Training to Failure Doubles 10Wk Biceps Gains Compared to Volume-Equ. Training - Difference to Control Even Larger

Beware, guys, training like these women may make your guns "bulky" ;-)

No, this is by no means the first article about training to failure I've written. In fact, I've published an article as part of a two-part series on "Intensity Techniques" in February, this year.  The reason(s) the latest study from the University of Brasilia (Martorelli 2017 | SuppVersity veterans will notice that this is yet another example of excellent resistance training research from Brazil I can write about) still made it to the SuppVersity News is that it is (a) one of the rare studies with young, healthy female subjects and (b) has both, a non-failure non-volume-equated and a volume-equated non-failure control group.

Don't fool yourselves, there is no single best workout for the rest of 'us life -- periodize!

30% More on the Big Three: Squat, DL, BP!

Confusion? Mixin' Things Up Yields Extra-Gains

Linear vs. Undulating Periodization

Velocity Training: End a Set if You Slow Down

Fast-Paced High Rep Training Beats Failure

Tapering 101 - Learn How It's Done!

Of the aforementioned strengths of the study (b) is unquestionably the real distinguishing factor. As Schoenfeld et al. pointed out in various reviews and independent research the training volume seems to be the only definite determinant of exercise-induced muscle hypertrophy (e.g. Schoenfeld 2010 & 2014). Accordingly, any meaningful comparison of failure to non-failure training needs to be volume-equated...

Figure 1: Insights from previous studies (Izquierdo 2006) and reviews (Stone 1996; Willardson 2007) of training to failure.

...that, however, reduces the practical significance of the results, because, for the average trainee, training to volume goes hand in hand with an increased training volume. After all, few of you will add extra sets to keep their volume constant when they switch back and forth between training to failure and stopping short before their muscles fail.

The study's most important strength is that it has sufficiently large volume-equated and regular no-failure groups and does, therefore, allow us to distinguish the effects of failure and an increased volume due to training to failure.

For their Experiment, the scientists randomly assigned eighty-nine active young women were randomly assigned to one of the previously hinted at three groups:

• repetitions to failure (RF; three sets of repetitions to failure)
• repetitions not to failure with equalized volume (RNFV; four sets of 7 repetitions)
• repetitions not to failure (RNF; three sets of 7 repetitions)

All groups performed the elbow flexor exercise (bilateral biceps curl) and trained 2 days per week using 70% of 1RM.

Figure 2: The volume standardization worked out quite well (left), the increase in muscular endurance was - within statistical margins - identical in all three groups (right); it did, however, show a non-sign. lower effect size in the non-volume equated vs. volume equated non-failure group after 10 weeks  - volume does, therefore, appear to be a relevant determinant of the exercise-induced adaptational response for muscular endurance - in the long run  (Martorelli 2017).

The scientists' analysis of the results show significant increases (p<0.05) in muscle strength after 5 (15.9% for RF, 18.4% for RNF, and 19.9% for RNFV) and 10 (28.3% for RF, 26.8% for RNF, and 28.3% for RNFV) weeks of training - and that "with no significant differences between groups" (Martorelli 2017 | my emphasis). Similar results were observed for the women's strength endurance, which increased after 5 and 10 weeks, likewise with no differences between groups.

Here's why it's important to wait 5 days before measuring sleeve sizes | more

An important note on how the muscle thickness was measured: All tests were conducted at the same time of the day, and the participants were instructed to hydrate normally for the 24 h before the tests.

Furthermore, measurements were taken 5 days after the last training session so that swelling did not affect the MT measurement). The actual measurement was conducted using B-Mode ultrasound (Philips-VMI, Ultra Vision Flip, model BF). The baseline test and retest intraclass correlation coefficient for the elbow flexor muscle thickness was excellent, namely 0.98 (0.98–0.99).

Differences were however observed for peak torque (PT), which increased significantly at 180°/s in the RNFV (13.7%) and RNF (4.1%) groups (p<0.05), whereas no changes were observed in the RF group (-0.5%) and muscle thickness

Figure 3: Relative changes in biceps size in the three study groups after 5 and 10 weeks (Martorelli 2017).

As you can see in Figure 3, the latter increased significantly (p<0.05) in the RF and RNFV groups after 5 (RF: 8.4% and RNFV: 2.3%) and 10 weeks of training (RF: 17.5%, and RNFV: 8.5%), whereas no significant changes were observed in the RNF group (3.9 and 2.1% after 5 and 10 weeks, respectively) - in fact, the reduction in sleeve size from week 5 to week 10 clearly indicates that the training stimulus of three sets of 7 reps was insufficient to trigger a consistent hypertrophy response (despite measurable, but also declining strength gains | see Figure 2, right).

Training to Failure - Overtraining Prone & Useless? | Part 1/2 of a Research Update of 3 Popular 'Intensity Techniques' | more

So, what's the verdict? As usual, you should keep in mind that this is only a single study. With its two "control" groups, it is yet also the first one I have seen to allow us to effectively distinguish between the effects of going to failure and the effect of the increased training volume that's usually associated with training to failure. In this respect, the data (a) confirm previous studies which point to training volume as a, if not "the" major determinant of skeletal muscle hypertrophy. The greater increase in muscle size in the RF group, however, seems to suggest that (b) training to failure has an additional beneficial effect on lean mass gains in the elbow flexors (biceps).

