Time Under Tension (TUT) Another Under-Appreciated Determinant of the Protein Synthetic Response to Exercise?

Image 1: Is it really time to buy some revolutionary new exercise equipment to time your time under tension? Or should you keep pumping away like there was no tomorrow?

If you have been following the SuppVersity news for some time now, you know that I am a "fan" of the research Stuart Phillips and his colleagues at the Department of Kinesiology at McMaster University in Hamilton, Ontario, are doing. Before I get to some details on their latest coup, I must yet express some concerns about Phillips' focus on immediate changes protein synthesis. Yes, amino acid ingestion and particularly leucine increase protein synthesis, yes, bolus ingestion of whey protein increases protein synthesis over sipping and yes, training with low loads (30%) and slow reps, as in the study at hand, increases protein synthesis,... but hey. Do you really give a damn about protein synthesis? No, you don't. Either you want to gain muscle or you want to get stronger and exactly here I am missing a link that would connect the short-term increases in the protein synthetic response to exercise Phillips and his colleagues are investigating in one study after the other and the long(er)-term real-world outcomes in terms of muscle size and strength gains.

Wait! Is protein synthesis really that important?

I will probably touch on this issue in tomorrow's installment of the Intermittent Thoughts, as well, so let me just say this: Muscle protein synthesis is only one out of two (maybe three processes) and probably not even the most important one, when your goals are getting really big or really strong. I mean, if increasing protein synthesis was all it would take to get as buffed as Phil Heath and as strong as Derek Poundstone, everyone would be training like a sissy (like in this study), take his BCAAs and whey protein and see amazing results... but I am once again getting off a tangent here, and as I already said, you will read more on that here at the SuppVersity in the future. So, for the time being, let's get back to the time under tension, i.e. the exact number of seconds your muscles are actually working (meaning contracting) during a given set.

Figure 1: Basic outline of the study first and second testing session (based on Burd. 2011)

For their most recent study Nicholas A. Burd et al. recruited 8 recreationally resistance-trained men (23.5 ± 1 years; 88.3 ± 5 kg; BMI=26.5 ± 1.0 kg/m²) who had performed lower body resistance exercise training with a frequency of at least 2x/week in the course of the last 2 years prior to the study [note: this certainly is a huge plus of the study, because we all know that you can have a newbie do nothing but climb stairs and he will still grow ;-] The individual one rep-max for leg-extensions was accessed once prior to the infusion trial (105kg right, 101kg left leg) and dietary intakes were recorded prior to both the resting and the exercise infusion trials, in the course of which the participants reported to the lab fasted (at 7am) before a catheter for the tracer infusion was inserted into their arm and a first (fasted) muscle biopsy was taken from their legs (3.5h after reporting to the lab).

Participants subsequently performed bouts of unilateral leg extension exercise at 30% of
their previously established concentric 1RM. Legs were randomized and balanced for dominance based on maximal strength to perform exercise at a slow lifting (SLOW) or an external work-matched control (CTL) conditions. The leg assigned to the SLOW condition performed exercise with a lifting/lowering cadence of 6 s concentric phase and a 6 s eccentric phase with no pauses until volitional fatigue (i.e. failure). Failure was defined as the point at which the participant could not lift through the full range or their technique to lift the load included motions at joints other than the knee. The CTL condition was completed with the contralateral leg and was matched to the experimental condition for contraction volume such that the leg performed an identical number of repetitions at an equivalent load, but not to failure, and was performed with a lifting cadence of 1 s concentric phase and a 1 s eccentric phase.

The participants performed a total of 3 sets with 2 minutes of rest between the sets for each condition. Lifting cadence was monitored by an instructor and by the use of a metronome. Moreover, the exact knee-joint angles were recorded by the means of a goniometer. After a subsequent 2nd blood sample was taken, all participants consumed 20g of whey protein isolate. 6h after, a 2nd bilateral biopsy was taken and the participants were fed a standard cafeteria meal. For the rest of the day they were advised to follow a diet that would mirror their previously recorded food intake, with the last meal being consumed before 22h, "to ensure a 10 h fast prior to the beginning of the 24 h post-exercise protein synthesis measurement", which took place the next morning after the consumption of another 20g of a tracer-enriched whey protein supplement.

Figure 2: Fractional protein synthesis (in % per hour) - left; and relative differences in protein synthesis of slow vs. ctrl condition - right (based on Burd. 2011)

The data in figure 2 clearly shows that going to failure (and this is what I consider even more important than time under tension when training with sissy 30%1RM loads) produces profound (compare the relative increases in the smaller graph on the upper right corner) increases in fractional protein synthesis, which are, in the time-window right after the exercise bout, particularly pronounced in the mitochondrial and sarcoplasmic compartment of the muscle. In this regard, Burd et al. point out that

[w]hat we observed here was a potentiated effect, from that seen in the fasted-state, of prior exercise in enhancing the feeding-induced myofibrillar protein synthetic rates. This effect appears to be dependent on maximal fibre activation during exercise, [...] The current study is noteworthy in that an enhanced effect of protein feeding during late exercise recovery was induced by a longer time under muscle tension rather than intensity-independent contraction volume, which we have previously examined (Burd. 2010).

As far as the delay in the normally immediate increase in myofibrillar protein synthesis is concerned, the researchers speculate that both the timing of the biopsies, as well as the training status of the subjects and the specificity of their protocol about which they state that with its long loading times at relatively low intensities it must have shifted the protein (immediate) myofibrillar protein synthetic response "toward increased synthesis of proteins in the mitochondrial and sarcoplasmic pools" (cf. figure 2) - a process the underlying causes and mechanisms of which are yet unclear.

Why would you change a winning team?

Image 2: When it comes to SST and all the other training types from the alphabet soup, I alway wonder why people keep questioning what has worked well for the majority of bodybuilders and athletes, they are looking up to and whose physiques they are admiring!?

