A new method of training: can resting for hours between exercises maximise your gains?Mon Nov 30 2020
~ 1600 words
After reading the scientific literature and thinking through first principles, I've been thinking about a training method that I believe (as far as the evidence goes) maximises hypertrophy but also happens to be very easy and painless. This training method deviates from most programs in two (three) main ways:
- Advocates full body workouts, 5 days a week
- Advocates long (~15--25 minute) rests between sets, and even longer rests (~hours) between exercises
- (optional) Consider cluster sets (resting a couple of seconds in between reps) and blood-flow restriction training
While I designed the method for my very particular set of circumstances and preferences (I have a home gym and prefer squeezing in sets throughout the day rather than blocking out a large block of time), I believe this method of training could actually be optimal for muscle growth.
The key idea is to maximise effective volume and muscle protein synthesis while minimising metabolic stress and muscle damage. The long rests between sets/exercises brings to mind the Greasing the Groove (GtG) protocol but focuses on near-maximal sets with high (7--8) RPE to maximise muscle tension/volume.
Microfoundations: what makes muscle grow?
TL; DR: The science suggests that muscle tension (force production and stretch) is the primary (and possibly the only) driver of growth. There is little evidence to show that muscle damage ("microtears") or metabolic stress ("burn" from lactic acid, "pump") contribute to hypertrophy, suggesting that we should maximise muscle tension and minimise muscle damage/metabolic stress.
The scientific consensus used to believe otherwise. In Brad Schoenfield's seminal paper (2010)
he writes that
Mechanically induced tension produced both by force generation and stretch is considered essential to muscle growth.. [but is] unlikely to be solely responsible for hypertrophic gains associated with exercise.
He points to muscle damage and metabolic stress as contributing factors, and concludes that
Current research suggests that maximum gains in muscle hypertrophy are achieved by training regimens that produce significant metabolic stress while maintaining a moderate degree of muscle tension. A hypertrophy-oriented program should employ a repetition range of 6-12 reps per set with rest intervals of 60-90 seconds between sets.
But in this video Schoenfeld updates his model. He says that the evidence for an additive effect of muscle damage or metabolic stress on hypertrophy is really equivocal and none of it is compelling.
In 2017 Menno Henselmans gave a talk where he cites a lot of papers and claims that both muscle damage (microtears in the muscle fibers) and metabolic stress (acidosis, lactic acid buildup, "pump", etc.) are not drivers of muscle hypertrophy. I haven't read the papers he cited but I trust him. The TL;DW is that:
i) muscle damage is a necessary byproduct of muscle tension, but does not itself stimulate hypertrophy. Increased muscle damage causes greater muscle protein synthesis, but no net muscle growth; the increased muscle protein synthesis simply repairs the damaged muscles. Additionally, blood flow restriction training seems to be able to induce similar levels of muscle growth with little to no muscle damage.
ii) training to failure causes metabolic stress to rise exponentially but we observe little to no increase in muscle growth (S-shaped curve).
There seems to be no good evidence to believe that muscle damage or metabolic stress contribute to hypertrophy. (Also, muscle damage and metabolic stress both hurt, and I don't like to hurt). This leads to a pretty counterintuitive conclusion: in order to maximise hypertrophy, we should aim to maximise muscle tension/force production while minimising muscle damage and metabolic stress.
If we accept this conclusion, that implies that we should take long rests between sets and perform few sets of exercises for a muscle group at a high intensity. Both these adjustments minimise metabolic stress and maximise volume.
Why long rests?
TL;DR: It allows increased volume---the primary driver of growth--- and also works much better with my schedule/preferences.
Exercise volume can be defined as the product of total repetitions, sets, and load performed in a training session (Schoenfeld 2010). If we believe that muscle tension (ergo volume) is the primary driver of hypertrophy, the idea then is simple: if we take longer rests, we can do more volume, which means more gains! Here's Henselmans:
In conclusion, your rest interval matters primarily because it affects your training volume. As long as you perform a given amount of total training volume, it normally doesn’t matter how long you rest in between sets... It’s the total volume, not how you distribute it over time, that determines the signal for muscle growth. However, in practice, ‘work-equated’ doesn’t exist, as it’s just you, so resting shorter for a given amount of sets decreases how many reps you can do in later sets and thereby your training volume. This means for most people, resting only a minute or less in between sets is probably detrimental for muscle growth rather than beneficial.
