7 Essential Exercise Variables for Building Muscle

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Step into any gym and most people are there to build muscle and improve their physique. When you first start working out you can do pretty much anything and your body will respond and grow muscle (if you are lifting weights). Unfortunately, those beginner gains run out and eventually being smarter with your training is a must. 

Believe it or not, your body is not a fan of putting on muscle. One of the reasons this is, is that it is metabolically costly to maintain, and for most of our evolution this was not ideal as food was scarce and we just did not have access to the energy we needed to build and maintain muscle. 

You also needed to expend a lot of energy in order to get your next meal so our body is really good at being efficient with its energy and storing what energy it can (body fat) in case food is limited. However, in today’s world you can consume thousands of calories with essentially no energy expended, so our bodies system of being efficient with its energy and storing that energy is outdated. 

One way to combat this outdated system is by building muscle. 

Now that food is literally everywhere and times of famine are very unlikely, taking advantage of muscle tissues high metabolic cost seems to be a good idea. Building muscle can be a safety net to ensure we do not put on excess amounts of body fat in today’s world. Muscle also has other benefits such as:

-Better mobility/flexibility

-Less injury prone

-Helps reduce sarcopenia (loss of muscle tissue as you age) in older adults 


-More powerful

-Enhanced aesthetics 


The issue we run into is that your body does not realize that there is an abundance of high energy food around and times of famine are highly unlikely in today’s world, so in order to build muscle we must go out of our way to push the body past where it is comfortable, and you have to give the body good reason to build this tissue that it finds to be very inefficient.

In this article I am going to go over the exercise variables of building muscle so you can push your body past where it’s comfortable to put on that trophy body tissue we call muscle. The cool thing is that once you spend a good amount of time building muscle, it’s very tough for it to go away, and if it does go away, it comes back fairly easy. 


1. Volume


The most important aspect of any muscle building program is volume. Volume is essentially the amount of work you do per session. Some popular ways it has been calculated is reps x sets, reps x sets x weight, reps x sets x weight x distance lifted. 

Since this is for muscle building, we are going to count volume as sets that are taken within 5 reps of failure. 

Volume is the most important aspect of training for muscle growth because without enough volume you will not grow. Time and time again multiset protocols favoring high volumes of resistance training optimize the hypertrophic response (Schoenfeld, 2016, p. 91). 

You could have the best exercise selection, optimal training frequency, and great recovery, but if you are not doing enough work in a given session or throughout the week, you simply will not grow.                                                            

The downside here is that while we need to make sure we are doing enough, we can also do too much volume.  We can do too much volume in one single session, or on a longer time frame we can do too much volume in a week or over months of training, but we will get more into periodization in a little. Lets go over the optimal amount of volume on per session basis and a weekly basis. 

inverted-uPicture of the inverted U hypothesis of volume and muscle growth (hypertrophy). As you can see, more is better, but only until a certain point and then muscle growth stops and eventually declines. This is on a per session basis. 


So in order to grow more muscle we know we probably need to do more than 0-1 sets per workout. What about too much? James Kreiger (2019) found that muscle growth seemed to max out around 8 sets per workout on average and can even regress after around 10 sets per workout. 

This information dispels the classic “bro” split where you hammer a muscle group with 15+ sets per workout. While this style of training will leave you sore for days after the workout and give you the assumption that you made more gains, however being excessively sore has been shown to potentially be detrimental to muscle growth. For most people, doing more than 10 sets per workout for a given muscle group is going to be inferior to 3-8 sets per workout for muscle growth. Beginners can get away with much less volume (around 2-3 sets per workout can be enough) than those who are intermediate or advanced. Once again, this assumes you are going to within 1-5 reps from failure on each set (more on this in a little). 

So that is on a per session level. What about a weekly basis?  10-20 sets per week on average seem to be best for most people. Some people can go into the 20-30 set range per week and some can even get up into the 30-45 set range. James Kreiger mentions that there is a large increase in gains from going from single digit set numbers to 10-20 per week, and then a very small advantage from 10-20 to 20-30 sets. So 10-20 seems to be the sweet spot per week. 

There are many factors that play a role in how much volume you can do throughout the week and session. These factors range from gender all the way to how much sleep you are getting. Let’s go over a few:


Body size– those that are smaller, on average can do more volume.

