Periodization

[Khazima]

A friend and myself were discussing the principles of Periodization today, we have a general understanding but not nearly as in depth as we'd (I'd) like.

I'd completely forgot about the conversation and the fact that I wanted to improve my knowledge for the sake of my own programming, when I came across this article on my Facebook.

I couldn't have asked for better timing or a better explanation, I felt I had to share!



THERE IS ONLY ONE TYPE OF PERIODIZATION - Part 1

BY GREG NUCKOLS Juggernaut

WE HAVE A PROBLEM WHEN WE TALK ABOUT PROGRAMMING AND PERIODIZATION.

We talk about periodization, and various aspects of periodization, as if they’re mutually exclusive. Most people who have spent a lot of time in the coaching game or who know more about formal periodization theory know this is nonsense, but it doesn’t seem like those folks have been able to explain these concepts in a way that most people can understand. That’s what we (Dr. Israetel is writing Part 2) hope to accomplish here: a straightforward, down-to-earth explanation of what periodization actually is, and how to tie together a lot of elements that people usually take to be entirely disparate concepts.

Here’s the most basic definition of periodization: It’s how you organize training.

The “period” in periodization refers to exposing the body to periods of different stressors, and more or less total stress, over the course of a training plan.

So really all periodization refers to is organizing training, and making decisions about when and what types of stress you place on the body.

With that in mind, let’s actually look at how you can go about organizing training.

TRAINING IS ORGANIZED ON DIFFERENT TIME SCALES.

It’s organized within a single training session itself, from microcycle to microcycle, from mesocycle to mesocycle, and from macrocycle to macrocycle.

Organization of the training session itself is outside the scope of this article, but it’s concerned with things like “if I’m doing heavy squats and high intensity sprints in the same session, which should I do first?” The typical answer would probably be squats, since squatting heavy in a highly fatigued state probably isn’t too smart, and since sprinting first would decrease subsequent squat performance more than squatting would decrease subsequent sprint performance.

A MICROCYCLE is usually synonymous with a training week. It has a slightly broader definition, but just to keep things simple, we’ll just think of a microcycle as a single week of training.

A MESOCYCLE is a group of consecutive training weeks that are focused on training the same skill or physical quality. They usually range from 2-8 weeks long, but for the sake of simplicity, we’ll illustrate using month-long mesocycles.

MACROCYCLES are the broader training plan. This could be 12 to 16 weeks of training to prepare for a powerlifting meet, the offseason training plan for team sports, year-long plans for athletes who focus their efforts on a single big national or world meet, or even 4-year quadrennial plan for an Olympic athlete. Just for illustrative purposes, we’ll use a 16 week training plan for a powerlifting meet.

Now that the boring terminology is out of the way, let’s delve into the stuff you’re really interested in: why people get so confused about periodization.

THERE ARE THREE MAJOR ELEMENTS THAT WE USE TO DEFINE HOW PLANS ARE PERIODIZED:
Undulation: changing the training volume and/or intensity to expose the body to different stressors
Linearity: Progressing a training stress or fitness characteristic in a linear fashion. This is roughly equivalent to “progressive overload” for single or multiple factors.
Conjugation: Regularly changing training stressors with the purpose of training different physical characteristics (like maximal strength and explosiveness, for example) simultaneously. For this article, we’ll be addressing this primarily as “change in exercises” because the other ways to accomplish conjugation are already encompassed in the concept of undulation.


When people talk about these notions, they usually speak as if they’re mutually exclusive.

“Westide is Conjugate Periodization!”

“Such-and-such powerlifter uses Daily Undulating Periodization!”

“Beginner or intermediate lifters should use a Linear Periodization program!”

It sounds like these are disparate concepts, when really almost all training plans weave all of these elements together to reach the desired end. They can do this because, as we touched on initially, training is organized on different time scales.

The easiest way to wrap our heads around these concepts is by use of a few examples.

Disclaimer: there are other, more advanced areas of program design, but understanding these three concepts is enough for most people, most of the time, and they’re the three that are most commonly misunderstood. Talking about the rest would be well beyond the scope of a single article. That’s why there are entire books about periodization.

