathway, and inhibitors.

Anabolic Pathway mTOR:

Mammalian target of rapamycin (mTOR) is a key regulator for maximizing skeletal muscle mass. The pathway is specifically: P13k/Akt/mTOR. This pathway is activated by mechanical tension, and eventually ends with protein synthesis. There are a few other mechanisms to be aware of. The mTOR pathway is sensitive to the amount of essential amino acids available, especially leucine. This makes sense because amino acids are required for protein synthesis. Growth factors such as insulin, IGF1, and testosterone have all been shown to activate the P13k/Akt/mTOR pathway. This is probably why having protein rich in amino acids specifically leucine along with some carbohydrates have been linked to muscle growth through protein synthesis. Of course this makes total sense as to why athletes that take testosterone add muscle so easily as well. I would like to add that this should also show the importance of dealing with stress and maintaining a solid amount of heart rate variability to maintain lower levels of cortisol and in turn higher levels of testosterone is so important to gaining strength and muscle mass. 

There are two other signaling pathways to be aware of. There can’t always be protein synthesis causing a cell to grow and grow because that is cancer. There’s also a catabolic pathway known as Nuclear Factor Kappa B or NF-κB/FoxO. Additionally, there’s also an inhibitor of muscle growth to be aware of, Myostatin (MSTN), also referred to as growth and differentiation factor-8. If you are a real meathead, then you have probably heard of myostatin inhibitors. Myostatin inhibitors allow bodybuilders to grow without anything to inhibit that growth. Before you go out and buy some on the streets, I want you to remember that cancer would be unchecked as well.

Gene expression:

The P13k/Akt/mTOR signaling pathway eventually ends in the cell nucleus. Gene expression takes place in the nucleus when a sequence of DNA goes through the process of transcription forming mRNA. The mRNA leaves the nucleus and binds with a ribosome in the cytoplasm, and this is where protein synthesis takes place in a process called translation. This is overly simplified, but I am just trying to give you an idea of what’s taking place.

Figure 5: Gene Expression

The key to adding muscle mass isn’t just protein synthesis. It’s the balance between protein synthesis and protein breakdown equaling more protein synthesis than breakdown. Resistance exercise, protein, EAAs, carbohydrates, and optimal hormonal levels are all required to maximize skeletal muscle hypertrophy. Now let’s look at best practices for becoming massive.

Hypertrophy: Image from Roberts, MD, et al., 2020 see reference #3 below

Image from Roberts, MD, et al., 2020 see reference #3 below 

Muscle Hypertrophy v/s Strength:

‘Best Practices for getting jacked in a way that fits your specific goals

When it comes to hypertrophy, there are two basic routes to take. You can go heavy for a few repetitions, or you can use relatively light weight for lots of repetitions. What is the one key that both options share? Whether you go heavy or light in regards to load, the only thing that matters is the number of sets to failure or near failure. From the literature, it would appear that the last five repetitions in a set to failure will yield maximum hypertrophy as long as the athlete is lifting with a maximum effort creating a maximum velocity. If the athlete is performing the repetitions with the aforementioned requirements, the last five repetitions will yield a repetition velocity slow enough to maximize the number of myofilament cross-bridges. Therefore, when training heavy, the latest literature suggests that heavy sets of five repetitions is the rep scheme yielding maximum hypertrophy and strength. 

Does hypertrophy increase strength?

The question you have to ask yourself is, “what is the intended purpose?” Even though 40% of your 1RM for a max set of repetitions is equal to 86% for 5 repetitions, both yield slightly different adaptations to consider. Light weight for maximum repetitions will get the athlete just as jacked, but probably not as strong in terms of a true 1RM. However, light weight for maximum repetitions is great for muscular endurance. 

Light weights v/s heavy weights:

So why doesn’t the low intensity set create the maximum amount of strength? This topic needs more research but as of now it appears that the low weight for high repetitions recruits the same amount of motor units, but it recruits those motor units over a longer period of time. That doesn’t allow the high threshold motor units to be recruited at the same time. This isn’t conducive for motor unit rate coding or for motor unit synchronization and coordination. 

Maximum strength requires the maximum number of high threshold motor units to be recruited as quickly as possible and as close to the same time as possible (synchronization). Here are a few other adaptations that come from traditional heavy weight and lower repetitions: (1) increases in lateral force transmission, (2) increases in voluntary activation, and (3) increases in tendon stiffness. All three of these qualities lead to improvements in strength along with maximum hypertrophy and the improved muscle coordination. 

High repetition hypertrophy with relatively lower loads will probably yield the same hypertrophy, but there is one other adaptation that might be important to a few athletes out there. This is possibly due to more of a sarcoplasmic increase versus myofibrillar hypertrophy. As I explained earlier, a predominantly sarcoplasmic increase leads to increases in mitochondria, glycogen, creatine, and sarcoplasmic reticulum all of which could improve the muscle fiber metabollicaly.  If muscular endurance is important, then you might consider this low load and high repetition stimulus. Several athletes out there might benefit from both stimuli like: CrossFit, wrestling, soccer, and cross-country. 

