There’s more to building muscle than simply lifting weights. This can certainly be an integral part of it, but anyone who has ever successfully achieved the goal of putting on muscle knows it’s not as straightforward as that.
In their attempts to discover how to develop bigger and stronger muscles, most people jump online.
There are lots of articles, programs, and plans on the internet that promise quick gains in size and strength, and while they’re often convincing, very few are evidence-based. That is, most are based on opinion and flawed reasoning rather than verifiable scientific research.
This makes it difficult to know what information and advice you can really trust. Unfortunately, when you follow untrustworthy exercise advice, your workouts are often ineffective and you rarely achieve the results you’re looking for.
Thankfully you don’t actually need to waste your time or money on fancy muscle-building programs.
Because scientific research – which you’re able to read and verify for yourself – has identified 6 basic principles that underpin muscle hypertrophy (the technical name for an increase in muscle size).
Understanding and using these basic principles will allow you to program your own workouts such that you build muscle as quickly and effectively as possible.
The 6 Principles of Muscle Building
Before we get started, there’s a couple of points we need to make. First, at the highest level, there are two things that stimulate muscle growth: 1) Resistance training; and 2) an abundance of amino acids in your system .
Resistance training is any deliberate exercise in which your muscles contract against an external force. Weight training is the most common and effective form of resistance training, and while it’s not the only form, it’s what we’ll be referring to throughout the article.
Amino acids are the building blocks of proteins, and proteins are the building blocks of muscle. Having an abundance of amino acids in your system (known as hyperaminoacidaemia), therefore is about your diet.
The first 5 principles relate to resistance training variables (i.e., things that can be easily changed), while the final principle relates to your diet.
The second point we’ll make is this: We’ve waded through the research, and simplified and summarized the basic principles behind muscle building for you. But you don’t have to take our word for it. This isn’t another one of those muscle-building articles or programs we mentioned earlier that tells you how it is and expects you to just believe it.
Throughout the article, we’ve cited our sources, and we’ve included a reference list at the end with all of the research named and linked (where possible) so that you can verify the information for yourself, if you so choose.
Admittedly, there is some of our own interpretation of the research in this article; for example, some people would argue there are more or less than 6 principles to muscle hypertrophy. That’s fine. The point is, you can check for yourself and see if you agree or not. We’re confident that our interpretation of the research is valid.
Now, with that out of the way, let’s get into the 6 principles.
Sometimes referred to as ‘load’ or ‘loading’, intensity has long been considered the most important component of resistance training as far as stimulating muscle growth is concerned .
Intensity is generally expressed as a percentage of ‘1 repetition maximum’ (1RM) – the maximum amount of weight that can be lifted in a single, complete repetition – and ultimately determines the number of repetitions (‘reps’) that can be performed with a given weight.
A foundational belief within resistance training circles is that sets of 6 – 12 reps are most effective for inducing muscle hypertrophy  , especially at loads greater than 60% 1RM . Recent scientific evidence challenges that belief.
A 2017 meta-analysis (a powerful type of research that analyses multiple previous studies) looked at 21 different pieces of research and found no difference in levels of muscle hypertrophy between high-intensity training (1 – 15 reps with loads >60% 1RM) and low-intensity training (15+ reps with loads <60% 1RM) .
Other research has shown similar results. Numerous studies examining repetition ranges have found little difference in muscular adaptations in rep ranges as diverse as 1 rep to 80 – 100 reps . It seems that the more important component of intensity is actually whether you complete sets to, or very close to (i.e., within 2 reps), momentary muscular failure – the point at which you can’t do another complete repetition with good technique .
Oldtime strongman, Kimon Voyages would be unsurprised by these findings.
Intensity and Muscle Building: What’s The Bottom Line?
If developing larger muscles is your primary aim then it almost certainly doesn’t matter how many reps you do of an exercise, as long as you’re completing sets to muscular failure , or within 2 reps of failure .
If you want to lift heavier, with low reps, then go ahead and do it. If you don’t have heavy weights, or you simply prefer to do higher repetition sets, then go ahead and do that knowing you’ll still be stimulating muscle growth. Finally, if you want to mix it up and train across a spectrum of intensities (i.e., high, medium, and low rep ranges), current research suggests that this may actually be the best method .
That said, lower rep sets with heavier loads is likely the more efficient method of building muscle mass. This is for the very simple reason that doing more reps takes more time, and potentially requires more effort, than doing fewer reps . Also, if you’re trying to build strength as well as muscle, then the meta-analysis mentioned above found that lifting heavy loads (>60% 1RM) is necessary .
