Posted: December 24, 2004

Science of Sport: The Principles Of Periodization

By Owen Anderson, Ph. D. - Copyright © 2002-2004

If you want to improve your performances, you can't train in the same way all the time. If you did, your body would simply adapt to the training you were conducting, your fitness would settle in at a fixed level, and you could train vigorously, year after year, without making one tittle of improvement. Hoping to perform better while utilizing an unchanging training program is like expecting to become highly skilled at calculus while working solely on the simple equations encountered in first-year algebra.

Does that seem obvious? It should, but many athletes nonetheless follow the same basic training plan, month after month, year after year, and yet expect to achieve PBs. An incredible number of endurance runners, for example, carry out speed work once a week, complete a tempo run or hill effort once weekly, and hit a long run on the weekend - throughout much of the training year! When their performances don't improve significantly, they scratch their heads and wonder what is wrong.

One of the key things that is wrong, of course, is that they have failed to periodize their training in a productive way. Periodization simply refers to changes in the volume, intensity, and frequency of training over time; it also encompasses the way in which the basic structure of training (in terms of the types of workouts which are completed) is a function of time.

The notion that proper periodization of training is necessary for the achievement of peak performance originated over 2000 years ago, when the "ancient Greeks" utilized basic, periodized training schemes to prepare their athletes for the Olympics. For example, the legendary Milo of Croton (not to be confused, of course, with the renowned Milo of Manchester) varied only the intensity of his training, lifting a bull-calf on a daily basis until it was fully grown, at which point Milo was able to lug the adult bull around the Olympic stadium. Another legendary figure, Galen (A. D. 129-199), was the first person to write at some length about periodization. A Turk born in Pergamum, Galen eventually became "doctor to the gladiators" in Rome and also took care of the Roman Emperor Marcus Aurelius and his son, Commodus. Galen believed that there were various types of exercise which needed to be blended in order to enhance performance; he classified exercises into those which exercised the muscles without violent movement (digging and weightlifting, for example), quick exertions which promoted activity (ball play and a form of gymnastics), and "violent" exercises, the ones which might be today called "plyometrics."

After Galen's death, periodization underwent a rather long "down period," but the philosophy of changing training as a function of time experienced a small rebirth in the 1950s and began to come into full bloom in the 1960s and early 1970s, at least partially as a result of some groundbreaking research carried out by noted physiologist Hans Selye, who ultimately formulated what he called the "general-adaptation syndrome" (1). According to Selye's theory of adaptation, physiological systems respond to any changes which they experience in ways which allow the "stressors" (those things in the environment which are different and challenging) to be coped with more readily. Once the adaptive response is completed, however, the physiological systems stop changing, and a new round of stressors is required to produce further adaptation. If stressors are uniquely and properly periodized, an organism (as a set of physiological systems) can continue adapting and - in theory - can continue to improve its overall physical capabilities, until its absolute upper limit of adaptation is reached.

Basic scientific research reveals that periodization does work, i. e., it produces enhanced improvements in performance, compared with non-periodized training programs. In the first periodization study ever published, for example, college-age males either completed a non-periodized strengthening program of 3 X 6 sets or a periodized program which progressed from high volume (lots of reps) and low intensity (low resistance) to lower volume and higher intensity over a six-week period (2). After six weeks, the periodized-group members were appreciably stronger during parallel back squatting, enjoyed a greater increase in lean body mass, demonstrated a larger downturn in body fatness, and also exhibited higher vertical jump power, compared with the non-periodized trainers. A major problem with this study, however, was that total volume of training was greater in the periodized group, and thus the advantages which accrued might have been purely a function of training volume rather than periodization.

In an outstanding follow-up study which partially eliminated this volume-of-training bias, Darryn Willoughby of the Department of Health and Kinesiology at Texas A&M University divided 92 previously weight-trained male college students into four equal groups (3). Average age of the subjects was 20 years, and mean body mass was 80 kilograms. All of the subjects could bench-press at least 120% of body weight and could parallel-back-squat a minimum of 150% of body weight (with the bar resting on their trapezius muscles). All individuals in this study had engaged in weight training using free weights for a minimum of three years.

At the beginning of this 16-week study, bench-press and parallel-back-squat strength was equivalent between the four groups, and these two exercises were the only ones utilized during training. Group 1 trained with five sets of 10 reps of each exercise per workout, with three-minute recoveries between sets and with resistance set at 79% of the one-repetition maximum (the maximum weight which could be lifted one and only one time). This relative intensity was kept constant throughout the study, although the absolute intensity (actual amount of resistance) could increase if the one-repetition maximum increased (one-rep max was determined for each exercise at four-week intervals). Thus, there was little periodization of training for Group 1 over the 16-week period; 50 reps of each exercise at 79% of 1-RM were completed during each and every workout. The only training variable which changed at all was the absolute amount of resistance, which could increase if 1-RM improved but did not automatically advance at regular intervals.

Group 2 trained with six sets of eight reps per workout, with the relative intensity set at 83% of the one-repetition maximum for each exercise. As was the case for Group 1, relative intensity remained etched in stone for the duration of the 16 weeks of training, although absolute intensity could head north if one-rep max burgeoned during the monthly strength exams. Group 3 enjoyed a more generous periodization program, hitting five sets of 10 reps at 79% of one-rep max per workout for four weeks, four sets of eight reps at 83% of 1-RM for the next four weeks, three sets of six reps at 88% of 1-RM per workout for four additional weeks, and then three sets of four reps at 92% of one-rep max per workout over the final four weeks of the study. For Group 3, relative intensity (% of 1-RM), absolute intensity (actual amount of resistance), and training volume (number of reps completed) varied during the study, and Group-3's protocol represented a more-or-less classical periodized plan, with training volume decreasing over the course of the training period, while training intensity advanced. During the second half of the study, Group-3 members lifted significantly less weight per week, compared with Groups 1 & 2, although Group-3 athletes were working considerably more intensely (lifting more weight per rep). For example, during weeks eight through 16, members of Groups 1 & 2 were bench-pressing over 12,000 kilos per week, versus just 3400-4800 kilos for Group 3; similarly, athletes in Groups 1 & 2 were squatting 16,000 kilos per week, against just 4200-6000 kilos for the Group-3 lifters. It should be noted that training frequency was the same among groups; all three groups conducted three workouts per week.

