Q&A: Is One Set Enough For Maximal Muscle Fiber Recruitment?

Question:

I completely agree with the one set to failure protocol, however, something plays on my mind. I’ve always read and been lead to believe that a certain amount of muscle fibres contract maximally to lift a weight – as apposed to fewer muscle fibres all contracting sub maximally. Therefore when I’ve finished my one all out set to failure, I’ve stimulated those fibres that contracted maximally. If I was then to reduce the weight I could keep going which suggests there were fibres that were not used in the first set. Therefore one all-out set followed by a descending set would guarantee all fibres being stimulated. Then again, I don’t want to use anymore reps than necessary to trigger adaptation. Is a descending set or other set extension technique necessary for maximum muscle fiber recruitment?

Answer:

A muscle fiber either contracts maximally or not at all. Muscle fibers are grouped into motor units of different sizes, and are recruited in order from the smallest to the largest depending on how much force the muscle needs to produce. During an exercise as some motor units fatigue and the combined force they are capable of producing decreases your body recruits more motor units to continue to produce the level of force required to overcome the resistance. As these newly recruited motor units fatigue more are recruited, until eventually every motor unit thus every fiber in the targeted muscles has been recruited. When you reach momentary muscular failure it means all of the motor units in the targeted muscles have been recruited and fatigued to the point where they are unable to produce the required level of force, and effectively stimulated to grow larger and stronger.

Neuromuscular junctions

It is not necessary to extend the set by reducing the weight or performing other set-extension techniques like forced reps or negatives to recruit all of the motor units in the targeted muscles. Doing so just retraces the same motor unit recruitment pattern which increases the stress on your body without significantly improving the stimulus for muscular strength and size increases. The only time I use or recommend set-extension techniques is if a trainee falls a rep or two short of their lower target repetition number, and this is usually for the purpose of increasing metabolic stress or to help acclimate them to greater exertional discomfort so they can learn to continue to contract intensely despite the burn. Depending on the person and the exercise or equipment being used I may have them extend the set to reach a time under load equivalent to their lower target rep number by performing a static hold or timed static contraction instead. Isometric holds and rest-pause repetitions are often more practical set extenders when performing bodyweight exercises or when training alone.

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  • Damien Apr 21, 2016 @ 22:11

    Ah, now i got it. Thanks mate. As always, love ya work.

  • Andrew Apr 22, 2016 @ 0:28

    For my own curiosities sake: have you ever trained a client that has NOT responded to HIT techniques? If so, how did you correct this?

    • Drew Baye Apr 22, 2016 @ 11:30

      Hey Andrew,

      No, I haven’t, because I use a principle-based approach to HIT rather than a specific rigid program or set of techniques, and I adapt the applications of the principles to the individual based on how their body responds to exercise and their particular goals. The principles of HIT are universal, but the best application of those principles depends on the individual and goals. Some people are slow responders and some are fast responders, but every normal, healthy person is capable of improvement if the principles are applied correctly (assuming they aren’t advanced trainees who have already maxed out their genetic potential). The key is making the program fit the individual, not trying to fit every individual into the same program.

  • Dan Apr 22, 2016 @ 7:15

    “When you reach momentary muscular failure it means all of the motor units in the targeted muscles have been recruited and fatigued to the point where they are unable to produce the required level of force, and effectively stimulated to grow larger and stronger.”

    They are not able to produce enqough force with a given weight but they are not fatigued if we reduce the weight.

    If someone is training with 100kilo he is able to maybe lift 80kilo if he was all-out with 100. So there is is enough force left for him to lift 80kilo

    An other person who is training with 70kilo is able to lift 60 after he was all-out

    The second person comes closer to the point where he has 0 force left.

    Why does it not work this way and we can stimulate our muscles enough, even when we have so much force left like the first person has?

    • Drew Baye Apr 22, 2016 @ 11:24

      Hey Dan,

      You could continue to reduce the weight and increase the degree of inroad but extremely deep inroad isn’t necessary to effectively stimulate muscular strength and size increases and too much can be counterproductive due to the increased demands on recovery.

