Q&A: Exercise Volume And Metabolic Versus Mechanical Work

Question: A reader asked for my opinion on an article in which the author claims, “…multiple sets are a must if you want to maximize your muscular potential.” I’ve written about this before, but since this is a subject a lot of people are still obviously confused about I’m going to break it down here and explain it as simply as I can.

Answer: Like most things, the answer is “it depends.” You do not need multiple sets to maximize your muscular potential, but for single set training to be effective you have to do it right. And, if you are doing it right, performing more than one set can quickly result in overtraining and slow or stop your progress.

To better understand this it helps to think of exercise volume in terms of metabolic rather than mechanical work. The stress on your body and stimulus for adaptation has little to do with how many times you lift and lower the weight, and a lot to do with the tension and metabolic demand placed on your muscles. Because of this, it is more appropriate to define exercise volume in terms of the magnitude and duration of muscular force application (force x time) than reps and sets. This is why isometric training methods like static holds and timed static contractions effectively build muscular strength and size without any mechanical work performed.

It also helps to keep in mind that different people have very different ideas about what a set is and how it should be performed, and this often determines how many they believe is necessary. For example, a person who performs four sets of ten repetitions of an exercise at a typical cadence – lifting the weight in a second then lowering it just as quickly – would have a cumulative time under load (TUL) for that exercise of eighty seconds (4 sets x 10 reps x 2 seconds per rep = 80 seconds). A person who performs just one set of ten repetitions of an exercise at a moderately slow and controlled cadence – lifting the weight in four seconds then lowering the weight in four seconds – would also have a TUL for that exercise of eighty seconds (1 set x 10 reps x 8 seconds per rep = 80 seconds). Although the first person performed four times as much mechanical work, assuming the same resistance the metabolic work would be roughly equal.

If you perform an exercise at a fast cadence – quickly throwing the weight up and dropping it – with typical repetition ranges your TUL per set would be very low and you would be able to perform more sets without overtraining. Even if your intensity of effort is very high you might need to perform multiple sets for optimal results if each of the sets is very short.

On the other hand, if you perform an exercise at a slower cadence – lifting, lowering, and reversing direction under strict control – with typical repetition ranges your TUL per set would be very long, and attempting multiple sets in this manner would result in overtraining.

There are a lot of examples of people who have gotten big and strong using both methods, and on the surface it might not seem to make much of a difference whether you perform multiple shorter sets or a single longer one if the cumulative TUL per muscle group is the same, but there are several disadvantages to performing multiple sets at a faster cadence.

The faster you move during an exercise the greater the force encountered when you reverse direction between lowering and lifting, where the muscles under load are most vulnerable. The more mechanical work you perform the more wear on your joints. The faster you move during exercise the less you are capable of maintaining proper body positioning and control over the path of movement. These all increase your risk of injury or developing joint problems over time. Additionally, the faster you move during exercise the less weight you can lift.

It could be argued that despite your muscles being able to produce more force at slower concentric contraction speeds dividing the TUL of an exercise into multiple, shorter sets with a few minutes of rest in between would allow the use of heavier weights. However, since most people do not train to failure on each set when performing multiple sets and your results from exercise have more to do with your intensity of effort than load, this wouldn’t appear to be any more effective than a single, longer set performed to muscular failure.

Of course, if you want to go as heavy as possible you can still do it with slower repetitions by performing rest-pause, with lower risk of injury and less wear on your joints.

While it probably makes little difference in muscular strength and size gains whether you perform multiple shorter sets or a single longer one provide the intensity of effort and TUL are similar, when it comes to safety and efficiency HIT style single sets are the clear winner.

High Intensity Training Venn Diagram: Effectiveness, Efficiency, and Safety

While a lot of training methods can be highly effective if done hard, progressively, and consistently, not all methods are equally safe or time efficient. If you have to choose between multiple methods capable of producing the same strength and conditioning improvements over time (which is limited by your genetics, regardless of the methods used), it makes sense to choose the method that is least likely to injure you or undermine your long term joint health and functional ability, and requires less time in the gym. Effectiveness alone is not enough. An exercise program should also be safe and time efficient.

The goal of exercise is to stimulate the body to produce improvements in all the trainable factors of functional ability, to improve your physical capabilities, appearance, and health. Even if a program effectively stimulates the body to do so, if it is likely to cause you injury it is going to undermine your functional ability and health in the long run.

The ultimate reason for exercising, for wanting to improve your physical capabilities, appearance, and health is to better enjoy your life. None of us knows how much time we have, and once we die that’s it. Unless you really enjoy hanging out at the gym (and some people do) spending any more time working out than necessary is a waste.