Height– Just like with body size, those that are shorter, on average can do more volume.

Gender– Goes hand in hand with the first two (since females are smaller most of the time), females can do more volume most of the time.

Training age– those who have trained longer need/can get away with more volume. 

Sleep– The less sleep you get over time, the less volume you will be able to do and recover from

Nutrition– The more food you consume (up until a certain point) the more volume you will be able to do and recover from.  

Stress– Those that manage their stress well on average can do more volume and recover from that volume. 

Exercise selection-  If your training consists of mostly compound exercises you will most likely reduce the amount of sets you can do and recover from, whereas if you do mostly isolation work you will be able to do more volume in terms of sets. We will go over exercise selection more in a little. **This is key when you are short on time

Intensity- The higher the intensity, the less you will be able to do. We will go over intensity more in a bit. 

Size of muscle group- Larger muscles like the quadriceps, won’t be able to handle as much volume as your side delts or biceps. 


One other thing on volume, while higher volumes of training are superior for muscle growth, this does NOT mean you should go high volume all of the time. We will go over periodization in more detail in a little. 


Multiset protocols are superior for muscle growth. Around 3-8 sets per muscle group per workout on average seems to be best in terms of muscle growth and from which you can recover. 10-20 sets seems to be best on a weekly basis for most people.  

2. Frequency


Frequency is the number of sessions in a given time frame, normally within a week. For this guide, since its for building muscle, we are more concerned with how many times you train a particular muscle group. For example, if you train chest 2 times in one week, that would be a frequency of 2. 

In the volume section, we found out the optimal volume range for most people is between 10-20 sets per week and some people see muscle growth into the 20-30 set range per week, however anything over 8-10 sets per workout seemed to see a plateau and even regression in muscle growth. In order to get to the 10-20 set range we can increase our training frequency to get more volume in per week. 

Studies show superior neuromuscular adaptations, hormonal markers for recovery, strength improvement, and gains in lean body mass in those performing volume equated programs with higher frequencies and less volume per session (Schoenfeld, 2016, p. 56-57).

Schoenfeld and colleagues (2016) found that the current body of evidence indicates that frequencies of training twice a week promote superior hypertrophic outcomes to once a week, however more research needs to be done to determine whether or not 3 times per week is superior over twice a week. 

James Kreiger (2019) ran a meta-analysis on training frequency studies (combined all research)  where they equated volume and he found that the research shows a slight advantage to 2+ times per week training frequency over one time per week, however training frequency plays a smaller role in muscle growth compared to volume. The main benefit of increasing your training frequency is that it allows you to do more total volume in a week. So there is no magical benefit to increasing training frequency that will cause muscle growth, it’s the fact you can do more volume and put in more quality sets per workout.



Overall weekly volume plays a larger role in muscle growth compared to training frequency. However, we can increase our training frequency as a way to increase weekly volume. There seems to be a large benefit in increasing frequency from 1x per week to 2x per week, but going from 2x per week and higher is still in question and this likely varies from person to person.


3. Training Intensity


Training intensity is simply how hard each training session or set is. For this guide, we are basing training intensity off of how hard each set is. Volume is still king in terms of muscle growth, however you could potentially be hammering away at 20-30 plus sets a week (because you heard more volume = more muscle growth) but if you are not training hard enough then we are leaving gains on the table and are probably training sub-optimally. 

Hard training for muscle growth would be a set that is taken to within 5 reps of failure. If you do a set and feel like you could do another 8 reps, then you are probably not training hard enough to grow any significant amount of muscle. This doesn’t mean you have to feel like you can’t walk or move your arms after each set, however if you get done with a set and barely had to push yourself, chances are you need to increase your training intensity to elicit the results you want.

This is far too common in the gym, on one side you have the guys and girls that will push to failure every single set every day (and we will find out here in a minute why that probably isn’t the best either, once again we need to find a middle ground), and then on the other end you have people who just don’t ever push themselves hard enough in the gym. 5 reps from failure would be a set where you had to challenge yourself a bit on at least 1 rep. 

So we know we want to be at least 5 reps from failure on each set, but we still are still leaving some gains on the table if we stay 5 reps on every set all of the time.  

It seems the closer you get to failure, the more muscle growth there is. The catch is though, is that the closer you get to failure on each set the more fatigue that is generated, too much fatigue generated in one session can hamper your recovery between sessions, and eventually can lead to overtraining and burnout. 

