Updated : https://bretcontreras.com/do-we-even-need-to-lift/

Bret gets it. LOL

Regarding the small sample size. You do realize how common studies of less than 20 people are? Large RTC studies are obvious the best but unless big pharma's backing you it's tough to find the funding.

Just saw this part "Even if you do completely unloaded bicep curls you will still stimulate red muscle fibers."

  • Type I - Muscle Fibers are Red due to myoglobin content / O2.
  • Type IIa (are Red / Pink)
  • Type IIx are (Pale / Whitish) as they are glycolytic.

It is well known, that slightly loaded work stimulates the growths of red muscle fibers and myogenesis.

I may be wrong but I believe Type I changes seen are more vascular and metabolically related. Do you have a study showing hypertrophy occurs in Type I fibers? I know that myofibrils / the overall number of sarcomeres increase with resistance training.

You're basically illustrating by accident why I find this study so interesting. What is inducing the hypertrophy? Are the IIx and IIa saying contacted for a sustained period? How?

Basically how are you getting to threshold to depolarize your largest muscle fibers? Sustained flexion I would think would have the opposite effect vs a normal isotonic concentric contraction. What's triggering this?

Wow didn't expect to find this. A study released less than a year ago compared left vs right arm muscle mass changes with the following setup

  • One arm no load (but maximally flexing muscle)
  • Other arm high load training (70% 1RM)

After 18 sessions they found:

Increased muscle mass on both sides
(with slightly greater gains on the heavy load side)

In a way it actually makes sense:

As muscle tension increases so does recruitment
(or the number of active motor units)

Size Principle: Motor Units are activated from smallest to largest
Motor Unit: Consists of a single motor neuron and all the fibers it innervates
Recruitment: The number of motor units that are active.

Anyone every seen a similar study?
How would you explain the hypertrophy with a load?
Do any hormonal changes occur by just flexing?


The acute and chronic effects of "NO LOAD" resistance training
Physiology & Behavior 2016 October 1, 164 (Pt A): 345-52

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  • Thanks for the updates. Interesting to read Bret's blog. – Gyrfalcon Jul 21 '17 at 18:06

The abstract of the study doesn't indicate the training level of the 13 participants, which is a ridiculously small sample size to start with. But I'll assume they are completely untrained and therefore will benefit from easy early gains. 18 sessions is also a relatively small amount of time.

"No Load" sounds like "isometric", so this isn't anything particularly new. The muscle has resistance against its also-flexed antagonistic muscle (like a bicep tensing against a tricep).

It's an interesting data point, but I don't see the applicability. If anything I could imagine a SUPER NO LOAD DVD EXTREME PACK being developed out of this and marketed as "research shows it's nearly just as effective and weight lifting!"

Digging in a bit and focusing on isometric activities, specific to cardiology there's a 1992 study that talks about the impacts of isometric exercises and the heart:

Thus, static exercise is characterized by a pressure load to the heart and can be differentiated from dynamic (isotonic) exercise, which involves a volume load to the heart. Physical training with static exercise leads to concentric cardiac, particularly left ventricular, hypertrophy, whereas training with dynamic exercise leads to eccentric hypertrophy. Furthermore, the magnitude of cardiac hypertrophy is much less in athletes training with static than dynamic exercise.

Isometric activities also create much lower blood pressure than dynamic (concentric) activities, which is helpful at risk for ischemic stroke or having other blood pressure related issues.

Again, I think the study mentioned in the question is valuable as a datapoint and there are surely a lot of people with health and mobility issues that make isometric activities the best or only option.