Volume is a function of intensity, multiplied by the number of sets and reps completed for each muscle / muscle group per workout. That is, sets x reps x load (intensity).
For example, if you’re doing barbell curls and you complete 3 sets of 10 reps with a load of 100 lbs., then the training volume is:
3 x 10 x 100 lbs.
= 3000 lbs.
There has been some debate about the importance of volume amongst exercise scientists. Conventional wisdom suggests that ‘more is better’ – i.e., the more resistance training volume you complete, the greater the gains in muscle growth.
In 2013, a systematic review of the scientific literature concluded that this was wrong. The authors of that review suggested that training volume (measured by the number of sets completed) doesn’t have a relationship to muscle hypertrophy, and that ‘more is not better’.
That conclusion was quickly dismissed by a 2016 meta-analysis that examined 15 separate pieces of research into the effects of training volume on muscle growth . Those researchers found that training volume does have a direct and significant relationship to muscle hypertrophy, and that, yes, ‘more is better!’.
The results of that meta-analysis suggest that 10 or more sets per week per muscle group is necessary to maximize muscle-building efforts .
“Holy crap!”, we hear you say, “I can’t lift that much every week!”.
Well, fear not. That 10+ sets per week is what’s needed to maximize muscle growth. That same meta-analysis found that “…substantial hypertrophic gains can be made using low volume protocols (less than or equal to 4 sets per muscle group per week).” .
Volume and Muscle Building: What’s The Bottom Line?
The best current research indicates that training volume and muscle growth have a ‘dose-response relationship’. That’s a fancy way of saying more sets and reps leads to more muscle building.
That said, there is an upper limit to this relationship. Too much volume can lead to overtraining. Yes, overtraining is a thing, and it sucks.
If you’re trying to maximize your muscle-building efforts, and you have the time and energy, then shoot for 10 sets per muscle group per week. If you’re pressed for time, or you simply don’t have the energy for so much working out, then at least do 4 sets per muscle group per week.
Resistance training frequency refers to the number of sessions per week used to train a specific muscle group. Unfortunately, it’s received a lot less attention in sport and exercise research than intensity and volume.
The limited research that has looked at the effect of training frequency on muscle building has generally found that doing more sessions per week results in greater muscle hypertrophy. Two notable studies, for example, found greater muscle hypertrophy in people who trained specific muscle groups 3 days per week compared to those who only trained 1 day per week  .
Other studies, however, have found conflicting results. A 2015 study out of Brazil found no difference in increases in muscle size between people who trained specific muscle groups on 1 day per week, to those who trained 2 days per week . Similarly, a very recent 2018 study looked at the muscle growth in experienced lifters who trained 3 days per week and those who trained 6 days per week, and found no difference between the two .
It’s important to note here that all of the above studies were ‘volume-equated’. This means that the same amount of volume was being lifted regardless of the number of training sessions per week. If we use our 3000 lbs. barbell curl example from earlier, this would mean…
- A person training biceps on 1 day per week would do 3 sets of 10 reps of 100 lbs. on that 1 day:
3 x 10 x 100 lbs.
= 3000 lbs.
- A person training biceps on 3 days per week would only do 1 set of 10 reps of 100 lbs. on each of those 3 training days:
1 x 10 x 100 lbs. = 1000 lbs. (day 1) +
1 x 10 x 100 lbs. = 1000 lbs. (day 2) +
1 x 10 x 100 lbs. = 1000 lbs. (day 3)
= 3000 lbs.
Again, we can look to a recent meta-analysis to provide some clarity around training frequency and muscle hypertrophy. Looking at 10 different studies on the relationship between volume-equated training frequency and hypertrophy, researchers found that greater frequency does lead to greater muscle building .
However, the relatively small number of studies analyzed meant that the conclusions drawn were also limited. The researchers were only able to say with confidence that, keeping volume constant, training specific muscle groups on 2 days per week stimulated greater muscle hypertrophy than training those same muscle groups 1 day per week.
Frequency and Muscle Building: What’s The Bottom Line?
The research is not exactly clear-cut here. Whether more frequent training sessions leads to greater muscle hypertrophy hasn’t been determined with great certainty.
What is clear-cut, however, is that greater frequency is not bad for muscle hypertrophy. That is, it won’t lead to less muscle growth; it just might not lead to more.
Therefore, if you want or need to spread your training of muscle groups out over multiple sessions per week, then go for it! Just make sure you’re doing enough total volume (i.e., 4 or more sets per muscle group per week).