EXAMPLE 1:

Let’s say someone sets up a plan utilizing “Daily Undulating Periodization:” changing weight, sets, and reps for their major movements on each training days during a week. They may squat 3 times in a week, and set up their training week like this:

Monday: Squat 75% 5×6

Wednesday: Squat 80% 3×4

Friday: Squat 85% 4×2

But that’s just one week of training. What do they do in their next week of training? Maybe they try to add 5 pounds on each training day. Maybe they do one more set per day, or one more rep per set. That’s a linear increase in intensity or volume. And assuming they don’t ONLY squat in their workout, but also do some accessory exercises, if they swap out accessories every month or two to address new weaknesses or to change the stressors they’re exposing their body too, that’s a conjugate element.

So that training plan wouldn’t just be a “Daily Undulating Periodization” plan. Rather, it would be a periodized training plan utilizing undulation day to day, linearity week to week, and conjugation month to month.

If they wanted to accomplish the changes in volume and intensity day to day by altering exercises (maybe front squats one day, high bar squats one day, and low bar squats on another), then both conjugation and undulation would be taking place day to day.

Or maybe when training for a meet, their first two months involve high bar squats, their third month involves low bar squats, and their fourth month peaking for the meet involves low bar squats with wraps. There would be conjugation and a linear increase in specificity month to month.

EXAMPLE 2:

Let’s say someone set up a basic, old-school “Linear Periodization” plan, increasing intensity and decreasing volume week to week leading up to a meet. They bench, squat, and deadlift twice per week, with a traditional “heavy day, light day” setup. They stick with the competition variants of the lifts for the entire training cycle for maximized training specificity, but after the meet they transition into a period of doing more exercise variants like front squats, deadlifts with the opposite stance, and close grip bench presses to bring up any weaknesses that may have developed from several months of highly specific training.

In this example, increase in intensity and decrease in volume are both linear.

Conjugation doesn’t take place within the meet prep macrocycle, but it does macrocycle to macrocycle.

Undulation occurs within the training week between heavy and light days.

So it’s not ONLY “linear periodization.” It’s a periodized training plan with undulation session to session, linear changes in volume and load on a weekly scale, and conjugation macrocycle to macrocycle.

EXAMPLE 3:

Let’s say someone is utilizing the Westside Barbell Conjugate Periodization plan. They change their max effort movement every 1-3 weeks, and alternate 3 week blocks for speed work, using straight weight for 3 weeks, chains for 3 weeks, and bands for 3 weeks. As per Westside recommendations, they do a lot of accessory work to bring up weaknesses, trying to increase weight and volume over time.

The conjugate element is obvious: switching out max effort movements regularly.

Each 3 week block of speed work employs linearity, either by increasing the bar week over the 3 week wave, or by increasing the chain weight or band tension. Additionally, increasing weight and volume for accessory exercises is a linear element.

Undulation takes place within the week (between max effort and dynamic effort days), and from week to week as different bars are used for max effort workouts that allow for more or less loading.

As you can see, none of these training plans are exclusively “linear periodization” or “undulating periodization” or “conjugate periodization.” So, just for the sake of argument, what would a plan with just one element look like?

PURE LINEAR PERIODIZATION

No changes in exercise ever. Any change from one session to the next must be some form of progressive overload. More weight on the bar, more reps, more sets, etc. However, once you gain some ground, you can’t ever go back. You did 25 total reps on the squat with 80% this week. Either you need to do more weight with the same number of reps, or you need to do more reps with the same weight. The next week, you have to either add more weight or reps again. If you add weight but decrease reps (with the intention of ever doing more reps again), that’s undulation. If you increase reps while decreasing weight (with the intention of ever using more weight again), that’s also some minor undulation.

A purely linear plan would probably be very boring, while also getting into a real of totally unmanageable volume and/or intensity very quickly for anyone who’s not a complete beginner.

PURE CONJUGATE PERIODIZATION

Exercises change all the time, and that’s about it. If you come back to the same exercise again, you have to do the same weight, sets, and reps again. If there’s no linear element to it, on any time scale, there’s no way to progress. Using the broader definition of conjugation to include undulating elements as well, you’re still no better off without also employing some sort of linearity.

PURE UNDULATING PERIODIZATION

Weights, reps, and sets can change day to day and week to week, but there can be no changes in exercises, and the overall average volume and intensity has to remain the same.