How can GymAware help?

The most important aspect that velocity based training helps a coach with is ensuring that the proper intent is reached during a training session. If myofibrillar hypertrophy occurs at loads greater than 70% and is maximized at failure, GymAware RS and GymAwareFLEX help ensure the proper adaptations are being made by measuring the following parameters:

  1. Initial repetition velocity is 0.7m/s (for squats) or slower
  2. The final repetition is as close to 0.35m/s as possible, which is 50% velocity loss

However, there are other considerations to be considered for optimal programming. Maximizing velocity loss is the best way to maximize hypertrophy, but there are some negative adaptations to consider for power driven athletes. Let’s take a closer look at those adaptations. 

Muscle Hypertrophy: Should you train to failure?

‘Why training to failure is a bad idea for some athletes

Before you think that it’s all about going to failure, there are a few other points to consider. First, there’s no extra benefit to going to failure when using heavy loads at 85% and above. The weight is heavy enough to recruit max motor units and the bar speed is slow enough for max actin-myosin cross-bridges. Therefore, gains in max strength, lateral force transmission, voluntary activation, motor unit coordination, and tendon stiffness are already maximized. Hypertrophy might not be completely maximized on the day, but the athlete will avoid unneeded muscle damage allowing for quicker recovery times.

Failure leads to more muscle damage:

Most consider eccentric training to yield the majority of muscle damage due to disruptions of the muscle fibers endured from the mechanical loading… However, it appears that muscle damage is also caused from sustained excitation-induced influx of calcium ions under conditions of low energy status and hypoxia. This is what happens when training under fatiguing conditions. When levels of calcium ions are elevated for an extended time, proteases known as calpains and phospholipases are activated. These break down the ultrastructure of the muscle cell and the sarcolemma, and can cause muscle fiber damage. (Chris Beardsley, ‘Strength is Specific’).

Therefore, training to failure might delay the frequency of training sessions. Fatigue can set in causing an athlete’s desire to train to drop, and this can increase the athlete’s rate of perceived exertion (RPE). Remember, it’s not about the volume of sets to near-failure or failure, it’s also about how often the athlete trains. Training to failure with light loads requires even more time between sessions. The art of coaching comes down to:

  1. How heavy
  2. How often

How can GymAware help?

We know that mechanical failure happens around 40-60% of velocity loss. That means, when an athlete squats 70% of their 1RM, the first rep is around 0.7m/s. When the velocity reaches 0.35m/s, the athlete has reached 50% velocity loss. You can establish velocity cut offs using the GymAware RS or FLEX units, which you can read about in our article Train to Velocity Failure, using Velocity Stops.

Since I train some of the best Olympic weightlifters in the world, we are normally after increases in high velocity force production. We are after hypertrophy of course, but not at the expense of speed. It’s not very advantageous for my athletes to squat his or her 1RM at 0.18m/s like most world class powerlifters. We aim for no more than 20% in velocity loss for the majority of training volume. You can read more about velocity loss here:

Hypertrophy first or strength first:

We know that muscle hypertrophy requires the recruitment of high threshold motor units, maximum effort, and performed at a maximum velocity. To recruit the maximum amount of high threshold motor units, the athlete has to be able to lift a weight heavy enough to recruit those motor units. That explains why beginner athletes can increase strength without gaining a lot of muscle size during the first few weeks of training. Most of those adaptations are neural in the form of technique improvements and intermuscular coordination, and neither one has anything to do with hypertrophy. However, when an athlete improves his or her technique or intermuscular coordination, they now have the ability to train with higher loads, recruit a greater number of motor units, and at a higher velocity all leading to greater amounts of hypertrophy. 

How can GymAware help with this process?

There are two main ways that GymAware can help, and that’s by measuring neural improvements:

  1. Bar Path
  2. Moving any particular load at a greater velocity 

Bar Path is a parameter that we don’t talk about enough. We know that certain bar paths are more conducive to optimizing joint moment arms than others. For example, in a deadlift, if the bar drifts forward off of the floor, the moment arms at the hip and each intervertebral joint is increased, increasing the stress at each joint. This movement flaw will immediately decrease velocity and lower the load that is possible. When the bar is swept in towards the body off of the floor, velocity and load can be maximized by the athlete. Of course measuring the velocity of any particular load will allow the athlete and coach to objectively measure neural improvements showing the athlete’s ability to increase the load being lifted. 