  • Mark Apr 22, 2016 @ 10:15

    “The only time I use or recommend set-extension techniques is if a trainee falls a rep or two short of their lower target repetition number”

    I don’t understand what the lower target rep number is. Please explain.

    Thanks.

    • Drew Baye Apr 22, 2016 @ 12:10

      Hey Mark,

      If your target repetition range is five to eight reps, your lower target repetition number is five and your upper target repetition number is eight.

  • Jack Apr 22, 2016 @ 11:32

    One issue I am having is the seated cable rows. The part between the bicep and forearm is what tends to give up first (brachioradialis?).I am not sure if this is part of the bicep and/or forearm. I usually get to a point where it is so worked up, I can only go to about 70% range of the movement and declining after each rep.

    At this point, the back is not the primary but the part between the bicep and forearm (brachioradialis?). My question, if it is a proper one, do I continue to do a few more reps, with good form but not the full motion of the actual workout to fatigue that muscle and/or should I stop because the back is not the primary anymore?

    • Drew Baye May 24, 2016 @ 14:13

      Hey Jack,

      The problem is that most cable row machines are not cammed properly to provide the decrease in resistance towards the end of the range of motion required to match the strength curve. Because of this extending your shoulders more than a little past neutral becomes disproportionately difficult as you become more fatigued. When using a machine with a poorly balanced resistance curve or when performing cable or free weight rows you should still attempt to extend the shoulders as far as you can (without elevating them) but continue the exercise as long as you’re able to pull your elbows at least slightly further back than the back of your shoulders.

  • George Sheehan Apr 22, 2016 @ 11:43

    Thanks Drew. I like using static holds, rather than counting reps. That time under load/static contraction is my favorite way of ensuring that all of the muscle fibers have been recruited. Using the most weight, holding for mazimum time, and slowly lowering this weight, is really all I need. There isn’t much left for the muscle to do i.e. it is well spent at the end of this static hold.

  • Mark Apr 22, 2016 @ 11:49

    After I trained at a SuperSlow -based facility for a few years, the MedX units they had no longer had enough weight to take me to failure in a SS-sets’ recommended timing. I’ve noticed that MedX from other years seems “heavier”. The “lighter” units seem to be the newer ones. Why would they do that?

    • Drew Baye Apr 22, 2016 @ 12:03

      Hey Mark,

      Some of the newer MedX machines have smaller weight stacks than the originals. This was probably done to reduce the cost.

  • Dave Apr 22, 2016 @ 12:01

    Drew,

    In regards to your statement “assuming they aren’t advanced trainees who have already maxed out their genetic potential”, do you still recommend using HIT? I have been training for 25 years now, competed once, but have been at a crossroad of doing HIT to maintain or higher volume, lighter weight not to failure. What’s your thoughts?

  • Sascha Apr 22, 2016 @ 13:22

    Failure is definded by not being able to perform another rep in perfect form. But in my experience many excercise like the military press, end not because of overall muscle failure, but just because of not getting over that one week bump wich just happens to be the weakest link in the movement. Is this still good enough to be cold “failure”?

    • Drew Baye Apr 27, 2016 @ 17:15

      Hey Sascha,

      This is less of a problem when exercises are performed on properly designed machines or when using body positioning that allows for a more balanced resistance curve on free weight exercises, but on exercise where it does happen it is because of muscle failure. If your available strength is too low to overcome the resistance at some point in the range of motion you have achieved momentary muscular failure. Sticking points and how to work around them is something I cover in the upcoming Elements of Form.

  • Julien Apr 23, 2016 @ 4:44

    Hey Drew,

    Is it possible to fatigue every muscle fibre, but still not create enough metabolic stress if the time under tension is not say at least 50 seconds? Or is the metabolic stress sufficient when muscular failure is achieved?

    Second,in terms of slower repetitions why do you think people dismiss the idea of time under tension for muscle fiber recruiment? it seems so logical to me.