Although the cumulative TUL of many HIT workouts is comparable to that of many multiple set bodybuilding workouts, because the work is more condensed they take much less time to complete. For example, if you perform a HIT workout consisting of ten exercises each performed for a single set of six to ten reps at a 4/4 cadence and rest a minute between exercises, your cumulative TUL would be a little over ten minutes and your total workout time would be around twenty minutes. Consider that many people who do HIT use even shorter rest periods and might complete the same workout in under fifteen minutes. Compare this with a typical bodybuilding workout consisting of a dozen exercises performed for three to four sets of eight to twelve reps at a 1/1 cadence and with a two to three minute rest between sets. Although the cumulative TUL would be about the same the total workout time would be one and a half to two hours because of how the work is distributed. Additionally, condensing the same cumulative TUL into a shorter workout increases the work to rest ratio and the effectiveness for cardiovascular and metabolic conditioning, making it unnecessary to spend more time performing other activities for that purpose.

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  • Greg Feb 26, 2015 @ 17:24

    Thanks again for a well written article Drew. I always wonder when I am at the gym what others may think. Not that I care, but I always train around the same time and day once a week. My total training time is between 6-9 minutes. I would say that I’m in and out pretty fast, but I am on the floor at the end of my session. Haha. I just find it interesting that no one asks about my training style. Everyone else in there is doing the standard multiple sets and certain amount of reps, while I’m there doing 3-5 exercises (1 set to failure each) huffing and puffing. It’s funny how the fitness industry has drilled into people what to do. Even family. They have seen the results and know how brief and infrequent I train. Yet still have another mind about it. I guess people must enjoy hanging at the gym and working out for as long as possible as a statement. Well that’s all from me. Thanks for all your articles. Great stuff always.

    • Drew Baye Mar 3, 2015 @ 15:16

      Thanks Greg,

      Ironically, although they probably do think you’re doing very little work their average cumulative hourly time under load is probably less than what you accomplish in under ten minutes.

  • Bruce Feltus Feb 26, 2015 @ 18:57

    Drew,
    Thanks for the article. It reinforces my mind for HIT when all the crap I learned from muscle mags over 40 years creeps in.
    You’d think the military would adopt this type of program to save time and injuries too.
    Bruce

    • Drew Baye Mar 3, 2015 @ 15:13

      Hey Bruce,

      I’d like to see a more joint-friendly bodyweight program like Project Kratos replace the high-speed, high-rep calisthenics most militaries use for PT. They’d get the same or better results with fewer injuries.

  • Brad Feb 27, 2015 @ 6:05

    Great explanation Drew and logically the only way to train, I did a full body hit workout yesterday and may have to scale back the Intensity a bit as I was beyond wasted today, and thats with only a warm up set followed by an all out set for chest , same for back, shoulders, and legs. The secret I believe IS in the cadence I could only muster out 6 reps at a slower cadence, and actually had to scale back the weight that felt 10 times heavier!
    But this control was so much friendlier on my joints! And most appreciated by a dude that just turned 52.
    So total working sets were 4 and I was outta the gym in 25 minutes, which I’m hoping to chop down to 15 next workout.The pump I got was incredible, I just ballooned up!
    Now I’m looking forward to the next 7-9 days off and growing! Always enjoy reading your articles, keeps me focused and motivated!

    • Drew Baye Mar 3, 2015 @ 15:10

      Hey Brad,

      No need to scale back your intensity. Over time you’ll adapt and feel less wasted after, even while reducing your rest between sets.

  • Roger Feb 27, 2015 @ 8:06

    I never would have believed how effective using one set to failure is until I switched to it over the past year. I workout once-per-week, resting about 1-2 minutes between exercises, alternating between the following two routines:

    Workout A:

    Sled Leg Press
    Hammer Incline Chest Press
    Hammer Seated Iso-Row
    Dips
    Standing Cable Curls
    Abdominal Crunch Machine

    Workout B:

    Trap-Bar Deadlift
    Standing Smith Machine Overhead Press
    Seated Pull-Downs (w/rotating handles)
    Dips
    Standing Cable Curls
    Abdominal Crunch Machine

    I’ve added either weight or reps (8-12 range) at almost every workout so far, except for the Dips and Cable Curls. Progress on those two exercises have slowed down some now, but on everything else I’ve continued to get stronger at practically every workout. Plus, I’ve went from 160 lbs to 172 lbs while keeping my body fat between 11-12%. At 49 years old, switching to a HIT routine has been the best training decision I’ve made in a very long time. I wish I would have done so in my twenties! I feel much better all around, and I’m in the best shape of my life. For all of you doubters out there, take a chance and give it a try for a few months.