Beware of overgeneralizing the study results: While I doubt that the gains are sex-specific, I can very well imagine that similar benefits won't be seen on (a) multijoint exercises, where often other muscle groups take over as you approach failure and (b) with workout routines with a generally higher volume [keep in mind, the three sets of 7 in the study at hand are sign. less than what the average trainee is doing for his biceps - both directly (e.g. curls) or indirectly (e.g. pull-ups)] and (c) in other subject groups like the elderly, who appear to suffer from an impaired ability to recruit satellite cells for muscle repair (and growth), or highly trained individuals in whom the overall gains and probably also the inter-group differences could be significantly attenuated.

Whether the same goes for male subjects and other body parts will have to be elucidated in future studies. Plus: We must not forget that the authors rightly conclude that "training of repetitions to failure do not yield additional overall neuromuscular improvements in young women" (Martorelli 2017) - in other words: training your biceps to failure makes sense only if your primary goal is to grow bigger guns. If you want to maximize your peak torque, on the other hand, you better add sets/reps without going to failure - after all, the latter reduced the considerable increase in peak torque from 13.7% in the volume equated no-failure (RNFV) group to zero (statistically speaking) when the subjects trained to failure | Comment!

References:

• Izquierdo, Mikel, et al. "Differential effects of strength training leading to failure versus not to failure on hormonal responses, strength, and muscle power gains." Journal of Applied Physiology 100.5 (2006): 1647-1656.
• Martorelli, Saulo, et al. "Strength training with repetitions to failure does not provide additional strength and muscle hypertrophy gains in young women." Eur J Transl Myol 27.2: 113-120.
• Schoenfeld, Brad J. "The mechanisms of muscle hypertrophy and their application to resistance training." The Journal of Strength & Conditioning Research 24.10 (2010): 2857-2872.
• Schoenfeld, Brad J., et al. "Effects of different volume-equated resistance training loading strategies on muscular adaptations in well-trained men." The Journal of Strength & Conditioning Research 28.10 (2014): 2909-2918.
• Steele, James, James Fisher, and Stewart Bruce-Low. "Resistance training to momentary muscular failure improves cardiovascular fitness in humans: a review of acute physiological responses and chronic physiological adaptations." Journal of Exercise Physiology Online 15.3 (2012): 53-80.
• Stone, Michael H., et al. "Training to Muscular Failure: Is It Necessary?." Strength & Conditioning Journal 18.3 (1996): 44-48.

Velocity Training Revisited: 20% or 40% Reduction in Bar Velocity on Barbell Squats - What'll Yield Greater Gains?

Squats, squats and, you guessed it squats - That's all the subjects did in this 8-week study W/ trained young men.

Back in the early days of the SuppVersity, I reported the results of a resistance training study which showed that interrupting your sets, when you can no longer perform the exercise at maximal velocity yielded quite astonishing increases in muscle gains - despite stopping several reps away from failure.

Spanish researchers have now attempted to gain further insight into the adaptations brought about by training close to muscle failure vs not to failure, and compared the effects of two RT programs that only differed in the magnitude of repetition velocity loss allowed in each set (20% vs 40%) on structural and functional adaptations.

I would suggest you consider periodizing going to failure vs. shying away from it.

30% More on the Big Three: Squat, DL, BP!

Mix Things Up to Make Extra-Gains

Linear vs. Undulating Periodization

12% Body Fat in 12 Weeks W/ Periodization

Detraining + Periodization - How to?

Tapering 101 - Learn How It's Done!

The scientists hypothesized that "despite a remarkably lower training volume, improvements in strength and performance will be greater with the RT program allowing only a 20% reduction in repetition velocity, whereas a 40% velocity loss will result in greater muscle hypertrophy" (). Or, in other words, the scientists expected that ...

• approaching failure would increase strength gains, 
• while shying away from it would increase hypertrophy. 

The results I've plotted for you in Figure 2 do yet show a different image. Over the 16 workouts (2 workouts per week for the twenty-four resistance-trained young and healthy men | full squat 1RM 106.2 +/- 13.0 kg) the subjects had done identical workouts - albeit with different termination conditions: While the 20% group terminated their set when they reached a velocity loss of only 20%, the 40% group kept going until a lift that would usually have taken them 1s took them 1.5s and thus 40% longer than usual. The only exercise that was performed was the barbell squat.

Figure 2: As you can see, the VL20 did - as it was expected and intended fewer reps, but at a higher velocity than the VL40 group who terminated their sets only after they had slowed down by >40% (Pareja-Blanco 2017).

Sessions were performed in a research laboratory under the direct supervision of the investigators, at the same time of day (+/- 1 h) for each subject and under controlled environmental conditions (20 °C and 60% humidity).

Related study shows: Velocity could replace subjective measures as effort gauges such as the rate of perceived exertion (RPE) scale-- The corresponding experimental study analyzed whether the loss of repetition velocity during a resistance exercise set was a reliable indicator of the number of repetitions left in reserve in novice, well-trained and highly-trained subjects. The results "indicate that by monitoring repetition velocity one can estimate with high accuracy the proximity of muscle failure and, therefore, to more objectively quantify the level of effort and fatigue being incurred during resistance training" (Morán-Navarro 2017).

Subjects were required not to engage in any other type of strenuous physical activity, exercise training, or sports competition for the duration of the present investigation. Both VL20 and VL40 groups were assessed on two occasions: 48 h before (Pre) and 72 h after (Post) the 8-week training intervention. Training compliance was 100% of all sessions for the subjects that completed the intervention.