    Thanks

    • Drew Baye Apr 23, 2016 @ 21:17

      Hey Julien,

      If you perform a very short maximum effort contraction you will recruit every muscle fiber but not fatigue them deeply. While performing a series of brief, max-effort isometric contractions for a muscle group can be effective for stimulating strength and size increases it would not create much of a metabolic or cardiovascular demand. While this would be a poor method for improving overall fitness it might be a good choice for someone who wants to get stronger but has a condition which requires them to avoid significant heart rate elevation.

      I think this is a semantic issue, and they are thinking time under tension is a method of exercise when it’s really just a measurement of exercise. Whenever you perform any exercise using any method your muscles are under tension for some amount of time and if the tension and time are high enough you will recruit all the motor units in the targeted muscles.

  • Eric Brantley Apr 23, 2016 @ 10:18

    Drew,

    Great article, i have high blood pressure and an advanced user of HIT, what precautions

    during training should i take? I train once every 5 to 7 days.

    • Drew Baye Apr 23, 2016 @ 10:41

      Hey Eric,

      With high blood pressure it is important that you breathe properly and avoid Val Salva’s maneuver during exercise. For more on that read Safety Considerations for Exercise.

    • Ben Tucker Apr 23, 2016 @ 16:58

      Eric,

      My dad is 73 and I check his blood pressure before and after every exercise. We usually train in a hit Big 5 Style with occasional single joint exercises thrown in. His blood pressure is very optimal for his age and he takes no medication whatsoever. He trains once a week or roughly every seven days.

      The only thing that he could tighten up on is his eating habits and probably sodium intake, which in turn, has a lot to do with overeating.

      And most definitely what Drew said about Val Salva.

      I hope this helps.

  • Hal Apr 24, 2016 @ 23:40

    What is your opinion of advanced trainees using a single set to failure with rest pause extension as in dc training? For me this gives better results than a simple single set to failure. Similarly a 20 rep widowmaker leg press using rest pause style reps gives better results than a simple sstf. Thank you

    • Drew Baye Apr 27, 2016 @ 12:36

      Hey Hal,

      It depends on why they’re doing it. Often, more advanced trainees need to use set-extension techniques less frequently rather than more because they’ve learned to train intensely enough without them. This is something I’ll be covering in the advanced repetition methods section of Elements of Form.

  • Simon Apr 25, 2016 @ 7:02

    Hi Drew,
    A little similar to Dan’s q’s, but an example of doing a 2nd set is myself: I do a chest press to failure followed by 3/4 other exercises (row type or leg), then I would do a flat bench dumbbell press to failure (so maybe 10 mins after chest press).

    This DB press would be at decent weight and in and around my tul (c. 60secs). So, how can I lift this after failure on the chest press – is it because my slow twitch fibres have rested and are ready to go again but I’m not getting any fast twitch fibres working on this 2nd set (as they take 48 hrs to recover?).

    Or has the rest helped and I’m working all fibres again and just gaining more inroading? Which presumably is good, so long as it doesn’t negatively affect recoverability (which it doesn’t seem to be doing)? It just feels a much more complete workout doing a second set (usually machine 1st and free weights / body weight 2nd).
    I’m just confused as to how I can go even do a decent 2nd set if I’ve already gone to failure – the break in between the chest work obviously helps things be ready again, i.e. I’d have a very short TUL if I went straight from chest press to DB press and don’t like doing it this way at all.

    As always, thanks again and interesting article.

    Simon

    • Drew Baye Apr 27, 2016 @ 12:35

      Hey Simon,

      If you rest long enough between sets of an exercise or between different exercises targeting the same muscles the targeted muscles may recover enough for you to perform a comparable amount of work. This isn’t necessary for effective growth stimulation, though, and you’re just increasing overall fatigue and the stress your body has to recover from between workouts.

  • Ron Shekels May 7, 2016 @ 15:30

    Drew, How would you recommend preparing for a workout session that includes the following:
    Squat 500×10; Bench 405×10; Stiff Leg Deadlift; 405×15?