Both James Kreiger (2019) and Brad Schoenfeld (2016) mention that persistently training to failure can lead to higher fatigue. In a perfect world where fatigue is not an issue, going to failure every set would be the best way to train for muscle growth, however we do have to worry about fatigue. 

Another downside of going to failure all of the time is that your injury risk will increase. Have you ever seen those guys in the gym that everyone is impressed with because they can do 5 plates on the squat or that put every 45lb plate on the leg press and half rep it for 6, but then every time you talk to them they have some sort of injury that is nagging them? Yeah that’s these guys. 

Before I go on, there are some guys in the gym who lift very impressive amounts of weight that are very smart about it, but go into your local commercial gym and you get the first example most of the time. 

Now we know training with over 5 reps in the tank is inferior for muscle growth but going to failure every set increases injury risk and can lead to overtraining and burnout, so what is the middle ground?

 According to James Kreiger (2019) the current weight of the evidence for bodybuilding and physique training suggests that training within 1-3 reps of failure on most sets is probably best for most, as this leads to the best compromise between maximizing muscle fiber recruitment while allowing for better recovery. 

As long as you are training with a high level of effort (1-5 reps from fail), training to failure on all sets is NOT necessary for hypertrophy (Kreiger, 2019). 



Sets taken far from failure (5+ reps in the tank) seem to be inferior for hypertrophy. While taking all sets to failure would be the ideal way to train, unfortunately training this close to failure all the time can lead to increased injury risk, potential overtraining and burnout. The best bang for your buck seems to be 1-3 reps from fail, as this is the best compromise for muscle growth and allows for proper recovery. 


4. Deloads/Volume Cycling/Periodization


Training with enough volume, increasing that volume over time, and making sure you are training hard enough are the basic fundamentals for gaining muscle. However, as we have learned, one of the downsides to higher volume and higher training intensity is the fatigue it generates over time, not only physically, but mentally as well. The higher your fatigue is, the higher the risk of injury and burnout from training. 

Generating too much fatigue also has many other downsides such as: a decrease in performance, high levels of inflammation, increase in catabolic hormones such as cortisol, decrease in anabolic hormones, sleep disturbances, higher levels of anxiety, lower sex drive, lower metabolism. 

One of the biggest mistakes made in the gym is people trying to do too much every time they workout. They want to feel super sore and worn down after each set, rep,  and every workout.  

Some common traits of this person:

– Always seem to have a nagging injury

– Go through periods where they push hard and then the next time you talk to them they had to take a few weeks off because they got sick, injured, or simply burnt out. 

-Tell you “you just have to work hard and lift heavy” 

-”Lift more weight!” 

-”Deloads? Thats a waste of time”. 

A quote I heard from Jared Feather on a Revive Stronger podcast seemed to stick with me, it went something along the lines of this: “if you don’t deload, your body will eventually take a deload for you”. 

Extended time off from the gym (from injuries, burnout, being sick) kills your progress more than anything else. Many people just dont think long term with fitness, it’s how they feel right this second. Muscle growth is such a long and slow process and cannot be thought of with such short term thinking. 

As Precision Nutrition puts it “Putting in a consistent good effort over the long haul is much more sustainable than cycles of “crash and burn”. 

Now some people will hear this and think you need to not train hard. However, this couldn’t be further from the truth. We just want to spend a little more time reducing our training intensity from time to time to let our bodies recover, but continue to spend time slowly increasing our intensity and really pushing ourselves. Just like we all need the weekend from work, we need to take some time to recover from training as well. We do this by cycling our volume and taking deload weeks periodically. 

Let’s first go over volume cycling. 

As we learned earlier, around 8-10 sets per muscle group per workout seems to be best for most and around 10-20 sets per week. However, we don’t want to just go straight into 8-10 sets per workout. 

A better approach would be to slowly increase our set volume over time, as this will reduce injury risk and excessive fatigue. We do this until a maximum effective amount is achieved (once again around 8-10 hard sets per workout for each muscle group, around 2-3x per week). Once there is a plateau in performance at high volumes, we must reduce our set volume to a maintenance level (around 2-4 sets per muscle per session, 2-3 times per week) for a period of time (around 4 weeks) to re-sensitize the muscle to a volume stimulus (Kreiger, 2019).  You then will repeat that process of slowly ramping set volume back up to around 8-10 sets per workout and the volume cycle is repeated. 