#4 Exercise Selection
Completing a variety of exercises when training specific muscle groups is important to ensure well-balanced and maximal muscle growth .
Utilizing different exercises forces you to modify aspects of bodily movement, such as angle of push / pull and position of the hands and feet. This ensures you’re taking advantage of different neuromuscular activation patterns and modes of leverage, which works all portions of specific muscles and assists in increasing their size most effectively .
For example, wide grip bench presses and pushups activate the lower part of the pecs (known as the sternal head) most intensely, while close-grip bench presses and pushups activate the upper pecs more intensely (known as the clavicular head). Doing both wide- and close-grip bench presses and pushups ensures that you’re working all parts of the pecs intensely, which will lead to greater hypertrophy.
Some strength and conditioning authors have recommended changing up exercises for specific muscle groups every 4-8 workouts (e.g., ). We’re not sure such frequent variation is necessary or practical, but we’ll leave that up to you.
Another factor to consider when selecting exercises is single-joint vs multi-joint exercises. Single-joint exercises (also known as isolation exercises) occur around one joint and involve a single muscle or muscle group.
Bicep curls and leg extensions are examples of single-joint exercises as they occur around the elbow and knee respectively, and involve only the biceps and quadriceps respectively.
Multi-joint exercises (also known as compound exercises) occur around multiple joints and recruit numerous muscles or muscle groups simultaneously.
Squats are the ultimate example of a multi-joint exercise as they occur around the hip joints, knees, and ankles, and recruit the quadriceps, hamstrings, glutes, abdominals, and numerous other muscles all at once (it’s been estimated that squats recruit up to 200 different muscles ).
It’s a long-standing belief in the resistance training community and amongst strength and conditioning coaches that training programs need to include both single-joint and multi-joint exercises in order to stimulate optimal muscle hypertrophy and strength gains.
Research into exercise selection challenges this belief.
On the whole, studies looking into the effect of multi- and single-joint exercises on muscular changes have found no differences in gains in muscle size and strength in individuals who use one or the other, or combine both in their training programs . That is, it’s almost certainly not necessary to do both isolation and compound exercises in order to build muscle most effectively.
Exercise Selection and Muscle Building: What’s The Bottom Line?
To ensure you’re developing your muscles in a balanced way, make sure to change up your routine at least occasionally, and employ a variety of exercises for each muscle and muscle group. Simply altering the position of your hands or feet, or angle of your body can modify most exercises, and target all portions of the respective muscles.
All things being equal, muscle building will be just as effective using single-joint exercises only, multi-joint exercises only, or a combination of both.
If you have a preference for isolation exercises, or they’re all you’re able to do due to personal circumstances, then do them without fear of compromising your hypertrophic gains. Ensure you incorporate the other principles in this article properly and you’ll be fine.
The same goes for compound exercises. If they’re all you want to / can focus on, then feel free knowing you will be building muscle effectively (as long as you have the other principles sorted, of course). In fact, because compound exercises work multiple muscles / muscle groups simultaneously, they’re generally a more efficient use of time.
Take the squat for example.
As we just mentioned, squats recruit an enormous number of muscles and muscle groups. To work all those muscles using isolation exercises would require an inefficient, and impractically large number of exercises. With one multi-joint exercise, you can achieve the work of dozens of single-joint exercises.
That’s not to say, however, that single-joint exercises have no use. They do. They have enormous value in selectively targeting and correcting muscle imbalances (e.g., underdeveloped biceps or triceps) , which many people naturally develop over time.
This is commonly called inter-set rest or rest interval and simply refers to the amount of rest taken between sets. Among strength trainers and bodybuilders it’s believed to be of key importance in building muscle.
A common view is that shorter rest periods (1 minute or less) are more effective for muscle hypertrophy than longer rest periods because they result in greater release of hormones that stimulate muscle growth (e.g., growth hormone and testosterone) . Others suggest that longer rest intervals (3 – 5 minutes) allow greater muscle recovery than shorter rest intervals, which in turn allows you to complete greater volumes of resistance exercise, which then leads to greater muscle growth .
Unfortunately, studies looking into the effect of different rest intervals on hypertrophy have produced somewhat mixed results.
A number of high quality studies have compared short and long rest intervals and found that shorter rest intervals (60 seconds or less) produce greater muscle hypertrophy than longer rest intervals (2 – 5 minutes)   . A number of other high quality studies have found the opposite effect (i.e., longer rest between sets has produced greater hypertrophy than shorter rest)   .