    (The only other exercise I do is treadmill interval sprints once-per-week about three days after my weight training workout…these two routines together work like a charm!)

    • Drew Baye Mar 7, 2015 @ 11:00

      Hey Roger,

      I’m glad you decided to give it a try. Most people have difficulty with the concept at first, but when they learn to push themselves to train intensely enough they realize why so little volume is necessary. That’s a solid routine, but I suggest adding some direct calf and neck work.

      • Roger Mar 17, 2015 @ 14:05

        Hi Drew,

        Actually, I do calf work on the sled leg press machine, once I’ve competed my primary leg press exercise (I just didn’t list it since it’s an “add-on” exercise that I don’t focus on very much). I simply catch my breath, and then perform one set of calf raises with the same weight to failure. I usually get close to the same amount of reps that I did with the leg press exercise.

        But I don’t do any direct neck work, as I’m happy with my current neck development as a result of my basic routine. I have no desire for my neck to get an bigger, merely for “cosmetic” reasons, and it seems to be strong enough for every other activity that I may engage in. Thank you for the suggestions though.

        Roger

        • Drew Baye Mar 21, 2015 @ 15:52

          Hey Roger,

          If you’ve already got a strong neck you don’t need direct neck work, but adding it in once every couple of weeks wouldn’t hurt and if it ever does start getting too big you can always back off on training it directly for a while. Having a strong neck is essential for anyone involved in contact sports or physically dangerous professions.

  • Andy Feb 27, 2015 @ 9:02

    Hi Drew,

    So if I’m training by myself and pushing each set to what I believe to be failure, how do I really know that I’m “doing it right”? And if I don’t have someone to push me, would it be beneficial to perform a 2X3 or a 3X3 routine instead? As it stands, I currently perform 1 set each of incline press, seated row and leg presses three times every two weeks.

    Thanks,

    Andy

    • Drew Baye Mar 4, 2015 @ 9:59

      Hey Andy,

      You would be better off working at learning to push yourself harder during your sets than adding more sets. 3×3 workouts are effective for general strength and conditioning, but not optimal for physique development due to the limited number of movements.

      • Andy Mar 5, 2015 @ 11:14

        Hi Drew,

        I’ve learned that channeling my intense anger towards my employer helps me to push each single set to the max. May not be the best thing but it sure does motivate me. As an aside, do you believe that that performing only those three exercises is sufficient for optimal physique development? Or do you recommend adding additional isolation exercises?

        Thanks,

        Andy

        • Drew Baye Mar 5, 2015 @ 12:14

          Hey Andy,

          No, performing only three exercises may take you pretty far but is not sufficient for optimal physique development because so few exercises do not provide optimal stimulus for all the major muscle groups. Alternating them with other pushing, pulling, and leg exercises and including work for your neck, calves, and forearms would be more effective for physique development. For more on this see High Intensity Workouts.

  • Donnie Hunt Feb 27, 2015 @ 9:38

    Great article Drew. I like how you point out how it doesn’t take much time to get in high quality exercise if you so choose. AND how you get more cardio and metabolic conditioning with shorter rests. Getting in there, working the body safely, in a short amount of time.

    • Drew Baye Mar 3, 2015 @ 15:03

      Thanks Donnie,

      It doesn’t take much time at all. As long as someone doesn’t have to wait for equipment they should be able to complete a workout in under half an hour. If it takes longer than that they’re either doing too many exercises or sets or resting longer than they need to between exercises.

  • William Go Feb 27, 2015 @ 11:53

    I’m have been reading Carpinelli etal (2004) lately, which observes that majority of primary sources of studies fails to show that multiple sets are superior to single sets.
    Reading through this study, I observe that. Most experiments did not state the rep speed used, except one.

    This is my question. If they are using the same fast reps for the single set groups, then they probably didn’t reach the effective TUL range of 40~90 seconds. If so, then the short term studies may have been the same since it is more of motor skill development than hypertrophy? While long term (6 months plus) studies show better results for multiple sets due to not performing enough TUL for the single set to improve? Am I correct?

    I think unless a study on twins are made, where one group of one of the twins are trained via multiple set, accdg to their periodization scheme, while the other group of the other twin trained via strict HIT standards, adjusting recovery period accordingly, each having their “knowledgeable” trainers from each group, long term, no drugs. Unless a study be made with those measures, there will always be a debate which is better.

