Figuring out Rest Periods for Your Training Goals

mc, PhD (human factors), CSCS, RKC

November 20, 2008 11:42 AM

A question that comes up frequently in discussions about exercise is "how much rest between sets" whether one is doing deadlifts or pullups.

To help folks answer this question for themselves, it might help to have an idea of what's going on with the usual weight/rest (or weight/wait) prescriptions, as each has different effects in terms of type of muscular changes and metabolic system adaptations. I hope at the end it will be even clearer that kettlebells really are remarkable fitness tools. It's hard to think of another fitness tool that works across as many of these variables.

As is generally the case in fitness, deciding what to do, such as figuring out how long we might want to have a break between sets, depends on our particular training goals.

To help put the recovery question into context, I'll go through the usual categories of muscular adaptation for strength, power, hypertrophy and endurance and the role of recovery in developing these kinds of adaptations. I'll wrap up by applying these approaches to Steve Freides' RKC Snatch Test Program (http://www.dragondoor.com/articler/mode3/429/).

Note, I started this article in May of 2008. Just this month, July 2008, a very good brief research review of the research literature on rest periods and types of strength has been published [will-2008b]. I'd recommend taking a look at that if after this piece, you're interested in more of the nitty-gritty.

Rest and Weight (or Wait and Weight)

First, rest is generally correlated to the weight being used, which is generally correlated to some kind of Rep Maximum. Usually a 1RM. Thus, rest in resistance training is largely related to goals - what you're trying to achieve in your training. Of course we can break for as long as we want, but length of break has an effect on types of results, and thus is best matched to types of load being used.

Rest for Muscular Strength & Power

Work on recovery for both Strength and Power has shown that both modes seem to require the same rest prescriptions. In strength, one is looking at performance of maximal loads - being able to do a single rep at a maximal level. In powerlifting, it's strength and speed of muscle action. [ACSM-02, Baechel-00] Training reps are usually in the 3-5 range. Here rest periods between sets are about 2-5mins long, depending on the papers you read (for example [Abd-99],[Law-06])

Why do you need that kind of recovery for these kinds of weights? Because these lifts use a particular part of our energy systems more than others, in this case the Phosphogen system, to generate the chemicals needed to fuel our muscles for these brief powerful bursts of energy, and that system gets tapped very quickly. It needs anywhere from 21 secs to a minute to about 3 minutes as shown by Fleck and Krammer [fleck-87], and by Harris [har-76].

An analogy of how the phosphogen system gets wiped out might be what happens when you go from a dark room to a bright one all at once: your eyes feel blinded - that's the rhodopsin in the rods of the eyes getting bleached - it takes some time for the chemicals to recharge and adapt back to the light. A set of intense near 1RM lifts likewise wipes out the chemicals in the phosphogen system (think creatine) that let the muscles contract.

In an overview of Rest literature, looking at optimal reps/power configurations, Willardson suggests one way to optimize power training is to use sets broken into blocks of triples with two minutes rest between blocks, and three minutes between sets. [will-08b]

For strength, the prescription is similar, except that here, when folks are working for absolute strength, they will from time to time go to sets for failure. In this case in particular, when doing more than five sets, rest intervals of 3 minutes between sets enabled more sets to be completed than with 1 or 2 minutes [will-03] Now that was with testing just the bench press, so there may be some variability in the squat, say, but 3 mins. is a practice you'll also see strength coaches use effectively.

So, if your goal is to do the Beast Challenge and do one pull up with a 48kg bell attached to you, you'd be doing 85-90% sets of 3 reps of whatever your current 1RM weighted max is with -2-3 min rests in between sets. Tight, comrades!

What's really neat is that it's our breathing hard between sets, during this rest, that helps us rebuild those chemicals we need for energy. So if you feel yourself *after* your last rep breathing harder than during your set, that's a good thing. Fleck and Krammer [fleck-87] did the foundational work to show that that's our oxidative system (aerobic work) resynthesizing phosophocreatine and ATP, the core ingredients for energy.

So, if we're looking for power or strength, decent recovery intervals are critical, otherwise we just don't have the fuel to power the lifts.

Rest in Muscle Fiber Development (Hypertrophy)

If your goal is to be whipping off more bodyweight pullups than the single beast pull up, we're shifting gears and actually pushing into the area of muscular hypertrohphy and endurance. This is not to say that to do lots of pullups you're not strong and powerful, or that if you do one beast pull up, you can probably bang off a dozen bodyweight ones; just that for that activity (more reps before a rest), you're actually working a different kind of engagement with your body than in maximal or near-maximal lifts.

