Metadata
- Authors: Dr. Mike Israetel Dr. James Hoffmann Dr. Melissa Davis Jared Feather
- Full Title:: Scientific Principles of Hypertrophy Training
- Category:: đź“šBooks
- Read date:: 2025-05-04
Highlights
practice with the same exercises improves mind-muscle connection—the ability to perceive tension and burn in the muscle you’re targeting, rather than just going through the motions14. Better mind-muscle connection has also been associated with more muscle growth15. (Location 198)
you have undoubtedly met someone who’s goal is to “get big”, but who trains near their 1RM (one rep maximum) all the time, unaware that lower weight and higher reps will stimulate growth more effectively20. (Location 283)
A lot of bodybuilders say they want bigger rear delts, but they never manage to formally rank rear delts as a high priority in their program. They simply continue to do the same standard muscle magazine shoulder workouts (essentially some variation of an overhead press, followed by some lateral raise variation, and rear-delt machine work once a week). If this isn’t one of the worst program designs for rear delts, it’s hard to imagine what is. Such training comes from a lack of a commitment to making training specific to the needs defined in the needs analysis. (Location 300)
Competitor or hobbyist, you must identify which muscle groups you need or want to grow during the training program you are preparing to write. While it is easy to say “all of them”; in most cases, especially for advanced lifters, growing all of them efficiently in a single training phase or set of phases is not realistic. (Location 315)
there is no evidence for the potentiation of growth via strength gains nor any logical mechanism by which this could occur. (Location 376)
There is a time and a place for super-focused priority programs, but that time and place is mostly reserved for highly muscular, very advanced (perhaps seven years or more) lifters. (Location 400)
doing training for one muscle group with a few different exercises per week causes more muscle growth than doing only one exercise per week, even if the number of sets is equated17. (Location 404)
variation every few mesocycles or so is advisable. (Location 419)
The sentiment that often leads to programs with very few exercises is the “hardcore, just the basics, brother” attitude. But like most simplistic notions, this one falls short of being the best advice. (Location 440)
the forces you can generate in compound movements, even when measured at the muscle level itself, are often higher with compounds than they are with isolation movements. (Location 448)
This ranking is based both on data that tease apart interacting elements to the extent possible and on practical program design: 1. Tension 2. Volume 3. Relative effort 4. Range of Motion (ROM) 5. Metabolite Accumulation 6. Cell Swelling 7. Mind-Muscle Connection 8. Movement Velocity 9. Muscle Damage Again, the above list is in order of the importance of these stimulators. That is, the ones towards the top should be prioritized aspects of most hypertrophy programs. (Location 657)
Muscle growth is probably triggered in proportion to both the amount of metabolites present and the duration of their presence. While the growth from these pathways probably does not compare to that resulting from tension-mediated pathways, it does likely produce robust hypertrophy. In addition, it seems likely that tension-mediated growth pathways are boosted in the presence of certain metabolites, giving metabolites an indirect growth effect as well as a direct one38. Since more metabolites are produced closer to failure, this is more support for the importance of relative effort38. (Location 846)
Direct research on cellular physiology has shown that the swelling of muscle cells actually itself stimulates muscle growth and that this might be especially true for faster-twitch muscle cells43,44,45,46. This means that “the pump” experience revered by bodybuilders through the ages is actually in some way a direct observation of stimulation of muscle growth. This does not mean a lack of pump during training means a lack of growth stimulus (lower rep heavy training does not produce much pump but can promote some growth), but it does mean that the pump can be sought in its own right. (Location 852)
The last five or so reps of a set taken close to failure sees the vast majority of the tension produced by the biggest and most growth-prone motor units. (Location 949)
Thus, performing most, if not all, working sets in a program at 5 RIR or less is probably best practice. The temptation is to see Figure 2.5 and conclude that 0 RIR training should be the goal of every program, but what is missing from this graph is the element of fatigue. (Location 977)
If we take both stimulus and fatigue into account, we come to a different conclusion— averaging 2-3 RIR likely allows the best stimulus to fatigue ratio for long-term growth (Figure 2.6). While one session at 0 RIR will cause more growth than one session at 5 RIR, the 0 RIR session will create vastly more fatigue61,62. This fatigue will limit your ability to progressively overload across subsequent weeks and therefore limit gains. (Location 980)
