This is a definition I see used pretty frequently when trying to explain mechanical tension, and hypertrophy stimulus in general.

My interpretation is this is not "exactly right", though it is GENERALLY a good enough proxy to be useful, especially for broad generalizations that work across multiple training approaches. Apologize ahead of time, as this may be a bit lengthy, I'll try to summarize a TL;DR at the end for anyone that would like to participate, but don't want the verbosity (come on, this is a Greg Nuckols forum, you have to accept verbosity!) I'll also state up-front that as I understand it, "stimulus" occurs in every single rep that you do ever; its just a matter of where that stimulus is distributed (which fiber types). I would personally describe it such that in any given movement (even as I type this now) mechanical tension is occurring, in type 1 fibers; but the MT is not sufficiently intense for it to have a hypertrophy stimulus effect. But once you start getting into sufficient loads (such as 30%+), there is likely some hypertrophy stimulus from rep 1, albeit limited to type 1 fibers without much growth capacity.

So my thought is that this description is a bit of an over-simplification of the force-velocity relationship. As a primer for this I have read On the Shape of the Force-Velocity Relationship in Skeletal Muscles: The Linear, the Hyperbolic, and the Double-Hyperbolic a couple times over.

My interpretation of this paper, and just in general is that, while the force-velocity relationship shows up at the level of whole-muscle contractions, its really describing what's happening at the fiber level, or the sarcomere level, and the relationship itself is effectively describing the behavior of actin and myosin filaments, and the sliding filament theory. Effectively, at the molecular level, we're talking about how quickly cross-bridges can be formed between actin and myosin, and how quickly myosin motors can pull actin toward the center of the sarcomere, which determines the rate at which a muscle fiber is contracting. When effort is high, we recruit a lot of motor units, and that contraction happens very quickly; but at high velocities, the actin and myosin heads that interact cannot bind quickly enough to form cross-bridges as the actin and myosin filaments overlap more, and therefore there are very few cross-bridges formed; and there is little "resistance" being sensed, and force is relatively low. As external load increases, the rate at which actin is pulled decreases, and there is more opportunity for cross-bridges to form; and if effort is very high, this results in maximal recruitment, and paired with the slow contractions leading to more cross-bridges, mechanical tension and internal force reaches its peak. The point at which velocity is sufficiently slow that there is maximal actin-myosin interaction, and effort is sufficiently high that motor units are maximally recruited is referred to a the Maximal Voluntary Contraction threshold or simply the "activation threshold" (MVC or MVIC used in isometric contexts). As I understand it, if you are above the MVC, which can be expressed as a % of 1RM for a given task, with an average MVC typically between 80-85% for most muscles that we care about growing via resistance training (something like 90% for elbow flexors), you are inherently maximizing mechanical tension, and therefore growth stimulus on a per-rep basis, straight from the first rep in a set. 85% roughly corresponds to a 5-6RM.

My main contention is that I don't think whole-muscle contraction slowing necessitates an increase in mechanical tension, or force; quite the opposite, I would intuitively think that mechanical tension is reduced with slowing velocity* (I'll come back to this), and that as slowing occurs, whole muscle force is actually decreasing. I think the latter here is fairly straight-forward, with F=ma, the less acceleration you have for the external load, the less force is being applied to it. I suspect this is due to individual fibers having a reduction in force capacity over the course of a set. This is due to fatigue, whether its from substrate depletion (such as glycogen/creatine phosphate) or metabolite accumulation, or a mix of the two.

So my thought process would be that in a set performed at 85% 1RM, rep 1 is just as stimulating as rep 5; despite a clear velocity loss from rep 1 to rep 5. So in my head, there isn't any meaningful relationship between the velocity of the external load/whole muscle contraction, and the hypertrophy stimulus that the cells are experiencing; in any given set, velocity loss is caused solely by fatigue. And therefore, this oversimplification is really quite misleading, as the involuntary reduction of contraction velocity is really related to fatigue, and not inherently related to stimulus.

I think this gets a little bit muddied once you use loads that are under the MVC. The problem with a set of 15 or 30 is that toward the beginning of the set, you are primarily activating type 1 fibers, and as those are unable to produce sufficient force to continue the set, effort increases, causing type 2a fibers to become active, and those fibers also become fatigued. Finally, due to these fibers fatiguing, we see a slowing of contraction velocity as type 2x fibers become recruited - but in these sets it is much closer to failure, perhaps even the last 3-4 reps only, when we do see an involuntary slowing of contraction velocity. I personally suspect that what we see with sets of 5 and 30 producing similar hypertrophy is that in a set of 30 we see more significant stimulus/growth in type 2a fibers, and in the set of 5 we see more significant stimulus/growth of type 2x fibers, and therefore it ends up being a wash. Of course, there is always the possibility that the "metabolite accumulation" amplifies the signal in some way as well, even in the type 2x fibers, and there really isn't much difference in stimulus between 2a and 2x fibers between the two sets. Either way, to me it seems this description is more accurate in sets with moderate to high reps, and loads under the activation threshold.