While the results of individual studies may be somewhat inconclusive, on balance the research does suggest that inter-set rest periods of 2 – 5 minutes are better than shorter rest periods in building both muscle and strength : But not better by much.
It seems that longer rest periods are superior particularly when training at high intensities. Indeed, the longer rest does appear to allow more time for muscles to recover, thus allowing you to train with greater volume .
Rest and Muscle Building: What’s the Bottom Line?
Simply put, science generally says you should use longer inter-set rest periods, especially if you’re training at high intensity (i.e., using heavy loads). But, we’d add if you have the time. Time is a major factor for many people when it comes to working out.
Increasing your inter-set rests by just 60s can increase the length of your workouts considerably (15+ minutes if you’re doing a decent session). If you don’t have that much spare time, then using shorter rest periods should be fine and are unlikely to detriment your muscle-building efforts too much.
We would suggest, however, that you keep an eye on your total volume. If you find that reducing your rest intervals leads to a significant reduction in volume, then you should probably go back to longer rests, and look for other ways to make your workouts more efficient.
Amino acids are the building blocks of proteins and proteins are the building blocks of muscle. When your muscles increase in size, it’s because you’ve stimulated the body to combine amino acids and create new muscle proteins: Two proteins in particular – myosin and actin .
When you eat protein-rich foods, your body breaks the proteins down into essential amino acids, which are then recombined in the muscles to create myosin and actin (primarily). So, in order for this process to work optimally and your body to build muscle efficiently, you need to be getting enough protein in your diet.
But how much protein is enough, you ask? Well, thankfully the answer to this question is pretty clear.
Research into the relationship between dietary protein and muscle hypertrophy has found that approximately 1.6 grams of protein per kilogram of body weight per day (1.6g / kg / day or 0.72g / lb / day) appears to be the optimal amount .
This means that if you weigh 200 lbs. (~91 kgs) then the optimal amount of daily protein to maximize muscle building for you is:
200 x 0.72g =
144g of protein per day
To give you an indication of what that looks like in terms of actual food, an average-sized egg contains ~13g of protein while chicken breast contains roughly 32g of protein per 100g of breast.
Protein and Muscle Building: What’s the Bottom Line?
In order to build muscle, your body needs access to protein. You need to give it access to protein by ingesting enough in your daily diet. Enough protein appears to be 1.6g / kg / day or 0.72g / lb / day. Although your body will still build muscle if you ingest less than this amount of daily protein, it may simply put on less muscle than it otherwise would. Ingesting more protein than the above amount is unlikely to have any additional benefit .
Now, many people find they struggle to eat as much food as necessary to provide the optimal amount of protein per day, which is why the use of protein supplements is common in resistance training.
A good quality protein supplement is a perfectly acceptable way of ensuring you get the amount of daily protein you need to optimize your muscle building efforts.
Additional Considerations for Muscle Building
We’re certain that many people will read this article and claim that we missed out various important principles of muscle building – things like repetition duration, exercise ordering, etc.
Therefore, we’ll do a quick overview of some additional things that may have an impact on muscle hypertrophy, but which we didn’t include because the research suggests they aren’t nearly as important as the 6 principles above.
Repetition duration refers to the total time it takes to complete a single repetition. It is typically comprised of the lifting portion (known as the concentric action), any pause at the top of the movement (known as the isometric transition), and the return to the starting position (known as the eccentric action). The length of time each of these actions takes is known as the Tempo.
Research suggests that repetition durations ranging from 0.5 seconds (which is a very rapid rep) to 8 seconds (which is a relatively slow rep) have similar effects on muscle hypertrophy, while durations of more than 10 seconds are probably ineffective .
That is, realistically it doesn’t matter if you do fast reps or slower reps, just make sure they’re not too slow, and that you’re controlling the weight all the way through the repetition.
It’s been suggested that certain exercises, and exercise types should be performed at the start of a training session.
For example, some authors believe that compound exercises that utilize the larger muscles and muscle groups should be done first, as this will ensure they receive sufficient training volume, and that good, safe technique isn’t compromised by fatigued muscles .
Very little research looking into the effects of exercise ordering on muscle building has been completed. The research that has been done, however, has generally concluded that you should order exercises based on your specific needs and goals .
The muscles trained at the start of a workout do tend to get fatigued more quickly and receive higher training volumes, and thus they increase in size to a greater extent. Therefore, if you’re trying to build size in certain muscles then work them first.