Figure 2: Changes in muscle volume due to 8 weeks of velocity-based resistance training for: (a) Whole quadriceps femoris; (b) rectus femoris (RF); (c) vastus medialis (VM); and (d) VL+VI (Pareja-Blanco 2017).

The scientists did not find their hypothesis confirmed when they analyzed their results: The expected strength advantage for the VL40 group was not observed:

"Following the training intervention, statistically significant increases were observed in 1RM strength (18.0% and 13.4%), AV (12.5% and 6.0%), and AV<1 (21.7% and 13.7%) for VL20 and VL40 groups, respectively" (Pareja-Blanco 2017).

Similarly, the quadriceps femoris volume (Fig. 3a) was increased by 6.0% (time effect P < 0.05). This was explained by a significant increase of VM volume (Fig. 3c) in both groups. In contrast to the scientists hypothesis, however, there was a small, but measurable benefit from doing more reps and going closer to failure for the sum of vastus lateralis (VL) + vastus intermedius (VI) gains, which increased exclusively in the VL40 group (group x time interaction, P = 0.05).

'Training on Cycle': Hitting the Weights Frequently (5x/WK), Alone, Very Unlikely to Trigger the 'Female Athlete Triad' | more

Bottom line & implications: As with the majority of previous studies, it would appear that going closer to failure and/or training at a higher volume will augment what many of you will be looking for: lean mass gains. For strength, on the other hand, trained healthy young men don't see a significant advantage of training closer to failure.

The results are thus in contrast to the authors' initial hypothesis and confirm the study results I have hinted at previously: if you abort your sets "early", i.e. when you slow down only 20% this is not going to ruin your gains.

What shying away from failure may do, however, is to reduce your injury risk (Tan 1999) - especially when we're talking about full-body free weight exercises as the full barbell squat that was used in the study at hand. If you feel that you're having trouble keeping up good form, you may thus choose to terminate your sets way before failure without seeing significantly compromised strength and size gains... on the legs, with the full squat - results may differ for other muscles and/or exercises | Comment!

References:

• Morán-Navarro, Ricardo, et al. "Movement velocity as a measure of level of effort during resistance exercise." The Journal of Strength & Conditioning Research (2017).
• Pareja‐Blanco, F., et al. "Effects of velocity loss during resistance training on athletic performance, strength gains and muscle adaptations." Scandinavian journal of medicine & science in sports (2016).
• Tan, Benedict. "Manipulating Resistance Training Program Variables to Optimize Maximum Strength in Men: A Review." The Journal of Strength & Conditioning Research 13.3 (1999): 289-304.

Training to Failure - Overtraining Prone & Useless? | Part 1/2 of a Research Update of 3 Popular 'Intensity Techniques'

No deadlifts in Nóbrega's training to failure study and + there are other issues w/ the "one-legged leg extension, only"-design.

Be honest, even though you may know that there's no convincing evidence of the superiority of training to failure, doing pyramid sets and/or drop-sets for increased size and strength your gut says: "Bro, that feels so damn challenging. It's got to work!"

That's not you? Well, I guess you will nevertheless be interested, whether the latest studies by Nóbrega et al. (training to failure | this part of the article) and Angleri et al. (pyramid and drop-sets | read about it in part 2 of the article) prove your gut feeling wrong, once and for all.

Don't fool yourselves, there is no single best workout for the rest of 'us life -- periodize!

30% More on the Big Three: Squat, DL, BP!

Mix Things Up to Make Extra-Gains

Linear vs. Undulating Periodization

12% Body Fat in 12 Weeks W/ Periodization

Detraining + Periodization - How to?

Tapering 101 - Learn How It's Done!

In this installment of this two-part review we will start with the never-ending debate about training to failure. A technique of which a 2007 review by Willardson et al. says that it "might provide the extra stimulus needed for advanced lifters to break through plateaus" (Willardson. 20017). Against that background, it appears to be logical that a cursory read of the literature suggests that there is a sign. number of studies to confirm that 'training to failure is more anabolic than shying away from failure'. A closer read of the corresponding studies, however, indicates that the hypertrophy and/or strength advantages many papers respond could well be the mere effect of an increased training volume. How's that and why's that relevant? Well, if one group of subjects stopped after 8 reps while the other did another 1-2 rep/s on almost every set, that's a 10-20% increased workout volume, which, in turn, is one of the few variables with sufficient scientific evidence that it facilitates skeletal muscle hypertrophy (Schoenfeld. 2010 & 2013).

Against that background, the results Sanmy R. Nóbrega and colleagues present in their soon-to-be-published paper in Journal of Strength and Conditioning Research are all-the-more surprising. After all, their study design did not equate the volume in the four groups of untrained young men (age: 23.0 ± 3.6 years; height: 176.0 ± 0.6 cm; BMI: 24.3 ± 3.9 kg/m²) who participated in 12x2 workouts per week over the course of the 12-week experiment:

• HIRT-F and HIRT-V: Three sets of unilateral (=single leg) leg extensions at 80% of the individuals' 1-RM twice a week performed to failure (HIRT-F) or the point where the subjects stopped voluntarily (HIRT-V), respectively
• LIRT-F and LIRT-V: Three sets of unilateral (=single leg) leg extensions at 30% of the individuals' 1-RM twice a week performed to failure (LIRT-F) or the point where the subjects stopped voluntarily (LIRT-V), respectively

What the study did do, unfortunately, is to use single-leg leg extensions to allow for four study groups with only 30 subjects by having each subject train his two legs differently - one to failure another to volitional interruption. And that's a problem...