In the Hard Style community there has been some diss'ing of hypertrophy because of associations with bodybuilding, and the sense of some approaches to bodybuilding that seem to be all about frankensteining body composition and less to do with athleticism and strength. But hypertrophy is a normal part of an athletic training cycle. So what is it, really? Hypertrophy is mainly a consequence of the cross sectional area of the muscle fiber increasing. This growth occurs as the muscle fiber adapts to particular kinds of loads. In particular, this increase is the result of the muscle developing more binding sites (myosin and actin bridges) along the muscle. These sites take up space. More of them means greater cross sectional area of muscle fiber.

Why develop more binding sites? That's related to how a muscle contracts: it's very similar to what Dr. Andrew Fry describes [fry-05] as adding more pairs of hands to a rope in a tug of war. Up to a certain point, the greater the number of hands, the better the ability to achieve work against the resistance. This is also, by the way, a good reason to ensure sufficient carbs and water in training: carbs are not only valuable fuel for training, they also help muscles retain water. That doesn't mean bloating, it means health - like a river that's within its banks rather than run dry from drought. The effect means that those binding sites when sufficiently hydrated literally have room to grab. To use the rope analogy: how effective are all those extra hands on the rope if they take up any available room to actually work the rope to pull it in? A dehydrated athlete likewise has compressed the room those muscle fiber sites have to grab and pull back on the muscle fibers in a contraction.

Muscle fibers are tiny thin things; they get bundled, and these bundles are wrapped in collagen as a protective cover - the same stuff that is found in bone, tendons and cartilage. This collagen can get thicker as part of the hypertrophic process. So, hypertrophy equals more sites to enable the muscle to contract; more sites, greater load.

Some bulking can occur from hypertrophic adaptation. Take a look at images of Tracy Reifkind's shoulders in her blog videos (http://tracyrif.blogspot.com/) that's an example of hypertrophy in a strong, powerful woman who swings. A lot. And snatches. A lot. Tracy did not necessarily traing to achieve big shoulders: they are an unavoidable consequence of the adaptation to support the work she does with a kettlebell.

So what prompts that adaptation in terms of rest and weight? First, it's lighter loads than strength/power. Maybe now that starts to make more sense as to why: lighter loads (not *light* just ligher) can be lifted for longer. You can pick up a 75% of 1RM weight more times than you can with a near 1RM. Second, there are also more reps in the sets (6-10; often to failure): lighter weight more reps for equivalent or greater volume of work to that of a powerlifter. Third there are shorter rest intervals between sets (30s - 1.5 mins, again depending on the papers you read). Why the shorter rest periods (and why to failure)? There's a bunch of reasons but a biggie is related to triggering an anabolic effect - that is, muscle growth, and that means triggering growth hormone (GH). So, gating at a 10 or 15RM, 10-15 reps per set, with 30sec-1min rest between sets.

Another biggie here, related to GH, is the energy system being taxed by hypertrophic training. In this case, it's the glycolytic system - the one that privileges carbs as the fuel source for intense but longer than a set of triples as a bout of work. It's in pushing this system that we start to hear about lactic acid, lactic acid buildup, and working so hard on a set someone pukes. As we know, working the system so hard that it cannot process the waste products like the H+ from lactic acid production is not a good thing. Some body builders may go to these edges occasionally, but they are the rare elite who have done Everything Else First to squeeze mass out of their efforts. Is that the profile of a Hard Style athlete?

For improving hypertrophy - literally *building muscle* - we need to make sure the load is appropriate to ensure 10-15 reps can be completed. This sounds like some of the rep ranges used by Hard Stylers when working with mid to heavy weight kb's: 10-15 swings; break. In other hypertrophy circles, we're looking at 6-12 reps.

So some degree of hypertrophy - muscle fiber growth - is not a Bad Thing. Even powerlifters or Olympic lifters will experience muscle growth, along with neuromuscular adaptation. Hypertrophy is a natural adaptation to the damage caused by taxing muscles. The ripped physique that Pavel applauds of the classic form is a consequence in part of high volume work with mid-heavy weights and short rests between sets. Sounds like the programs of a lot of kettlebellers.