Actually this observation takes us full circle to my introductory remarks on the possible short-sightedness of measuring acute fractional protein synthesis. After all, what we are seeing here is rather the response we would expect as a consequence to a rather endurance-oriented exercise regimen. Whether the latter would entail the "size" (and strength) gains everyone currently associates with the magic words "increases in protein synthesis" remains thusly highly questionable.

This is particularly true if we take into account the results of another pretty recent study be Eonho Kim et al. (Kim. 2011), which found that an even slower (10s concentric, 10s eccentric) training protocol at 50% or the 1RM led to greater increases in flexibility but highly variable and overall lower strength gains than a traditional protocol with (4s total TUT at 80%RM) in college-aged women. This basically confirms what previous studies by Keeler et al. (+39% in traditional, only +15% in slow training; Keeler. 2001) have already established: (Super) Slow Training works, but it does not work as well classic resistance training.

And no matter whether you train slow or fast - in the end, intensity will always be determined by a matrix of loads, volume, TUT and training density and I doubt we will see a study that controls for all this variables even in the remote future (and if that happens you know that the SuppVersity is the place where you will read about it, first) - so the best thing you can do, is to rely on what worked for generations of physical culturists and that was definitely not training with 6s concentric and 6s eccentric reps ;-)

Fast & Slow, Heavy & Light, Eccentric & Concentric: Do All These Fancy Training Variables Really Matter? Probably For Power. Not So Much for Size, Though.

Image 1: According to Sakamoto, 2011, EMG
activation during the bench press increases
with rep-speed & weight (pic from mylot.com)

"Go heavy or go home!" You probably have heard this advice time and again and, after all, two recent studies appear to suggest that, when all is set and done, ah... I mean all sets are done, the thing your muscles seem to care most about is workload. While the study by More et al. (Moore. 2011) does not tell us anything about the effectiveness of training with different rep speeds, it goes to show that concentric and eccentric training are similarly effective, when it comes to building sleeve bursting biceps. Sakamoto et al. (Sakamato. 2011), on the other hand, found that EMG activity of the pectoralis major increases with rep speed and (readers of the SuppVersity EMG Series know that already) weight. Now, before we jump to any preliminary conclusions, let's tackle the studies in some more detail...

The nine healthy, but previously not weight-training average Joes (mean age: 22yr; height: 1.75m; weight:78.3kg) from the Moore study (Moor. 2011) performed single arm biceps curls on a dynamometer twice per week. The volume increased from week one to week five from 2 to 6 sets and was cut back again in the last (ninth) week before the final testing session. Other than in similar studies on the effectiveness of eccentric vs. concentric training, the subjects did not perform their dynamometer curls either concentrically or eccentrically, but were instructed to perform concentric curls with one arm and eccentric curls with the other. Right and left arm had previously been randomly assigned to either the maximal lengthening (eccentric) or shortening (concentric) condition, so that limb dominance (n=5 dominant; n=4 non-dominant) was adequately counterbalanced. Moreover, the subjects had to perform ~40% more repetitions on the concentrically trained arm, to ensure total work was equal, or, put differently, to make up for the greater muscle force generation (+60% total work per repetition in eccentric vs. concentric) during eccentric dynamometer curls. Thusly, the participants performed the same 51.8MJ of work with each of their arms in the course of the 9-week training program.

Under these equalizing conditions, workoutput for both conditions rose similarly over the 9-week training program:

Total work per repetition increased from week 1 to week 9 for both LC and SC (main effect for time, P = 0.001) with no difference between conditions (time by condition interaction, P = 0.63). The average increase in work per repetition was similar between LC and SC (17.2 ± 6.3 vs. 22.1 ± 8.9%, respectively; P = 0.69). There were increases (at least P<0.05) in peak torque for all velocities tested (*8–20%) with no significant difference between conditions.

The scientists also found similar results for the muscle crossectional area (CSA), which had been "virtually identical (P = 0.99) before training" (48.5mm² vs. 48.4mm², for the ecc. and con. trained arm) and "increased similarly between conditions" (ecc. 6.5 ± 0.6% vs. con. 4.6 ± 0.4%, respectively; interaction, P = 0.37). What may initially sound like one of those statistically induced geeky underestimations of real world effects, i.e. calling 6.5% vs. 4.6% increases in muscle CSA "similar", turns out to be actually negligible if you calculate the respective absolute difference in CSA increase which is less than 1mm², or an area with the size of a pinhead.

Figure 1: Other than total work per repetition, the respective peak torque development did vary significantly (+8.9% vs. +13.5% for con vs. ecc) between the concentrically and the eccentrically trained arm (data adapted from Moor. 2011)

If, however, you plot the peak torque data from table 1 from the Moore study (I did that for you in figure 1), you will realize that, after all, there is more of a difference between the two training regimens than Moore and his colleagues dissertations would make you think. In fact, their assertion that "there was a main effect for condition for peak torque measured at 0.79 rad/s [slow concentric] in that LC [eccentrical training] was *8% greater than SC [concentric training]" is simply not consistent with the data they provide.

Note: A comment by "anoymous" (guys give me at least a pseudonym!) reminded me that in yesterday's hurry I forgot to mention a major caveat to the study. The latter is directly related to the unilateral training protocol which could potentially (or rather certainly) lead to cross-over effects from one arm (probably the eccentrically trained one) to the other. Similar effects have been observed in e.g. Adamson et al., 2008, where rate of force development and maximal isometric contraction (37% vs. 35%) in 10 adult females increased similarly in both arms, although the ladies had trained only one arm. It is yet notable that the 1RM increased almost exclusively in the trained arm and that the strength increases in the Adamson study occurred in the absence of muscular hypertrophy and are thus attributed by the authors to neurological addaptions of which obviously both arms benefited to a similar degree.

