Build Size & Strength With Isometric Co-Contractions: 4% Increase in Arm Circumference and ~20% More Strength With Less Than 10 Minutes of "Flexing" Per Week

Big guns without weights? True - the question yet remains: "How big?"

I am psyched and the reason is the advanced access publication of the results of the latest study from the Department of Sports and Life Science at the National Institute of Fitness and Sports in Kanoya, Japan (Maeo. 2013b).

Why? Well, it claims to solve two of the most urgent issues that keep our sedentary fellow men (and women ;-) from working out: The lack of equipment and the lack of time, exactly those two factors the average American and European slacker pleads as an excuse for not making the necessary, since potentially life-saving physical investments into "metabolic currency" (this is a term my good friend Carl Lanore uses to refer functional muscle mass).

"Big guns without weights? You're kiddin', bro!"

Actually the idea of using simultaneous voluntary contractions of antagonistic muscle pairs (aka co-contraction) to improve muscle strength in the absence of external apparatuses is not new. The voluntary co-con traction of elbow flexors and extensors you can see in the photo in the red "This is how it's done" box, for example, may look ludacris (imagine doing that at the gym), its efficacy is however backed by previous research and its working principle is as simple as ingenious: Biceps and triceps, i.e. elbow flexor and extensor, produce resistive forces that act against each other (Tyler. 1986), so that one muscle actually "trains" the other.

You can learn more about training biceps & triceps at the SuppVersity

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Disproportionate Triceps Growth? Is It Real?

In their initial investigation into the effects of muscular co-contraction, the results of which have been published in the International Journal of Sports Medicine in July 2013 (Maeo. 2013b), the researchers have been able to confirm that the muscular activity that occurs during the voluntary co-contractions is a sufficient training stimulus for improving the strength capability of both muscles (Maeo et al. 2013a).

"In fact, previous studies that adopted co-contraction training for elbow flexors and extensors (Driss et al. 2013; MacKenzie et al. 2010; Maeo et al. 2013) found significant increases in the strength capability, as well as agonist electromyographic (EMG) activity during isometric maximal voluntary contraction (MVV) (MacKenzie et al. 2010; Maeo et al. 2013), of the two muscle groups. the previous findings cited above support the idea that co-contraction can be an effective training modality, which does not require any external apparatus, for increasing muscle strength." (Maeo. 2013b)

So, while we are pretty certain that "standing there and contracting your bis and tris" can increase muscle strength (learn how to build strength), there is a scarcity of evidence that would allow us to make reliable statements about the effects of voluntary muscular cocontractions on muscle size (learn how to build muscle). It is thus only logical that the intention of Sumiaki Maeo's, Yasuhide Yoshitake's, Yohei Takai's, Tetsuo Fukunaga's and Hiroaki Kanehisa's follow up study was "to clarify neuromuscular adaptations following 12-week maximal voluntary co-contraction training" (Maeo. 2013b). In that, the researchers hypothesized that

• 

  If you feel like a shadow of yourself, betaine may help | learn more

  the training modality with maximal voluntary co-contraction would increase both size and strength capability of the exercised muscles, and
• training unsing co-contractions does not change involuntary coactivation level during MVC of the agonist alone

In other words: The researchers wanted to make sure that (a) this form of training builds strength and muscle and (b) that it does not have lasting potentially performance decreasing effects on the co-activation of the triceps / biceps, when you actually want to use only one of them (imagine you want to curl the weight up and your triceps works against you).

The study protocol

To satisfy their research interest, the researchers from the Department of Sports and Life Science at the Japanese National Institute of Fitness and Sports in Kanoya recruited 16 healthy young men.

Don't neglect the proven benefits of periodization: "Six Weeks On + Three Weeks Off" Macrocycle Yields Identical Gains Strength and Size Gains as Continuous Training | more

The guys, who were in their early twenties, lean, healthy and habitually active, but not involved in regular exercise programs with a duration and frequency of more than two 30 minute exercise sessions per week, were then randomly assigned to two groups: A training group (T) with 9 participants and an inactive control group (C) with 7 participants. It goes without saying that all participants had to abstain from additional physical activity over the course of the whole study period during.