As you can see, none of these plans are very good. A purely linear plan can work for a short period of time, but is clearly not a viable long-term approach. And without any linear elements, pure conjugate or undulating plans wouldn’t get you anywhere. Proper organization of training blends all of these elements together, on different time scales, to achieve the desired results. That is periodization. Not linear periodization, not conjugate periodization, not undulating periodization. JUST periodization.

The real question isn’t “what kind of periodization is best?” It’s, “what are the most effective ways to weave these elements together to accomplish my goals?”

LINEARITY

The time scale linearity takes place on is relative to the experience of the lifter, factors in their life that influence their ability to recover from hard training, and the distance from their genetic potential. But the quick and dirty answer is “as fast as possible.”

For someone who’s brand new, that may mean linear increases in weight on the bar or training volume, every training session, for quite some period of time.

For someone who’s been in the game for a few years, it may be possible to increase weight or training volume week to week (microcycle) for each discrete workout (i.e. doing more this Monday than you did last Monday), while employing more undulation or conjugation within the training week itself (i.e. doing something different this Wednesday than you did this Monday).

For someone who’s more experienced yet, it could mean every month (mesocycle). Your workouts this month may correspond with workouts last month (i.e. doing more this Monday than you did on Monday 4 weeks ago), with more undulating or conjugate elements within that month. Or it could mean linear organization on two different time scales – maybe increasing volume week to week over the course of a month, and repeating the process with heavier weights on the next month.

For someone who’s nearing their potential, or for someone whose progress has slowed down due to life circumstances interfering with recovery from workouts, actualized improvements in strength may only occur at the end of a longer macrocycle, with other linear, undulating, and conjugate elements integrated into that macrocycle, eventually leading to the desired linear strength increases macrocycle to macrocycle.

UNDULATION

The question of undulation isn’t one of “if,” but rather “to what degree, and on what time scale?”

There aren’t tidy answers to these questions, because we honestly don’t know.

In general, if you train a lift more than once per week, it seems wise to undulate training within the training week. If you did sets of 5 with 80% today, you’d probably be better served by doing something other than sets of 5 with 80% if you do the same lift later in the week.

Undulation week to week should also be discussed if you aren’t able to progress linearly week to week anymore on one element, while holding other elements steady. For example, you may doing something like this over a month-long span, for a particular workout:

Week 1: 75% 5×5

Week 2: 85% 4×3

Week 3: 80% 5×4

Week 4: 90% 3×2

However, you could also do the same set of workouts with a linear setup, and not need to undulate week to week. For example:

Week 1: 75% 5×5

Week 3: 80% 5×4

Week 2: 85% 4×3

Week 4: 90% 3×2

Both setups would probably work equally well, and would ultimately amount to a matter of preference. Degree of undulation within the training week is probably more important than degree of weekly undulation.

However, degree of undulation within the training week isn’t something that has clear guidelines either. On one hand, research has clearly shown that small amounts of undulation within the training week can be very effective – ~10% fluctuations in intensity within a training week producing substantially better results than a purely linear approach. However, as the Westside approach of 100% max effort work with speed work in the 60-75% range within the same training week, and the oldschool “heavy day, light day” approach of heavy sets of 2-5 reps one day and “bodybuilding” work with sets of 8-15 reps have shown, many people can also be successful with much greater degrees of undulation within the training week as well.

As a general recommendation, however, degree of undulation day to day should probably decrease somewhat as you approach a competition, so you can increase training specificity. Using the examples above, the Westside approach does this by substituting regular speed days with “circa max” workouts, utilizing much heavier loads than would typically be used for speed day. The “heavy day, light day” approach also tended to increase loads on the light day as a meet approached, usually ending up with fairly heavy sets of 5-8 reps on the light day as a meet drew near.

10 weeks out from a meet, big swings in volume and 30% swings in intensity may be acceptable for building a general strength base via a broader array of stressors, but 2 weeks out from a meet, training specificity should have increased to match the immediate demands at hand – lifting as much weight as possible at the meet. You may be able to practice adequately to lift 100% loads utilizing 80% and 90% loads within the same training week, but that practice would be less specific to the task at hand utilizing 60% loads and 90% loads for your main lifts instead.


CONJUGATION
Conjugation is similar to undulation, in that the primary question isn’t “should I use some conjugate elements,” but rather “how much and on what time scale?”

And again, there’s not a clear cut answer, except that some variation tends to be better than none.