Figure 1: Maximal dynamic strength (1-RM) and muscle cross-sectional area (CSA) at baseline (Pre) after 6 (6W) and 12 weeks; *Significant difference compared to Pre; †Significant difference compared to 6W (Nóbrega. 2017)

Why's that a problem? Well, while there is no conclusive evidence that training one leg will have the other grow, as well, there are at least a good dozen of ways training one leg to failure could have affected the adaptive response in the other leg that have not been convincingly disproven, yet. Catoire et al. (2012) have observed sign. gene changes, for example, in both the trained and untrained legs, Fimland, et al. (2009) and similarly Kannus et al. (1992) report that neural adaptations lead to strength gains in the untrained leg, and Munn et al. (2004) conclude in their meta-analysis that "[p]oling of all available data shows that unilateral strength training produces modest increases in contralateral strength" - 7.8%, a strength increase that's small, but could be pronounced enough to mask an inter-group difference in the study at hand. Not to mention difference according to the muscle group you train and the exercise you do (doing only leg-extensions is not exactly all-encompassing and obviously does not allow for reliable conclusions about the effects on e.g. hamstrings, glutes, triceps, biceps, chest, and doing the corresponding exercises to failure or not).

Figure 2: Effect of unilateral resistance training on the strength of the contralateral limb (Munn. 2004);
last paragraph of the conclusion of Munn's meta-analysis (inset in the lower right corner).

And that's not the only methodological characteristic of the study at hand that refutes the initially alluded to hypothesis that it would provide "proof" that training to failure doesn't add to the exercise-induced increases in strength and hypertrophy. Another, caveat that's at least as relevant is the lack of training experience of the thirty-two subjects - there's, after all, a good reason scientists love untrained subjects: they will see impressive gains, (almost) no matter what they do. The impressive responsiveness of newbie-muscles to any muscle-building stimulus alone could thus have masked an inter-group difference and thus the benefits of training to failure... which brings us back to the initially cited statement from the conclusion of Willardson's 2007 review: "Training to failure might provide the extra stimulus needed for advanced lifters to break through plateaus" - do you notice something? Yes, Willardson et al. were careful or precise enough to highlight who will benefit from training to failure, i.e. "advanced lifters".

And there's more. The scientists from the Eastern Illinois University also highlight that this intensity technique should be "incorporated periodically into short-term microcycles". Eventually, the question whether you should train to failure or not may thus be reduced to the question of when in your macrocycle will you have microcyles (4-6 weeks) of training to failure, but that's a topic for a completely different article.

Reps to failure can propel your gains when you train w/ light weights | more

So, there's there's still hope that all your "failures" were not in vain? Yes, there is. With the study at hand (a) being conducted in untrained subjects in whom their heightened responsibility to strength and size gains, which may have masked any beneficial effects training to failure, and (b) the unquestionably suboptimal way of having subjects train one leg to failure while using the other leg as (non-failure) control-leg, it is another, imho not the most convincing contribution to the partly contradicting research on whether training to failure provide a unique stimulus to strength and muscle gains or not.

Don't get me wrong: I am not saying that the absence of convincing evidence of its fruitfulness would prove that training to failure works. Rather than that I am saying that the study at hand adds to what all previous research appears to suggest: "It depends"... which reminds me of pointing out that training to failure on every set of every workout of a 5-day-split can easily increase your risk of overtraining and/or injury (Stone. 1996) and would, in that case, clearly reduce, not increase your gains. As Willardson et al. hint at in their 2007 review, training to failure could and maybe even should thus be used by (i) advanced trainees and (ii) only sporadically and within a well-planned periodization scheme | Comment and read the second part of this review!

References:

• Catoire, Milène, et al. "Pronounced effects of acute endurance exercise on gene expression in resting and exercising human skeletal muscle." PloS one 7.11 (2012): e51066.
• Fimland, Marius S., et al. "Neural adaptations underlying cross-education after unilateral strength training." European journal of applied physiology 107.6 (2009): 723.
• Izquierdo, Mikel, et al. "Differential effects of strength training leading to failure versus not to failure on hormonal responses, strength, and muscle power gains." Journal of Applied Physiology 100.5 (2006): 1647-1656.
• Kannus, P., et al. "Effect of one-legged exercise on the strength, power and endurance of the contralateral leg." European journal of applied physiology and occupational physiology 64.2 (1992): 117-126.
• Munn, Joanne, Robert D. Herbert, and Simon C. Gandevia. "Contralateral effects of unilateral resistance training: a meta-analysis." Journal of Applied Physiology 96.5 (2004): 1861-1866.
• Nóbrega, Sanmy R., et al. "Effect Of Resistance Training To Muscle Failure Versus Volitional Interruption At High-And Low-Intensities On Muscle Mass And Strength." The Journal of Strength & Conditioning Research (2017).
• Schoenfeld, Brad J. "The mechanisms of muscle hypertrophy and their application to resistance training." The Journal of Strength & Conditioning Research 24.10 (2010): 2857-2872.
• Schoenfeld, Brad J. "Potential mechanisms for a role of metabolic stress in hypertrophic adaptations to resistance training." Sports medicine 43.3 (2013): 179-194.
• Stone, Michael H., et al. "Training to Muscular Failure: Is It Necessary?." Strength & Conditioning Journal 18.3 (1996): 44-48.
• Willardson, Jeffrey M. "The application of training to failure in periodized multiple-set resistance exercise programs." The Journal of Strength & Conditioning Research 21.2 (2007): 628-631.