In those 12 weeks the subjects in the the subjects in T group participated in a 12-week training program with maximal voluntary co-contraction of the elbow flexors and extensors of the right arm 3 times per week.

Usually this would be the paragraph of this SuppVersity article, where I would give you a concise summary of the exercise protocol. In view of the fact that I doubt that many of you are actually familiar with muscular co-contractions, I decided to use a somewhat abridged quote of  the scientists' lengthy, but comprehensive explanation of the procedure (see red box).

This is how it's done: In a standing position with the feet shoulder width apart, upper arm vertical to the ground, the elbow joint at 90° (full extension = 180°), forearm in a neutral (middle of supinated and pronated) position you will perform a 4-s muscle isometric co-contraction followed by 4-s muscle relaxation (total volume: 10 times per set, 5 sets per session; rest: 2 min between sets). Make sure to perform each voluntary co-contraction as rapidly as possible and sustain maximal effort for full 4s!

Basically what the subjects were doing could be summarize as 10x4s maximal isometric muscle contractions with 4s break between each contraction for one set and 5 of these sets with an interim of 2 minutes between each of them three times per week.

Now for those surprisingly impressive results

If you do the math and add up the actual time under tension for this 12-week experimental intervention, you will get 10 × 4s isometric contractions × 5 sets × 3 / week × 12 weeks = 7200s or 2h. That's not really much considering the fact that it lead to strength and size increases of +15% / +27% and 4% / 4% in the elbow flexors (biceps) and extensors (triceps) of the previously more or less untrained, but no necessarily sedentary subjects.

Figure 1: Pre vs. post measures of muscle thickness, MVC torque and coactivation level (Maeo. 2013b)

As you can read in the small box in Figure 1 the increases in size and strength did not occur rapidly after two or three weeks and were then followed by a plateau.In fact, the researchers recorded statistically significant strength and measurable, but statistically not yet significant size gains after 4 weeks.

Probably effective for increases in dynamic performance, as well

Now, brute strength and a huge muscle mass are by no means what all athletes are striving for. For many athletes improving their dynamic performance and strength, which would have required the measurement of changes in isokinetic torques for elbow flexors and extensors in both eccentric and concentric conditions, is at least as important. It is thus more than noteworthy that data from Maoe et al.'s previous 4-week study (Maeo. 2013a),

"[...]in which untrained individuals conducted 4-week co-contraction training, showed that the co-contraction training significantly increased isokinetic torques for elbow flexors and extensors in both eccentric and concentric conditions." (Maeo. 2013b)

As the researchers rightly point out, we do thus have reason to believe that "contraction training is also effective for improving dynamic performance, at least for untrained individuals" (Maeo. 2013b). With respect to trained athletes, the reaserchers do yet argue that they'd require higher exercise intensities to achieve additional improvement in muscle strength than non-athletes (Alway. 1992; Cormie. 2011). This, as well as the emphasis sports specific training puts on ballistic, plyometric, and weightlifting exercises involving sports-specific and/or multi-joint movements (Cormie. 2011), make it difficult to believe that similar training results could be achieved by performing maximal voluntary co-contraction.

Suggested read: "Advanced Trainees Benefit from Increased Training Volume!" | more

Great! But nothing a trained individual can benefit from? It's obvious that someone with a 50cm biceps is not going to add another 2cm in 12 weeks in the course of which he lies around on the sofy and performs 5 sets of voluntary maximal co-contructions thrice a week.

This does yet not mean that this relatively unknown training stimulus cannot make a valuable addition to his training regimen... and let's be honest, haven't we all had a pro-bodybuilder give us a bro-scientific lecture on how flexing, in and out of itself nothing, but a voluntary maximal contraction (albeit not necessarily with antagonistic co-contractions for every muscle part) is a vital part of any hypertrophy oriented strength training routine?

