Training for Size & Strength - Does the Rest Matter? Study Finds 7-9% Greater Increase in Muscle Size With Decreasing Rest Periods.

Image 1: If you want to build Arnold-esque arms you better not sit around too long in-between your sets.

"Short rest periods to burn fat, medium rest periods to build muscle and long rest periods to build strength" - it's actually pretty likely that one of your trainers, gym buddies or fatherly mentors told you something along those lines in the past. In view of the results of a soon to be published international study by Brazilian researchers from the State University of Campinas and the Federal University of Rio de Janeiro and their American colleagues from the Eastern Illinois University, the University of Memphis and the Colorado College (Souza-Junior. 2011), this is probably the next item on list of widely accepted bodybuilding myths that have a spark of truth to them... at least for recreational strength trainees who use some creatine monohydrate to promote their strength and mass gains.

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For their study, the results of which are going to be published in the next issue of the Journal of the International Society of Sports Nutrition, Tacito P. Souza-Junior and his colleagues recruited 22 "recreationally trained" men with a minimum of one year resistance training experience at a frequency of 4 sessions a week, who were randomly assigned to one out of two exercise protocols, which differed only in the time the subjects were allowed to rest in-between sets (cf. figure 1).

Figure 1: Identical training protocol for all subjects participating in the study (compiled based on information from Souza-Junior. 2011)

The only difference between the groups was that half of the subjects trained with a constant rest time of 2 minutes between sets over the whole 8 weeks (CI group), while the remaining subjects had to decrease their rest times from week to week (DI group) according to the scheme illustrated in figure 2. The training sessions were supervised and the subjects were " verbally encouraged to perform all sets to voluntary exhaustion". Considering the overall workload and the training frequency, this were probably pretty hard weeks for the 22 trainees.

Figure 2: The rest times decreased according to a standardized protocol by 15 sec each week.

In addition all subjects, who btw. did not follow a standardized diet, consumed the proven creatine + maltodextrin mix (7 day loading phase with 20g/day creatine + 20g maltodextrin followed by a maintenance dose of 5g creatine + 5g maltodextrin taken immediately post workout) that has been used in numerous studies before.

Figure 3: 1RM performance (in kg) for bench press and barbell squat before and after the 8-week training period in subjects with constant and decreasing rest periods (data adapted from Souza-Junior. 2011).

Now, if the initially stated "wisdom" held true, then the 11 subjects with constant rest periods should either have gained more muscle (if you consider 2 minutes a "medium" rest period) or built more strength (if you would say that 2 minutes belong to the realm of "long" rest periods) - yet figures 3 and 4 seem to indicate that neither of that was the case.

Figure 4: Muscle CSA (in cm²) of arm and tigh muscles before and after the 8-week training period (data adapted from Souza-Junior. 2011).

If we have do yet a closer look at the effect sizes, there is yet a notable advantage of the DI protocol in terms of the measured increases in muscle CSA with +14% and +19% in arm and tigh CSA in the constant rest interval group (CI) and +21% and +28% in the decreasing rest interval (DI) group.

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There is a spark of truth to every myth To give you an idea of how significant - and I am talking about "posing significance" not statistical significance here - this is, I have calculated the respective increases in arm- and tigh-circumference, which would differ by 0.4cm and 0.7cm, respectively. Not really outstanding, but nevertheless an important finding of which the researchers say that it lends support to the notion that

decreasing [rest] interval[s] seems to be more efficient than constant interval to produces [sic!] hypertrophic responses.

It has yet to be stated that the 11 subjects in the decreasing rest interval group paid dearly for this increase in muscular hypertrophy, as their "exercise performance" as measured by the total workload per session decreased profoundly from week 1 to week 8: -35% total volume for barbell squats and -30% for bench presses.

The subjects who used constant rest periods, on the other hand, increased their total volume by +20% for squats and by +30% for bench presses. That being said, all powerlifters out there better stick to their constantly (long) rest periods if they do not want to compromise their game.

Tabata Workouts: Do They Work & How Energy-Demanding Are They? 14.5 Kcal/Min Sounds Nice, But You Must Earn It!