Without considering the proximity to failure (the relative effort variable), notable growth in healthy subjects is seen at weights above 60% 1RM (and especially above 75% 1RM). Thus, in older research, 60% 1RM was marked as the bottom of the hypertrophy stimulus threshold for tension because proximity to failure wasn’t factored in18. When working in close proximity to failure, however, we can see robust growth starting at around 30% 1RM7,13. This is our tension stimulus threshold. (Location 1008)
the amount of growth stimulus per set is very comparable for sets of anywhere from five to 30 reps so long as the sets are close to failure. (Location 1042)
we get very close to equating growth stimulus just by counting the number of “hard sets” (sets taken to within 5 -0 RIR) in a program, (Location 1044)
Sets x reps x weight can just be simplified to sets since, as we have seen, reps and weight more or less cancel each other out. So, we end up with sets again proving to be a fairly accurate and very convenient measure of volume. (Location 1052)
Your MEV depends on a lot of things, but the biggest determinant by far is your training age. (Location 1065)
there is no need to program extremely heavy weights7,13. (Location 1084)
sets of fewer than 10 reps might be so heavy that trying to maintain awareness of individual muscles is either not possible or distracts from effectively moving the weight. This leaves us with a rep range of around 10-20 for best mind-muscle connection for most people. (Location 1103)
For the time being and until much more research on the topic becomes available, if you’re in control of the weights and you’re not taking more than three seconds on any of the concentric, pause, or eccentric phase, you’re probably getting maximum or near-maximum effect55. (Location 1160)
probably best in most programs to do straight sets first, and then do metabolite work afterwards. (Location 1186)
“A meaningful amount of work” means that the muscle can do at least five reps. (Location 1195)
It might only take a minute to go from 50% to 90% recovered after an average set, but another two minutes to go from 90% to 95% and another 10 minutes to go from 95% to 99%! If we look at it from an efficiency perspective, doing ten “90% effective sets” in 30 minutes time is vastly more efficient than doing just a couple “99% effective sets” in the same timeframe. Because per-set hypertrophy is such a powerful modulator of growth, ten “good sets” will cause vastly more growth than two “almost perfect sets.” (Location 1233)
make sure you’re never cutting into the number of 5-0 RIR “effective reps” in any of your working sets. (Location 1265)
While low rep straight sets might target tension more, high rep straight sets might target the pump more, and short-rest sets like myoreps and drop sets might target metabolite summation more. All modalities target all three of the primary growth pathways to some extent, but some emphasize one more than another. You don’t need to use all or even most of these options in your training. If you’re well prepared for heavy training and have the time, straight sets are a great tool. If (Location 1438)
An effective hypertrophy stimulus involves a good mind-muscle connection as defined in this chapter to include the perception of tension or the burn of metabolites accumulating. (Location 1457)
the feeling of the muscle working close to its limits. (Location 1467)
If during a working set, your target muscle feels like it is losing the ability to generate high-force contractions, that is a very good sign of an effective stimulus. (Location 1482)
Just adding sets is a fine way to progress, but if that were the only progression we used, we would run some problems: (Location 1586)
as your reps stay within their target ranges, you can progress via reps and sets every week for as long as that lasts. Once maintaining your 5-0 RIR (Location 1594)
add some weight to the bar just about every week. (Location 1599)
Because volume adaptation occurs faster than strength increases (in the short term), most individuals can benefit from both load and set progressions week to week. You’d start a training plan at around your MEV, and then, as recovery dictated, add sets until you hit your MRV. At the same time, you would add load in small increments, progressing on two variables at the same time. (Location 1607)
The “RP MEV Stimulus Estimator Algorithm”: (Location 1675)
The “RP Set Progression Algorithm”: (Location 1708)
your body adapts faster to volume than to weight increases in most cases, you’ll usually find that you can add quite a few sets over the course of your mesocycles even if you cannot increase weight weekly. (Location 1742)
it’s almost always better to low-ball the volume at the beginning of the program rather than get too ambitious too soon. You can always add more sets, but reducing excessive fatigue means stopping or heavily modifying the program, which highly interferes with results. (Location 1744)