If 'Size' is Your Goal, 30s Rest & 20 Reps Beat 3 Min Rest & 8 Reps to Failure -- Extra 100% Biceps Gains in 8 Week Study

Do women have to complain that training makes them "bulky", because they're doing it right (high rep, low weight, short rest) while their boyfriends don't?... What? Don't worry, I am just kiddin'.

As a loyal SuppVersity readers, you will remember my 2016 article: "Not Resting Long Enough May Ruin Your Gains! 1 vs. 5 min Cut Post-Workout Increase in Protein Synthesis by 50%!" (read it). Now, back in the day I already pointed out that "the study at hand only proves what we already knew - training volume is more important than metabolic stress when it comes to hypertrophy gains" (SV. 2016) and still many people (mis-)interpreted the results in their black-and-white world as "final evidence" that you'd have to turn your workout into a coffee (or intra-workout) party to make the gains you feel you deserve. That's a mistake you should not repeat by taking the publication of a recent study from the Nippon Sport Science University as a reason to stop resting (and using heavy weights) altogether.

Don't fool yourselves, there is no single best workout for the rest of 'us life -- periodize!

30% More on the Big Three: Squat, DL, BP!

Mix Things Up to Make Extra-Gains

Linear vs. Undulating Periodization

12% Body Fat in 12 Weeks W/ Periodization

Detraining + Periodization - How to?

Tapering 101 - Learn How It's Done!

But before we get to the implications, let's first take a look at the study itself. The corresponding experiments were conducted by Julius Fink, Naoki Kikuchi and Koichi Nakazato (Fink. 2016); and the authors did two things McEndry et al. the authors of the previously cited acute-phase study of the protein anabolic response to exercise failed to do in their study:

• Fink et al. investigated the effects of volume-matched resistance training (RT) regimen, and
• they tested both, the acute responses and long-term muscle and strength gains

McEndry et al. (2016) had stuck to the acute protein response to non-volume matched training regimen. That's not necessarily worse, but it limits the significance of the study results in a different way than the design of the more recent study by Fink et al., in which

More protein helps more?!

"[t]wenty young athletes (members of a university gymnastics club) volunteered to participate in this study [with previous] weight training [experience of >2 years] were randomly assigned to either the SL group (30-s rest, 20 RM) or the long-rest and LH group (3-min rest, 8 RM) and performed the same number of sets and exercises for the arm muscles three times per week for 8 weeks" (Fink. 2016).

Both groups performed each set to failure and used the same set of exercises: three biceps and three triceps exercises in form of

• barbell curl,
• preacher curl,
• hammer curl,

• close grip bench press,
• French press and
• dumbbell extension

Even though I doubt that this was necessary for the majority of the experienced trainees, all participants were familiarized with the exercises 2 weeks prior to the start of the experiment by qualified trainers. The same goes for the differential training styles, the authors describe as follows:

• The SL group did each exercise with a rest of 30 s between sets and exercises at 20 RM. 
• The LH group rested 3 min between sets and exercises with a training intensity of 8 RM. 
• In both groups, each set was performed to failure with a cadence of 1 s for the concentric and 2 s for the eccentric part of the movement. 
• The training sessions were performed three times per week for 8 weeks and supervised by a staff of qualified personal trainers.

Over the course of the 8-week study, the weight was increased by 10%, whenever, the participants, whose training experience of >2 years and body fat % of 10.9 and 13.3%, in the SL and LH group, respectively qualifies them as fitness enthusiasts, could perform more than 20 repetitions for the SL group or more than eight repetitions for the LH group. As previously pointed out, the volume (reps x load) was supposed to be identical and that worked out quite well - with one exception, the barbell curl, where the SL group trained at a sign. higher volume (see Table 1), of which one must, however, doubt that it alone could explain the already hinted at SL advantage.

Table 1: Total training volume, calculated as number of repetitions x training load ( SD) for three sets of each exercise; SL, short rest with the low-load protocol; LH, long rest with the high-load protocol (Fink. 2016).

The acute change in muscle thickness (MT) was assessed before and immediately after a single bout of RT via ultrasound imaging (Prosound 2; Hitachi Aloka Medical, Ltd., Tokyo, Japan | same method as in Schoenfeld et al., 2015a,b), the chronic adaptation was measured with MRI (AIRIS II; Hitachi, Ltd., Tokyo, Japan) 72–96 h after the last RT session (learn why this is important).

Figure 1: Acute growth hormone response to SL and LH workouts and the lack of correlation between acute GH increases and gains in terms of actual muscle circumference gains (CSA, right | Fink. 2016).

The analysis of the hormonal response to exercise (plotted in Figure 1), is unsurprising. We already knew from previous studies that the SL protocol would produce greater increases in growth hormone (GH) than the LH protocol with its long rest-times. The same must be said of the correlation (and implied effect) of these increases with the subjects' size gains which did - as in almost every previous study - not correlate with the hormonal response to the workouts (see Figure 1, right).

Should I change my workout style now? No. If you're still making progress, I would not hectically change everything. What I would do, however, is to read up on periodization (learn more) and plan to change your workouts regularly using both lower and higher weights and shorter and longer inter-set rest times periodically and for your own benefit.

Figure 2: Rel. size (top) and strength gains (bottom) over 8 weeks (Fink. 2016)

If we compare the long-term effects on the muscle cross-sectional areas (CSAs), as well as the changes in muscle strength (measured as maximum voluntary contraction (MVC) of the biceps) between studies, however, the differences approach statistical significance.