Ideally, you would spend around 8-12 weeks ramping up your volume before going back to maintenance levels.  

Here is the cool thing, it takes very little amount of work to maintain your strength and muscle mass. Mike Matthews has a great article here, going over how little you have to do to maintain muscle and strength. You can use these maintenance cycles to focus on other aspects of your life outside of the gym as well. 

So that is a more long term approach to ensuring you get the most out of your training to avoid injury, excessive fatigue, and potential injury. It would also be wise to implement week long maintenance periods every 4-6 weeks called deloads. 

Deloads are short periods of reduced training intensity and/or volume. These should be integrated into your program to facilitate rejuvenation and recovery (Schoenfeld, 2016). 

3:1 to 4:1 ratios seem to be best for deloads. For example, you would spend 3 weeks increasing volume or intensity, then the fourth week you would deload. 3-4 weeks is a good starting point, after a few deloads modifications should be made depending on how the individual responds. 

Even if you don’t think you need a deload, it probably is a good idea to take one anyways. To quote Jared Feather again, “if you don’t deload, your body will eventually take a deload for you.”


The goal would be to reduce the volume by around 25-50% from your last weeks numbers. If you finished with 15 sets of chest, the deload week could be around 5-10 sets. We also want to leave around 5+ reps in reserve (RIR) during these deload weeks. 


By giving our body designated periods to recover from training, it allows us to really push ourselves the rest of the time and it can add years onto your lifting career by reducing injury risk and burnout. 

However, there is one caveat to all of this. If you are not consistent with your training AND dont come within 5 reps of failure on your sets, then all of this is a wash. Your focus should then be on staying consistent and focusing on training harder before worry about deloads. 

Here is an example of how this would look:

Chest (sets are per week)

Week 1: 8 sets Week 6: 9 sets Week 11: 10 sets
Week 2: 9 sets Week 7: 10 sets Week 12: 11 sets
Week 3: 10 sets Week 8: 11 sets Week 13: 12 sets
Week 4: 10 sets Week 9: 12 sets Week 14: 14 sets
Week 5: (Deload) 5 Sets Week 10: (deload) 6 sets Week 10: (deload) 6 sets

*this is just an example


Volume cycling can be a way to ensure progress, but also reduce fatigue. Volume should increase for around 8-12 weeks, followed by a low volume maintenance period. Deloads are a temporary reduction in volume and/or intensity (about a week) and are a good idea to take every 3-4 weeks. 


5. Rep Ranges


While rep ranges are important, the more information that comes out for hypertrophy, the more we realize that rep ranges are not really as important as we think. Currently the consensus out there is that anywhere from 5-30 reps per set set seems to be best for muscle growth. 

The caveat to this, is that no matter what rep range you choose, you need to make sure you stay within 5 reps of failure. As long as you are within 5 reps of fail, then any rep range will work for muscle growth. I say this because the perception is that the “optimal” hypertrophy rep range is around 8-12 reps per set (and there is some good reason for this), but for example, let’s say you do a set of 12 reps and at the end of your set you feel like you could have gotten to 20 reps, yeah you hit the “hypertrophy rep range” but the set was just not hard enough to maximize muscle growth, so in this case 8-12 reps was NOT the optimal hypertrophy rep range. 

Essentially it comes down to preference for the individual. If you enjoy lighter loads and higher reps, then you can gravitate towards this style of training. If you are injured and cannot lift heavy, then you can also go lighter with the weight and do higher reps. 

However, there is some merit to spending time in all rep ranges at some point. Meaning, if you really enjoy the 6-10 rep range and find that most of your training is there, then it probably would be a good idea to spend some more time in the 10-20 range and the 20-30 range. 

On the other hand, if you spend most of your training in the 15-30 range, then incorporating some heavier style training in the 6-10 rep range will probably be great for you. As long as your reps from fail are within our 5 reps we discussed earlier (if you do not know what I am talking about go check out the training intensity section). 

In saying all of this, there is some merit to spending most of your hypertrophy training in the 8-15 rep range. As this allows a good amount of weight to be lifted, but also a good amount of volume to stimulate muscle growth. 