Free Weights vs Machines
This is perhaps the most controversial topic in the realm of resistance training.
We’re going to avoid getting caught up in this controversy, so we’ll try to be objective here.
The research that has compared free weight training (i.e., with barbells and dumbbells) to training with machines (e.g., cable weight machines, Smith Machines, etc.) has found little to no difference in the muscle-building achieved with each . That is, the best current scientific evidence suggests that whether you train with free weights or machines, you’ll be able to build muscle effectively. In fact, the resistance type seems to matter far less than the way you train – i.e., how well you use the 6 principles above.
For the record, we at The Home Fit Freak believe that the barbell is the single most effective training tool available to humans and that a good barbell set is the best investment you can make for muscle and strength building.
Ultimately, these are all exercise training tools, and the research suggests that, as far as building muscle is concerned, it really doesn’t matter which tools you use, as long as you use them intelligently.
We’ve covered quite a lot of ground in this article. But if we could boil it down to a sentence it would probably be:
Effectively building muscle requires the intelligent manipulation of 5 key training variables, and ensuring you’re giving your body enough protein
We’ve gone ahead and summarized the 6 principles of building muscle in the table below.
|The 6 Principles of Muscle Building|
|All repetition ranges and loads can be used to build muscle equally effectively. It’s more important to train to momentary muscular failure.||Schoenfeld et al. 2017|
|At least 4 sets per muscle group per week is needed, with 10+ sets being optimal.||Schoenfeld, Ogborn & Krieger, 2016|
|Evidence suggests that 2 – 3 sessions per week is better than a single session for each muscle / muscle group, however the research is not clear-cut.||Schoenfeld, Ogborn & Krieger, 2016|
|Ensure you’re giving your muscles an effectively balanced workout by varying your routine occasionally. All things being equal, muscle building will be just as effective using single-joint exercises only, multi-joint exercises only, or a combination of both.||Bloomer & Ives, 2000
Gentil, Steele & Fisher, 2016
|Longer inter-set rest periods (2 – 5 minutes) are generally more effective than shorter rest periods (less than 1 minute), especially if using very high intensities.||Grgic et al. 2017|
|1.6g protein / kg / day or 0.72g protein / lb / day is optimal for supporting muscle growth. More than this likely has little additional benefit.||Morton et al. 2017|
Well, there you have it: The 6 principles of muscle building.
Armed with the above knowledge, you should be able to design your workouts so that you’re maximizing your muscle building efforts.
Keep a look out for the other articles in our ‘Back to Basics’ series:
- Exercise Training 101
- How to Build Strength
- Increasing Endurance
- Developing Flexibility
They’ll be available soon.
If you found this article helpful, then why not share it with your friends and family on social media?
Until next time, remember: When it comes to our health and fitness, we can either make the effort or make excuses, but we cant make both.
All the best with your home workouts,
THFF (The Home Fit Freak)
 ACSM. (2009). Progression models in resistance training for healthy adults. Medicine & Science in Sports & Exercise, 41(3), 687-708.
 Bloomer, R. & Ives, J. (2000). Varying neural and hypertrophic influences in a strength program. Strength and Conditioning Journal, 22(2), 30-35.
 Buresh, R., Berg, K., & French, J. (2009). The effect of resistive exercise rest interval on hormonal response, strength, and hypertrophy with training. Journal of Strength and Conditioning Research, 23(1), 62-71.
 Colquhoun, R., et al. (2018). Training volume, not frequency, indicative of maximal strength adaptations to resistance training. Journal of Strength and Conditioning Research, 32(5), 1207-1213.
 Fink, J., Kikuchi, N., & Nakazato, K. (2016). Effects of rest intervals and training loads on metabolic stress and muscle hypertrophy. Clinical Physiology and Functional Imaging, 38(2), 261-268.
 Fink, J., Schoenfeld, B., Kikuchi, N., & Nakazato, K. (2016). Acute and long-term responses to different rest intervals in low-load resistance training. International Journal of Sports Medicine, 38(02), 118-124.
 Fisher, J., Steele, J., & Smith, D. (2013). Evidence-based resistance training recommendations for muscular hypertrophy. Medicina Sportiva, 17(4), 217-235.
 Fisher, J., Steele, J., Bruce-Low, S. & Smith, D. (2011). Evidence-based resistance training recommendations. Medicina Sportiva, 15(3), 147-162.