As far as peak torques are concerned the available data (with reservations that the data the authors provide in table 1 of their paper is correct) would suggest that the peak torque increments in the concentrically trained arm for different repetition tempos were on average 4.6% greater than those for the eccentrically trained arm, or, in other words, the higher rep lower weight concentric training resulted in greater strength improvements than the higher weight, lower rep eccentric training, which is so contrary to what you see in similar studies that I would assume that the authors just got the captions wrong and the data in figure 1 would have been reversed, i.e. what now is red should be blue and what now is blue should be red... but who cares, anyway? Focus on getting a good contraction on both the con- and the eccentric phase of your curls, do the exercises described in the SuppVersity EMG series and grow ;-)!

Figure 2: The time [in s] to "speed failure" (i.e. not being able to complete another rep at the given tempo / slow: 5.6s; medium: 2.8s; fast: 1.9s) increases with increasing tempo and load expressed in % of 1 repetition max, 1RM (data adapted from Sakamato. 2011)

Fortunately, the Sakamato study does not contain similarly confusing results. In essence the study, which investigated muscle activations under varying speeds and intensities during bench press using surface electromyography (EMG) found that in the 13 weight-trained men (21.7 ± 3.6-year-old) who performed bench press until fatigue under five intensities (40–80% 1RM), and four speeds (slow 5.6-s/repetition, medium 2.8-s/repetition, fast 1.9-s/repetition, and ballistic maximum speed), found that ...

...faster conditions [...] produced a significant fall in amplitude during the final concentric phase compared to slower movements [while at the same time] after fatigue, EMG amplitude increased, with the speed effect being maintained. 

This means that in the rested state at the beginning of the training you still have the explosiveness to really "pump" the weight up and thus pump out more reps. On the othrt hand, maximum muscle stimulation does not occur before your pectoralis major brgins to fatigue later in the exercise session (cf. figure 3).

Figure 3: Normalized EMG activity at five time points for a given rep tempo / slow: 5.6s; medium: 2.8s; fast: 1.9s / in the rested and fatigued state (data adapted from Sakamato. 2011)

According to the EMG data in figure 3, it does make sense to start (after an appropriate warm up) with heavy and explosive sets / movements and to switch to medium weights and tempo later in a training session. But wait, isn't that exactly what generations of successful trainees have been doing already? Well, I guess this is then another case, where practical training experience beat exercise science by decades and thus further evidence that much more than in the case of nutrition & supplements most of the research that is put into specific exercise programs does little more than reproduce pieces of the knowledge that has accumulated in the heads of trainers and trainees all around the globe ever since the earliest days of physical culture.

"Go Hard or Go Home?" Study Reveals Different Anabolic Signalling in Response to "Heavy" vs. "Medium" Intensity Leg Extensions at Different Times Under Tension

Working out ain't child's play, right? "Go Heavy or Go Home!" this is the mantra of true champions, but is it also the mantra of skeptical scientists?

I guess, it's important to say this first: The results of the study Daniil V. Popov et al. conducted at the Institute of Biomedical problems of Russian Academy of Sciences in Moscow need to be interpreted to have any relevance in terms of the question all of you keep asking yourselves: "What is the best training intensity to make fabulous gains?"

The data the Russian researchers offer is acute, not chronic. It's not based on muscle size measurements, but on the measurement of anabolic signalling proteins and the expression of MyoD, IGF-1, myostatin & co. We know that all of them are involved in the process of skeletal muscle hypertrophy, but even if all of them are elevated, this is not identical to muscle size increases as you would measure them in a long(er)-term study.

Learn more about effective training techniques at the SuppVersity

Optimizing Rest for Size and Strength Gains

When Rodents Squat, We Can Learn A Lot!

Farmer's Walk or Squat? Is Strong- men T. For You?

Full ROM ➯ Full Gains - Form Counts!

Battle the Rope to Get Ripped & Strong

Up Your Squat by 25% With Sodium Bicarbonate

I hope that the previous elaborations were detailed and convincing enough to increase your awareness of the limitation of the data I am about to cite.

Figure 1: Toque and angle during knee extensions in the high intensity (HI), medium intensity (MI) and medium intensity continuous tension trial (MIR) - the subjects did bilateral leg extensions (Popov. 2014)

Data that was recorded with 10 strength-trained athletes who performed high-intensity [HI, 74% of 1 repetition maximum (RM)], middle-intensity (MI, 54%1RM), or middle-intensity (54% 1RM) no-relaxation exercise (MIR; continous tension on the trained muscle).

"High intensity" vs. HIGH intensity: I am pretty sure most of you read my articles closely, for the rest it's important to note that the high intensity group trained at ~74% of the 1-RM - that's about 10 Reps to failure and actually not as heavy as some people may expect, when they hear "high intensity". Just remember one thing: Heavy ≠ intense - I see guys at my gym training with maximal weights and minimal intensity.

Figure 2: Changes in p21, MyoD, myostatin and MGF in response to each of the three training regimen (Popov. 2014)

The previously mentioned parameters were measured before, 45 min, 5h, and 20 h after exercise - you can see the results in Figure 2. The lactate concentration, which is not shown in Figure 2 was approximately 2-fold lower in the MI vs. the MIR & HI. It was the highest in the MIR session, and would thus coincide with the expression of the pro-anabolic protein p21 and the maximal early reduction in myostatin.

Over the course of the 24 study period, however, the high intensity trial yielded distinctively more pronounced anabolic effects.

A more pronounced and sustained elevation in p21, a maximal increase in MyoD, a marker of satellite cell (muscle precursor cell) activity, a significantly more pronounced increase in the intramuscular isform of IGF, i.e. MGF (learn more) and, last but not least, a sustained reduction of the muscle growth break myostatin.