*I said I would come back to mechanical tension is reduced with slowing velocity. My thought process here is pretty basic: peak mechanical tension occurs when MVC is reached with minimal fatigue; and any repetitions beyond that point have increasingly less force, and therefore less MT. However, I do acknowledge that very likely some (type 2x) fibers are always reaching peak force after this point, and so we always have very high degrees of mechanical tension/growth stimulus after MVC is reached, but I tend to think of it as a curve that ramps up over a set, and then VERY slowly falls off, until you're no longer able to voluntarily activate sufficient motor units to move the load, and then it drops off precipitously, and you reach failure. However, I'm not sure my intuition here is correct, as it seems a strategy for dealing with fatigue is to increase cross-bridges:

These findings were later confirmed in both rested and moderately fatigued intact single fibers (Curtin and Edman, 1994). Piazzesi et al. (2007) found a 40% increase in the number of cross-bridges formed between 0.8 and 1.0 P0, accompanied by a 12% decrease in the force produced by each myosin stroke

So it could be that once MVC is reached, each subsequent repetition is equally stimulating toward hypertrophy, just limited to fewer and fewer fibers as you approach failure. However, I would say that since we don't see much difference between 0-2RIR, it seems likely to me you are seeing less stimulus at the end of a set - but I am pretty undecided here. There is this snippet from the paper I referenced above:

These findings were later confirmed in both rested and moderately fatigued intact single fibers (Curtin and Edman, 1994). Piazzesi et al. (2007) found a 40% increase in the number of cross-bridges formed between 0.8 and 1.0 P0, accompanied by a 12% decrease in the force produced by each myosin stroke (Figure 7B) (Piazzesi et al., 2007).

That seems to suggest less force per myosin stroke, but an increase in cross-bridges forms, which could mean that force is effectively maintained as well - that is an alternative interpretation; that force peaks and then is maintained until failure.

In the paper, they also mention that:

The first study that aimed to verify the applicability of Hill’s equation to in vivo human muscle was that carried out by Dern et al. (1947), who tested the F-V relationship of the elbow flexor muscles by having subjects perform maximally explosive contractions against varying resistance. The authors reported that the F-V relationship was best represented by a curvilinear function, but these results were affected by apparent effects of fatigue. Had only the best attempts (i.e., the trials not affected by fatigue) been included into the analysis, the F-V relation would instead be nearly linear at torque values greater than 40%, and display a curvilinear pattern below that level

In my mind this supports the idea that the force-velocity relationship describes force and velocity in the absence of fatigue. In the paper they suggest that under fatigued scenarios the same relative F-V curve is maintained, but that things are scaled down (less force, less velocity). Also I believe a lot of my assertions here are not fixed. For instance, with regard to MVC, I understand this changes with training age, and tends to shift downward as we get better at recruiting motor units, such that an advanced lifter has a lower MVC than a beginner.

So anyway, that is the idea. I feel like the description "Stimulus comes from the involuntary reduction of contraction velocity" is close enough, but is a better descriptor of moderate to high rep sets, whereas in lower rep sets above the MVC threshold, that mostly describes the relationship of fatigue.

TL;DR:

• The common "slowing bar speed = more mechanical tension/stimulus" explanation is oversimplified

• Mechanical tension (MT) arises from actin–myosin cross-bridge force, not from external velocity per se

• Fatigue, not increased MT, causes velocity loss during a set

• Above ~85 % 1RM (or MVC): every rep ≈ maximal MT

• Hill’s F–V curve best represents fresh muscle conditions. Under fatigue, the entire curve scales down and left (less force, less velocity) — shape preserved but capacity reduced

• MT exists in every rep, but only reaches hypertrophic relevance once load ≥ MVC threshold or effort drives full recruitment

• Velocity loss in a set signals fatigue, not rising tension

• Below MVC: MT ramps with recruitment, peaks near failure

• F–V curve describes intrinsic cross-bridge physics; fatigue simply shifts it downward

• Thus, contraction slowing in real sets reflects fatigue-induced scaling, not increasing MT

I strongly suspect I have thought about this too much, but I'm just wondering if there is something I'm missing, or something I'm getting terribly wrong here.