You can progress through RIR as described earlier (working from 4-5 RIR in the first week up to 0-1 RIR in your last). (Location 1747)
Because the magnitude of loading (with close proximity to failure) is not very impactful on muscle growth, but the degree of volume is, rushing to lift more weight or more reps by keeping set volumes low will not yield the best muscle growth results. (Location 1752)
We try to progress more on the exercises that feel better (and expect the harder to feel easier)
We start week one with three sets of each, and, as usual, gauge how fatiguing and how stimulative it was. Maybe squats felt pretty tough, the technique was a bit shaky, and your mind-muscle connection was fairly low. On the other hand, maybe hack squats felt super crisp and generated a big pump for what felt like very little effort. When adding two sets to this session next week, you might be better served adding both to the hack squat. (Location 1779)
In very simple terms, this advanced method basically adds sets to exercises that seem the most effective and least fatiguing in order to maximize results. (Location 1789)
If heavy work is just not feeling great but light work is moving along, adding more sets to the light work and fewer to the heavy might not be a terrible idea. (Location 1791)
you might preferentially add volume to lifts you like doing better, even if they are not as stimulative. Now, you should very much want to add more sets to the exercises that feel like they are the least taxing in order to keep fatigue controlled, but that has to be weighed against the perceived stimulus magnitude of the exercise as well. (Location 1922)
If all of your working sets are always between 30% 1RM and 70% 1RM, that’s all in the effective stimulus range, but skipping 70% 1RM to 85% 1RM loads means you are missing out on a fraction of growth, specifically for your most growth-prone muscle fibers. Short of injury or risk management in special situations, most lifters aiming for best growth should train heavy, light, and everything in between within the effective stimulus range. (Location 1929)
Underdosing volume is incredibly common. (You might expect this sentiment from the authors that coined the volume landmark terms, but it’s nonetheless true!) As has been borne out by numerous recent studies, many people train with considerably less volume than they could benefit from, often by as much as a factor of three89,90,91,92. (Location 1933)
Even a once-weekly 20 set workout for a muscle group might be only half of someone’s weekly MRV. Because adding any sets to that single workout is likely catabolic (due to the excessive damage caused by high single session volumes), the only effective way to add volume in such cases would be to increase frequency (add another weekly session), a practice that the dogma of “one muscle group per week” training often prohibits57,93,94,95. (Location 1942)
It is nonetheless something to be aware of and assess, especially on high rep sets or metabolite techniques where the pain makes you want to stop long before failure. (Location 1956)
A big problem with using partials is lack of safety. When you can control a weight in its full ROM, you are prepared to handle it during all parts of the lift. With partial ROMs, the weights are often so heavy that controlling them within even a slightly bigger than planned ROM is not guaranteed. (Location 1963)
problem with this is that adding sets every week without adding reps or weight would eventually mean that the first few sets of a session would fall short of 0-5 RIR (as you became capable of more reps, but were not adding them in order to add sets). (Location 2005)
Over-prioritizing load progression is also detrimental. If you add too much weight to the bar each week you might not recover enough to add reps or sets if you want to. (Location 2013)
Adding a combination of sets, weight, and (if/when needed) reps is the most effective (Location 2019)
The following list includes both these cellular stimulators and the training stimuli that produce them in order of importance for growth. 1. Tension 2. Volume 3. Relative effort 4. Range of Motion (ROM) 5. Metabolite Accumulation 6. Cell Swelling 7. Mind-Muscle Connection 8. Movement Velocity 9. Muscle Damage (Location 2051)
There is a great deal of individual variation and large differences between beginners and advanced lifters however and determining individual approximate MEV and MRVs will make training most productive. You can use the MEV Stimulus Estimator Algorithm to find your MEV. (Location 2069)
blue So no need to look for this explicitly it training near 5 RIR
Training that presents MEV-MRV volumes at RIRs of 5 or less sums enough metabolites and causes enough cell swelling for best growth. (Location 2075)
A very simple way to sum up the entire Overload principle’s implications for hypertrophy stimuli is as follows: “Do multiple sets of 5-30 controlled, full-ROM reps that take three to nine seconds per rep. Take them close to failure (5-0 RIR in most cases), where the target muscle is the limiting factor, and repeat this approach as often as you are recovered enough to do so.” (Location 2084)