    I suspect that even if the same TUL range is employed, if the single set group will train 3x a week for say 6 or more months, then recovery will suffer, which might create an illusion that multiple sets are better for longer durations of time.

    I would appreciate it to hear your view in this matter.

    • Drew Baye Mar 3, 2015 @ 14:55

      Hey William,

      This is a possibility. A lot of these differences start to make more sense when you start comparing time under load or force over time instead of sets and reps.

      I don’t know whether a single set to failure program would be more likely to result in overtraining over a longer term than a multiple set program matched for volume if everything else is equal, although this might depend on the structure of the workouts. The higher work to rest ratio may be more difficult to recover from despite the same average time under load, so for a fair comparison the rest periods would need to be increased for the single set group to make the average work to rest ratio the same between groups.

      • William Go Mar 3, 2015 @ 15:24

        Thanks Drew,

        Your point regarding the long term studies and the work to rest ratio makes sense.

        By the way, nice article! Even your answers to questions are informative.

        • Drew Baye Mar 4, 2015 @ 9:53

          Thanks William,

          This needs to be studied more and the studies need to be done better, but to really be useful in addition to comparing the effects on muscular strength and size gains they need to compare effects on other factors of functional ability, rate and severity of injuries, and the time required. It is not enough for a method to be effective, the benefit to risk ratio and return on investment (time efficiency) are also important.

  • Forest Feb 27, 2015 @ 15:05

    When I do pullups with the 4/4 cadence I can barely complete three of them. I have to add several rest pause doubles and singles before I feel like I have stimulated my pull up muscles enough to last for a week.

    A couple of months ago I could only do singles, and before that I had to go to the gym and use a machine for weight assisted pullups, so I feel like I’m making pretty good progress for a 67 year old.

    • Drew Baye Mar 3, 2015 @ 14:59

      Hey Forest,

      If you’re only able to do three repetitions at a slow cadence additional repetitions following a short rest pause would be beneficial. It is also possible to scale the difficulty of bodyweight exercises by manipulation of leverage and timing, which I explain in detail in Project Kratos.

  • Don Hyrkas Feb 27, 2015 @ 15:48

    Drew — Would love to hear you opine re: A single 5 sec.up/5 sec. down set for 90 – 120 seconds per day working a body weight protocol on a 5-day rotation. (Day one for example – one set of rows; day two – one set of push ups; day three – squats; day four – inverted rows; day 5 – calves. Or variations) Abs/Lower back could be worked in every other day with planks, 3-way crunches, trunk raises etc. Due to my schedule at the moment, I can better deal with 5 minutes and one set of an high intensity exercise than 30 or more minutes of a whole-body “big five” routine. I’m aware of the potential overlap that could happen, but is this a significant concern with this approach? Naturally, each set would be to positive failure The intensity progression would be per the techniques you’ve outlined in previous posts. “One set and done for the day” …sounds good! No? OR? Love your stuff! “Live! Love! Laugh! DH

    • Drew Baye Mar 3, 2015 @ 14:40

      Hey Don,

      This could work, and if it’s all your schedule allowed for it’s a practical solution. I highly doubt you could overtrain doing this if working a different muscle group each day.

  • Trace Feb 27, 2015 @ 16:27

    Drew, I admire your persistence in figuring out new ways to communicate the facts about EXERCISE. Some get it, some will get it, the rest don’t and won’t. All you can do is educate and instruct. But people also have to be able to reason for themselves. Here’s a concept that was given to me as an example of what makes sense to the “masses.” Participants are instructed to mimic the same movements that are performed in daily life until exercise “effects” are produced. As ludicrous as this idea may be, it’s not that different from most other conventional recommendations that place all the emphasis on mechanical work and never mention anything about meaningful loading. Somehow more need to understand what’s at stake for them personally and treat the subject with the seriousness that it demands. Keep up your valuable work!

    • Drew Baye Mar 3, 2015 @ 14:32

      Hey Trace,

      The more I learn and think about exercise the more I realize how much of it is counterintuitive to most people, and the issue of mechanical versus metabolic work is a tough one to get people to understand unless you are able to put them through a workout so they understand. There is a saying, “For those who understand, no explanation is necessary; for those who don’t understand, no explanation is possible.” Unfortunately, a lot of exercise is like this, and the need for only a single properly performed set is something best taught in the gym.