Tabata training is intense: So if you don't have the guts to do it on your own, find someone to suffer next to you. Trust me that'll keep you going, if you'd have long surrendered if you had trained alone. Some gyms even offer special courses.

Most of you will probably be familiar with the ultra-short + ultra-intense HIIT prescription that's known as the Tabata protocol. Not really? Well, here is the elevator pitch, then:  "Tabata training," was first described by the Japanese scientist Izumi Tabata in 1996. Tabata and his colleagues (Tabata.1996) conducted a study that compared moderate-intensity continuous training at 70% of maximal oxygen consumption (VO2max) for 60 minutes, with HIIT conducted at 170% of VO2max. The HIIT training consisted of eight, 20-second all-out exercise bouts followed by 10 seconds of rest for a total of 4 minutes of exercise. Based on what you have read about the contemporary HIIT research here at the SuppVersity, you will be aware that Tabata's protocol is more intense, but also much shorter than the currently favored HIIT regimen with their ~1-4min (sometime even 8min!) intervals at 80-100% intensity.

Now, the "original" study found that HIIT improved aerobic capacity to a similar degree as moderate intensity continuous training (aka LISS). Nevertheless, it did resulted in an impressive +28% increase in anaerobic capacity.

Tabata 2.0? Is it time for a modification?

Meanwhile Tabata training has evolved to include a variety of modes and exercises. What has always remained an essential characteristic of this type of HIIT training, though are the classic 20-10 patterns (i.e., 20 seconds of all-out effort followed by 10 seconds of rest).

According to Talisa Emberts, John Porcari , Scott Doberstein, Jeff Steffen and Carl Foster, the general physiological effects of this type of training are well documented. What would be lacking, however, is data on the the relative exercise intensity and energy expenditure of Tabata training (Emberts. 2013). Therefore, the purpose of the study at hand, which comes right from the labs of the Department of Exercise and Sport Science at the University of Wisconsin, was to determine the u exercise intensity and energy expenditure of a Tabata workout.

What did the scientists do?

In order to measure the energy expenditure, the researchers recruited 16 trained volunteers (8♂: 35.3 ± 8.1 years, 1.81 ± 0.06 m, 93.7 ± 8.70 kg, 53.2 ± 0.6 ml·kg·min -1; 8♀: 28.4 ± 9.3 years, 1.71 0.09 m, 71.9 ± 12.0 kg, 42.9 ± 11.3 ml·kg·min -1). After the usual initial fitness tests, each subject completed two identical workouts.

Table 1: .Exercises included in the 20-minute Tabata workout; each exercise was repeated twice at a ratio of 20 sec exercise/10 sec rest

• workouts consisted of four, 4-minute "segments".
• segments consisted of performing the exercises listed in table 1 twice in succession.  

• subjects completed as many repetitions of each exercise as possible in 20 seconds followed by 10 seconds of rest.

• there was 1 minute of rest between each segment.  

As Emberts et al. point out, they "chose to do the four segments of Tabata in succession, since one of the criticisms of Tabata training has been that individuals cannot burn a sufficient number of calories in 4 minutes to favourably impact energy balance" (Emberts. 2013)

Figure 1: Energy expenditure per minute and total energy expenditure in 20 vs. 4 min TABATA studies (Emberts. 2013; Olsen. 2013)

A brief glimpse at the data in figure 1 goes to show you that the relative energy expenditure per minute was as impressive as in previous studies:

"Caloric expenditure averaged 14.5 ± 2.7 kcal·min -1 , which is very similar to the value found by Olsen (2013), who reported a slightly lower value of 13.4 kcal·min -1 . This was probably due to the fact that her study included 13 women and only 3 men. Total energy expenditure ranged from 240 to 360 kcals for the 20-minute workout, which is significantly higher than the estimated 54 kcals expended during the 4 minutes of exercise reported by Olson." (Emberts. 2013)

What was also impressive, though, was the rate of perceived exertion (RPE), which averaged 15.4  ±  1.3 for the two workouts and was that rated as "hard" by these already trained subjects. I mean, ask yourself what an untrained individual would have been telling you after high knee runs, plank punches, jumping jacks, side skaters, rope jumping, in/out boats, line jumps, push-ups, burpees, russian twists, squats, lunges, mt. climbers, push-ups, split squats and box jumps... right probably nothing: The average sedentary inhabitant of the Western Obesity Belt would simply have collapsed after two exercises ;-)

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If you are a pro (and I mean "are" and not think of yourself as one) looking for an intense workout that will help you cut body fat and gain muscle at the same time, look no further. The cross-fit protocol Smith et al. used in a study I wrote about earlier this year has what you are looking for - unfortunately it has a similarly insane intensity: "From 16% to 8% Body Fat in 10 Weeks: Crossfit Workout Gets The Leanest Shredded - But Only the Fittest Survive" (learn more).