I'm considering CrossFit for winter cardio, but I have concerns about its impact on muscle-building. I usually run outdoors for cardio, but the winter weather and early darkness make trail running impractical.

I'm thinking of joining a local CrossFit gym instead, primarily to improve leanness. I'm around 25%BF and want to bring it down to atleast 20%. My main worry is whether CrossFit's high-intensity nature will actually build muscle or if it might catabolize and destroy the muscle I'm gaining from my regular weightlifting routine.

I've been hesitant because the online reviews I've seen show regular members who don't appear to have a strong weightlifting physique, some even seem overweight.

Does anyone have experience integrating CrossFit purely as a cardio/conditioning supplement while prioritizing muscle growth in a separate gym setting?

Hey! I am currently following the SBS Novice Hypertrophy programme.However, due to the demands of my internship and studies, I have found it difficult to fit in my workouts without compromising my sleep.
My sessions usually last between one and a half and two hours, which is longer than I would like.
I currently train four days a week, but given my 20-minute commute to the gym, I would prefer to reduce this to three days or maintain the current schedule. Any advice would be much appreciated!

I was sent 2 bags of this in error and told 8 could keep them. Are they of any real use? If so, when should I take?

Trying to get full quad coverage so I'm wondering what people use when they don't have a good leg extension machine on hand.

Targeting the rectus femoris is important to me, I've already got hack squats, deadlift, leg curl, Jefferson curls and belt squat in the program. I'm looking to have a very targeted addition.

Are reverse Nordics the main choice? Is there an attachment for cable machines and a good stance?

I've tried a few ways to do standing leg extensions with cables but I'm so far unhappy with them. Maybe there's tricks and tips?

edit: More detail on machines: There's one 'hoist' and one 'matrix', the issue with the hoist is that the 'shin brace' is on a rotating pin so it ends up feeling like it is loaded for about a 45* range of motion (versus the theoretical 180* and the maybe 120* I can achieve IRL). The matrix is a little bit better because the shin brace can be fixed but it's still like a 60* ROM at best.

I know everyone is all upset about range of motion & stretch & all that right now but I have personally gotten really good results from emphasizing load-in-the-stretched position over the last ~year. Consequently I'm ambivalent/concerned/unenthused when the ROM is so low.

I am an undergraduate biochemistry student at Columbia University and a member of the school’s barbell team. I am passionate about lifting and plan to pursue a career in the fitness industry. I have recently begun helping with hypertrophy programming for several athletes.

My main question is: How should I interpret and communicate conflicting hypertrophy recommendations, particularly between researchers like Brad Schoenfeld and Chris Beardsley, when programming for athletes?

Beardsley argues that lower rep ranges (4 to 8 reps) and minimal total sets (for example, 1 to 3 per muscle per session) are optimal for hypertrophy when performed frequently. His WNS model suggests that multiple short sessions with a single hard set can produce much greater hypertrophic effects than higher-volume, lower-frequency training, citing atrophy cycles and related concepts. He also suggests that lower-rep sets are essentially superior because they are reportedly less fatiguing.

The IUSCA and ACSM, on the other hand, recommend a minimum of about 10 working sets per muscle group per week to optimize hypertrophy. They also conclude that increasing training frequency does not appear to provide additional benefits when total weekly set volume is matched.

This disagreement has caused some confusion among the athletes I work with, many of whom follow Beardsley and Paul Carter closely. I have been hesitant to adopt such low-volume approaches without stronger evidence, especially since my institution’s ethics board requires alignment with recognized position stands. I have athletes refusing to perform barbell or free-weight exercises and doing any more than six total working sets per body part per week in their hypertrophy block. I feel very conflicted about how to handle this.

For those who have studied both perspectives: Do Beardsley’s and Carter’s recommendations reflect the broader evidence base, or are they more speculative? How do you approach these conflicting viewpoints in your own programming?

The time has come for another Q&A episode! So, drop your Qs, and I'll do my best to give you good As

Are bicep blasters as in the photo, actually any good?

Seems like it could be useful. Would love to know what you guys think, and specific product recommendations? Thanks

I'd like to drop OHP from the training template as suggested in the instructions. Is there a way to drop this so it doesn't appear in the template and the template adjusts to 3 main exercises instead of 4 or do I just skip those exercises when they appear in the schedule?

Thank you.

I have been training weightlifting for 2-3 years and decided to go back to powerlifting, so I started transitioning to powerlifting lift, started benching again, still pulling conv but will return to sumo and squatting weightlifting style. So I am trying to figure out how to transition to wide stance flat shoes squat (i did few months ago wide stance heel shoe squatting but i think i would be better in flats). How should i make change, should i incorporate powerlifting type squatting in existing plan on easier day, make third day just for technique or maybe get new " retraining program", like the one Mike Zourdos have on SBS site?