Check out Part 3 video presentation below:


Muscle hypertrophy in training:

You have learned a lot up to this point, but you probably have a few questions. How do I maximize hypertrophy? Let’s go over this question in detail. When it comes to hypertrophy, there are certain variables that affect the amount of hypertrophy one adds:

  • Intensity
  • Volume
  • Rest Interval
  • Types of contraction
  • Velocity of contraction
  • Exercise order
  • Frequency


Let’s look at the best practices for each. We have already shown that intensity can be anywhere from 30% of one’s 1RM and up. Whether you are doing multiple sets at 40% or multiple sets at 75%, as long as you get the same amount of sets to near failure, you will create the same amount of hypertrophy. However, there are a few differences. Heavier loads will probably make you stronger. However, there will be a bit more muscle damage with the greater loads. Therefore, if you are a beginner, low load hypertrophy might be the better choice due to less muscle damage allowing for more frequency to practice the movement. Higher loads are probably better for more experienced athletes to create more functional growth. One thing to consider is that proximity to failure is the variable to be experimented with the most. Complete failure isn’t required for hypertrophy, so a balance has to be struck between proximity to failure and frequency. 

Volume i.e. how many sets and reps:

When an athlete is getting started, one set to almost failure will be adequate for inducing maximal amounts of hypertrophy. However, the more advanced an athlete becomes, more and more sets to near failure will be required. We have already mentioned that hypertrophy is maximized at five repetitions. Therefore, whether you are performing 70% for ten repetitions or 80% for six repetitions, it will be the final five repetitions that begin to slow down that hypertrophy is maximized. Research has shown that hypertrophy is maximized at around 5 to 10 total sets to near failure. Research has also shown that sets greater than ten per body part doesn’t appear to increase the amount of hypertrophy, but instead will simply add to the fatigue and muscle damage allowing for less frequency.

Rest Interval:

Miranda, et al. (2007) looked at the difference in hypertrophy with rest intervals of one minute and three minutes. This research showed conclusively that three minutes of rest produced more hypertrophy. However, Ahtiainen, J. P., et al. (2005) looked at the difference in hypertrophy between sets with rest intervals between two minutes and five minutes, and found no difference in hypertrophy. There are several other studies, but it appears that resting somewhere between two and three minutes is the optimal amount of rest to maximize hypertrophy. 

Types of Contraction:

During a typical repetition, there are two main contractions: concentric and eccentric. The concentric contraction is the shortening of a muscle or the completion of a repetition. The eccentric contraction is the lengthening of a muscle. Both have their own distinct adaptations that relate to hypertrophy. Eccentric contractions produce more overall force than concentric contractions around 120-130% of the concentric contraction due to the elements in the body that resist stretch like titin, nebulin, and connective tissue. Research has conclusively shown eccentric contractions to activate the p70S6K and rpS6, elements in the mTOR anabolic intracellular signaling pathway, to a greater extent than isometric or concentric contractions. 

Yet, multiple studies have shown an equal amount of hypertrophy for concentric and eccentric contractions. This is probably due to the increase in satellite cell content found only in concentric contractions, or possibly the contribution of nuclei  to myofibers by satellite cells and the response of interleukin 6 (IL-6), which is associated with satellite cell signaling, since both are associated with muscle growth. Yet, there isn’t a conclusive answer leaving one possibility. If muscle growth is the goal, dynamic repetitions consisting of an eccentric and concentric contraction are recommended. As far as isometric contractions are concerned in regards to hypertrophy, it appears that you can gain some muscle, but not as much in comparison to dynamic repetitions. However, isometric contractions performed at longer muscle lengths are shown to produce more hypertrophy than isometric contractions at shorter lengths. Depending on what point the joint experiences maximum force to overcome is directly related to the muscle being recruited. Therefore, isometric contractions will maximize the muscles that are recruited at the specific angle of contraction for example the adductor magnus is recruited for hip extension at the bottom of a squat over the gluteus maximus. Once again showing isometric contractions superior for strengthening a joint at a specific angle.

Velocity of Contraction:

This is a variable often overlooked in most studies. However, it appears to be of great importance in a couple of ways. First, maximizing an athlete’s eccentric contraction has shown to maximize the hypertrophy of Type II fibers specifically, which is the goal for most athletes looking to maximize speed and power. Other than that, the key is maximizing the velocity of each repetition as it relates to the load being lifter for maximal hypertrophy. That means, if you are lifting 70% of your 1RM in the back squat, the first rep should be as close to 0.7m/s as possible (on average), and the final rep should be as close to 0.35m/s (50% velocity loss) as possible for maximal hypertrophy. 

Purposely lowering a repetition slower than normal isn’t the cause of hypertrophy like most coaches believed in the past. For athletes that desire to induce maximum Type II fiber hypertrophy, I recommend lowering the weight as fast as possible under control, and then performing the concentric contraction as fast as possible on all repetitions. The bar should only slow down with fatigue. 