Even for untrained lifters, there’s evidence showing that a mixture of lower body exercises, including squats, leg press, deadlift, and split squats, can increase their squat more than squatting alone.

The exception might be for the most advanced lifters. Chad Wesley Smith alludes to this with his “pyramid of strength.” Someone like Ilya Ilin has a very bare-bones program of almost exclusively squats, front squats, clean&jerks, and snatches, but early in his training career he did a much broader array of exercises to build the general strength base necessary for him to take advantage of such an extreme degree of specificity. Andrey Malanichev is someone else who uses very few exercises in his training, but he is also an incredibly elite lifter.

The rest of us benefit from a somewhat broader array of exercises to build a generalized strength base.

Examples of successful programs run the gamut from switching out exercises weekly (Westside’s max effort work), to every macrocycle (sticking to competition lifts for a whole meet training cycle, then including more variety after the meet to bring up weaknesses). You can also employ conjugation by keeping the competition variants in your program all the time, while doing different exercises during the week – conjugating on different time scales. Sheiko is one such example – you’ll always be doing competition variety squats, benches, and deadlifts, but variants such as front squats, close grip bench press, and deadlifts from blocks are included from time to time.

Conjugation can take place across different time scales, and it can also take place to different degrees. For example, a high bar squat with a belt, or a low bar squat without a belt, are both pretty similar to a low bar squat with a belt. A high bar squat without a belt is less specific, so it represents a greater degree of conjugation. A paused, beltless front squat is less specific yet.

Similar to undulation, it’s generally wise to reduce conjugation (both the amount of exercise variation, and how different those exercises are compared to your competition lifts) somewhat the closer you get to a meet. Again, this is for purposes of training specificity and ensuring that your motor patterns are well-tuned so you can perform at your maximal level on the platform.

PUTTING IT ALL TOGETHER

When thinking about periodization, stop thinking about it in terms of this or that specific program, or looking at elements of periodization as if they’re entire training programs in and of themselves.

There is no one-size-fits-all best training plan, but almost all successful training plans have all three of these elements – linearity, conjugation, and undulation – and I’m having a hard time thinking of a single program that’s been successful for a population of lifters other than complete newbies that doesn’t employ at least two of these elements.

Even the ruthlessly minimalistic Bulgarian program utilized undulation (more or less training volume depending on the lifter’s readiness and state of recovery) in addition to linearity (always trying to add more weight to the bar).

The key, then, isn’t to look for the one key to building a successful program, but rather to look for the traits that many successful programs for lifters with your goals and general level of experience have in common.

Observe how these elements are employed across different time scales – daily, weekly, monthly, or macrocycle to macrocycle, strive for measurable improvement at the fastest rate your body is capable, and decrease degree of conjugation and undulation to enhance training specificity as you get closer to a meet.

Source: http://jtsstrength.com/articles/2014...zation-part-1/

[Khazima]

THERE IS ONLY ONE TYPE OF PERIODIZATION - Part 2

BY MICHAEL ISRAETEL Juggernaut

This is a continuation of THIS article. If you haven’t read part 1 yet, check it out before diving in.

CHOOSING THE RIGHT MIX OF PROGRAM FEATURES

Now that we’ve managed to illustrate that all programs are simply composed of differing forms of training organization, that all programs use all of these forms to some extent, and now that we have defined these three primary forms of training organization, we have to ask a question that arises almost automatically from these conclusions.

The question is; “how much linearity, exercise variation (used from now on in place of the term ‘conjugation’) and volume-load undulation produces a BEST result in a program. Of course, there are multiple considerations to input, and the result will not (ever) point us to ONE OPTIMAL PROGRAM FOR ALL. But, by using the four-step filtering process below, we can narrow down the list of potential programs to the small fraction that are designed with the best features (or quantities, rather) of linearity, exercise variation, and undulation.

Imagine we have the potential to train in any kind of program we want. We survey the internet and find, let’s say, 100 programs in total to consider. These programs range from recommendations in backwater forums to the personalized programs written by Boris Sheiko himself.

Now, what’s the first step in concluding which programs are better and which likely won’t produce best results? The first filter we’ll apply is that of Sport Science research and the experience of the best coaches.

