I’ve spent much of the last few months (and posts) thinking about the basic training variables that influence hypertrophy, namely how altering training intensity alters the hypertrophic results from training. The main idea of these posts was that, when taken to failure, light training loads (30%-1RM) can produce comparable hypertrophy to high intensity loads (80-90%-1RM). While the location of growth may vary, being higher in type I fibres with low-load, type II fibres with high intensity (1), ultimately, whole-muscle hypertrophy is very similar across intensities when trained to failure (2).
From a training perspective, this suggests that load (intensity) compensates for time-under-tension, so that as load decreases, total work and time under tension (TUT) increase (3).This was clearly demonstrated by Burd et al (3), who found a somewhat similar protein synthetic response to a single training session at either 90%-1RM or 30%-1RM to failure, an effect that didn’t occur with light load, work-matched training (non-failure). Their subsequent training study validated that comparable hypertrophy occurs in untrained subjects trained in a similar fashion (80%-1RM vs 30%-1RM) over a number of weeks (2).
One assumption in these previous posts was that both work and time-under-tension increase as training intensity decreases. This assumption is absolutely correct assuming that all your repetitions are performed at a similar tempo but tempo, work and time-under-tension, at any given training intensity, are competing variables. If you slow down your repetitions, you ultimately perform less work, however the TUT is usually higher than when reps are performed faster. So slower tempos come with greater TUT at the expense of the total work performed during the set.
Tempo disrupts the relationship between time-under-tension and work
You probably don’t need a peer-reviewed paper to tell you this, but if you slow both the eccentric and concentric rep speed, you’ll perform fewer reps than at a faster rep speed for a given training intensity (4-6). As the number of reps impacts work, less work is performed in a slow set at an equivalent intensity, but the time-under-tension is usually much greater (5,7). Tempo then, disrupts the relationship between time-under-tension and work. This leaves us with the question, when training at a similar intensity (%1RM), is training with a slow tempo to maximize TUT, or a fast tempo to maximize work optimal for muscle hypertrophy?
Does time-under-tension trump work?
Spend any time searching for tempo and time-under-tension, and more often than not you’ll see a recent study from Burd et al (8) offered up in favour of extending time-under-tension through slow-tempo lifting. The authors compared the protein synthetic response following unilateral leg extensions completed at 30%-1RM performed either at a slow tempo (6/6) to failure, or a work-matched faster tempo (1/1). The myofibrillar, mitochondrial and sarcoplasmic protein synthetic responses were greater following the slow-tempo to failure than the work matched condition, suggesting that greater TUT is favourable when tempos are work-matched at an equivalent training intensity.
While this study may seem like increased TUT can promote a favourable protein synthetic response, we can’t be certain that it’s not related to the fact that one group trained to failure while the work-matched group did not. To really get at this question, it would’ve been great to have a third condition in the study where training was completed at the faster tempo, but to concentric failure (non-work matched). As is always the case, this study also only represents an investigation of the acute response to a single training session, which may not be indicative of the ultimate adaptations to training. Fortunately we have more to go on than studies of the acute protein synthetic response to a single training session that further our understanding of the role of tempo in hypertrophy.
Tanimoto and Ishhi (9) compared the effects of slow tempo training at 50%-1RM (3/0/3/1) to failure with training at 50%-1RM at a ‘normal’ tempo (1/0/1/1; work-matched to the slow training) and heavy, ‘normal’ training (80%-1RM, 1/0/1/1) to failure to clarify the role of intensity and tempo and muscle hypertrophy. Following 12 weeks of training, both the low-intensity slow training and heavy training produced comparable quadriceps hypertrophy (5.4%, 4.3%), whereas the work-matched low-intensity group had no growth. All groups increased their strength, however as expected, those that trained with heavy weights improved the most.