  • Ian Wilson Feb 28, 2015 @ 0:12

    Drew I train in my tool shed ( which is more tools then shed room) I havea leg press and also incorperate bench press into my workout. unfortunately since I train alone, I can only train to near failure on both of these exercises. Do you think an additional set would be beneifical under these circumstances, or would increasing the TUL by performing a rest pause be better?

    • Drew Baye Mar 3, 2015 @ 14:19

      Hey Ian,

      No, because intensity of effort, specifically training to the point of momentary muscular failure, is far more important than the volume. One set to failure is more effective than two or more stopped short of an all-out effort. Instead, I recommend modifying your leg press so the weight can be set down at your start point and either getting spotter stands for your bench if you have room, or switching to dumbbell bench press, push ups, or parallel bar dips for chest.

  • Andy Feb 28, 2015 @ 3:56

    Great article Drew … IMPRESSIVE!

    Thanks, Andy

  • Jamieson Bardy Mar 2, 2015 @ 12:57

    Wonderful article Drew, as always!
    It never fails to amaze me how often the metabolic effect of HIT workouts is completely ignored by the majority of lifters, most of whom have never tried a true HIT set in their lives.
    To a man, all the lifters I’ve discussed your ideas with have all said ‘1 set just doesn’t cut it’, sure, 1 set done in sloppy form and resembling dropping and throwing the weights wouldn’t, but done properly 1 set is really all one needs.

    Keep up the good work!

    • Drew Baye Mar 3, 2015 @ 13:48

      Hey Jamieson,

      When people say things like “one set isn’t enough” or “I feel like I need to do more” I tell them if they believe that they’re not doing it right, because if they were they’d understand why it only takes one and they would not feel like they need more.

  • Steven Turner Mar 4, 2015 @ 16:54

    Hi Drew,

    Great article,

    Is there a way of measuring the metabolic work as opposed to measuring the mechanical work? I think if you could measure metabolic work that is required to stimulate adaptations than this would be beneficial.

    I was recently asked a question why are there so many different guide figure numbers example 3-8 sets, 8 to 12 reps. And then most of the different authorities provide a huge differences in the sets and rep ranges. Is it just a case of toss out a wide range of different numbers and hope for the best, or know that most will fail and than sell the person something else worhtless.

    This also puzzles me in the fitness industry with personal trainers (PT’s) it is well known that most people reasons for not undertaking health and fitness are time constraints. PT’s are taught exercise by so-called experts and what do the so-calld experts teach the PT’s exercise programs that will require the client t go to the gym 3-5 days per week for one -two hours. Most of that time is wasted time sitting around between exercises. And then if you want to undertake advanced exercises programs and get even better results you now have to now go to the gym 5-7 days per week, add a huge number of exercise to the program that will now take you 2-3 hours per session or may have to go the gym twice a day.

    Personal Trainers wonder why the average life time working in the fitness industry is 1-2 years.

    Drew you have provided the solutions.

    • Drew Baye Mar 5, 2015 @ 12:27

      Hey Steven,

      I’m going to answer all of this in more detail in another post, but here are the short answers:

      The most practical way to estimate metabolic work is to multiply the force the working muscles are applying by the time they apply it (force over time). It simply is not practical or cost efficient to have someone work out while connected to metabolic rate testing equipment. For example, if you perform a barbell squat with 315 pounds for ten reps at a 3/3 cadence your force over time would be 315 lbs x 60 seconds. While still not perfect, it’s much better than using mechanical work for reasons I’ve covered elsewhere.

      One reason there are many different repetition ranges recommended is because a variety of repetition ranges can be effective, but people tend to settle on the range that works best for them and assume it’s optimal for everybody else. Another reason is some people believe different repetition ranges are required to address different expressions of strength (max effort, endurance, etc.).

  • dan Mar 7, 2015 @ 10:07

    hello Drew, as always another great article. I do have a question pertaining to your reply to Andy’s question about optimal physique development,

    what if one day a week perform all compound exercises with the big three and another day of the week perform isolation exercise (i.e. sunday would be compound and Wednesday would be isolation), both days would be full body workouts?

    dan

    • Drew Baye Mar 25, 2015 @ 13:06

      Hey Dan,

      Any combination of exercises that effectively works all the major muscle groups will be effective. Compound movements are just more time efficient. I design most of my workouts around a few basic compound movements, usually either squat, chin-up, and overhead press, or deadlift, parallel bar dip, and compound row, with simple movements added to round them out. My book High Intensity Workouts contains several examples of this along with a detailed explanation of the exercise selection process.