Learn more about the fundamental signals that trigger and sustain muscle hypertrophy at the SuppVersity | more

Bottom line: The 24h+ reduction in myostatin in response to the high intensity trial alone would support the statement "Go Hard or Go Go Home!" In conjunction with the significant increase in MGF, the data Popov et al. present in their latest paper provide compelling evidence in favor of heavy resistance training as a means to trigger a maximal hypertrophy response - and that despite the fact that another often-measured indicator of skeletal muscle hypertrophy, i.e. ERK-1/2 (linked to protein synthesis) did not depend on exercise intensity and was thus identical for the similarly stressing MIR and HI trials.

As mentioned in the introduction, though, the acute changes in any of these measures are indicative of muscle growth, they are not identical to muscle growth. Thus, only a 6-12-week study with a training regimen that mimics the different training intensities could prove that high intensity is required to maximize muscle growth, when the basal stress is identical (i.e. HI would build more muscle than MIR).

References:

• Popov, Daniil V., et al. "The Influence of Resistance Exercise Intensity and Metabolic Stress on Anabolic Signaling and the Expression of Myogenic Genes in Skeletal Muscle." Muscle & nerve (2014).

Full ROM = More Growth, More Strength, More Structural Changes & More Sustainable Gains & Fat Loss - Insights from Realistic 8 Weeks Leg Training + 4 Weeks Detraining

"That's not 90°, yet. Do deeper!"

I guess you will be remembering last week's post on the superior growth effects of full vs. partial squats, hah? Now, the results of the Bloomquist study certainly raise the question, whether the same or similar effects must be observe with different exercises or even different body parts, as well. After all, it would be bro-science at its best to generalize the result "full squat = full quad development" to "partial ROM  = partial strength and hypertrophy response" without the least hint of evidence that this hypothesis is more than just the "proposition or principle put forth or stated (without any reference to its correspondence with fact) merely as a basis for reasoning or argument" ("hypothesis, n.". OED) the word "hypothesis" implies - right?

The good news is that it appears as someone has heard my lamentations about the scarcity of respective research, or - what's in this case more probably - feel the same about the necessity to generate data that would be necessary to base our workout protocols on more than just "hearsay", hypothesis and "N=1 experiences" and a single study.

Ok, enough kiddin' around let's get to the facts

Table 1: McMahon's interpretation of an "ecologically valid resistance training program"; * denotes static holds for time in s, DL = double, SL = single legged (McMahon. 2013)

Despite the fact that the study I tried to make tempting to you in the introduction is again build around a leg training routine, it has two major advantages compared to the Bloomquist study: (1) The participants performed a complex, multi-exercise leg-training protocol, (2) the study used the vastus lateralis as yardstick for the size gains, (3) the effect of full vs. short ROM (range of motion) on strength, muscle structure and body fat were also measured and (4) the study had an active training part (8 weeks on the protocol outlined in table 1) and - and this is pretty unique - a subsequent 4-week follow-up in which the subjects did not train (detraining) that allow us to determine whether the persistency of the gains will also depend on whether you achieved the training with a limited 50° vs. a "full" 90° specific angle of knee flexion (McMahon. 2013).

With the the specified angle being defined as the "position at which the training load is held isometrically for two seconds",

• the 50° regimen involved a shorter ROM (SR) in the dynamic phase of the exercise and thus a shorter ‘average muscle length’, whereas
• the 90° regimen involved a longer ROM (LR) in the dynamic phase of the exercise and thus a longer ‘average muscle length’
  *you will learn more about the importance of muscle lengthening later this week, so stay tuned!

McMahon & Onambélé-Pearson hypothesized that the group training "at longer muscle length" (90°) would undergo a greater amount of skeletal muscle hypertrophy and concomittant strength development and that these differences would be "due to increased physiological stress and stretch on sarcomeres compared to the group training at 50°" (McMahon. 2013) and that these effects would be evident even during / after the deloading phase.

Figure 1: Cross sectional area (CSA) of the vastus lateralis measured at 25, 50 and 75% of the femur length for the full range (LR), partial range (SR) and a non-exercised control group (McMahon. 2013)

If we take a peak at changes in muscle cross sectional area (CSA) in figure 1 this hypothesis appears to be roughly accurate. There are however significant differences in the growth response the scientists measured at 25%, 50% and 75% of total femur length (VL25-75), with a statistically non significant advantage for the high(er) load, short-ROM approach (the higher load is a natural consequence of the RM prescription) and a highly significant advantage for the low(er) load, full-ROM approach, when it comes to that part of the muscle you want to shine, as it contributes to that massive "tear-drop look".

"CSA increased significantly (p<0.05) relative to baseline following training at all sites in both training groups. The significant training effect remained during the whole detraining period in both training groups at both 50% and 75%, but was not evident at 25% of femur length after week 10. There was a trend for LR to exhibit greater relative gains in a CSA compared to SR at all sites, which was significant at week 8 at 75% of femur length. It was found that there was not only a main training effect (p<0.05) but a main group effect after week 8 (p<0.05) with LR exhibiting a 59±15% compared to SR showing 16±10% increment in VL CSA." (McMohan. 2013)

To the surprise of the researchers, the "following the first two weeks of detraining the group effect was no longer evident (p=0.07)" (McMohan. 2012). In the end, the existing advantage of training over the full-ROM, as pronounced as it may be at the CSA75 site, is thus short lived in this group of previously non-resistance-traind 26 volunteers (14 males and 12 females). The fasicle length, which increased by
23±5%, 19±4%, 16±4% at weeks 8, 10 and 12 in the LR and by only 10±2%, 6±2% and 2±2% in the SR group (data not shown), on the other hand, were persistent - yet only in the full range (LR) group.

"And body fat? What about the body fat"

Crossfit doesn't fit well with everyone. In  fact, you have to be pretty fit already if you intend to benefit - specifically if you don't have someone who tailors the workouts to your specific needs. If you the shed 8% of your already low 16% body fat in 10 weeks workout routine I wrote about in February, chance is you'll just get injured or burned out (learn more)

The local reduction in subcutaneous fat that was likewise assessed based on the ultra-sound images the scientists used to evaluate the structural changes and CSA increases did not show significant group effects at 25%. The relative changes of 5% in the partial (SR) and 22% at the 50% measuring mark in the full ROM (LR) groups, clearly suggest that "going all the way" would still be the way to go if you don't want to look hypermuscular, but lean (ladies?). The latter is particularly true in view of the facts that the ...