The scientific literature doesn't seem to examine very long rest periods, probably because nobody has the time to sit around for ages doing nothing. But I do because I now have a home gym and can bang out a set in between Pomodoro timers of 25 minutes. It's unlikely that resting for a long period would lower hypertrophy precisely because metabolic stress and/or muscle damage don't seem to be important for growth (but see the Appendix for concerns about "cooling down").
In essence, hitting one muscle group a lot in one session with not-very-long rests between sets both decreases volume causes a great deal of metabolic stress compared to doing the same exercises over several days AND taking long rests between them. The best part is that if you do them spread out you can do more volume which means more gains---AND you hurt much less.
Why a 5-day full-body workout?
TL;DR: Training each bodypart more frequently maximises muscle protein synthesis.
Damas et al. (2015) found that muscle protein synthesis (MPS) in trained individuals returns to baseline just 12 hours after working out, which means that in order to keep muscle protein synthesis at its peak for a particular muscle one should be working that muscle every single day---possibly even two times a day for elite athletes.
Additionally, muscle growth is a hyperlocal phenomenon: elevated MPS in your chest isn't going to make your arms or quads bigger.
This is why we should work full-body. Since
- MPS is hyperlocal,
- MPS drops off 12 hours after working out,
- MPS causes muscle hypertrophy,
it therefore follows that we should work each body part every 12 hours (or as often as possible, anyway) to maximise MPS and muscle hypertrophy.
Additionally, there's the concept of "maximal effective volume": there may or may not be a hard cap of how much volume a muscle group can be worked in a session to see more gains. See Menno again.
Both these factors combine to suggest that body-part splits are suboptimal: if you really demolish one body part for a workout then not only do you get fatigued and can't really maximise volume/get the full mind-muscle connection, but that massive volume load can only really cause a spike in muscle protein synthesis for 12 hours anyway.
Empirical evidence seems to support this: Zaroni et al. (2019) found that a 5-day per week whole-body workout gave significantly greater hypertrophy on trained men.
The purpose of this study was to compare the effect a split training routine with muscle groups trained once per week (SPLIT) vs. whole-body split training routine with muscle groups trained 5 days per week (TOTAL) on neuromuscular adaptations in well-trained men... TOTAL induced a significantly greater increase in MT of the forearm flexors and vastus lateralis (p < 0.05)... TOTAL may confer a potentially superior hypertrophic effect.
Why five days, and not six or seven? I'm not sure (and would have to do more research on this) but it could be a way to reduce accumulated fatigue
Why cluster sets/blood flow restriction training?
This part is more speculative.
Cluster sets (sets with built-in, short rest periods of 5-20 or so seconds) decrease metabolic stress and allow you to get more volume in. If you rest between sets you can lift more weight more times --> more volume --> more hypertrophy.
But take note that in order to maximise muscle fiber recruitment one might want to work at a high intensity (high % of 1RM): you don't want to do cluster sets with too low weight as that might only recruit the lower-threshold muscle fibers. See the section in the Appendix (under "What about the notion of 'effective reps'") for details.
Blood flow restriction training might decrease muscle damage which might be useful, but this is really speculative.
Questions I still have
Will long rests make your muscles cool down? Will you have to warm up between sets?
Anecdotally, powerlifters seem to rest for ~15 minutes between sets without having to warm up between sets so maybe this is OK? Not sure.
You might need to elevate your core temp again between exercises if you've rested a long time between them.
5 days a week full body hitting 10-20 sets of volume for each body part Dumbbell + calisthenics only because that's what I have.
Might take a look at Jeff Nippard's video for some ideas.