This study suggests that, when performed at an equivalent training intensity, time-under-tension compensates for reduced work with slow-tempo lifting. The fact that both the high and low intensity groups had comparable growth agrees with previous literature on training intensity (2), and the fact that they used different tempos suggests the speed of your reps may not matter for muscle growth when training to failure. Just as we saw with Burd et al (8) this study would have benefitted from another group that trained with low-intensity to failure to really clarify the relationship between tempo, work and TUT when training to failure.
In agreement with Tanimoto and Ishhi (9), Claflin et al (10) compared high and low velocity training with heavy and light training loads respectively, in both young and old males and females who completed a 14 week training program. Participants were randomized to perform training for three sets at 10RM (third set to concentric failure) at two different training velocities that influenced training load (fast = 250-250 degrees per second at the hip, 100-160 degrees per second knee, slow =30-90 degrees per second at the hip, 20-40 degrees per second at the knee).
Type I fibres were unaffected by the training program in either condition, whereas type II fibres increased in size (8.3%), and this change was independent of the velocity (and load) of training. In fact, of all the single fibre contractile properties investigated, only the increase in the peak power of the type II fibres could be explained by lifting velocity. Seemingly counterintuitive, the increase in peak power occurred due to low velocity training. Either way, these data suggest that the majority of training adaptations occurred independent of age and sex, but more importantly, of velocity (tempo) as well.
While these studies cumulatively suggest no main hypertrophic detriment to slow tempo training, the case for the indifference of work and TUT with respect to tempo is not air-tight. Recently Schuenke et al (11) investigated an array of training variables, namely the role of various training intensities and tempo on the adaptations to training. Participants were divided into four groups performing traditional strength training (TS; 80-85%-1RM, 6-10 RM, 1-2/1-2), endurance-oriented training (TE; 40-60%-1RM, 20-30 RM, 1-2/1-2), super-slow training (SS; 40-60%-1RM, 6-10RM, 10/4), or acted as sedentary controls. The TS and SS groups were matched for the number of repetitions, although performed at different intensities, and TE and SS were equated for intensity, but NOT the number of reps and ultimately work performed.
After six weeks of training, only the traditional strength and super-slow group had appreciable muscle fibre growth (TS=39%, SS=11%) although the large difference between the two groups was not statistically significant. The traditional strength group had growth across all fibre-types (I, IIa, IIx), whereas the SS group affected Type IIa and Iix fibres only. The fact that the SS group outgrew the TE group who performed more repetitions and total work indicates that, at least in this study, time-under-tension trumps work at an equivalent training intensity.
While there are some disagreements in the literature, this data supports that, when training to failure, the total amount of work and time-under-tension, both influenced by tempo, do not impact the amount of growth following training. Future studies are definitely required in order to conclusively determine the statement above, however, I wouldn’t spend too much time worrying about how your lifting tempo may be impacting your hypertrophy results.
At the end of the day, pick the speed you feel best lifting at
From a performance perspective, it’s hard to make a compelling case for slow rep speeds. Decreased work, power outputs, reps at an equivalent training intensity (6,12,13,14), and ultimately reduced strength and power gains (17-21) won’t win over anyone concerned with how well their muscles actually work (4,5,16,20).
But as far as pure hypertrophy is concerned, the culmination of these studies indicates that tempo is largely irrelevant when training to fatigue/failure (21), although TUT may still be more important than total work (11,22). The tempo of your reps determines whether you perform a high work (fast reps) or greater TUT (slow reps) set, however the muscle growth in either case may largely be the same.
I see this literature as largely freeing from a programming perspective, as it means one less training variable to lose sleep over, and indicates that you can pick the speed at which you feel most comfortable lifting without having to worry about compromising your gains. You can vary tempo across exercises without worry, or stay firmly entrenched in either the “grip it and rip it” or “move slow to grow” ideologies without missing out on extra pounds of muscle mass.
- Fry, A. C. (2004). The role of resistance exercise intensity on muscle fibre adaptations. Sports medicine, 34(10), 663–679.