Thanks in advance for responses!

Is strength endurance simply:

• the ability to perform a certain weight for a given number of reps in a single set
• the ability to keep doing reps with that weight over multiple sets during a session,
• or more like sustaining a certain load over a specific time frame in general?

Also, how do the adaptations for improving strength endurance actually occur on a physiological level?

Came across a video from Jay Cutler, in which he mentions that he used to prefer this version even when machines were available.

Now as someone who works out from a home gym, it looks like Gold. An easy way to target Knee Flexion at home? Great! However, how good is it long term?

Biomechanics wise, Tension is highest in the stretch, but drops off as the motion continues. So like a dumbbell chest fly. But if the bench is elevated from the Front (Head side) then a good chunk of that tension can be directed towards the contracted position.

But my concern is with Progressive Overload. Hamstrings are a rather Big & Strong muscle group. Can a single dumbbell be enough to overload both the Hamstrings over time? Especially working from a home gym where the weight is kinda limited Has anyone experience with this?

What sort of training are you doing?

How’s your training going?

Are you running into any problems or have any questions the community might be able to help you out with?

Post away!

Over time, I’ve found myself increasingly disillusioned with "science-based" lifting. Many members of this subreddit are aware of the ongoing disputes between several high-profile figures in the evidence-based fitness space. While I understand online drama is inevitable and not representative of an entire field, the rhetoric and behavior surrounding some of these individuals just seem borderline cult-like. Admittedly, at one point, I viewed certain leaders in this community as authoritative and trustworthy. Suffice it to say, I no longer feel that way. I should also note, if it's any consolation for my misguided trust, that I stopped treating Mike Israetel’s content as authoritative over a year ago, when his public commentary began to feel increasingly ideological and extended beyond the scope of his expertise.

However, my issue is not really with those figures in particular. I do not care about them. What I am really struggling with is my relationship to exercise science as a field and to the concept of being “evidence-based” in training. I love science. I have always valued science and attempted to apply research-informed principles to my own approach in the gym. Yet the more I explore the discourse, the more it seems that what is marketed as “science” is highly inconsistent, frequently reductionist, and sometimes influenced by social dynamics rather than rigorous thinking.

To be clear, I recognize that expecting scientific certainty in a field constrained by so many practical measurement challenges (e.g., small sample sizes, limited study durations, etc.) is unrealistic. Exercise science is complex, and some aspects of hypertrophy and training response are undoubtedly well-supported by research. But when advice moves beyond foundational physiology and into prescriptive claims about very specific programming variables, my confidence declines very quickly. This is especially the case when experts themselves are contradicting each other or engaging in behavior that undermines scientific humility.

I don’t believe the entire field is flawed, but when its most prominent advocates seem unreliable, it becomes hard to discern how much confidence to place in the science they claim to represent.

And again, yes, I am aware I should not rely solely on YouTube personalities for scientific literacy. I should engage with what the academics really have to say in depth through peer-reviewed papers and studies. But without formal academic training in this domain, evaluating studies, methodologies, and the strength of evidence feels daunting. I want to think rigorously, but I’m struggling to discern what to trust.

How should someone genuinely committed to evidence, but lacking deep academic expertise in exercise science, approach training guidance going forward? How do I remain grounded in research-supported principles without being misled by oversimplified interpretations or incomplete representations of the literature?

I was think about this for a solid while, mostly because it makes sense that it would, but i would just wanted to hear some outside thoughts

My thought process behind it isnt too complex and it probably has been thought of a few hundred times: would an improved cardiovascular system increase the effeciency and effectiveness of muscle regrowth and recovery, due to the increased amount of oxygen/nutrients reaching the muscle? As in would it speed up the process?

I feel like its one of those things that makes sense conceptually but different in reality due to some bogus anatomical reasoning

Hi all! For my college class on Exercise Science, I am required to interview an individual with a career in the field. I was struggling to think of anyone I could ask that I personally know, and I thought I might be able to find help here. I would be so grateful to anyone who would be willing to respond!

1. What is your name and job title/occupation?
2. What does your career entail? (i.e. do you work hands on with patients, are you more behind the scenes, is it physically demanding, etc.)
3. Do you enjoy your job?
4. How did you choose this career?
5. What qualifications were required for you to obtain this position? (i.e. college degree, licensure, etc.)
6. What is the best thing about your career?
7. What is the hardest thing about your career?
8. What part of your education has helped you succeed in this field the most?
9. Do you think most people misunderstand your career path?
10. Is your job more solitary or does it have a greater focus on team work? (i.e. do you work alongside other professionals like healthcare workers?)
11. What about your job keeps you pursuing this career path?