References:

• Alway, S. E., Grumbt, W. H., Stray-Gundersen, J. & Gonyea, W. J. (1992). Effects of resistance training on elbow flexors of highly competitive bodybuilders. Journal of Applied Physiology, 72(4), 1512-1521.
• Cormie, P., McGuigan, M. R., & Newton, R. U. (2011). Developing maximal neuromuscular power. Sports medicine, 41(1), 17-38.
• Maeo, S., Yoshitake, Y., Takai, Y., Fukunaga, T., & Kanehisa, H. (2013). Neuromuscular adaptations following 12-week maximal voluntary co-contraction training. European Journal of Applied Physiology, 1-11.
• Maeo, S., Yoshitake, Y., Takai, Y., Fukunaga, T., & Kanehisa, H. (2013). Effect of short-term maximal voluntary co-contraction training on neuromuscular function. International journal of sports medicine, (EFirst). 
• Tyler, A. E., & Hutton, R. S. (1986). Was Sherrington right about co-contractions?. Brain research, 370(1), 171-175.

Shorter Inter-Set Rest Periods Maximize Muscle Activation During Antagonist Super-Set Training - Downstream Effects on Strength and Size Gains Less Unambigous

You don't have to push and pull at the same time - don't worry!

You may have read Menno Henselmans', Brad J. Schoenfeld's review of the effects of inter-set rest periods on muscle and strength gains in the latest issue of Sports Medicine (Henselmans. 2019). In said paper, Henselmans and Schoenfeld conclude that the increase in the production of purportedly anabolic hormones in response to the reduction of rest-times to 1 min or less is, at best, weakly related to the long(er)-term study outcomes.

The reason I am repeating this previously cited conclusion is simple, I don't want you to overrate the increase muscular activation Marianna F. Mai and colleagues from the Federal University of Rio de Janeiro and the  Eastern Illinois University report in a soon-to-be-published paper in the Journal of Strength and Conditioning Research (Maia. 2014).

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In the corresponding randomized cross-over study the scientists randomly assigned their fifteen recreatinally trained male subjects subsequently to one out of the six resistance training modes outlined in Figure 1:

Figure 1: Summary for experimental protocol trials. TP = traditional protocol; PMR = paired sets with minimal
allowable rest; P30 = protocol with 30-second rest interval; P1 = protocol with 1-minute rest interval; P3 =
protocol with 3-minute rest interval; P5 = protocol with 5-minute rest interval (Maia. 2014)

The recovery period between the experimental protocols, which were executed on conventional resistance training machines, was between 48 and 72 hours. The number of repetitions performed and the EMG activity of vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) muscles were recorded during the knee extension set in each protocol.

So, how exactly did the resistance training protocol look like?

Before all protocols, warm up sets for the knee flexion (KF) and knee extension (KE) exercises were performed for 10–15 repetitions with 50% of the 10RM load, and then a 2-minute interval was instituted before initiating each protocol. To verify the acute effect of rest interval between paired sets of agonist and antagonist muscles, 5 experimental protocols were applied as the following.

• 

  SuppVersity Suggested Read: "Want to Design a Killer Workout? Reduce the Rest Times and Burn 37% More Energy During Your Workout!" | more

  Traditional protocol: the subjects in this protocol performed a set of KE with 10RM loads until concentric failure;
• PMR (antagonist paired sets = APS with minimal allowable rest interval): the subjects in this protocol performed a set of KF followed immediately by a set of KE. In addition, the time allowed for changing exercises (KF and KE) was fixed and controlled at 15 seconds.
• P30: the subjects in this protocol performed a set of KF and after 30 seconds of rest performed a set of KE;
• P1:the subjects performed a set of KF and after 1 minute of rest performed a set of KE;
• P3: the subjects in this protocol performed a set of KF and after 3-minute rest performed a set of KE; 
• P5: the subjects in this protocol performed a set of KF and after 5-minute rest performed a set of KE. 