240-360kcal/s in 20 min - is that worth it? It stands out of question that trained individuals who are willing and able to give their muscles and more importantly their central nervous system the recovery time they will need after these workouts will greatly benefit from the intensity of a Tabata routine like this. This is after all, the "uncomfort zone" in which someone with years of training experience under his / her belt can still enforce adaptation.

Contrary to the trained athlete, for whom the total amount of energy expenditure is secondary to proving new "growth" (the word refers to general growth as in increases not just in muscle power or size, but also overall conditioning) stimuli, the rookie and even many intermediate trainees are however going to be overwhelmed by the physical (some also by the mental) demands of this workout. For him / or her, a combination of strength training and LISS (rookie, or someone trying to cut weight) or strength training and "regular" HIIT (advanced trainee) may be thus in fact be  better choice. Not necessarily because it would burn more calories, but rather in view of the fact that it is not as overtraining prone as a 20min session of Tabata training.

References:

• Olson M. Tabata  interval  exercise:   Energy  expenditure and post-exercise responses. Medicine & Science in Sports & Exercise 45. 2013; S420.
• Emberts T, Porcari J, Doberstein S, Steffen J, Foster C. Exercise Intensity and Energy Expenditure of a Tabata Workout. Journal of Sports Science and Medicine. 2013; 12:612-613

True or False? Lower Rest Times Equate Lower Total Work Volume for a Given Workout. Plus: The Volume-Increasing Beauty of Progressive Exercise-To-Rest Ratios

Are short rest periods overtly exhausting and will reduce your training volume and compromise the beneficial effects of your workouts?

It sounds completely logical. If you rest less you cannot move as much weight, because you will feel jaded due to the "insuffient" rest (I wonder who defines what "insufficient" is...?). Scientists from the University of Rio de Janeiro have now put this cornerstone of conventional training wisdom to the test and found that things are - once again - not as easy as it would seem.

To this ends, the researchers recruited 16 young trained subjects with at least 1 year of previous training experience and tested the effect 5 different rest protocols would have on the total volume of otherwise identical workouts.

Short vs. long, progressive vs. constant and fixed intervals

Now, instead of telling their subjects to simply rest one minute or three, the researchers had them train the same bench press and triceps extension protocol with 5 sets for each exercise following

• 

  Suggested read: "Does Rest Matter? Study Finds 7-9%  Increase in Muscle Gains W/ Decreasing Rest Periods." | read more

  exercise to rest ratios (ERR) of 1:3, 1:5, 1:7 and 1:9 (meaning if an exercise lasted 30s, you would rest 90s, 150s, etc.), or
   
• progressively increasing exercise to rest ratios (i.e 1:3 after the first, 1:5 after the 2nd, 1:7 after the third and 1:9 after the fourth set), or
   
• fixed 2 min rest intervals as you can find them in many of the cookie cutter training prescriptions out there

According to the researchers, these intervals were chosen based on the recommendations by Pincivero et al. (1997) and amount to rest times between 45s and 270s depending on whether trainees perform their exercises at 75% or 90% of the RM (75% ~30s TUT; 90% ~15s TUT).

So what's the optimum, then?

The researchers assessed the number of repetitions per set, the total volume in each set & the whole exercise and calculated the percent variation of the maximum number of reps that were performed within a set. As you can see in figure 1 the differences in terms of maximum reps were not exactly earth shattering - still based on what we see here, you could argue that at least the 1:2 protocol offers a bit too little rest for a compound exercise such as the bench press.