The 1-5 rep range is fine from time to time, however this type of training requires very heavy weights. This type of training gets you really strong, but it is not the most optimal for hypertrophy. The reason being is that this training is very intense and the heavy loads it requires can increase injury risk, and adds a ton of fatigue for very little muscle stimulus. So unless you are a powerlifter, I dont see much reason to ever really training in the 1-5 rep range. If you love lifting heavy however, then there is nothing wrong with lifting this way from time to time, just realize the trade offs. 



As long as training is within 5 reps of fail on each set, you can grow muscle anywhere from 5-30 reps per set. Training in the 1-5 rep range is ok from time to time, but is not optimal for muscle hypertrophy in the long term. 


6. Rest Times


Another variable that gets too much stock is rest times between sets. The reason it is not as important as other variables is because if you are not training hard enough and are not doing enough volume to grow, then rest times won’t matter. In saying that, we can manipulate rest times to help us get more volume in and train harder during each set.  

Recent research suggests resting at least 2 minutes between sets provides an advantage to muscle growth compared to shorter rest periods because of the ability to maintain greater volume (Schoenfeld, 2016). However, it seems prudent to include training cycles that limit rest periods to around 60-90 seconds, in particular high reps sets may benefit from short rest periods given the reduced need to exert maximal force (Schoenfeld, 2016). 

A good rule of thumb, do another set when you are ready. If you are still breathing heavy from your last set and still feel worn down, then it probably is NOT the best idea to go again, as the limiting factor would be your cardiovascular system rather than your muscles. 

If muscle growth is your goal, ask yourself what is the point of doing another set of squats if I am  still breathing heavy and my quads are not fully recovered? As this will surely lead subsequent sets being  sub-optimal.  

What you find out is that you end up resting longer on your compound exercises like squats, bench, deadlifts, rows etc. On isolation exercises like calf raises, bicep curls, lateral raises etc. just do another set when the muscle no longer has that burning sensation, since your cardiovascular system (breathing heavy) most likely will not be a limiting factor for these type of exercises. This could be 10 seconds, it could be 45 seconds, or it could be 90 seconds, feel it out, but you most likely will not have to rest 2 plus minutes for isolation exercises. 

We can discuss what the most optimal rest time is for muscle growth, but at the end of the day look at the big picture, if time is an issue for you then resting shorter between sets might be a sacrifice you just have to make for the time being. 



Rest around 2 or more minutes between sets on compound exercises. Rest as needed on isolation exercises. 


7. Exercise Selection 


This is the last variable to discuss because there is no one exercise that you need to do for muscle growth. Everyone is built differently, and one exercise that is perfect for George may not fit Rick well at all. So there is a ton of variability from one person to the next. 

In saying that, for overall muscular development we want to make sure we are hitting all of our major muscle groups at least once throughout our program. Instead of thinking about exercises in terms of what muscles they work, a better way to think about it is by thinking of them in terms of movement patterns (as this ensures we are hitting everything). Here is a list of the essential movement patterns:

Vertical Pull (lat pulldowns, chin ups, pull ups etc.)

Horizontal Row (Any row variation)

Vertical Push (overhead press variations)

Horizontal Push (dumbbell bench, incline press etc.)

Quad Dominant (squats, leg press etc.) 

Hip hinge/posterior chain (deadlift variations) 


This is a good foundation here. Once these are covered then you can look at adding in isolation work like bicep curls, tricep work, side delt work (lateral raises), rear delt work, and calves based on how much time you can commit to the gym. 

One mistake I see a lot of people make is that they do not have a ton of time to commit to the gym, and when you look at their program most of it consists of isolation type work like biceps, side delts, and calves. This is very sub-optimal and this person would be better off focusing on the essential movement patterns listed above. A good analogy for this would be someone who spends all of their money on really good speakers in their car, but the car has worn out tires, the engine is failing, and it has many dents in it. Yeah great speakers do improve the car, but just at a very tiny percentage. You would would be better off focusing on the foundational stuff first like fixing the engine or getting new tires (compound exercises). 

A good question to ask yourself if a particular exercise is good for a certain muscle group is do I feel that muscle working when I do the lift? If not, then it may not be the best for you for that particular muscle group. For example, people will ask if dips work the chest or triceps, but if every time you do them you feel it in your chest (this assumes you have done it more than a few times to improve your technique) then you have your answer. Don’t overthink it. 