Exercise Order:

Performing the movements of greatest importance first will ensure skeletal muscle hypertrophy linked to improving that movement. Also, it’s important to put the movements that require multiple joints first in the exercise order because they will recruit the greatest amount of high threshold motor units. If the muscles are fatigued from performing single joint exercises, a less degree of muscle fibers will be recruited. Along the same lines, it’s important to place movements that require maximum velocity first in the exercise order to ensure maximum velocity. 


Total volume is more important than frequency in regards to maximizing hypertrophy. Yet, we know that hypertrophy is maximized at around ten total sets of five repetitions where velocity is decreasing due to fatigue. It’s hard to bust out ten sets of back squats with repetitions nearing some form of failure. Therefore, it might make sense to spread those hypertrophy inducing sets over two to three days to ensure each set is performed with maximum effort and velocity. It’s even more important when you are performing movements that require maximizing technique. It’s hard to perform that tenth set of back squats if you are already exhausted without performing some flawed repetitions putting the athlete at risk of injury.

Variety is still important:

I am not as big of a proponent of variation as I used to be. We know that specificity is king, but there is still an important reason for maintaining some variation. Muscles don’t experience the same amount of growth in all regions. Now it’s not proven yet, but Dr. Andy Galpin seems to believe that using multiple machines and variations of movements might help to grow muscles more symmetrically, and I tend to agree with him. There isn’t concrete evidence to back our hypothesis, but I have 40-years of experience to back it up. 


  1. Sets of a heavy five repetitions is best for maximizing strength and hypertrophy
  2. 30-60% for maximum repetitions is great for maximizing hypertrophy and muscular endurance.
  3. Heavy sets around 80-85% for five repetitions getting close but not actually reaching failure are best for maximizing hypertrophy, strength, and training frequency. 
  4. Change up exercise variations and movements to ensure symmetrical growth. 
  5. Ten total sets per body part
  6. Maximize the velocity on each repetition
  7. To maximize Type II fiber hypertrophy, it’s important to maximize the velocity of the eccentric contraction. 
  8. Dynamic repetitions consisting of a concentric contraction and eccentric contraction are best for hypertrophy
  9. Isometric contractions are good for hypertrophy and strength at a specific joint angle
  10. A frequency of 2-3 times per seek for a total of ten sets per body part might help to maximize effort and repetition velocity to ensure maximum hypertrophy.
  11. A rest interval of 2-3 minutes is best for hypertrophy.
  12. Place the multi-joint, higher velocity, and the most important movement first in the exercise order.

How can GymAware help?

GymAware will ensure that each repetition is performed with maximum velocity and therefore maximum effort. GymAware RS and FLEX units also track the load, number of repetitions, speed of the eccentric contractions, rest interval times, and velocity loss. Basically, GymAware tracks all the necessary variables while the athlete focuses on the task at hand. Like I always say, you are either measuring or guessing. I am trying to produce Olympic champions and some of the greatest athletes in the world, I can’t afford to guess. 


Now we know that going to complete failure is probably not good for maximizing strength and training frequency. We also know that failure leads to a transition from Type IIX to Type IIA meaning the athletes are getting slower. There are a few other adaptations that lead to slower movement like increased pennation angle, but there is something you can do to maximize strength and power. 

We know that muscular failure happens with a typical heavy set of 5 with 40-60% velocity loss. That’s why we use our GymAware RS and FLEX units to monitor velocity loss. If you stay around 20% or less of velocity loss, you will ensure that maximum strength is the priority with hypertrophy still taking place just not at the expense of the rate of force development. However, if maximizing hypertrophy is the priority, you can consider sticking to that 40-60% velocity loss suggestion. 

The art of coaching when it comes to hypertrophy comes down to:

  1. Heavy weight for low reps or light to medium weight for high reps?
  2. How close to failure and how often?
  3. How do you optimize reps to near failure and frequency for the individual?

Using velocity to measure and monitor for the sport, group, and individual is the best practice so far in quantifying the optimal practices with the known variables. I recommend sticking to 20% or less of velocity loss for the majority of time measured with GymAware RS or FLEX units to maximize muscle and the rate of force development. I’m not saying that we never take things to failure. There are times of the year where hypertrophy is the main adaptation that we are looking to improve, but the majority of the year is spent optimizing speed and strength (power). This was a lot, but I believe that we have been able to deliver the best practices for hypertrophy regardless of the sport of desired adaptation. 
If you have any questions, email me at, and I will gladly answer them.

Download: How to get started with velocity based training [use case]

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Coach Travis mash


Travis Mash

Being a World Champion in powerlifting, Travis competed at a world-class level in Olympic weightlifting and has coached professional Olympic weightlifters alongside Don McCauley and Glenn Pendlay at Team MDUSA. Now Travis coaches the most successful weightlifting team in the USA.