Figure 1: Relative decrease on the transition from one set to another during the 1:3-1:9 exercise:rest ratio intervals, the progressive exercise:rest ratio (IP) and the fixed 2min rest condition (Monteiro. 2013)

On the other hand, the progressively increasing exercise to rest ratios seem to be something that may actually be worth copying. After all, the performance loss on subsequent set appears to be minimal with this workout strategy.

Figure 2: Total volume in reps for the different ERR conditions (Monteiro. 2013)

With an identical total volume (see figure 2) and given the fact that the workout density, i.e. the ratio of training volume to training time, appears to have beneficial effects on the "anabolic hormones", and clear advantages for anyone trying to get rid of some body fat, the IP strategy that did use exercise to rest ratios (ERRs) of 1:3, 1:5, 1:7, 1:9 would probably be a great compromise. That will allow you to handle maximal weights up to the last set and still train with a high volume, while taking advantage of a faster pace on the earlier sets in your workout.

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"Ah come on, just another set!" ... "I don't know man, we've already pumped away 100,000kg today... do you really believe that's going to be productive, I mean, yeah, we are cuttin', but still... I mean I don't dig this epic!", "EPOC man, it's called EPOC!" *shakes his head* "Call it whatever you want, bro, I am out!" Interested in the background of this conversation (read more)?

Bottom line: Coming back to the original question from the headline, the most astounding result of the study at hand may in fact be that only the 1:3 exercise:rest ratio produced a statistically significant reduction in total volume. And we do noteven know for sure, whether it would result in suboptimal lean mass and strength gains. Mass gains, in particular, have after all not been found to benefit from rest times beyond 90-120s (Ahtiainen. 2005); and as of now it is unclear whether they would be compromised by rest times ranging from 40-90s, as they were recorded in the 1:3 condition in the study at hand.

So, even if the results of this study tell us only little about the optimal length of the rest period, they do tell us something about an (imho) quite interesting yet rarely applied approach to determine the amount of rest you would need in-between sets, namely by specific ratios of total time under tension to subsequent rest - or, put differently: By resting X seconds for each Y seconds you've just been lifting.

References:

• Ahtiainen JP, Pakarinen A, Alen M, Kraemer WJ, Häkkinen K. Short vs. long rest period between the sets in hypertrophic resistance training: influence on muscle strength, size, and hormonal adaptations in trained men. J Strength Cond Res. 2005 Aug;19(3):572-82.
• Monteiro WD, Venturim FO, Perez AJ, Farinatti PT. Work volume in strength training is not affected by rest interval strategy. J Sports Med Phys Fitness. 2013 Jun;53(3):312-8.
• Pincivero DM, Lephart SM, Karunakara RG. Effects of rest interval on isokinetic strength and functional performance after short-term high intensity training. Br J Sports Med. 1997 Sep;31(3):229-34.

Intra-Set Rest Periods Boost Power (+38%) & Strength Gains (+65%) Without Hampering Muscle Hypertrophy

Up your strength /check! Up your power /check! Up your muscle gains in the long term /likely!

Intra-Set Rest Periods? No, that's not identical to "clustering" or "cluster training", although it may appear as if it was. Ok, let's briefly summarize what IRS / clustering is: Basically the idea is to perform the exact same amount of reps and thus work with a heavier weight than usual to induce greater gains (usually strength gains). Now how can you do that? Well, one possibility would be to simply add another set, so that you would now be doing 4 set of 10 reps instead of the usual 3 sets of 10 reps. Unfortunately, this is yet nothing but another instance of the notorious more helps more approach of which you should by now have realized that it is pointless and ineffective.

Now things are getting a little complicated, because contrary to a classic clustering regimen, where you would add weight to the bar, do say 8 reps, take 10 breaths and rep out the other two, the intra-set rest (IRS) period protocol in the Oliver study employed a tightly controlled and not an "ad hoc" variety of "clustering". Contrary to the control group who performed a regular 4x10 routine, the IRS group broke their 4 sets of 10 with 120s rest between sets up to eight sets of five with only 60s of rest in-between the exercises (see table 1 for more details)

Table 1: Overview over the workout program (adapted based on Oliver 2013)

It's easy to see, there is no black magic involved. Same lifts, same plan, same progression, but different set x rep scheme and inter-set rest for the STD vs. ISR groups. In the fourth unloading week, tests were conducted and the same protocol was repeated with accordingly increased weights. All sessions were supervised and the compliance was 95% over the whole 3x4 week study period.