    • Drew Baye May 17, 2016 @ 12:27

      Hey Ron,

      I recommend performing exercises to momentary muscular failure rather than for an arbitrary number of reps, using a load that allows failure to be achieved within a sixty to ninety second time under load as a starting point (about six to ten reps at a 4/1/4 cadence). Assuming someone is strong enough to perform those exercise with that much weight for that many reps in what I would consider good form, and they have no injuries or joint conditions for which a separate warm-up or other preparation is required, the only preparation I would have them perform is mental. If they are able to perform the exercises with form that is up to my standards for that many reps no other preparation would be necessary.

      If they are not able to perform the exercises with form that is up to my standards for that many reps I would reduce their weights until they could, which would be just as effective as and safer than using the heavier weight for a shorter set with looser form.

  • Sandor May 17, 2016 @ 18:49

    Hey Drew,
    Thanks for the article. I would really love to hear your opinion related to electrical muscle stimulation in general. Those who recommend the use of EMS devices claim that the muscle tension produced in a maximal EMS contraction can be up to 30% higher than a maximal voluntary contraction. They state that the body is always holding some back from even the most demanding load to maintain a reserve. Therefore, it’s impossible to voluntarily contract all fibers simultaneously, not even when you reach momentary muscular failure. EMS works directly on the muscles, bypassing the body’s energy conservation system, thus there’s no limit to the percentage of fiber that can be activated, resulting in a training stimulus that’s unattainable by any other means.
    Do you have any knowledge related to this, is there any truth to these claims?
    I would really appreciate your thoughts on this topic.
    Thanks

    • Drew Baye May 18, 2016 @ 11:50

      Hey Sandor,

      While this might help some people train past their psychological limits and get closer to the physical limits of their abilities, since there are risks involved I do not recommend it for people not trained in the proper use of these devices.

  • Roger Dec 28, 2017 @ 9:06

    While I agree that one set to failure using an appropriate time under tension (e.g., 45-90 sec) is sufficient for muscular strength and hypertrophy, I have experimented with adding a few additional non-failure sets (1-2 reps shy of perceived failure) over the past year with very good results. In fact, I actually “enjoy” this type of routine better than when I was training with one all out set to failure for each muscle group. So, with the risk of being accused of HIT heresy, here’s what I’ve been doing with an upper/lower split every other day.

    I pick one exercise per body part for 5 total sets. All reps are performed with a moderately slow tempo and good form throughout. On the first set I use a weight that I can get approximately 30 reps with one or two reps left in the tank. Second set I increase the weight slightly and shoot for approximately 25 reps with one or two reps left in the tank. Third set I increase the weight slightly and shoot for approximately 20 reps with one or two reps left in the tank. Fourth set I increase the weight slightly and shoot for approximately 15 reps with one or two reps left in the tank. Fifth and final set I increase the weight slightly and shoot for approximately 10 reps, but I push this set to positive failure with a static hold of about 5 seconds on the last rep. Since this last set is to failure, I may get a few reps lower or higher than 10, but that is the amount of reps that I aim for.

    These additional sets haven’t affected my recovery ability in the least, and I get a much better “burn” and “pump” in the trained muscle this way. Anyway, I’m not trying to convince anyone that this is the best possible way to train, or to adopt this style of training. I’m simply sharing what has been working well for me and throwing it out there for those who might be interested.

    BTW, thank you Drew for an excellent training site and all of the great article you continue to put out!

    • Drew Baye Jan 25, 2018 @ 11:22

      Hey Roger,

      For some people depending on recovery ability, total workout volume, and other factors, a few additional lower intensity sets may not be significantly counterproductive, but they are also not necessary for long term improvement in physical appearance or functional ability and would unnecessarily increase the time required to complete a workout. This is not HIT heresy because it isn’t HIT at all. If you enjoy it and if you don’t mind spending the additional time working out for that purpose that’s fine, but I recommend people use exercise to meet their physical needs and find other activities to meet their psychological ones.