Time Under Tension: Key to Growth or Pointless?

It definitely matters, a 10 rep set stimulates way more hypertrophy than doing a 1RM. And 2 sets of 10 stimulate more than 1 set of 10.

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I think that may be more a factor of a higher number of high tension reps. If you take a set to failure in 10 reps, you had about 5 effective growth stimulating reps or contraction’s vs just 1. However a set of 30 doesn’t produce more growth than a set of 10 if they’re both taken to failure, you’re still ending up with about 5 effective reps where you’re receiving peak levels of mechanical tension. I would subscribe to the thought that there is a “Time under effective tension”


I’m going say though if you look at all the research, much of that doesn’t fit like some studies or authors tend to say.
Example, this study showed almost 2x the hypertrophy with 30RM to failure vs 90% of 1RM to failure. Low-Load High Volume Resistance Exercise Stimulates Muscle Protein Synthesis More Than High-Load Low Volume Resistance Exercise in Young Men - PMC (nih.gov)

Also, this article is outstanding and fits my view of ‘effective reps’ which is way too simplistic and leads people kinda wrong actually. Give this a careful read, he does a great job on it.
The Evidence is Lacking for “Effective Reps” (strongerbyscience.com) He also goes into, and references research on the idea of how people are putting too many eggs in their ‘tension basket’ , which I agree with also from all the research I’ve read. (many facets of fatigue do stimulate hypertrophy)

I also think of BFR and other lighter load training it seems it’s more ‘time with high activation levels’ over actual tension that keeps Titin open, raises calcineurin along with many other signal factors in the cells.


I appreciate the detail you go into here. I think that we still are largely lacking in hard science on muscle growth in general. 5 Effective reps may not be perfect, but it makes sense from personal experience. I think there’s an excellent case to be made that it’s smart to use a variety of rep ranges from 5-30 to get the maximum benefits out of your training that both ends of the spectrum have to offer. But generally I do believe it is important that regardless of your rep range, you train to our very close to (within about 2 reps) failure on your working sets.


in general for sure, we know that each rep is ‘more’ effective than the previous, but that all reps, have ‘some effect’ (mostly due to progressive recruitment and rate coding). Now many though have gotten really good results with multiple sets at a higher RIR (I have myself too), even up to 4-5 RIR, which in theory, should remove all effective reps, yet it doesn’t. But, for confidence in a set, getting to 2RIR is probably perfect (since many newer studies now are showing blunted hypertrophy if a person goes all the way to failure).

True, we don’t have a full picture of hypertrophy, I think though just knowing that people can induce marked hypertrophy with anything from very heavy to extremely light, with failure and all the way to very far from failure, it seems the main stimulating factor sure isn’t effort, nor load.

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Check out Ryan Humiston’s vids on YouTube for a guy who lives and dies by the Higher Reps to Failure philosophy.

oh yeah that guy is pretty huge, his videos are great too

Great stuff. Yes, it seems like there are multiple pathways to ‘get there’. It kind of makes sense from the body’s standpoint to be able to adapt (via muscle growth) to various types of resistance ‘stressors’.

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That’s a great paper! I remember reading some of Nukol’s comments on effective reps awhile ago, but I don’t remember seeing that much detail.

The appeal of the effective reps theory for me was that it explained studies which showed the need to go close to failure with light loads, but not necessarily with heavy loads. I did have the sense that Beardsley turned it into a prescription that was too precise given the nature of the evidence.

The Potvin paper is particularly interesting with regard to where individual high threshold muscle fibers experience maximum tension, which is only at the beginning of a max effort isometric contraction, when the muscle is unfatigued. I guess that means maximum tension in the absence of fatigue doesn’t trigger much of an adaptation, otherwise we would all be doing 5 second isometrics and getting huge.

At least for submaximal contractions, the Potvin model is consistent with some other ideas that I’ve come to accept, i.e., with a submaximal contraction, the highest threshold units don’t really kick in until the latter part of the set, and they experience their highest tension level of the set during the latter portions of the effort (though not necessarily at the very end). Also, submaximal contractions with higher %RM produce higher peak tensions in the set (just not as high as a max effort with fresh muscle).

I guess what we need is a more nuanced version of the effective reps theory, one that considers how tension and fatigue interact to trigger adaptive signaling? It almost seems like, if fatigue levels are high enough, you can settle for lower tension and still get hypertrophy. Then you have to decide if you enjoy training muscles in a highly fatigue state, or would rather stick with shorter rep sets.

Good summation and thoughts. I agree.
How I think about it, and how I’ve seen it written in physiology texts, is that during a set, recruitment and rate coding increase to ‘maintain tension’. If we take a set with a muscle group where you know the approximate recruitment threshold, (where most mid sized muscles are in the 65-85% of full effort range), and we use say a true 8RM load, all fibers are working even during the first rep. As fatigue builds, the neural impulses (rate coding) increase to maintain the force in the fibers. So tension doesn’t increase during a set, it maintains. And since we also know that BFR with loads as low as 30% still induce the same hypertropy as heavy loads, the actual tension a fiber generates obviously isn’t a key factor, it’s more than it’s highly active and the longer it is active, the longer the signal factors are ‘on’.

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