Remember: This is not "clustering"! When you "cluster" your training volume will increase, the IRS protocol, on the other hand, is standardized in a way that the total workload will (and in in the study at hand did) remain the same.

The participants of the study had all been doing upper + lower body resistance training for at least 2 years and were thus familiar with the basics of strength training, before the study they received nutritional counseling which is probably the reason that all of them increased their protein intake significantly (ca. +50g to ~190-200g/day; no inter-group difference).

The same goes for the changes in muscle fiber and body composition. All subjects experience an increase in MHC-IIa fibers (glycolytic) and gained lean mass continuously. Unfortunately, they also gained body fat, so that the body fat % (DEXA measured) did not change at all.

The power and strength advantage

What did however react to the modified rest times were the changes in strength and power on all the major lifts. According to Oliver, et al.

Table 2: Effect size and qual. inferences on intergroup difference; (t)rivial, s - (s)mall, (m)edium., (l)arge (Oilver. 2013).

"Only subjects in ISR experienced an increase [in 1RM bench press & squats] at 4, 8 and 12 weeks. This corresponded to greater increases at 4 (ISR, 6.6±6.6 kg; STD, -1.4±6.2 kg; p= 0.012), 8 (ISR, 9.9±6.8 kg; STD, 2.9±5.8 kg, p = 0.016) and 12 (ISR, 15.1±8.3 kg; STD, 9.1±3.7 kg; p = 0.051) weeks.

[...] Again, only ISR increased at 4, 8 and 12 weeks. Greater percent increase from baseline was observed in ISR at 4 and 8 weeks (p = 0.017 and 0.034, respectively), with 12 weeks approaching significance (p = 0.082)." (Oliver. 2013)

Similar differences were observed on the power output strength, where the group difference at both 8 weeks (ISR, 151.0±74.0 W; STD, 97.5±60.9 W; p = 0.084) and 12 weeks (ISR, 282.1±104.1 W; STD, 204.9±70.2 W; p = 0.063) approached significance with subjects in ISR showing a greater increase. Interestingly, the advantage became even more obvious, when the changes for normalized for the subjects' body weight (from p = 0.084 to p = 0.016 and p = 0.063 to p = 0.038 after 8 and 12 weeks, respectively - that means what may be at best a trend on an absolute level is a statistically significant advantage if you take the muscle mass into account, as well)

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Bottom line: It sure looks as if IRS would in fact be a viable training strategy for anyone training for muscle hypertrophy, strength and power. Neither the workload, nor the workout time changes and still the results improve. And I can hardly phrase it better than Oliver et al. did:

Suggested read: "Training for Size & Strength: Does Rest Matter? Study Finds 7-9% Greater Increase in Muscle Size With Decreasing Rest Periods." (read more)

"Based on these results, it could be suggested the incorporation of ISR in the hypertrophic phase of a traditional or non-traditional periodized training program would allow for greater improvements  in strength and power. 

Whether these improvements would result in greater gains in strength and power output over an entire mesocycle is unknown, but hypothetically entering the strength and power phases of a training mesocycle at higher performance ability (strength and power) would allow a continued improvement above that achieved during traditional training models." (Oliver. 2013)

What? Oh, yes... I will tell you if the researchers ever conduct this study. To be honest, I am yet pretty sure that this is not going to happen. After all, the results won't be patentable and since we are dealing with healthy people (worse athletes!) the governments of the Western Obesity Belt are more likely to burn a few additional millions to find new pharmacological methods to prolong the misery of the increasingly obese majority of their citizens - I mean, who would vote for them if they told people that we already had the solution to the obesity epidemic, but it was not available in convenient pill form?

References:

• Oliver JM, Jagim AR, Sanchez AC, Mardock MA, Kelly KA, Meredith HJ, Smith GL, Greenwood M, Parker JL, Riechman SE, Fluckey JD, Crouse SF, Kreider RB. Greater Gains In Strength And Power With Intra-Set Rest Intervals In Hypertrophic Training. J Strength Cond Res. 2013 Jun 3. [Epub ahead of print]