During the resistance exercises (KF and KE), the 10RM loads were adopted, and the number of repetitions completed were recorded in each protocol. The EMG signal of the VL, VM, and RF was also recorded during the KE exercise.

Will this work for back and chest, as well? Due to the fact that the biomechanics are different, the outcome of antagonistic sets of say bent over row and bench presses will probably be very different. Still, studies by Robbins et al. (2009 & 2010a,b) suggest that push and pull training could produce superior results compared to regular push or pull workouts.

All subjects had previous RT experience (2.7 +/- 0.8 years), with a mean frequency of four 60-minute sessions per week, using 1- to 2-minute rest intervals between sets and exercises. Subjects were on their typical diet, not permitted to use nutritional supplementation, and did not consume anabolic steroids or any other anabolic agents known to enhance performance.

Figure 2: Number of repetitions completed in each protocol and RMS average of EMG amplitude for the muscles evaluated in each protocol; data expressed relative to group means (Maia. 2014)

As you can see there were two factors influencing the muscle activation: The inter-set rest periods and the execution of knee flexion (KF) and knee extension (KE) exercises shortly after each other.

Increases in activity and rep-max (volume) = growth triggers?

Consistent with previous studies by Baker et al. (2005), Balsamo et al. (2012), Burke et al. (1999), Joean et al- (2001) and Roy et al. (1990), the repetition performance increased in response to the antagonist preactivation. This effect was albeit only evident, when the timespan between knee flexion and extension, i.e. the inter-set rest was below 3 minutes.

"Collectively, greater KE repetitions were demonstrated during the PMR, P30, and P1 protocols vs. the TP, P3, and P5 protocols. These data suggested that limited or minimal rest between APS provides the optimal window to enhance repetition performance and muscle activation for the agonist musculature. The longer rest intervals in this study (e.g., P3 and P5) seemed to negate the potentiation effects demonstrated in repetition performance and muscle activation." (Maia. 2014)

As Mia et al. point out, the significantly greater muscle activation observed in the RF and VM muscles for the PMR and P30 protocols might be associated with the increased number of repetitions
completed for these conditions.

Similar results have been generated by Roy et al. (25) who suggested that the preactivation characteristic of APS training has a positive effect on agonist muscles because of the facilitatory stimulation of Golgi tendon organs of knee flexor muscles and muscle spindles of extensor
muscle.

So, shall I train like this? In the absence of data on the chronic effects of the different exercise modalities it is difficult to answer this justifiable question.

Supersets are also among Adelfo Cerame Jr's favorite training techniques | learn more about his "Fave Five", here at the SuppVersity.

The authors of the study at hand are unquestionably right, when they say that "[e]xercise models performed using a reciprocal antagonist/agonist protocol, as in this study, might be less time consuming and could be useful in clinical practice as well as sports performance training." (Mia. 2014).

Next to the increased time efficacy, there may be benefits related to the increase in muscle activation of which you should remember that it is restricted to the 2nd exercise in the superset. In other words, if you decide to copy the protocol in the study at hand, you should be aware that your quads, not your ham strings will benefit. Whether this is also going to result in increased strength and size gains, however, is - as mentioned in the context of rest times in general at the beginning of this article, questionable. In view of the fact that the knee flexions increased not just the muscle activation, but the number of reps, as well, I wouldn't be surprised if the consequent increase in training stimulus would pay off over time | Comment on Facebook!