Whether and in which way (corollary or mechanistically) the long-term extra gains in the SL group (see Figure 2, top) are related to the observation that the muscle thickness increased significantly only after a single bout of SL training  (35 .2 +/- 16- 9%, P<0 05) (ES = 3 17), but not after a bout of LH training (13. 7 +/- 10. 8%) would warrant further investigation.

What appears to be easier to understand than the hypertrophy advantage of the SL training is the fact that the lack of heavy resistance training in the SL group (the SL group showed a non-significant decrease in strength of 5 .9 +/- 8. 6%; ES = 0 46) lead to a decrease in MVC in this group of previously resistance trained individuals (see Figure 2, bottom).

Shall you forget about long rest times? I understand that you gravitate towards simple solutions. Unfortunately, those simple solutions are the reason you are not making the gains you could make if you finally got rid of the stupid idea that there was one ideal workout routine, you'd just have to find and could then follow for the rest of your life.

Strength Plateau? Try Daily Changing Loads: To Boost 6-Week Strength Gains on All Major Lifts by ~40%.

How's that wrong? It's what the study says SL is better than LH, right? Well, the study at hand does indeed suggest that training with more reps and low(er) rest builds more muscle (note that the results could be very different for other muscles, e.g. the legs, or other trainees, i.e. rookies), while training with long(er) rest and more weight will boost strength gains. Eventually, however, the differences are (a) not statistically significant and (b) not independent of each other. Strength and size gains are not like the two sides of the same coin. They are yet also not unrelated.

Accordingly, the question is not whether you want size or strength/ power and thus train with short(er) rest and low(er) weights or long(er) rest and high(er) weights. No, making optimal gains is rather a question of balancing all three domains of "gains", i.e. size, strength and anaerobic power (Pasiakos. 2015) within a well-planned periodization regimen that would - if the volume is controlled for - favor size gains during the short rest, high rep / low weight and strength gains during the long rest, low(er) rep / high(er) weight phases | Comment!

References:

• Fink et al. "Effects of rest intervals and training loads on metabolic stress and muscle hypertrophy." Clin Physiol Funct Imaging (2016) - Ahead of print.
• Pasiakos, Stefan M., Tom M. McLellan, and Harris R. Lieberman. "The effects of protein supplements on muscle mass, strength, and aerobic and anaerobic power in healthy adults: a systematic review." Sports Medicine 45.1 (2015): 111-131.
• Schoenfeld, Brad J., et al. "Effects of low-vs. high-load resistance training on muscle strength and hypertrophy in well-trained men." The Journal of Strength & Conditioning Research 29.10 (2015a): 2954-2963.
• Schoenfeld, Brad J., et al. "Longer inter-set rest periods enhance muscle strength and hypertrophy in resistance-trained men." Journal of strength and conditioning research/National Strength & Conditioning Association (2015b).

Training to Failure and Modifying Rest Times: Two Ways to Maximize Muscle Activity? Two Studies, Similar Implications

This is what science looks like... Well, at least in the Hiscock study, where the subjects, 10 young men with at leas 12 months of training experience did regular and hammer dumbbell curls on the preacher bench - (photo | Hiscock. 2015).

In today's SuppVersity feature article, I am going to address not one, but two potentially highly relevant articles from the Journal of Strength and Conditioning Research (Looney. 2015) and the European Journal of Sport Science (Hiscock. 2015). What makes these papers interesting is the fact that both investigated the effect of commonly prescribed remedies to "bust a plateau" by providing novel growth triggers: (a) Training to failure and (b) modifying rep schemes and whether you fail or don't fail on every set.

If you believe in what you can read in many articles on strength training, both, training to failure and decreasing rest times / drop sets should significantly increase the muscle activity and thus - this is the most important thing - the number of motor units that are recruited during the exercises.

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But is this actually true? I mean, is there a link between EMG activity, the number of motor units that are firing and the way you train? I guess, it would be wise to take a brief look at the pertinent research before we get to design and results of the individual studies. So, what do we have? As Looney et al. point out, motor unit activity can be measured through electromyography (EMG) which is commonly considered to reflect the neural drive to the muscle. Since the electrical impulse should be proportional to the number of motor units that are firing and in view of the fact that the latter determines the acute force output, it should be obvious that increasing force demands result in higher EMG amplitude due to the greater recruitment of motor units and faster firing rates necessary to increase the contractile force.

Figure 1: Previous studies show that the motor unit recruited (or at least it's indicator, the mean EMG values) increases over the duration of sustained or repeated muscle actions at a constant force level (Masuda. 1999 - l; Mottram. 2005 - r)

Unfortunately, more does not necessarily help more. If you take a closer look at the existing research you have to realize you cannot stretch this proven increase of the EMG amplitude (Carpentier. 2001; Fuglevand. 1993; Lind. 1979; Masuda. 1999; Mottram. 2005; Petrofsky. 1982) infinitely. Over prolonged exercise / contraction times, the initially increasing firing rates will eventually decrease. That this is the case is interpreted by many scientists as evidence of the the fact that the initial rise in EMG amplitude is just a compensatory mechanism for sustaining contractile force as fatigue accumulates (when the individual fibers fatigue, more are recruited to sustain the same force). This hypothesis appears to be confirmed by numerous investigations that have demonstrated that EMG amplitude increases during dynamic exercise as the extent of the effort, or number of repetitions performed, increases (Hasani. 2006; Spreuwenberg. 2006; etc.).