- Chest: pushup variations, incline DB press, flat DB press,
- Arms: skullcrushers, bicep curls, tricep extensions
- Lats: unilateral DB rows, humble rows, archer pullps, weighted pullups,
- Traps should be worked by heavy shrugs
side and front delt don't need to be isolated
and will be worked with seated or standing DB press
- Rear delts should be isolated with ~15 sets a week: unilateral bent over external shoulder rotation, band face pulls,
- Abs: leg raises, ab slides, double leg thrust
- Legs: lol what are these
Mix between unilateral and bilateral execrises, calisthenics and dumbbells
- Chest: DB bench
- Shoulders: Seated DB OHP
- Back: DB rows
- Arms: Hammer curl
- Back: weighted pullups
- Chest: floor press
- Back: weighted shrugs
- Shoulders: Lat raises
- Arms: concentration curls
- Abs: ab roll
- Back: archer pullups, face pulls
- Shoulders: Unilateral bent over external shoulder rotation
- Chest: DB bench
- Back: Humble row
Things that don't fit in the main article
Notes I took from Menno's video
Three primary drivers have been proposed for hypertrophy:
- Mechanotransduction (tension on muscle stretch)
- Myogenic signaling (IGF1 IL6) signals
- mTOR signal integration and translation initiation --> (MGF Mechanogrowth factor)
- MPS muscle protein synthesis
- Myonuclear addition
Muscle damage: no compelling rationale.
- microtears repair, satellite cell activation, inflammatory response, repaired myofibre and gets larger.
- muscle damage triggers muscle growth, but not NET muscle growth. Cast doubt ... muscle damage is something we want to avoid. (Which study?)
- Another study: triggering the "repeated bout effect" in the treatment group. Muscle growth same with big difference in muscle damage.
- Long believe ecc > con for muscle damage & growth. KAATSU: no muscle damage, adding occlusion gives more muscle growth but no more muscle damage. Creatine (seems to) decreases muscle damage yet improve muscle growth.
Metabolic stress Accumulation of metabolic byproducts in the muscle: lactate, phosphate, hydrogen ion, along with hypoxia. Why might it work? Increased inflammation, fiber recruitment, cellular swelling (ergo PUMP: extracellular water enters the sarcoplasm outside the myofibers) HIIT high metabolic stress and muscle damage but little growth? (Cypryan 2017)
Rest intervals: broscience says long rests for strength, short rest If you have people resting longer, more muscle growth, you do more volume, put more tension
Henselman and Schoenfeld: volume > metabolic stress
Low reps high reps doesn't matter, mechanical tension
Training to failure: metabolic stress rises exponentially but no/little increases in myuscle growth (S-shaped curve )
Cluster sets: rest a couple breaths between sets (lot more work done): same growth, much less metabolic stress. --> Oliver et al. 2013 (check this study methodology though)
KAATSU works not via metabolic stress, but rather making exercise harder, causing more muscle activation + more mechanical tension
Conclusion: Mechanical tension is the only (or by far the primary) cause of hypertrophy!
What about the notion of "effective reps"?
"Effective" reps seem to be a thing (ergo you maximise hypertrophy by going close to failure, with diminishing returns the closer to failure you go). Some have claimed that this is due to a metabolic stress effect. However this is probably a muscle recruitment effect (recruiting higher-threshold fibers) and not a metabolic stress one.
Goto et al (2005) found that people who took a 30s rest in between 10 reps of lat pulldowns got less growth than people who did them all in one go. This is readily explained by the muscle recruitment hypothesis though. As you go closer and closer to failure you recruit more and more fibers, and recruiting more fibers means more hypertrophy. So I believe that resting 30s meant that participants continued to activate their low threshold fibers. They were not able to get full motor recruitment and thus had less hypertrophy.
BUT see also this correction by Grgic and Schoenfeld (2019): (https://physoc.onlinelibrary.wiley.com/doi/pdfdirect/10.1113/JP278627) looks like the evidence is equivocal on whether or not load (% of 1RM) is an important determinant of muscle fiber activation vs hypertrophy.
Also, a more recent study by Carroll et al. (2019) found that not going to failure resulted in greater hypertrophy.
In the interview I posted above Schoenfeld mentioned SOME evidence that acidosis prevents contractability in the fast twitch fibers. Less contractability means less fiber recruitment means less hypertrophy. This suggests that decreasing metabolic fatigue (ergo less acidosis) can directly increase hypertrophy.
He also says that there is no study yet on whether moderate or low sustained muscle damage or metabolic stress has an additive effect on hypertrophy, and part of the reason is that it's really difficult to isolate the individual effects in an RCT.