Reference:

• Baker, Daniel, and Robert U. Newton. "Acute effect on power output of alternating an agonist and antagonist muscle exercise during complex training." The Journal of Strength & Conditioning Research 19.1 (2005): 202-205.
• Balsamo, Sandor, et al. "Exercise order affects the total training volume and the ratings of perceived exertion in response to a super-set resistance training session." International journal of general medicine 5 (2012): 123.
• Burke, Darren G., Thomas W. Pelham, and LAURENCE E. HOLT. "The influence of varied resistance and speed of concentric antagonistic contractions on subsequent concentric agonistic efforts." The Journal of Strength & Conditioning Research 13.3 (1999): 193-197.
• Henselmans, Menno, and Brad J. Schoenfeld. "The Effect of Inter-Set Rest Intervals on Resistance Exercise-Induced Muscle Hypertrophy." Sports Medicine (2014): 1-9. 
• Jeon, HS, Trimble, MH, Brunt, D, and Robinson, ME. "Facilitation of quadriceps activation following a concentrically controlled knee flexion movement: the influence of transition rate." J Orthop Sports Phys Ther 31 (2001): 122–129.
• Maia Marianna F. et al. "Effects of Different Rest Intervals Between Antogonist Paired Sets on Repetition Performance and Muscle Activation." Journal of Strength and Conditioning 28, 9 (2014): 2529-2535.
• Robbins, Daniel W., et al. "Effects of agonist–antagonist complex resistance training on upper body strength and power development." Journal of sports sciences 27.14 (2009): 1617-1625.
• Robbins, Daniel W., et al. "The effect of a complex agonist and antagonist resistance training protocol on volume load, power output, electromyographic responses, and efficiency." The Journal of Strength & Conditioning Research 24.7 (2010a): 1782-1789.
• Robbins, Daniel W., Warren B. Young, and David G. Behm. "The effect of an upper-body agonist-antagonist resistance training protocol on volume load and efficiency." The Journal of Strength & Conditioning Research 24.10 (2010b): 2632-2640.
• Roy, M-A., et al. "Proprioceptive facilitation of muscle tension during unilateral and bilateral knee extension." International journal of sports medicine 11.04 (1990): 289-292.

Sequential or Alternating Resistance Training for Maximal Size, Strength and Endurance Gains!? Plus: Basic Blueprint for a 2x2 Day Alternating Muscle Split Workout

If you want to try something new, but feel that this is a bit over the top, why don't you try an alternate workout regimen to escape the daily grind?

It's funny and sad that studies like the one at hand, which investigate basic training principles and their effect on your real world results in the gym are so scarce. I mean, let's be honest. With a few exceptions, all of us will probably get much more out of training optimization than of any available supplement and maybe even drug. As far as supplements goes, you are bombarded with unwarranted claims and the occasional non-significant (per design) study on newly available products. On the training side of things, on the other hand, there is little to no innovation - probably for a good reason, but still: Would you be able to tell me for sure if and why training sequentially, i.e. finishing all sets of one exercise, is "better" than alternating training, where you would, for example do a set of leg curls followed immediately by leg extensions (not necessarily without rest)?

What's better sequential or alternating?

I see, you are scratching your head... well, maybe you'll feel enlightened, after having read what Hamid Arazi, Siavash Rahmati and Samira Zaheri from the Department of Exercise Physiology, Faculty of Sport Sciences at the University of Guilan in Rasht, Iran have found in their most recent study on the effectiveness of 10 weeks of alternating vs. sequential push and pull training of the large and small muscle groups in 24 healthy male athletes (age 22y, BF% 14, weight 72kg) with a history of at least 3-6 months of weight training (Arazi. 2013).

The actual training protocol, the two groups followed was virtually identical except for the exercise order, of course:

• frequency: 3x /week
• rest: 48h between workouts; 2 min between upper, 3 min between lower body ex.
• duration: 70-80min per workout (20 minutes warm-up + cool down) 
• progression: linear, every two weeks - 60%1RM\12reps < 65%1RM\12reps < 70%1RM\10reps < 75%1RM\10reps < 80%1RM\8reps

• exercise selection: 3 sets of leg extensions, leg curls, rows and bench presses for the major and 3 sets of bicep curls and triceps extensions for the smaller muscle groups
• push vs. pull: leg extension, chest press, and triceps extension are push exercises; leg curl, biceps curl and rowing are pull exercises