Why is it even important that all muscle fibers contract? The reason should be obvious, but I am happy to explain it once more. It is the contraction that's responsible for the exercise induced increase in GLUT-4 receptor expression and mTOR phosphorylation. In view of the fact that the latter determine the increase in glucose uptake and protein synthesis after a workout, you obviously want as many muscle fibers to contract as possible. Or, to put it differently: If you don't use it you won't grow it, bro... well, at least not to the same / optimal extent.

This is where the "train to failure to maximize motor unit recruitment"-theory comes from. After all, this observation indicates that usually inactive motor units are going to fire only during prolonged training at high intensities (best to failure). As usual, though, there are problems with this theory:

"While the increase in EMG amplitude observed during repeated muscle actions has been explained by increased central drive necessary to sustain force as fatigue accumulates, it is inconclusive whether fatigue derived from earlier performed exercise induces greater EMG amplitude during subsequent exercise. Previous studies have shown EMG amplitude diminishes after strenuous resistance exercise protocols. In contrast, Smilios et al. demonstrated progressive increases in EMG amplitude over a series of 20-repetition sets with gradually decreasing resistance interspaced with 2-minute rest periods. Further uncertainly exists pertaining to consecutive maximal effort sets with progressively lighter resistance performed without allotted rest periods. This frequently incorporated training technique, commonly known as a “drop set”, has remained relatively uninvestigated" (Looney. 2015).

Needless to say that we all expect that lighter weights can stimulate greater motor unit recruitment, if you use them in dropsets, but as Looney et al. say, the science that would conclusively confirm that is simply not there (yet). The goals of Looney's study were thus as follows:

• Firstly, confirm / refute the assumption that EMG amplitude would be significantly greater in light resistance exercise (50% 1RM) performed in rested conditions to a maximal number of repetitions than to a submaximal number of repetitions. 
• Secondly, assess whether the EMG amplitude would be significantly lower in maximal repetition sets performed in rested conditions with 50% 1RM resistance than with heavy resistance (90% 1RM). 
• Thirdly, test whether the EMG amplitude would be greater in maximal repetition 50% 1RM resistance sets performed in pre-fatigued conditions (no prior rest period) than in rested conditions. 

As the authors rightly point out, the "findings of this investigation would provide critical information on understanding the changes in neuromuscular physiology during dynamic exercise related to variable levels of target repetitions, resistance, and fatigue" (Looney. 2015) and may thus be of great value to scientists (initially, because the would have to still check the practical consequences of any increases in motor recruitment) and coaches + athletes (later). What the Hiscock study in which the researchers evaluated the rate of perceived exertion (RPE) and its correlation with muscle activation and lactate levels can add to the table is information on the effect of another parameter: Different rest times.

If you don't do them as an intensity add-on / finisher don't do partial reps at all - "Full Rom, Full Gains" | more

Don't forget that form, time under tension and the range of motion matter, as well. In 2013, for example, I discussed the results of a study by McMahon et al. that leaves little doubt that the increased mechanical stress and workload (remember work is the product of force x time) from doing exercises over the full range of motion will trigger greater morphological and architectural adaptations in response to resistance training than doing the same exercises over only a partial range of motion. Unfortunately, the evidence in favor of the significance of optimal form (beyond going over the full range) and the time under tension for optimal gains is less convincing and in parts contradictory.

In order to avoid any confusion, though, let's initially look at the Looney study in isolation. In said study ten resistance trained men (age, 23±3 yr; height, 187±7 cm; body mass, 91.5±6.9 kg; squat 1RM, 141±28 kg) had EMG electrodes attached to their vastus lateralis and vastus medialis muscles on two occasions:

• A drop set day, on which he subjects performed three consecutive maximal repetition sets at 90%, 70%, and 50% 1RM to failure with no rest periods in between. 
• A single set day, on which the subjects performed a maximal repetition set at 50% 1RM to failure (no "dropping" involved). 

The analysis of the EMG data yielded overall unambiguous results: The maximal repetition sets to failure at 50% and 70% 1RM resulted in higher peak EMG amplitude than during submaximal repetition sets with the same resistance. In view of the fact that the peak EMG amplitude was significantly (P ≤ 0.05) greater in the maximal 90% 1RM set than on any of the other sets the subjects performed, the classic drop set with 90%, 70% and 50% 1RM should thus still have an edge over any regular "low intensity + high rep to failure" single set training. The question remains, however, whether it will also have the edge over conventional training?

Figure 2: Very general summary of the research interests and designs of the two studies discussed in today's SuppVersity article by Looney et al. (2015) and Hiscock et al. (2015)

We will get back to that question in the bottom line. In the mean time, let's briefly take a look at another, quite surprising result, one that will also lead us to the results of the previously mentioned study by Hiscock et al. (2015): The lack of association between the ratings of perceived exertion (CR-10). In contrast to what most of you certainly expected, the fatigue levels did not differ over the intensity range of loads and did not reflect the degree motor unit recruitment in any way (see Figure 3). You as an individual without the necessary technical equipment are thus probably unable to tell hor many motor units you've actually recruitment in a workout; and - even more importantly - the mere fact that you have to crawl instead of walk out of the gym is not a sign of a productive workout.

Figure 4: Mean number of repetitions (left, top), rate of perceived exertion (RPE | left, bottom), and peak EMG amplitude as a measure of motor recruitment (Looney. 2015).