"[...] main effect of group remained during weeks 10 and 12, as SR regressed toward baseline by week 12, whereas LR still possessed significant losses at this phase (-10±6%)" (McMahon. 2013)

and that there was a similar trend seen at 75% where a main effect of both group and training existed at week 8 (p<0.05) - even if the latter vanished in the course of the 4-week detraining period 7±3% SL and 9±1% LR).

Regional growth and angle-specific strength gains

Contrary to all previously reported values, which were - if they were group specific at all - regionally different, the changes in strength showed - as you would expect it - an angular specificity. While both groups did increase their strength, there were more than just minute differences between the partial (SR) an the full ROM (LR) groups:

• at the end-ranges, the maximal volunary contractive force increased 5±10 for SR at 50° and 30±5% for LR at 90°, respectively
• there was evidence of angular specificity of training in both groups with SR significantly (p>0.05) increasing MVCs at 50, 60, 65, and 70° , only, wheres the participants in the LR increased their MVCs values over the entire angular range.

What's remarkable, yet non necessarily beneficial, is the fact that the angle of peak torque which had been 75° at the beginning of the training intervention decreased to 70° within 8 weeks of training over the short ROM (SR) and remained there for the duration of the detraining (i.e. the change was at least persistent, if not permanent). No such effect was observed in the LR group.

"By week 10, both groups displayed an average 6±2% strength reduction (relative to the post-training strength values), with SR not significantly above baseline (0±2%) in contrast to LR remaining significantly above both baseline (p<0.05) and SR (p=0.027) at weeks 10 and 12."

Overall, the changes in contractile force and the angle at which they were elicited reflect the structural changes that were brought about by the more pronounced muscle lengthening that's a prerogative of training over the full range of motion (ROM).

---

To ensure that all participants conducted the complex exercises at the correct knee angle a goniometer was attached to their knees (photo velamed.com)

Bottom line: As far as the practical implications of his findings are concerned McMahon and Onambélé-Pearson reemphasizes that the specific muscle mechanics are of paramount importance, "when choosing a range of motion for a resistance training protocol." (McMahon. 2013)

With resistance training protocols that enforce a full range of motion having the ability to influence force and power production to a greater extent than protocols where the range of motion is not as extensive, he is therefore right to point out that it would be a mistake to allow your ROM to be compromised "in order to accommodate a greater absolute external load, in an attempt to increase the stress of mechanical loading" and advises coaches to "reinforce a more complete ROM, even when absolute load maybe reduced, in order to provide a greater internal stress and more potent stimulus for adaptation" (McMahon. 2013).

Aside from the fact that  this advice is obviously as relevant for trainees, like yourself. The one thing I would like to add to McMahon's "bottom line" is a reference to the structural changes and their importance in view of maintaining the strength gains you achieved. Moreover, it is, as you will be learning in an article I am still working on, likely that the extend of the observed and accompanying, but not evaluated changes in muscle structure facilitate future muscle gains. Therefore, you would in fact be ill-advised not to "leave your ego at the door" if you want persistent size gains and increases in strength over the full range of motion that do not vanish, when you are taking 2 weeks off.

Handpicked suggested reads:

• 

  The Jack-of-All-Traits Leg Workout from the Sáez de Villarreal study I discussed on July 15, 2012, would also be something you may want to look into if you need some inspiration for your own routine.

  You Want Maximal Performance & Size Gains + Complete Thigh Development? Then Full Squats are For You! (read more)
• SuppVersity EMG Series - Gluteus maximus, Quadriceps femoris, Gastrocnemius, Soleus & More: The Very Best Exercises for Tree-Trunk Legs and Herculean Calves (read more)
• The Step-By-Step to Your Own Workout Routine Guide (read it)
• All posts leg training at the SuppVersity (read them)

References:

•  "hypothesis, n.". OED Online. March 2013. Oxford University Press. 6 May 2013 <http://www.oed.com/view/Entry/90588?redirectedFrom=hypothesis>.
• Eugene McMahon G, Onambélé-Pearson G. Impact of range-of-motion during ecologically valid resistance training protocols, on muscle size, subcutaneous fat and strength. J Strength Cond Res. 2013 Apr 26.[Epub ahead of print]
  

Time Under Tension (TUT) - Random Numbers or Forgotten Determinant of Training Success? What Does Science Say?

"Go slow, grow fast" - does it really work this way?

I have to admit that I didn't have time to write "complete" article, so I will just work out an introduction and a bottom line to a never-finished draft that discusses an - in my humble opinion -  still unresolved question:  "Does the time under tension, which must not be confused with the simple number of reps let alone the set, matter when it comes to strength or muscle gains?"  As I said, based on my knowledge of the contemporary literature this is still an unresolved issue. Mostly, because slow (by necessity) means "light weight" and is hard / impossible to distinguish from the rep-number.

The methodological issues are probably also part of the reason that it would be an exaggeration to say that there are only "few" studies that investigate the influence of the time under tension (TUT) on hypertrophy or strength gains - but alas, I have collected the science-crumps for you. So here you go (for a preliminary list):

• 

  Figure 1: Myofibrillar fractional protein synthesis (%/h; Burd. 2012)

  Low load + slow movement = high TUT ➫ increased protein synthesis -- The 175% increase in muscle protein synthesis in response to leg extensions that were performed with a TUT of 6s in the concentric, and 6s in the eccentric phase of the movement Nicholas A. Burd et al. report in their a 2012 paper in the Journal of Physiology is one of the is one of the few very concrete results from studies that were designed to isolate the effect of the time under tension (Burd. 2012).
  