- Mitchell, CJ et al (2012). Resistance exercise load does not determine training-mediated hypertrophic gains in young men. Journal of applied physiology, 113(1), 71–77.
- Burd, NA et al. (2010). Low-load high volume resistance exercise stimulates muscle protein synthesis more than high-load low volume resistance exercise in young men. PLoS One, 5(8), e12033.
- Headley, SA et al (2011). Effects of Lifting Tempo on One Repetition Maximum and Hormonal Responses to a Bench Press Protocol. JSCR, 25(2), 406–413.
- Hatfield, D. L., Kraemer, W. J., Spiering, B. A., Hakkinen, K., Volek, J. S., Shimano, T., et al. (2006). The impact of velocity of movement on performance factors in resistance exercise. JSCR, 20(4), 760–766.
- Sakamoto, A., & Sinclair, P. J. (2006). Effect of movement velocity on the relationship between training load and the number of repetitions of bench press. JSCR, 20(3), 523–527.
- Watanabe, Y et al (2013). Increased muscle size and strength from slow-movement, low-intensity resistance exercise and tonic force generation. Journal of aging and physical activity, 21(1), 71–84.
- Burd, NA et al (2012). Muscle time under tension during resistance exercise stimulates differential muscle protein sub-fractional synthetic responses in men. The Journal of Physiology, 590(Pt 2), 351–362.
- Tanimoto, M., & Ishii, N. (2006). Effects of low-intensity resistance exercise with slow movement and tonic force generation on muscular function in young men. Journal of applied physiology (Bethesda, Md : 1985), 100(4), 1150–1157.
- Claflin, D. R., Larkin, L. M., Cederna, P. S., Horowitz, J. F., Alexander, N. B., Cole, N. M., et al. (2011). Effects of high- and low-velocity resistance training on the contractile properties of skeletal muscle fibers from young and older humans. Journal of Applied Physiology, 111(4), 1021–1030.
- Schuenke, MD et al. (2012). Early-phase muscular adaptations in response to slow-speed versus traditional resistance-training regimens. European journal of applied physiology, 112(10), 3585–3595.
- Schilling, B. K., Falvo, M. J., & Chiu, L. Z. (2008). Force-velocity, impulse-momentum relationships: Implications for efficacy of purposefully slow resistance training. J Sports Sci Med, 7, 299–304.
- LaChance, P. F., & Hortobagyi, T. (1994). Influence of cadence on muscular performance during push-up and pull-up exercise. JSCR, 8(2), 76–79.
- Keogh, JW et al (1999). A cross-sectional comparison of different resistance training techniques in the bench press. JSCR, 13(3), 247–258.
- Keeler, L. K., Finkelstein, L. H., Miller, W., & Fernhall, B. (2001). Early-phase adaptations of traditional-speed vs. superslow resistance training on strength and aerobic capacity in sedentary individuals. JSCR 15(3), 309–314.
- Rana, SR et al (2008). Comparison of early phase adaptations for traditional strength and endurance, and low velocity resistance training programs in college-aged women. JSCR, 22(1), 119–127.
- Neils, CM et al (2005). Influence of contraction velocity in untrained individuals over the initial early phase of resistance training. Journal of strength and conditioning research / National Strength & Conditioning Association, 19(4), 883–887.
- Padulo, J et al (2012). Effect of different pushing speeds on bench press. International journal of sports medicine, 33(5), 376–380.
- Munn, J et al (2005). Resistance training for strength: effect of number of sets and contraction speed. Medicine and science in sports and exercise, 37(9), 1622–1626.
- Pryor, RR et al (2011). Optimizing power output by varying repetition tempo. JSCR 25(11), 3029–3034.
- Young, W. B., & Bilby, G. E. (1993). The effect of voluntary effort to influence speed of contraction on strength, muscular power, and hypertrophy development. JSCR, 7(3), 172–178.