• sequential training: "Sequence means each exercise is performed for 3 sets (with intervals of rest) and then next exercise starts moving again." (Arazi. 2013)
• alternating training: "Each session was conducted by leg extension (1 set) and leg curl (1 set). The alternative means the opposing muscles (requires push and pull) that were trained alternatively ." (Arazi. 2013)

The main outcome measures were muscle circumference (hypertrophy), muscle strength and muscular endurance, and the results look like this:

Figure 1: Relative changes in arm and thigh circumference (Arazi. 2013)

As you can see in figure 1 the increases in arm and thigh circumference were more yet not statistically significantly more pronounced in the sequential training group. An observation that would suggest that hypertrophy requires a certain amount of body part specific training density, which is obviously reduced it you do one set of one exercise, rest for 2-3 min, do one exercise for the other muscle group and rest for another 2-3 minutes - that's 4-6 minutes of passive and ~1 min of active rest (while you perform the other exercise) between sets and that's imho simply too much to gain.

Figure 2: Changes in muscular strength and endurance (Arazi. 2013)

Both, strength and strength endurance don't show a clear response - overall maybe a marginal benefit for the longer rest times, but certainly not impressive. At least wrt to the increase in strength endurance once could maybe argue that is may be a simple result of an increased total training volume and - maybe even more importantly - more reps per set, when you train alternately instead of sequentially.

Suggested read: "Intra-Set Rest Periods Boost Power (+38%) & Strength Gains (+65%) Without Hampering Skeletal Muscle Hypertrophy" (read more)

Unfortunately, the "discussion" of the results, the authors provide is not exactly helpful in this regards (it is not exactly legible, either, by the way, and I am usually the last to criticize other non-native speakers for their command of the English language).

Still the overall message the researchers formulate in the conclusion to their paper, where it says that it would be "suggested to use the opposing exercises for strengthening agonist –antagonist exercises" (Arazi. 2013) is not totally beside the point. Nevertheless,I'd expect better hypertrophy effects if you reduce the inter-set rest times  from 2 minutes to 60s and from 3 minutes to 90s for the large and small muscle groups, respectively.

---

Blueprint for a 2-day alternating muscle split to be trained twice a week: Day 1: 4x6-8 bench presses / pull-ups, 3x8-10 military press / your favorite version of rows, 3x12 biceps curls / nose breakers; Day 2:  4x6-8 squats / stiff legged deadlifts, 3x8-10 bent over lateral / front raises, 3x15 leg extensions / hamstring curls; optional 5 min ab training on day 1 and 5 min calve training on day 2; inter-set rest 90s for complex, 60s for isolation exercises.

Bottom line: While the study at hand certainly doesn't provide a conclusive answer to the question whether alternate or sequential training is the way to go for strength trainings, my personal experience is that alternating between exercises for antagonistic muscle groups as in a chest / lat,  biceps / triceps, front delts / upper back, and quads / hams + glutes 4- or 2-day split with relatively short inter-set rest periods (90s for larger, and 60s for smaller muscle groups) can be more than just a diversion from the daily grind at the gym.

You can be in and out of the gym in <40 min and still lift a pretty decent amount of weight; and that, at a lower risk of CNS burnout than with a classic super-set training, where you would not rest between the push and pull movements, at all. The latter allows for a relatively high training frequency, but I would still take a day off between workouts, unless you are trying to cut weight at all costs. In that case, a fast paced training split build around the concept of alternating back and forth between exercises for agonist and antagonist can actually be worth way more than hours of classic "cardio" training or HIIT training. Just don't overdo it! While the individual muscles may still get enough rest, any increase in workout density will also increase the load on the central nervous system.

References:

• Arazi H, Rahmati S, Zaheri S. The Effect Of Two Sequence Patterns In Resistance Training On Strength, Muscular Endurance And Circumference In Novice Male Athletes. Hrvat. Športskomed. Vjesn. 2013; 28: 7-13.