As for not wanting to get bulky, remember, individual muscle fibers are really really small. It takes a lot of effort to pack on noticeable amounts of "bulk." It also takes fuel. You have to *feed* muscle growth with carbs and amino acids. Most hard stylers do not either eat or perform the volume of work to enduce mega mass. So, a hard styler may get more wiry or "hard" rather than body-builder bulky. Ya don't really have to worry about getting strong without getting bulky. Muscular bulk doesn't happen by accident; it takes intent.

What about Failure?

Just to put this point in context, i mentioned "failure" above - another dirty word in the Hard Style community. Even powerlifters occasionally train to failure. Emphasis here is on occasionally as part of absolute strength work.

With respect to hypertrophy, research that looked at *just* the production of growth hormone showed that athletes who went to failure vs those who did not in their sets had higher levels of GH after their bouts [lin-05]. Great. But what's the down side? Burn out? Being taken out of action so that no more reps are possible? Is there anything wrong with a little less GH? Live to train another day, perhaps?

Indeed there are numerous training systems for hypertrophy from Charles Staley's Escalating Density Training massive arms program

(http://store.staleytraining.com/index.asp?PageAction=VIEWPROD&ProdID=38) to Boris Klein's Hypertrophy Specific Training (http://www.hypertrophy-specific.com/hst_index.html), that show great effect without training to failure. The results of these protocols are demonstrated through the testimony of the programs' designers with their clients and the number of trainers who have applied these programs with their clients, as opposed to specific clinical trials.

Endurance

Besides hypertrophy, hypertrophic-like sets can have a carry over into endurance: these shorter breaks not only contribute to muscle fibers growth, but they also help improve our ability to process lactic acid, via interval training like Kenneth's VO2max protocol. Remember most of this hypertrophy work is taxing the glycolytic energy system. There's a threshold not only of how long this system can provide energy before it's depleted, but consequently the maximal amount of work it can do before it's depleted. So ideally, we want to be able to do more work without taxing that energy system (or what's more currently called the "fast glycolytic" system).

A bit of background:

Most endurance work is carried out with our aerobic system - the energy system we use predominantly with every breath we take. This is the primarily fat burning system. How can you tell which energy system you're using. Here's an easy heuristic: can you carry on a conversation while you're doing the activity? If you can't, or can barely get two words out, you're likely going anaerobic. If you can. Even. with. pauses. in. between. words, you're likely mainly aerobic.

So you may happily be able to swing a 12kg kettlebell for 20 mins non stop and carry on a conversation - with - breaks - between - words - but - still - ok to talk - at a certain speed. But what happens if someone says "swing faster"? We can no longer carry on a conversation; to keep up that pace we have to shut up and swing, and can only swing for a limited period of time. Why? we've pushed into the shorter lasting glycolytic system for our muscle fuel at this point.

So, how do we get greater work (heavier loads for longer or same loads faster for longer) and stay down in that fuel rich aerobic, fat burning space? We work on improving our capacity to use oxygen in the body, or what's commonly known as our VO2max. In this case, athletes work for brief periods *above* their VO2max capacity - they work in the glycolytic or mainly anaerobic system, and then they recover for about the same time as they work. To achieve the right above VO2max levels, they need to achieve a particular cadence of activity at a particular intensity for that particular period. In the Kettlebell world, Kenneth Jay's VO2max Snatch Protocol

(http://rifsblog.blogspot.com/2007/07/original-kenneth-jay-post-on-dragondoor.html) is an excellent example of determining what the cadence with a particular weight bell needs to be for a given interval to achieve that above VO2max level of effort.

A quick aside: it may seem a wee bit weird to say do work OVER 100% of VO2max. Afterall, we can't go *over* our max heart rate. VO2max, however, means our capacity to use oxygen for effort. As we've already noted we have other energy systems that do not use oxygen to provide fuel. We don't mean that we stop breathing - we'd be dead. We mean that we use fuel other than 02 for effort once we go beyond what that O2 system can provide. That's why we want to improve our capacity to do more work in the O2 space, and so save those limited non-02 dependent fuel stores for when we really need them.

VO2max work has a terrific consequence of also adapting our bodies to be able to use and clear greater amounts of lactic acid for energy in our system. It's not well known that our muscles even at rest are producing lactic acid, but they do all the time. Our muscles use this acid for fuel on a regular basis (check out monocoaboxylate transport for more info if you're interested) [brooks-05]. Indeed, rowers are famous for instance for being able to handle what to an untrained population would show up as levels of blood lactate only seen in heart attack patients [green-05]).