  • I'd like to understand the mechanism behind it. Similar studies would be amazing. The major thing with the study being the duration of contraction, recruitment, and TUT are all increasing (no other contraction does this does this) during muscle shortening. – Mike-DHSc Jul 20 '17 at 19:24
  • Neural Conduction via Cardiac Tissue is completely different. It’ changes everything. This is skeletal muscle. You’re taking about Left Wall Hypertrophy (Heart) which is a healthly adaptation seen in aging adults (to counteract the increasing systole BP). – Mike-DHSc Jul 21 '17 at 15:41
  • It's my read on it. Boiled down, I see concentric exercises as clearly the most effective technique across nearly the entire population. If there's an option for folks with reduced mobility, cardiac issues, and ischemic stroke risk where isometric activities are better, that's rad. I just see the whole isometric exercise pack as an edge case that has some value for specific and narrow populations. If there's more that I need to gather from this I'm all ears. – Eric Jul 21 '17 at 15:47
  • 1
    Concentric contractions to do what the most effectively? If it’s increase size / strength or increase collagen formation during rehab that’d be eccentric contractions. Flexing as done in the study is not an isometric contraction – it’s concentric (isotonic). I’ve never said anything relating to isometric exercises. – Mike-DHSc Jul 21 '17 at 16:07

"No load" means no dumbell

The study investigates "unilateral elbow flexion exercise". That is one arm bicep curls.

The abstract says "without the use of an external load", which means no dumbell or other weight, but they did not mean without any load: Now, straighten your arm and do a bicep curl with your bicep brachii contracted as hard as you can through a full range of motion as stated in the abstract.

You will A) Hit yourself in the face with your fist or B) Inhibit the movement by contracting your triceps too.

I feel absolutely sure that B) is the case for the tests in this paper. This means, the load for the study is the maximum muscle tension allowed by the participant's nerve system. The tension is limited by their 'will' and by reciprocal inhibition (antagonist muscle relaxes when agonist muscle is flexed)

Even if you do completely unloaded bicep curls you will still stimulate red muscle fibers.

If any surprises in this study, I think it is the fact that reciprocal inhibition does not limit the use of the antagonist muscles as load and the participants has almost full hypertrophy in the arm exercised without weight. Perhaps this is due to the that participants most likely are untrained persons and they only completed 18 sessions. I think it would be a surprise, if you could do bodybuilding without any weights at all.

"These results extend previous studies" indicates that you can find similar studies in the reference list.

"Any hormonal changes" is a very broad question: Cortisol, insulin, glucagon, testosterone etc.

Yes, I think it has repeatedly been proven that almost unloaded muscle work (e.g. walking) leads to an improved response to insulin.

It is well known, that slightly loaded work stimulates the growths of red muscle fibers and myogenesis.

Unloaded exercises for sure do not lead to overtraining and production of cortisol, and even moderate use of a muscle inhibits catabolic processes.

And testosterone? You certaintly get a testosterone kick when do a perfect barbell snatch with a weight at the level of your PR, but even the size of the kick is releated to size of the weight, the kick originates from your brain more than from your muscles. Couldn't you get that kick too by doing unloaded flexings of your biceps in front of a mirror? ;)

  • The load is the force exerted by the object of focus (a dumbbell, wall whatever). Contractile force is a measure of the tension generated by the muscle in question. (myosin-actin cross bridge formation). You are not understanding the study my friend. – Mike-DHSc Jul 21 '17 at 13:26
  • I regret, I have only access to the abstract. Please provide us with the full text or at least vital parts of the study. I've noticed your update of the question. – Gyrfalcon Jul 21 '17 at 14:05
  • I found an article talking about this study. Just flexion through a ROM causes hypertrophy? Subjects switched arms so the control is yourself. What info are you looking for to answer that question? Mechanically it makes no sense. – Mike-DHSc Jul 21 '17 at 15:10
  • @JohnP: I would like to talk with you, but I think a discussion in the comments would be a violation of the general policy and we have to move it to a chat or likewise. – Gyrfalcon Jul 21 '17 at 17:35
  • @Mike-DHSc I have upvoted your comment on Eric's answer concerning isometric contractions. It reflects my oppnion and is in compliance with Bret Contreras' interpretation as "80 maximum voluntary contractions in around 5-6 minutes." If you want to discuss my answer further, I suggest that we continues in a chatroom. – Gyrfalcon Jul 21 '17 at 18:18

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