“Do multiple sets of 5-30 controlled, full-ROM reps that take three to nine seconds per rep. Take them close to failure (5-0 RIR in most cases), where the target muscle is the limiting factor, and repeat this approach as often as you are recovered enough to do so.” (Location 2085)
Start your session volumes at around your MEV (about 2-4 sets per session per muscle group in many cases) and add sets via the Set Progression Algorithm. This generally means adding 2+ sets per session per week if your soreness is low and performance is rising, adding 0-1 sets per session per week if your soreness is significant and your performance is stable, and considering a recovery session, half-week, or deload if your performance falls week to week. (Location 2110)
If you are normally very dedicated and train whether or not you feel like it, but you suddenly lose interest and stop caring about training, fatigue management might be in order. Continued fatigue accumulation might result in feelings of helplessness, powerlessness, and general malaise—at (Location 2436)
Axial fatigue results from loading weight onto the spine and is an interesting intersection between local and systemic fatigue. Technically it is a type of local fatigue produced in the muscles (Location 2447)
It is important to recognize, however, that a complete lack of fatigue is not necessary (and might be impossible) for effective training—just feeling sore or tired is not by itself a sufficient reason to take training down to recovery levels in most cases. (Location 2483)
Effort perception is often tied closely to axial loading. (Location 2526)
This does not mean that large perceived effort is always a bad thing, but the trade-off must be worthwhile. A quintessential example of excessive effort that does not pay off for SFR is cheating on strict movements—using momentum to heave heavier weight on a movement generates more fatigue without providing more stimulus to the target muscles. (Location 2530)
For example, for many people, high bar squats are probably more stimulative than leg presses for quad growth, but they are also more fatiguing—meaning the SFRs of the two exercises might actually be very comparable. (Location 2618)
While the conventional deadlift does stimulate the hamstrings, it also causes massive axial loading and systemic disruption, all while not taking the hams through a long range of motion. Stiff legged deadlifts, on the other hand, target the hams directly, increasing the stimulus, but use less weight for this purpose so that axial and systemic fatigue components are lower and thus the SFR is higher. (Location 2624)
You can stimulate great muscle growth from two sets of properly done stiff legged deadlifts, but most people will need perhaps double that volume in leg curls to make the same kind of progress. Since the leg curls cause so much less fatigue, however, there’s still no clear winner in terms of SFR. (Location 2629)
A pro bodybuilder may have to train nine times a week for hours on end to get a measly five pounds of muscle per year, whereas a beginner might train for 45 minutes three times a week and gain 10 pounds in their first year of training! (Location 2717)
If you don’t want to mess with altering RIRs over the course of a mesocycle, shooting for around 2 RIR on all sets should get you very close to the best results. Even lifters who choose to stay at 2 RIR the whole time might consider going to 1 or 0 RIR in the last week before deloading, since the extra time to recover may justify the larger raw stimulus magnitudes of the lowest RIR training. (Location 2724)
For most individuals, an accumulation phase (the path from MEV to MRV) will last between 3-8 weeks, (Location 2757)
If your mesocycles are within these ranges and you get to the final week thinking “there is no way I could handle one more week of accumulation,” you’re probably on the right track with your program design! (Location 2759)
The bad news is that everything counts, so you must be very mindful with your training plans to get your absolute best results. On the other hand, this reality gives you more control to mitigate unplanned deviations. (Location 2762)
Ramping volume up and changing load very little results in “wear and tear” type injuries (like joint pain, for example). (Location 2769)
Increasing load preferentially with little change to volume on the other hand, increases the likelihood of acute, traumatic injuries (like muscle tears, for example). (Location 2770)
Neither type of injury is great, but because wear and tear can be managed and acute injury often comes without warning and can take you out of training completely for some time, the latter is probably the worst of the two if hypertrophy is your long-term goal. (Location 2773)
the best hypertrophy results come from challenging yourself with a progressive volume of hard sets, not by challenging yourself with a progressive loading of “just enough sets.” The latter is ideal for strength development, but not muscle growth. (Location 2777)