So, intense appropriately cadenced intervals improve endurance by improving capacity to do more work aerobically rather than anaerobically. A key part of that protocol is the interval, or the work/rest ratio, so let's consider how that works to improve endurance.

Work/Rest Prescription for Endurance

Endurance work in the resistance space generally means lighter (not light; lighter) loads, shorter rest intervals (30 secs or less), and more reps (greater than 12) (Camp-02). Combining these variables means higher levels of fatigue. It should be obvious now why the load has to be lighter: a lighter load means going for longer; if only fewer reps are possible, you're pushing into hypertrophy or strength, not taxing or training the aerobic system.

That said, with endurance work, the state of the individual may need to be taken into account: someone untrained may need greater rest intervals initially to achieve benefit, vs someone more trained, who requires less than 30sec rest times to continue to make progress (Wil-08).

Note this is resistance training type work, where a LONG set is the ten minute SSST. In athletic events like distance running or cycling, training cycles are longer, and "staying out for time" is a critical part of adapting energy systems and muscular function. In these cases different types of muscle fibers are privileged than in resistance work. What each of these endurance activities have in common, however, is that each focuses on pushing more work to be able to be done longer and more efficiently at an aerobic level, rather than taxing the glycolytic system; and when the glycolytic system is taxed for fuel, we are better able to handle and flush the waste products created by that, and thus off set fatigue for longer, resulting in getting more work done.

In this case, of pushing the lactic acid threshold, and of simply working hard for longer, improving our maximum oxygen uptake so that our muscles can utilize more oxygen (stay anaerobic longer) that adaptation means greater mitochondrial density - greater ability to carry O2 to the muscles - better aerobic capacity. More work gets done at that non-pukey, breathing ok, level.

Putting it together with the Snatch Test and Longer

Steve Freides' article on the Snatch Test Prep program (link/ref) is an excellent example of work that takes us through converting the snatch test from a strength/power focused activity into a hypertrophy/endurance one.

Consider, as Steve puts it

Level 1: Short Sets, Full Recovery, Perfect Technique

Level 2: Increase Volume

Level 3: Shorten the Rests

Level 4: Long Sets

In level 1, the KB feels pretty dam heavy to snatch once. If it didn't you wouldn't need this program. Therefore doing a few reps, with long breaks, means you're building up strength. Without basic strength there's no endurance.

In Level 2, as you build up more sets with similar rest periods, you're bulding more strength.

You're working that phosphagen energy system and working on replenishing it with the rests to be able to support you with what still feel like those all out efforts.

In level 3, as you shorten the rest breaks, and perhaps getting more reps into a set, you're moving away from brute strength (because you're stronger and the weight hasn't changed) to hypertrophy: building muscle mass now, too. That lean mass is good for you on a number of levels. Go for it! good for you. Assuming you have enough fuel in your system to provide energy, fatigue is still an issue if you don't have breaks to regnerate that energy. As you work at this level, breaks are getting shorter: happy days, your lactate threshold may also be moving up as it takes longer for fatigue to set in at this weight of bell.

In level 4, you guessed it: with set breaks reduced to zero, you have longer sets, into minutes at a time, and you're now talking endurance. Your fatigue level with this weight of bell has gone down sufficiently to allow you to keep going for the necessary period.

Now, ok, technically for the RKC Snatch Test, you may only be going for a wee bit over three minutes, if that, and that's barely getting into what is technically an endurance level activity - that is, moving from predominantly the glycolytic metabolic effort and into the oxidative one. Folks like Tracy and Rif, and Girevoy Sport practitioners, however, are doing exactly that move into the oxidative/endurance space when they're swinging non-stop for anything over 3 mins. Endurance - efficient use of energy systems - is critical.

These same phases of strength/power, hypertrophy, endurance are modeled in Pavel's ETK for building up to a heavier kettlebell in pressing, complemented with arbitrary length swing/snatch session: tapping those different energy systems with balance of weight/rest for success: do ladders progressively with one weight; then go back down and start again with the next weight, laddering up. As the starting rung it's heavy, so only a few rungs; over time with the ability to do more rungs/reps, it's lighter. The weight moves from strength work to hypertrophy work. The swings/snatches get endurance work in their to round everything out.