- Mikesky, AE et al (1989). Muscle enlargement and exercise performance in the cat. JSCR, 3(4), 85–92.
- photo credit: wwarby via photopin cc
In regards hypertrophy, if local metabolic effects/fluid pressure differences are important, wouldn't the tempo perhaps make a difference? Fast tempo reps could produce less intramuscular pressure, if performed through a full range of motion, than a more slow tempo(Tanimoto) and thus, if the before mentioned influences promote hypertrophy, be less useful?
If you manipulate the rep, reducing the range of motion, emphasizing the the stretch/longer muscle length range, and perform reps at a fast tempo, perhaps this would encourage a hypertrophic environment?
Great question. Regarding metabolic effects, if you take a set at an equivalent intensity, but perform one with "slow" reps, one with "fast" reps but both sets to failure, is it safe to assume that the slow tempo would have greater metabolic stress? I would think they would be likely very similar. Also interesting to note here is that the Hunter 2003 reference that demonstrates the uncoupling of mechanical work and energy expenditure with slow tempos still favoured traditional tempos to a "super-slow" protocol for total energy expenditure. This increase may not reflect the demands on the agonist muscle directly, as I suspect greater decelerative demands on antagonist muscles would ratchet up the energy demands as compared to slow tempos.
From a pressure standpoint, since this is likely related to muscle force production, we could argue that peak pressure would be higher with fast tempos since peak force is greater, but maybe average pressure is greater with slow? Stating which one is more important, or even relevant would be pure speculation at this point.
I can certainly make physiological arguments in support of the superiority of either tempo, but at the end of the day the data on actual muscle growth wouldn't support them. At the end of the day, for my programming this means I don't lose any sleep over it, and in reality personal preference takes priority. You could always play it safe by integrating multiple tempos, and in this case I would favour explosive concentrics on the multi-joint exercises like squats, deads, OHP and bench, but perhaps utilize slow tempos on single joint, more "isolation"-type exercises.
Lower load training is my area of interest. I may be misunderstanding your views but I believe you are suggesting that as long as the training set/sets are taken to momentary failure, tempo etc. will not make much difference in skeletal muscle hypertrophy.
My thinking is that if the set/sets are constructed in a way that produces more consistent intramuscular pressure, using techniques like static contractions/isometric holds and/or working mostly in ROM that help maintain this effect(Popov), ex. eliminating the upper third of the squat and/or performing even shorter range movements in a rapid cadence may be more conducive to promote hypertrophy than simply performing sets to failure with more simple applications.
Taking the simple push-up and perform a set to voluntary failure and note the physical reaction. Next, alter the performance of the push-up by adding a 5 sec. hold half way up/down in the execution concentrically and eccentrically, eliminate the lockout and not allow the abdomen to touch the ground, still performing to failure. I believe you will note a difference in the physiological effect, using the "same load", possibly due to changes in cross bridging, neurological stimulus of unique contraction points and ischemia of the chronic hold. I know this is a subjective observation but the difference in the "quality of work" is usually quite noticeable.
That is what the literature on tempo and hypertrophy currently supports. In addition, recent studies suggest this may also be the case for training intensity as well, and you may want to see my previous posts on that.
That's not to say your protocols aren't effective, I'm very interested in how others train and what they have found, or perceive to be successful. In this case, however, the data reconciles how someone could be successful using your techniques with slow tempos and isometric holds, or by taking the opposite, "grip it and rip it" approach to lifting.
I view the "rules" of hypertrophy training as much more flexible than we have traditionally made them out to be, and this can explain, in part, how so many people manage to grow using such diverse training protocols.
Thank you for your response. I am very familiar with the McMaster studies as well as Tanimoto's work and many others. I am also well acquainted with the papers on blood flow restriction/Kaatsu.