  In view of the pathetic load (30% of the 1RM) and the matched volume, the practical relevance of these figures is yet highly questionable. For me personally, it is thus more surprising that the difference between ...
  
  • doing 12, 7 and 6 reps @ 30% of the 1 rep max to failure for 198±10 s 119±9 and 90±7s, respectively (SLOW condition w/ TUT of 606), and 
  • performing the same number of reps with the same weight, this time obviously not to failure, within 25±2s, 14±1s, and 11±1s, respectively,
  ...was not even more pronounced than the +/- 49% difference (175% vs. 126%) Burd et al. observed in their eight young male subjects after performin three sets of unilateral leg extensions. 
• Longer TUT, greater anaerobic energy expenditure - Inspite of the fact that it appears logical that longer times under tension would be associated with increases in energy expenditure, you as a SuppVersity reader know very well that not all things that exercise and nutrition science is not necessarily logical.
  
  In view of the overall scarcity of literature it is thus more than worth mentioning that Christopher B. Scott's 2012 study into the effects of time-under-tension and weight lifting cadence on aerobic, anaerobic, and recovery energy expenditures found that both, the anaerobic (=glyoclytic) energy expenditure and post energy oxygen consumption (EPOC) were significantly increased, when you train with a cadence of 4:1 or 1:4 and a corresponding TUT of 25s instead of 1.5:1 (TUT = 15s).

  

  Figure 2: Anaerobic energy expenditure, post exercise oxgen consumption and total energy expenditure (all in kJ) in the low TUT (1.5:1.5; 15s) vs. high TUT trials (Scott. 2012)

  It is thus only logical (you see, sometimes there is logic in exercise science ;-) that the total energy expenditure in the 25s TUT trials was ~30% higher than in the 15s TUT trial with its 1.5s up : 1.5 down cadence (see Figure 2).
  
  In view of the fact that the majority of us are hopefully not hitting the gym to "burn calories" (learn why that's simply dumb), these findings are interesting, but of similarly irrelevant as the previously cited increases in protein synthesis in the Burd study.
• Concentric tension time is key to muscle growth -- I know that broscience dictates otherwise, but the evidence from a human study by Gillies, Putman & Bell suggests just that: It's the concentric portion of the exercise that stimulates skeletal muscle hypertrophy in response to leg presses, parallel squats, knee extensions and knee flexions in 28 healthy young women with previous strength training experience (Gillies. 2006).

  

  Figure 3: Fiber area (µm²) of type I & II fibers before and after the 9-week training intervention (Gillies. 2006)

  As you can see in Figure 3, the baseline fibre size(s) of the subjects were yet so different that the participants that had been randomized to the group with an emphasis on the concentric phase (4:1 cadence) had an unfair growth advantage compared to the ladies in the eccentric emphasis group.
  
  In view of the fact that the eccentric emphasis group did also record greater strength gains, it appears unwarranted to change your training regimen from explosive / fast concentric vs. slow eccentric movements to the "concentric emphasis" pattern with its 4s : 1s cadence that was used in the study at hand. 
• Heavy and fast or "slow" and long - it does not even matter -- In 2006 and thus 6 years before the previously discussed study by Burd et al., Michiya Tanimoto and Naokata Ishii, two scientists from the University of Tokio conducted a similar, yet more realistic study which compared
  

  • 

    Figure 4: Cross-sectional area of the knee extensor before (open bars) and after (solid bars) LST, HN, and LN exercise training for 12 wk (Tanimoto. 2006)

    a low-intensity training regimen [ 50% of onerepetition maximum (1RM)] with slow movement and tonic force generation (3 s for eccentric and concentric actions, 1-s pause, and no relaxing phase; LST), to a
  • a high-intensity training regimen ( 80% 1RM) with normal speed (1 s for concentric and eccentric actions, 1 s for relaxing; HN), and 
  • a low-intensity with normal speed training regimen (same intensity as for LST and same speed as for HN; LN)
  and found what most of you will probably already have expected: As far as muscle growth there was no difference to be seen between the LST and the HN regimen after 12 weeks. The LN = low-intensity, normal speed training on the other hand sucked was a total waste of time and did not increase the size of the quadriceps muscle that had been hammered with three sets thrice a week at all.

Bottom line: As a seasoned SuppVersity reader you should not need me to tell you that the data does not allow for a conclusive decision if (a) time under tension matters at all, and if so, if it may (b) actually be the main determinant of muscle growth.

The green dots are satellite cells, muscle precursors as they are built with high volume leg training | more

I know at first that may sound hilarious, but if you think about the average bro in your gym who complains about "no gains", he will either be making tons of reps at a velocity that generates a momentum that reduces the TUT of an already fast 1-s rep to 0.1s, or he will tell you that only hitting it hard counts and his three reps on the bench press which are over in 6 seconds should actually make him grow.

To elucidate if (a) or (a) and (b) was right, we would yet need at least a dozen of well-designed studies, where - just as it was the case in the Burd study - the time under tension is the primary variable and reps, sets and weights only a means to modulate it. Until this data is available, it does probably not matter that I didn't have to dig up each and every article on that matter that exists... and if it did, I will just write another article ;-)

References: 

• Burd, N. A., Andrews, R. J., West, D. W., Little, J. P., Cochran, A. J., Hector, A. J., ... & Phillips, S. M. (2012). Muscle time under tension during resistance exercise stimulates differential muscle protein sub‐fractional synthetic responses in men. The Journal of physiology, 590(2), 351-362. 
• Gillies, E. M., Putman, C. T., & Bell, G. J. (2006). The effect of varying the time of concentric and eccentric muscle actions during resistance training on skeletal muscle adaptations in women. European journal of applied physiology, 97(4), 443-453.
• Scott, C. B. (2012). The effect of time-under-tension and weight lifting cadence on aerobic, anaerobic, and recovery energy expenditures: 3 submaximal sets. Applied Physiology, Nutrition, and Metabolism, 37(2), 252-256. 
• 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, 100(4), 1150-1157.