BOUNDED BY SPORT SCIENCE RESEARCH AND COACHING EXPERIENCE

Sport Science has been formally practiced in the Eastern Bloc from the late 1950’s onward, and in the West shortly after that. Over a cumulative 50+ years of formal research, sport scientists have managed to draw some definitive conclusions about what programming features work well and in what quantities. The benefit of sport science has not only been to discover what works, but discover what likely does not work as well. It’s these “what’s not best” discoveries that are really important to us here, because they give us information with which to rule out extreme applications of program features (too much linearity or not enough, for example) and never bother making those costly mistakes ourselves.

The lessons of sport scientists (especially in the Eastern Bloc where science and coaching were closely connected) were parleyed into the practices of sport coaches. After decades of coaching application, some very serious and incredibly knowledgeable coaches literally “grew” out of their experiences, insofar as they adopted the best practices and abandoned the worst as they were introduced. These coaches directly applied the lessons of sport science and were able to add a vast amount of knowledge to the field, especially in the realm of “how much” of a program feature to apply. For example, sport scientists discovered that adding elements undulation worked definitively better than pure linearity, but it was not clear how much undulation was best for a particular sport or phase of training. Coaches, through decades of implementation, got the best idea of what level of undulation worked best, and how much was too little or too much.

Oftentimes, the best coaches would engage in practices that had not even yet been studied by sport scientists, and thus the relationship was reversed. However it tended to happen, what we have now is the sum total of all of that integrated knowledge.

So here’s the big hit of this first filter: if sport scientists and the best elite coaches through the times tend to shy away from a certain type of programming, it’s likely not going to work best. For example, you’d be VERY hard pressed to find elite coaches and top scientists that support a purely linear program. Just the same (aside from Louie), very few coaches recommend altering exercises every single session. Lastly, hardly any of the best coaches and scientists would recommend radical undulations in repetition ranges and weights within the week, as in sets of 15 reps and sets of 3 reps in the same week. This kind of undulation both violates an essential principle in sport science (directed adaptation) and is very rarely found in the programming of top coaches in sport around the world.

Next time you go program hunting or writing, check with the basic sport science texts and read about the programs of top coaches first. If it looks a bit extreme, maybe it’s not the best program.

WHAT SPORT YOU’RE DEALING WITH

Program feature inclusion is somewhat sport-specific. While the general principles from the first filter always apply, there is some variation within that range depending on the sport in question. For example, the primary overloading variable for short-distance sprint training is velocity. If peak velocity in training is down by just a small fraction, overload becomes difficult to present (You’ve gotta run fast to get faster. You can’t half-sprint and expect the same results). Thus, fatigue management becomes much more important in basic sprint training than in the average sport.

Not by accident, good sprinting programs usually tend to have a higher degree of undulation. One way to do this is via fast sprints and heavy weights in the beginning of the week, then much lighter weights (and lower volumes of training) later in the week, paired with non-overloading technical work on the track. This arrangement of high undulation allows sprinters to carry low fatigue at the beginning of most training weeks, which allows them to have the kind of top-speed workouts that really push the greatest speed adaptations, never mind reduce the potential injury rate from trying to sprint while fatigued or very sore.

On the other end of the undulation spectrum is the sport of bodybuilding. The primary overloading variable for bodybuilders is the total volume of work they can accomplish in training and actually recover from, so long as the predominance of that work is above around 60% of the 1RM of the movement. Additionally, constantly trying to reduce volume loads to keep fatigue down greatly inhibits how much total work can be done in any unit of time, so that if you’re managing fatigue too much in bodybuilding, you end up always having great workouts but never really improving as fast as you could be, because you’re taking too many light days and not enough stimulus is actually being elicited.

So long as fatigue doesn’t get too crazy (and that’s what deloads every 4-5 weeks are for), bodybuilders are best served training with consistently high volumes. That means almost every bodybuilding workout will be of roughly the same volume (as close to maximal recoverable volume as possible), and the degree of undulation is very slim indeed. There will be SOME undulation to manage some local fatigue (rowing-heavy vs. vertical pulling-heavy back workout alterations, for example), but certainly not as much as we’d see in sprinter training.

Of course the same sport-specificity applies to linearity and exercise variation features. Your job as an intelligent programmer (or program shopper) is to make sure your program follows the general feature guidelines of that chosen sport. If your sprinter program has you squatting for 5×10 Mondays and Thursdays all season long, you may have a problem. Speaking of season length, that’s our next consideration for program feature selection!