You don't want to believe that? Well, bad luck for you: This result appears to be confirmed by Hiscock's study, in which 10 recreationally trained (>12 months of previous resistance training) did DB Curls and DB Hammer Curls on the preacher bench for three sets with their preferred arm at a constant load of 70% of their individual 1-RM over 4 trials:

1. 3 sets × 8 repetitions × 120 s recovery between sets; 
2. 3 sets × 8 repetitions × 240 s recovery; 
3. 3 sets × maximum number of repetitions (MNR) × 120 s recovery; 
4. 3 sets × MNR × 240 s recovery.

After each of the exercises the participants rated their overall and active arm muscle rate of perceived exertion (RPE-O and RPE-AM) and the data was correlated with the biceps brachii and brachioradialis muscle EMG activity during each set for each trial.

Figure 5: Despite sign. higher volumes (see boxes) and a 100% increase in rate of perceived local muscular exertion there was no significant increase in muscle activity with lifting 70% of the 1RM for 8 vs. to failure (Hiscock. 2015).

Just like in the Looney study, the measured rates of perceived exertion in the Hiscock study had did not correlate with with either the muscle activation or the lactate accumulation in the biceps. Rather than that, it appears as if the subjects' bicepses didn't even care about rep schemes and failure. While the RPE increased significantly, when the subjects trained to failure, the mean and peak EMG activity levels in Figure 5 are more or less identical for all rep x intensity (+/- failure) schemes.

So what's the significance of the results, then? If you put some faith into Looney's conclusion, it is that the results of his (and I may add Hiscock's study, too) confirm "previous recommendations for the use of heavier loads during resistance training programs to stimulate the maximal development of strength and hypertrophy" (Looney. 2015).

SuppVersity Suggested Topical Article: "Failure, a Necessary Prerequisite for Max. Muscle Growth & Strength Gains? Another Study Says 'No Need to Fail, Bro!'" | read more

Reducing the load and training to failure (Looney's "single set" day) or reducing the rest times and or switching from a set rep number to training to failure (Hiscock's groups A-D), on the other hand, has no effect on motor recruitment and could, in view of potentially increased recovery times due to higher rates of perceived exertion w/ training to failure, rather hinder than facilitate rapid strength and size gains. Whether the same is the case for the drop-set, though, is not 100% clear. With the peak muscle activity occurring in the first set, you cannot argue that the stimulus was weakened. On the other hand, there's a proven reduction in total volume (reps x weight | Melibeu Bentes. 2012) of which long-term studies would have to investigate whether the can impair your strength and size gains.

Overall, there is still little doubt that the results of the two studies I discussed today support the notion that "going heavy" is still the way to activate a maximal number of muscle fibers. Whether this does also mean that it is necessarily the best way to make those fibers grow and or increase their glucose uptake, however, is still not fully proven. The same goes for the usefulness of training to failure, of which some studies suggest that failure does not matter, while others appear to indicate that "failing" is almost necessary to maximize your gains - as usual, I've written about both of them and will continue to do so in the future, so stay tuned if you want to be among the first to learn what works best for strength and hypertrophy training ;-) | Comment on Facebook!

References:

• Carpentier, Alain, Jacques Duchateau, and Karl Hainaut. "Motor unit behaviour and contractile changes during fatigue in the human first dorsal interosseus." The Journal of physiology 534.3 (2001): 903-912.
• Fuglevand, A. J., et al. "Impairment of neuromuscular propagation during human fatiguing contractions at submaximal forces." The Journal of physiology 460.1 (1993): 549-572.
• Gibson, A. St Clair, E. J. Schabort, and T. D. Noakes. "Reduced neuromuscular activity and force generation during prolonged cycling." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 281.1 (2001): R187-R196.
• Hassani, A., et al. "Agonist and antagonist muscle activation during maximal and submaximal isokinetic fatigue tests of the knee extensors." Journal of Electromyography and Kinesiology 16.6 (2006): 661-668.
• Hiscock, Daniel J., et al. "Muscle activation, blood lactate, and perceived exertion responses to changing resistance training programming variables." European Journal of Sport Science ahead-of-print (2015): 1-9.
• Lind, Alexander R., and Jerrold S. Petrofsky. "Amplitude of the surface electromyogram during fatiguing isometric contractions." Muscle & nerve 2.4 (1979): 257-264.
• Looney, David P., et al. "Electromyographical and Perceptual Responses to Different Resistance Intensities in a Squat Protocol: Does Performing Sets to Failure With Light Loads Recruit More Motor Units?." The Journal of Strength & Conditioning Research (2015).
• Masuda, Kazumi, et al. "Changes in surface EMG parameters during static and dynamic fatiguing contractions." Journal of Electromyography and Kinesiology 9.1 (1999): 39-46.
• McMahon, Gerard E., et al. "Impact of range of motion during ecologically valid resistance training protocols on muscle size, subcutaneous fat, and strength." The Journal of Strength & Conditioning Research 28.1 (2014): 245-255.
• Mottram, Carol J., et al. "Motor-unit activity differs with load type during a fatiguing contraction." Journal of neurophysiology 93.3 (2005): 1381-1392.
• Petrofsky, Jerrold Scott, et al. "Evaluation of the amplitude and frequency components of the surface EMG as an index of muscle fatigue." Ergonomics 25.3 (1982): 213-223.
• Smilios, Ilias, Keijo Häkkinen, and Savvas P. Tokmakidis. "Power output and electromyographic activity during and after a moderate load muscular endurance session." The Journal of Strength & Conditioning Research 24.8 (2010): 2122-2131.
• Spreuwenberg, Luuk PB, et al. "Influence of exercise order in a resistance-training exercise session." The Journal of Strength & Conditioning Research 20.1 (2006): 141-144.