Lastly, try to stick to the same exercise for at least 4 weeks or so before subbing it out. It takes time to really nail down your technique for an exercise, so if you continually switch out exercises week to week you are missing out on good muscle growth because you spend more time relearning the technique. 


There is no one best exercise for muscle growth. However, it is a good idea to make sure you have all of the essential movement patterns down, and then focus the rest of your time on isolation work based on your schedule and time available for the gym. Focus on keeping each exercise in your program for at least 4 weeks at a time. 




Lets now go over how to apply all of this:


1. Pick how many days you can commit to working out each week. If you can only do 3 that’s fine. It is important to pick an amount you know you can stick to each week. IMPORTANT NOTE: If you can only workout 3 days per week then expecting to do 20 working sets for one body part per week is probably not feasible, remember we use training frequency as a way to manipulate volume. 


 2.  Make sure you have all of your basic movement patterns in your program AT                       LEAST 1x, think of this as your foundation, here they are:


-Vertical Pull (lat pulldowns, chin ups, pull ups etc.)

-Horizontal Row (single arm dumbbell row, bent over db row, barbell bent row etc.)

-Vertical Push (Db seated press, military press, standing overhead press etc.)

-Horizontal Push (dumbbell/barbell bench, dumbbell/barbell incline press etc.)

-Quad Dominant (any squat, leg press etc.) 

-Hip hinge/posterior chain (deadlift variations such as stiff leg, romaninan, conventional)


Once you have at least one of each of these movement patterns in your program you can then add in any exercise you want for each muscle group. For example, we know squats hit the quads, but if you do not want to do 10-20 sets of squats per week, then you can do something like this: Squat 8 sets, leg extension 4 sets. OR however you want, remember the more muscle mass an exercise uses the less sets you will be able to do for that body part. 

If you are strapped for time, then doing more squats vs. leg extensions would be wise. If time is not an issue for you then you could break it up however you like. 

3. Pick your weekly volume for each muscle group.  Remember 10-20 sets per week seems to be best, however we dont want to jump right into 20 working sets per week. So start around 8-12 sets per week and then go from there based on recovery. 

4.Add in accessory volume like bicep, tricep, calves, side delts, abs based on how much time you can commit to the gym, once your foundation movement patterns are programmed. 

A good resource if you need help choosing specific exercises is from Renaissance Periodization. Here is the link:





Schoenfeld B, Ogborn D, Krieger J, (2016). Effects of Resistance Training Frequency on Measures of Muscle Hypertrophy: A Systematic Review and Meta-Analysis. Sports Med. 2016 Nov;46(11):1689-1697

Berardi J. How intense workouts (and overtraining) can ruin your results. Precision Nutrition. Retrieved from: https://www.precisionnutrition.com/are-you-overtraining

Schoenfeld B, Contreras B, Krieger J, Grgic J, Delcastillo K, Belliard R, Alto A. (2019). Resistance Training Volume Enhances Muscle Hypertrophy but Not Strength in Trained Men. Med Sci Sports Exerc. 2019 Jan;51(1):94-103.

Schoenfeld B. (2016). Science and Development of Muscle Hypertrophy. Human Kinetics. 

Kreiger J. (2019). Set Volume For Muscle Size: The Ultimate Evidence Based Bible. Weightology. Retrieved from: https://weightology.net/the-members-area/evidence-based-guides/set-volume-for-muscle-size-the-ultimate-evidence-based-bible/

Kreiger J. (2019). Research Review: To Fail or Not to Fail? The Impact of Training to Failure on Strength and Size. Weightology. Retrieved from: https://weightology.net/the-members-area/weight-training-research-reviews/research-review-to-fail-or-not-to-fail-the-impact-of-training-to-failure-on-strength-and-size/

Kreiger J. (2019). Research Review:  Straight Sets, Drop sets, or Pyramids for Muscle Size? Weightology. Retrieved from: https://weightology.net/the-members-area/weight-training-research-reviews/research-review-straight-sets-drop-sets-or-pyramids-for-muscle-size/

Kreiger J. (2019). To Fail or Not to Fail, Part 4:: Another Chapter on the Impact of Training to Failure on Hypertrophy. Weightology. Retrieved from:  https://weightology.net/to-fail-or-not-to-fail-part-4-another-chapter-on-the-impact-of-training-to-failure-on-hypertrophy/


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