Exercise Research Quickie: HIIT vs. Steady State, More on the Hormonal Response. Light Training, High TUTs & Peak Contractions - Not Just for The Elderly. Train Your Left, Grow Your Right Leg - Contralateral Training Effects

The role of the innervations between our muscles as well as to our brain is often overlooked, when we are talking about size gains. The image shows stained nerve fascicles from the Song study, which brings this wiring back onto the radar.

I know that we have had the short news on Saturday only and that there are of course tons of short news on Facebook everyday, but the studies I am going to present you in this exercise research quickie were so in-between (meaning not really worth a full post, but still way too good to be wasted on facebook) that I decided to devote a post of its own to the research on the hormonal effects of interval vs. steady state training by Hackney et al. (Hackney. 2012b), the impressive and certainly not totally irrelevant effects of slow movement, low-intensity resistance training in the elderly Watanabe et al. describe in their latest paper and the surprising muscle building (Watanabe. 2013) and growth priming carry over effects Song et al. observed in response to unilateral electrical muscle stimulation (Song. 2012).

Although, the latter post is pretty theoretical I hope that all of you will find something that enlightens, amuses or entertains them in this "threesome" ;-)

More T, more DHT, more cortisol - that's the HIIT vs. LISS formula

(Hackney. 2012b) -- In fact the results of two subsequently published papers by Hackney et al. would suggest that it's about as easy. Work out hard and fast and see greater increases in testosterone levels, but also testosterone turnover (into DHT via 5-alpha reductase), but don't forget that aside from these (questionable) anabolic benefits, your thyroid hormone levels are going to take a dive (as reported previously), as well.

Figure 1: Comparison of the hormonal responses measured in the plyometrics (left) and the HIIT vs. LISS (right) study (based on Ozen. 2012 and Hackney. 2012)

The figure above is actually from a post where I discussed this before, so if you cannot remember all the details, briefly go back before you take a look at the summary of results of the more recent study by Hackney.

"Dihydrotestosterone (DHT) - Bigger, Stronger, Faster or just Balder, Fatter and Unhealthier?" That's the question I asked in one of the installments of the Intermittent thoughts on building muscle. A post I would highly suggest you read, by the way ;-)

In this 2nd paper that was published right before Christmas in the Journal of Endocrinological Investigations the researchers were able to show that repeated periods of 90-sec treadmill running at 100-110% maximal oxygen uptake (VO2max) and 90-sec active recovery at 40% VO2max for 42-47 min (which is obviously pretty long!) caused  just a significantly more pronounced increase not just in free testosterone, but also in its conversion to testosterone's big brother DHT (as indicated by statistically higher levels of the 5α-reductase marker 3-α Diol G at 12POST HIIT vs. LISS). This is interesting, as dihydrotestosterone (DHT) which is often falsely associated only with hair loss, prostate cancer and even obesity, does also play an important role in strength development (click here to learn more) and appears to do it's magic via the MAPK receptor. Now, MAPK in turn can activate PGC-alpha and that the latter is way more than just the endurance / mitochondria builder it was long thought to be is something you should still remember from the post on the"The IGF-1 Promoting, Myostatin Reducing, Muscle Building Effects of PGC-1 α-4" (read more).

Bottom line: It is becoming more and more clear that HIIT is in fact somewhat of a chimera that shares beneficial and detrimental effects of both classic cardio and classic strength training with mammoth sessions like the one performed in the studies at hand triggering similar hormonal cascades that will - despite probably causing beneficial adaptations - simply require longer rest times than a classic LISS regimen.

A  note of caution: Both these studies point to the highly questionable "value" of taking a bunch of people letting them do whatever type of training once, measure some stuff of which you do only have a very rough idea of what it's actually doing and then have a bunch of morons like myself try to come up with "practical implications"

So if you do HIIT, stick to the principles "short and hard" (I would never suggest doing the >40min interval sessions for anyone whose primary goal is to be healthy and look good naked, by the way; add a walk on the treadmill if you want to train longer like on a combined HIIT + LISS cardio only day. But most importantly don't forget to enjoy your well-deserved, highly productive off-time and remember that it's during those hours, when all the hard work is paying off... ah I almost forgot, this is a tried and proven way that happens to be confirmed by studies like Hackney's and not vice versa.

 Light training, high TUTs and peak contractions - not just for the elderly?!

You cannot only implement"light" training into your established routine (see last paragraph), but should also think of the often forgotten benefits of periodization, detraining & co (learn more), as well as times, when you may be injured or otherwise disabled and cannot lift heavy.

(Watanabe. 2013) -- It may sound like a study for the elderly, but just as the best-agers among the SuppVersity readers can learn something from studies done in the the younger fellows, the younger weightlifters may well get some intriguing insights from studies with older participants - studies like the one by Watanabe et al., for example.

When the researchers from the Department of Life Sciences at the University of Tokyo compared the hypertrophy and strength gains of two exercise regimen using a low resistance of 50% of the personal 1-RM max of their 59-76yr old subjects, the scientists found that slow movements with tonic force generation were superior to the regular 1s concentric vs. 1s eccentric reps I guess most of you will be employing in their training routines.

The subjects who had been randomized to the LST group and performed their reps with a 3s concentric, a 3s eccentric and phase and most importantly a peak contraction in-between did gain a similar amounts of strength as those subjects who performed the standard protocol for 10 weeks (the 12-week study had a 2-week familiarization phase), but contrary to they did also record statistically significant increases in muscle size.

Alternative exercises on which peak contractions work well, are the fly (preferably on a machine or using cables), the lat pulldown, cable crunches, all sorts of triceps extensions, the scott curl (where you would do them midrange), every form of calf raises. Always remember, though: A peak contraction is never done in the full stretch position, but always either midrange or as the name implies at the peak of the contraction, before the eccentric phase begins.