As someone who has utilized resistance training for over 45 years and was in a field where I treated many who demonstrated the possible "wear" of chronic higher load training, personally I think it is time that training models that optimize the use of lower loads should be reviewed.
At present, from my readings, other than the suggestion that if lower loads are performed to voluntary failure and perhaps greater volume(sets), we have little experimentation where comparative low load training protocols have been compared and tested. At present, I develop training models from existing studies with no claims to having found the Holy Grail.
I was wondering what you think about the following. In order to engage both hypertrophy and strength training would it be a decent idea to work out in the 1-6 rep range on Monday and then work out in the 8-12 rep range on Wednesday? Let’s say we’re talking about biceps and so two times in the week I train the muscle but one day strength and one day hypertrophy so as to accomplish both ends. Thoughts?
There are many ways you can incorporate multiple rep ranges into your training, and periodizing load by alternating intensity across training session is one way to go about it.
I do believe that there are certain exercise that may not be well suited to very high loads, and for biceps I generally don’t go below a 5-6RM. That’s not to say you can’t or others don’t, but very hard to load curls that heavy and maintain some semblance of good technique (for me at least).
You could also vary by exercises within the session (barbell bicep curls 5-6RM; alt DB curls 8-10RM), or across session as you mentioned.
Always good stuff!
Quick reactive thoughts:
1. If TUT is so important — extending set time by reducing weight for a slower tempo is pretty claustrophilic! Just start at 85% 1RM and do some rest pause reps to a total of 12 at a high intensity protocol, e.g., tempo’s P0X+0; P is for Plyometric, 0 for bottom transition time, X+ for explosive Positive and 0 for top transition time.. Or a bit less intense 1010, or 20X+0. or 2022 with 2 second max contraction at top!
Then drop some weight maybe down to 60% 1RM at a 1010 or 2120 or whatever!
Again drop the weight down to 40% 1 RM @ whatever tempo feels right, 2222 is a great tempo and,
finally drop down to 20-25% 1RM. TUT will be up to 60+ seconds.
Repeat once more if advanced! Now the exerciser is training at a TUMT — Time Under Max Tension protocol.
The point of course is to begin heavyish and just do drop sets until TUT is maximized at ~30% 1RM. Tempo’s — infinite possibilities? Going from 85% 1RM to 60% to 30% should work fine also.
Good article and great topic!
How does partial reps fit in this whole grand scheme?
Eg complete bicep curl vs partial curl around the max tension location (usually 90 degrees elbow flexion, assuming you are doing the curls with weights, standing up).
The partial will allow higher load or higher reps compared to the complete rep. TUT can be manipulated, but assuming same angular velocity, the TUT per rep of a partial would be less than complete rep.
1. In case of same load, does the total TUT per set (= TUT per rep X no of reps) in case of partial rep case equal the complete reps when we do reps till failure?
2. Similarly fixing the total TUT per set, does the partial rep allow higher loads to be lifted till failure compared to complete reps?
3. In both the cases (1 and 2) separately , what would in greater hypertrophy: partial or complete rep
The following hypothesis is consistent with (and makes sense out of) all of the results you reported in this article:
The muscle building stimulus of a set done to failure is proportional to the square root of the time under tension regardless of the tempo so long as the tempo is approximately constant.
If you slow the tempo as failure is approached (to prolong the time to failure) and still continue to failure, the effeect is similar to ending with drop sets, which increases the muscular stimulation beyond the square roo of the TUT.
Here’s an example of how to guage the effect of a set that stops short of failure: a lifter stops who stops a set after 45 seconds feels that he has four seconds left in the tank. Had he continued to 49 seconds he would have garnered 7 points, since 7 is the square of 49. But since he stopped 4 seconds short, he must subtract the square root of 4 from the square root of 49 to get the net points. He gets 5 points the same as if he had done 25 seconds to failure (with a heavier weight or with a much faster tempo).
Muscle building stimulus proportional to the square root of TUT? Where’d that come from?