WHAT PHASE THE SPORT IS IN

Program features not only change with the sport itself, but with the phase of training being done for that sport. To give a simple example, as mentioned earlier in this article, the specificity of a program should likely increase as the competitive season (or single competition depending on the competitive schedule of the sport) draws nearer. The means exercise variation (aka conjugation) should be more prominent in the offseason (or general preparation phase) in most sports, and should dwindle down in magnitude as the competition phase or date approaches.

For example, hypertrophy work in powerlifting is best done far in the offseason, and can be performed using a wide variety of exercises that can be altered quite often. On the other hand, as competition nears, the athlete must become muscularly, neurally, and technically most familiar and adapted to the actual competition moves. This means that in a peaking phase right before a powerlifting meet, fancy board presses or cambered bar work is best replaced with a steady diet of heavy competition-standard lifts for best performances on the platform. As mentioned in Part 1, even the super-conjugate heavy Westside System began to recognize this need and altered programming to match.

After narrowing down the general recommendations of sport coaches and scientists, choosing the sport to be trained, and zooming in on a particular phase of sport training, we can (finally) consider the last variable of program feature selection: the individual athlete’s proclivities and declivities.

THE INDIVIDUAL ATHLETE

Not all humans are exactly the same, and certainly not all athletes are. For each of the program features (and certainly for the 3 discussed in this article), every individual will respond best to a particular magnitude of feature. For example, some athletes thrive on linearity. These tend to be athletes that both recover quickly and have limitations in athleticism (for example, technical execution of the lifts does not come easily to them, and technical consistency does not hold well in absence of continual practice). For such athletes, very linear programs are great, because they allow them to make consistent gains while getting better and better at executing the lifts or sport moves being training. For these athletes (in powerlifting, for example), too many lift variations and undulations can be technically overwhelming… and when they come back to, say, heavy squats, all kind of technical issues resurface after only a short layoff! More intermediate athletes tend to have a better technical basis for lifts and other sport moves, so they don’t have to be as linear as relative beginners, for which high linearity is usually much more effective. To paint an extreme counterexample, there have been 15 year old girls training in the Conjugate Method and getting into powerlifting equipment before they could even squat 1.5x bodyweight…. THAT is an example of poor feature selection.

On the other hand, more intermediate athletes can disrupt homeostasis to such a degree in training that they simply need more undulation to recover. Additionally, their technical proficiency in the basic lifts or sport moves is now high enough that it can be retained for long periods of training alteration. That means they can now benefit from a higher degree of exercise variation without sacrificing basic technical abilities.

TOWARD A UNIFIED VIEW OF PERIODIZATION

When making a periodized plan for ANY particular athlete, all of the four considerations/filters in the section above must be taken into account. Every single time a good coach sits down to write a program, he considers every single pertinent feature of the athlete, training phase, sport, and general theory.

This is a process that has been followed around the world for decades by the best (usually national and Olympic team) coaches, and has been studied and refined by the international sport science community.

This process and the study of it has revealed a network of practical and theoretical principles which are used by coaches to organize training. And guess what? It’s even got a name: Modern Periodization. That’s right, the informed and filtered selection of programming features (including consideration of linearity, exercise variation, and undulation) utilized to draw up macrocycle plans that enhance training gains and competitive performance while reducing injury rates is called Modern Periodization. Phew, that was a long definition!

Modern Periodization is a close relative to block periodization and features linear, conjugate (exercise variation), and undulating elements throughout its design. Almost all current Olympic training centers around the world use it and sport scientists almost universally accept it.

So in fact, there is only ONE kind of periodization but the features of the programs within a periodized plan tend to vary considerably depending on the sport, phase, and athlete (just like evolution occurs by natural selection, bottlenecks, and genetic drift all at the same time).

Moral of the story? There is not a pure and perfect program, and there is not a competition between various programming features as to which one is best. There is a unified system of training, and it integrates ALL programming features in a way that promotes best results. How much study and practice does it take to master the system of Modern Periodization? No one yet knows, because the system is always being updated and improved per new discoveries, the best coaches and sport scientists all say that even with all of their understanding, they’re just scratching the surface.

Source: http://jtsstrength.com/articles/2014...zation-part-2/

[Khazima]

Found a really useful video on periodization.

BioLayne Video Log 30 - Periodization - YouTube