when you hit your MRV, you’ll know. If you are truly hitting your MRV you will feel like you’re pushing that muscle to its limits and often find that your reps are off by 3-5 or even more from your target for a given session. (Location 2804)
Many a lifter has noticed the reduction in their fatigue and injury rates when switching to full ROM lifting, especially while maintaining eccentric and amortization control. (Location 2819)
look for variations that stress your muscle more and your joints less. (Location 2840)
Proper technique can be humbling, and it might mean that you have to reduce the weights you’ve been using for some exercises, but if you take the time and commit yourself to good technique, you will experience lower fatigue and be able to get that much more stimulus (Location 2863)
If you have three pushing sessions per week, you might do chest first on one of them, triceps first on the next, and front delts first on the last one so that each gets a day to be prioritized, but all are worked on all three days. (Location 2877)
Rotating heavier and lighter training sessions for the same muscles and prioritizing different muscle groups on different days allows some individual fibers to reduce fatigue while others are trained and lets connective tissues recover between high tension exposures without sacrificing weekly stimulation. (Location 2888)
We can further manage fatigue by rotating movement type. For example, if you train your back two days per week, you can have a heavy vertical pulling day and a heavy rowing day. (Location 2891)
For example, you can train heavy chest, legs, and back earlier in the week keeping arms, shoulders and calves lighter, and then switch later in the week (Figure 3.5). Mind you, all muscles are trained during both parts of the week, but the heaviest and highest volume sessions for the big muscles occur earlier. (Location 2910)
Our first recommendation is to take one full day off per week. Our second recommendation is to look over your program and see if you can condense any shorter, easier workouts to free up a second rest day. (Location 2931)
Lifters should use only as many sessions as needed and not, for example, do biceps and calves alone on a day when those low-impact lifts could have been added at the end of other training days and allowed for a full rest day. (Location 2935)
At some point in their training careers, the average individual muscle MAVs of nearly all lifters will sum to a higher volume than their systemic MRVs. This means that such lifters will have to employ specialization—training some muscle groups at MEV or MV volumes for a training block in order to free up the recovery resources needed for other muscles to be trained at MAV. (Location 5475)
In some cases, this specialization process might be needed irrespective of MRV ceilings. For those who have a very limited number of hours to train per week, training all of the desired muscle groups even at MEV might take more time than is available. (Location 5480)
use the RP MEV Stimulus Estimator Algorithm and the RP Set Progression Algorithm (Location 5934)
The most effective relative effort stimulus range for hypertrophy is between 5-0 RIR. (Location 5939)
On a per week basis the best range of exercises per muscle group is likely around 2-4 exercises. (Location 5959)
At least four weeks of accumulation should be the goal in either case. Training with increasing focus (Location 5974)
advanced lifters need very little stimulus to keep their gains, but a whole lot to make new ones. In other words, the gap between their MV and MEV is large. (Location 5990)
Typical accumulation duration is 4-8 weeks, with longer durations more common for beginners and shorter for more advanced lifters. (Location 6014)
In an ideal situation you would be able use your ending weight from one mesocycle as the start weight for the next, but this ideal circumstance is not often the case. (Location 6019)
This strategy, though likely optimal for gains, means that your sessions in week one might last 45 minutes each while your sessions in week five last nearly two hours. (Location 6230)
As discussed, advanced lifters in particular need considerable volume to progress, but very little to maintain muscle. Advanced lifters with limited time to train might be best served using very distinct specialization phases. For example, a lifter might train only two (Location 6241)
muscle groups very hard from MEV to MRV, but train the rest of their muscles at MV. This would advance the target muscles while maintaining the others, and switch out which muscles are prioritized every couple mesos. (Location 6244)
NEAT (Non Exercise Activity Thermogenesis—calorie burning activities of daily living like walking around, playing with kids, cleaning the house, etc.) can burn a huge number of daily calories and is minimally fatiguing. For this reason, keeping NEAT high is often a better choice than adding cardio for those focused on hypertrophy (especially if their cardiovascular fitness is already fairly good). (Location 6274)
High intensity interval training (HIIT) is not best choice for hypertrophy goals (Location 6293)