 Gentil, P., Fisher, B., Martorelli, A., Lima, R., & Bottaro, M. (2015). Effects of equal-volume resistance training performed one or two times a week in upper body muscle size and strength of untrained young men.. The Journal of Sports Medicine and Physical Fitness, 55(3), 144-149.
 Gentil, P., Fisher, J., & Steele, J. (2016). A review of the acute effects and long-term adaptations of single- and multi-joint exercises during resistance Training.. Sports Medicine, 47(5), 843-855.
 Grgic, J., Lazinica, B., Mikulic, P., Krieger, J., & Schoenfeld, B. (2017). The effects of short versus long inter-set rest intervals in resistance training on measures of muscle hypertrophy: A systematic review. European Journal of Sport Science, 17(8), 983-993.
 Henselmans, M. & Schoenfeld, B. (2014). The effect of inter-set rest intervals on resistance exercise-induced muscle hypertrophy. Sports Medicine, 44(12), 1635-1643.
 Hill-Haas, S., Bishop, D., Dawson, B., Goodman, C., & Edge, J. (2007). Effects of rest interval during high-repetition resistance training on strength, aerobic fitness, and repeated-sprint ability. Journal of Sports Sciences, 25(6), 619-628.
 Howe, L., Read, P., & Waldron, M. (2017). Muscle hypertrophy: A narrative review on training principles for increasing muscle mass. Strength and Conditioning Journal, 39(5), 72-81.
 McDonagh, M. & Davies, C. (1984). Adaptive response of mammalian skeletal muscle to exercise with high loads. European Journal of Applied Physiology and Occupational Physiology, 52(2), 139-155.
 McLester, Jr., J., Bishop, P., & Guilliams, M. (2000). Comparison of 1 day and 3 days per week of equal-volume resistance training in experienced subjects. The Journal of Strength and Conditioning Research, 14(3), 273-281.
 Morton, R., et al. (2017). A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. British Journal of Sports Medicine, 52, 376-384.
 Phillips, S. (2004). Protein requirements and supplementation in strength sports. Nutrition, 20(7-8), 689-695.
 Phillips, S. M. (2014). A brief review of critical processes in exercise-induced muscular hypertrophy. Sports Medicine, 44(S1), 71-77.
 Sampson, J. & Groeller, H. (2015). Is repetition failure critical for the development of muscle hypertrophy and strength?. Scandinavian Journal of Medicine & Science in Sports, 26(4), 375-383.
 Schoenfeld, B. (2010). The mechanisms of muscle hypertrophy and their application to resistance training. Journal of Strength and Conditioning Research, 24(10), 2857-2872.
 Schoenfeld, B., et al. (2016). Longer interset rest periods enhance muscle strength and hypertrophy in resistance-trained men. Journal of Strength and Conditioning Research, 30(7), 1805-1812.
 Schoenfeld, B., Grgic, J., Ogborn, D., & Krieger, J. (2017). Strength and hypertrophy adaptations between low- vs. high-load resistance training: A systematic review and meta-analysis. Journal of Strength and Conditioning Research, 31(12), 3508-3523.
 Schoenfeld, B., Ogborn, D., & Krieger, J. (2015). Effect of repetition duration during resistance training on muscle hypertrophy: A systematic review and meta-analysis. Sports Medicine, 45(4), 577-585.
 Schoenfeld, B., Ogborn, D., & Krieger, J. (2016). Effects of resistance training frequency on measures of muscle hypertrophy: A systematic review and meta-analysis. Sports Medicine, 46(11), 1689-1697.
 Schoenfeld, B., Ogborn, D., & Krieger, J. (2016). Dose-response relationship between weekly resistance training volume and increases in muscle mass: A systematic review and meta-analysis. Journal of Sports Sciences, 35(11), 1073-1082.
 Schoenfeld, B., Ratamess, N., Peterson, M., Contreras, B., & Tiryaki-Sonmez, G. (2015). Influence of resistance training frequency on muscular adaptations in well-trained men. Journal of Strength and Conditioning Research, 29(7), 1821-1829.
 Van Roie, E., Delecluse, C., Coudyzer, W., Boonen, S., & Bautmans, I. (2013). Strength training at high versus low external resistance in older adults: Effects on muscle volume, muscle strength, and force–velocity characteristics. Experimental Gerontology, 48(11), 1351-1361.
 Villanueva, M., Lane, C., & Schroeder, E. (2014). Short rest interval lengths between sets optimally enhance body composition and performance with 8 weeks of strength resistance training in older men. European Journal of Applied Physiology, 115(2), 295-308.