So what does that mean? Certainly not that all of you should stop lifting heavy weights, because 50% 1-RM was enough if not superior to the regular 70-90% that are recommended in most serious training regimen. Rather, these results should remind young and old trainees alike of keeping an eye on your form and making sure that you stimulate the muscle and don't just move whatever weight from place A to place B.

That said, try to incorporate peak contractions with every rep on the auxilliary movements of your next workout. Start your leg workout with regular squats, for example, 5x5 TUT 101 (meaning 1s eccentric, 0s rest at the bottom, 1s concentric), but instead of the 4x10 leg extensions you would usually do for your quads, you lower the weight somewhat and do them with a slower rep-speed (somewhere in between 1-3s) and a peak contraction (meaning you really squeeze the muscle in a position, where your knees are almost locked out). Done right, this is going to give the word DOMS (=deep onset muscle soreness) a whole new meaning + you will have to reduce your weights, anyways.

Train your left leg and your right one will grow as well

(Song. 2012) -- Do our bodies know something about aesthetics? Well, if that were the case, the legs of some of the gymbros who "don't train legs, because [they] play soccer" shouldn't look the way they do... but I am digressing here. According to the study by Yafeng Song et al. have just published in the open access journal Plos ONE, there appears to be a certain carry-over effect - at least if the growth stimulus is chronic and profound.

To achieve the latter, i.e. a chronic and profound training stimulus, the researchers from the Umea University in Sweden exposed the soleus and gatrocnemius muscles of rabbits to a 6-week electrical muscle stimulation + exercise protocol and measured muscle changes and inflammation on weeks 1, 3 and 6 of the study. Now, the clue of the study was that the unilateral "exercise" was actually mechanically and electrically enforced, so to say:

"The movements are produced by a pneumatic piston, in which the range of motion can be controlled. The range of movement was set to 9.5 cm, given a range of motion in the ankle of 55–65u of which 20–25u was dorsiflexion and 35–40u was plantarflexion. The right leg was attached to the piston and the pelvis/hip region was strapped down to restrict the motion in the left non-exercised leg. The left leg was unattached. During the plantar flexion of the right leg, an active contraction was induced by electrical muscle stimulation via surface electrodes placed 2 cm apart over the right triceps surae muscle. The stimulation was synchronized with the plantar flexion movement of the piston by a microswitch, which trigged the stimulator unit".

I will spare you the further details... just think of a modern rabbit torture machine that was designed to "work the rabbits right extremities out". As you would expect from any good torture machine this device brought about a significant amount of tissue damage and a corresponding increase in the number of necrotic fibers.

Figure 2: Variability in fiber size, fibers with internal nuclei, inflammation in soleus (left) and gastrocnemius muscle (right) in response to the exercise + electrostimulation program. Mind the similar responses in the exercised (E) and the non-exercised (NE) limb (Song. 2012)

Now what's surprising though is the fact that despite the local damage, the inflammation had a systemic component, which happened to be more pronounced in the untrained soleus vs. gastrocnemius muscle (slow vs. fast twitch, by the way).

Against that background it is still only a little less surprising that the variability in fiber size, the number of fibers with internal nuclei (=sign of restructuring process, cf. "The Skeletal Muscle Hypertrophy 101") and even the fiber splitting were virtually identical. After all, this would mean that systemic parameters do matter. But haven't we just discarded this notion yet another time in the first of the items in today's exercise research quickie? Yes we have, but in that case we were talking about the usual subjects, the "anabolic" and "catabolic" hormones, Song et al. on the other hand speculate that

"[t]he collateral muscle changes and inflammation after unilateral EMS/E observed in this study may be caused by [a] neuronal mechanism. Since there is some evidence for a commissural system in the spinal cord that mediates transmedian signaling with a fairly precise bilateral representation, nerve signals from the trained side may pass over to the contralateral muscles through commisural inter-neurons. If this is the case, unilateral injury caused by EMS/E may cause a cross-transfer up-regulation of neuropeptides that can be involved in the inflammatory response in the contralateral muscles." (Song. 2012)

The researchers indicate that their current, as well as previous results from their laboratory would support this hypothesis and that any systemic or circulatory effects must actually be excluded, because these would not have occurred only focally, but generally within all muscles. They also point towards previous studies in which the signalling between contralateral and ipsilateral limb was blocked and the observed cotralateral responses were abolished.

So what's the point? I will openly admit that the practical relevance of these results (esp. for you as a hopefully healthy trainee) is as of now still very questionable, but the fact alone that it brings the nervous system back on the "scientific" radar was certainly worth including it in this "threesome" - don't you think so? No, well... maybe you like the scientists own rational who argue that the findings are (a) important in the context of a wide range of musculoskeletal and neuromuscular disorders and (b) relevant for each and every unilateral exercise experiment, where the contraleteral limb is used as a control - and you know there are plenty of them!

References:

• Hackney AC, Kallman A, Hosick KP, Rubin DA, Battaglini CL. Thyroid hormonal responses to intensive interval versus steady-state endurance exercise sessions. Hormones (Athens). 2012a Jan-Mar;11(1):54-60.
• Hackney AC, Hosick KP, Myer A, Rubin DA, Battaglini CL. Testosterone responses to intensive interval versus steady-state endurance exercise. J Endocrinol Invest. 2012b Dec;35(11):947-50.
• Ozen, SV. Reproductive hormones and cortisol responses to plyometric training in males. Biol Sport.2012; 29 (3).
• Song Y, Forsgren S, Yu J, Lorentzon R, Stål PS. Effects on contralateral muscles after unilateral electrical muscle stimulation and exercise. PLoS One. 2012;7(12):e52230.
• Watanabe Y, Tanimoto M, Ohgane A, Sanada K, Miyachi M, Ishii N. Increased muscle size and strength from slow-movement, low-intensity resistance exercise and tonic force generation. J Aging Phys Act. 2013 Jan;21(1):71-84.