Summary

+ Strength/Power - Phosphagen System mainly - full recharge needs 2-5 minutes based on a high load few rep set

Can add volume (no. of sets) without changing rep scheme or break length

+ Muscle Fiber Building/Hypertrophy or just want to get to somewhat longer sets
Taxing Glycolytic system and growht hormone triggering - recovery is not full recharge
6-10 reps at 75% load-ish, 30sec - 1.5 mins rest

+ Endurance - want to just keep going
Tapping into oxidative system with 50%'ish RM loads (or less)
lighter loads, longer sets, less breaks - 10-15 reps with 30 secs breaks, max, if trained; longer if not.

I hope the above helps make clear another reason why kettlebells are such powerful tools: they make it easy to work ourselves out wholistically: we get time in a KB cycle to work out each energy (metabolic) system; we consequently get to work our muscles in a variety of ways for strength, power, hypertrophy and endurance. And it's good to have 'em all: a lowly bodybuilder could lift a lighter weight longer than a power lifter, even though the power lifter is "stronger"; a runner will get away from the tiger even though the strong person *may* be able to crack open its jaws to get his head out, but a hardstyle kettlebeller is truly smart, and will have read the sign that said "wild tigers loose" and gone to swing somewhere else, and live to press another day.

mc
PhD (human factors), RKC, CSCS
http://begin2dig.blogspot.com
http://nopain2.org
http://nopain2.org/geekfit

Endnotes:

[Abd-99] Abdessemed, D, Duche, P, Hautier, C, Poumarat, G, and Bedu, M. Effect of recovery duration on muscular power and blood lactate during the bench press exercise. Int J Sports Med 20: 368-373, 1999.

[ACSM-02]American College of Sports Medicine. Position stand: Progression models in resistance training for healthy adults. Med Sci Sports Exerc 34: 364-380, 2002.

[Baechel-00] Baechel, TR, Earle, RW, and Wathen, S. Resistance training. In: Essentials of Strength Training and Conditioning. Beachle, TR and Earle, RW, eds. Champaign, IL: Human Kinetics, 2000. pp. 395-425.

[brooks-05] Brooks, George A., Gahey, Thomas D., Baldwin, Kenneth M.. "Glcogenolysis and Glycolysis in Muscle: The Cellular Degradation of Sugar and Carbohydrate to Pyruvate and Lactate," Exercise Physiology: Human Bioenergetics and Its Applications, 4th Ed. NY: MacGraw-Hill Company, 2005, 83-91.

[camp-02] Campos, GER, Luecke, TJ, Wendeln, HK, Toma, K, Hagerman, FC, Murray, TF, Ragg, KE, Ratamess, NA, Kraemer, WJ, and Staron, RS. Muscular adaptations in response to three different resistance-training regimens: specificity of repetition maximum training zones. Eur J Appl Physiol 88: 50-60, 2002.

[Flec-87] Fleck, SJ and Kraemer, WJ. Designing Resistance Training Programs. Champaign, IL: Human Kinetics; 1987.

[fry-05] Fry, Andrew. Muscle Structure and Function. Structure and Function of the Muscular, Respiratory, and Cardiovascular systems in Essentials of Strength Training and Conditioning Symposium (Audio CD), NSCA Certification Commission, Lincoln, NE, 2005.

[green-05] Greenwoord, Mike. Aerobic Exercise and Interval Training Prescription in Essentials of Strength Training and Conditioning Symposium (Audio CD), NSCA Certification Commission, Lincoln, NE, 2005.

[har-76]Harris, RC, Edwards, RHT, Hultman, E, Nordesjo, LO, Nylind, B, and Sahlin, K. The time course of phosphocreatine resynthesis during the recovery of quadriceps muscle in man. Pflugers Arch 97: 392-397, 1976.

[Law-06] Lawton, TW, Cronin, JB, and Lindsell, RP. Effect of interrepetition rest intervals on weight training repetition power output. J Strength Cond Res 20: 172-176, 2006.

[lin-05] Linnamo, V, Pakarinen, A, Komi, PV, Kraemer, WJ, and Hakkinen, K. Acute hormonal responses to submaximal and maximal high intensity resistance and explosive exercise in men and women. J Strength Cond Res 19: 566-571, 2005.

[will-2008b] willardson, J. A Brief Review: How Much Rest between sets. Strength and Conditioning Journal, June 2008, 30:3

[will-06]Willardson, JM and Burkett, LN. The effect of rest interval length on bench press performance with heavy versus light loads. J Strength Cond Res 20: 400-403, 2006.

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