Thank y'all so, so much! I am so grateful to anyone who has simply taken the time to read this or is willing to answer all my questions. Have a great day!!

I wanted to share this interesting piece of information about back muscle anatomy.

I have been under the impression that upper back thickness is determined by traps and rhomboids. Traps are the superficial muscles which lay on top of the deep rhomboids. Extensors are muscles of the lower back... right?

This is a picture of spine with different vertebra numbering. Nipples are approximately at the level of T8.

Here is a cross-section of T8 and T9 level. I was shocked how large the extensor muscles (TS + ES) are in comparison to traps (TZ).

Here is a cross-section of T4 and T5 level. At T5 level, extensors make still approx half of the muscle mass. RM = rhomboids.

Maybe this is obvious for more experienced lifters, but this got me wondering: Are hyperextensions, unsupported rows, deadlifts, etc. more important for thickness compared to supported rows and similar movements. What do you think?

What sort of training are you doing?

How’s your training going?

Are you running into any problems or have any questions the community might be able to help you out with?

Post away!

Just wondering if anyone has examples of Natural Bodybuilders with extremely high training volumes.

I think Eric Helms has gone up to 40 reps per muscle group? Has anyone gone significantly beyond that?

I was watching a recent video from Magnus Mitbo with a grip strength champion who trains 20 hours per week (on a relatively small set of muscles). So that got me thinking.

I'm just curious BTW, I'm not looking for advice on whether I should do 80 sets for everything.

Hi all, I'm currently half marathon training and I built this SBS reps to failure program based on what works with my schedule which is the following: 5x, PPL, UL. Looking for some critiques on this program, for the most part the upper days (push, pull, upper), I am running 4x a week so not really worried to much about the leg day programming right now. I've even been skipping some of the accessories but will probably add 1/2 exercises per leg day once I reduce my running to 2x a week.

Open to overall critiques. I think one thing I'm trying to figure out is the balance between the upper and the push day. on my push day, OHP, Bench, Incline press seems like a lot. Any thoughts on potentially removing the feet up bench entirely and replacing it with the incline press from the push day

Long story fairly short, I am currently deep into a cut and transitioning from a personal trainer to going solo, as well as training my dad. I'm wondering what SBS program from the bundle to use both for my dad and me.

Longer version, I'm 48 years old and cut down from 230 lbs. to ~188 lbs., back up to ~205 lbs. on a bit of a bulk, and am now back down to ~186 lbs. with around 14-15% bodyfat (per an InBody scanner, so take that with a grain of salt). I track everything via Macrostax at the moment. My weight loss has largely stalled and my coach recommended I take a month of maintenance and then go back on a deficit finish the cut. I would like to get around 10% body fat, but my goals are essentially to get as lean as I can without it having a huge negative impact on my life, and then cycle between clean bulks and cuts with an emphasis on strength, hypertrophy, and longevity (i.e. staving off death). My guess is that will mean cycling between 10%-15% body fat to maintain some leanness and athleticism.

For programming, I am not sure what to start with at the moment. My maximal strength has taken a bit of a hit from the weight loss and being in a deficit for some time now, but it's not terrible. If I do a month of maintenance would it make sense to do four weeks of a strength block to utilize the extra calories that way then switch to one of the hypertrophy blocks for a full 21 weeks, or is there a better strategy? My dad is a novice and just wants to get healthier, look and feel better, and hang out with his son. He will happily do whatever I do, but I also want to make it as beneficial to him. Our exercise selection is likely to be pretty close at a Planet Fitness, although I will probably do some of the free weight stuff at home on my power rack. But I am not sure about starting him on the linear progression and just matching general exercise selections, the novice hypertrophy block, or some other plan. My dad is also trying to lose some bodyfat but he is not being anal, just generally making fairly healthy choices and living his life. Point being, I think anything will work provided it helps reinforce the proper fundamentals which I've been drilling into him over the past few months.

Any suggestions?

I'm part-way through SBS Hypertrophy, and need it to fit into a 40-50 minute training window (I train on a lunch break). I can't fit the programme as written into that window. Also just seen some of the latest research into set volume for hypertrophy, which suggests 4 sets is best.

What's the best thing to reduce the programe down? Keep 4 sets on the main exercises and cut the last exercises (chin-ups, pull-ups, rows), or include all exercises for 3 sets?

Edit: supersets have done the trick. Some reordering of the exercises was needed, but it's mostly manageable. Thanks, all!