Group 4 had it easy, playing badminton throughout the 16-week period and engaging in no parallel-squat or bench-press training. Group-4 members did, however, get check-ups for 1-RM at four-week intervals, just like the strength-trained athletes.

As it turned out, the individuals in Group 3 were the winners in the strength-gain game. After 16 weeks, Group-3 members were stronger in both the bench press and parallel squat, compared with Groups 1, 2, and 4 (strength was measured during 1-RM testing). How should this be interpreted? Dr. Willoughby suggested that a key take-home lesson was that variation is an important component of training programs, but we can go a bit deeper. Basically, intensity tends to be a more potent producer of fitness, compared with mere volume or frequency of training. Athletes who organize (periodize) their training so that the average intensity of training increases over time should triumph over those competitors whose intensity remains flat. In this study, intensity was raised by giving strength-trainers higher relative and absolute resistances, but the principle would also work for endurance athletes. Cyclists, for example, could gradually increase average training intensity by pedaling faster during quality workouts, or padding the number of quality sessions conducted per week.

So, periodization which pushes quality appears to be a good thing. One major, problem, however, is that there are so many different types of quality workouts to consider. Endurance athletes, for example, might choose to train at 130% of VO2max, 115% of VO2max, VO2max itself, 88% of VO2max, or some intensity in between; certainly, any effort carried out at between 85% of VO2max and max movement speed would have to be considered a quality exertion. Power-type athletes might select plyometric sessions, general-strengthening drills, movement-specific strength training, or classic upper- and lower-body strengthening efforts. As noted strength expert Steven Fleck points out, strength trainers can vary the number of sets performed of each exercise, the number of repetitions per set, the actual exercises performed, the quantity of exercises conducted per training session, the rest periods between sets and exercises, the resistance used with each set, the muscle action performed (eccentric, concentric, or isometric), and the number of training sessions completed per day and per week (4). How should these possibilities be brought together in a cohesive plan?

As one thinks about this periodization conundrum, it is important to remember, too, that periodization should always be goal-oriented. Periodization should be planned so that fitness increases steadily during the training period - and reaches a maximum reasonably in advance of the major event of the season or year. In addition, the endurance athlete needs to periodize workouts so that vVO2max, lactate threshold, economy of movement, event-specific strength, power, and event-specific preparation are optimized: How can all of that be accomplished? With four key variables to consider (intensity and type of workout, plus our old friends volume and frequency) and an incredibly wide range of values associated with each variable, athletes have an almost limitless number of ways in which they could train. How does one pick the right periodization system?

It's a question that science has had a tough time answering. Outstanding, practical, well-controlled scientific investigations on periodization are few and far between, as a quick search through Medline or a similar scientific database would quickly reveal to you. This may seem a bit surprising, given periodization's general popularity, but one of the basic problems is that exercise scientists often feel that they need to limit the lengths of their research studies to 12 weeks or so, as part of the "publish-or-perish" academic syndrome. It is very difficult to complete a comprehensive periodization study in just 12 weeks; at least some significant fraction of periodization research should cover fairly broad sweeps of time. When we examine the differences in training between athletes who are consistently successful and those who perform inconsistently, we are most interested not in what the high-performing athletes have done over the past week or even the past month or two - but in how they have organized their training over at least the last year. Proper periodization means coordinating training optimally over extended periods of time - long enough to make large gains in fitness and prepare properly for major competitions. The various types of training which athletes need to carry out can be included to only a limited degree in an investigation as short as 12 weeks, and during a three-month time frame it is also difficult to tweak athletes' training schedules with oscillations of the key variables - volume, intensity, and frequency - which are characteristic of longer time periods (bear in mind that few athletes confine their serious training to 12 weeks out of a 52-week year).

Another obstacle to periodization research is that it can be hard to get a group of athletes to adhere to a specific training program for a year or more at a time; many athletes will drop out, others will not follow the prescribed training very closely, and some will get hurt. For an exercise researcher, embarking on a long-term periodization project is a pretty risky thing to do, because the whole thing may blow up in his/her face after many precious months of very hard work.

As a result, research scientists have tended to bite off small parts of the periodization puzzle. For example, one of the questions they have been most interested in is whether "linear" periodization is preferable to "undulating" periodization. The resulting research is actually fairly interesting, especially since many athletes follow some form of the linear-periodization plan. In linear periodization, athletes generally build up their total volume of training in a linear way and then gradually (linearly) decrease their volume of training while steadily increasing their training intensity (this is the basic approach followed by the strength-trained athletes in the Texas-A-&-M investigation mentioned above). Generally, training volume reaches its nadir and training intensity attains its apex shortly before the most important competition of the overall training cycle, which is commonly pegged at six or 12 months (we won't discuss macrocycles, mesocycles, and microcycles in this article, because such discussions are generally as useful to athletes as discourses about motorcycles).

Although linear periodization is appealing to athletes, there is nothing particularly appealing about it from a scientific standpoint. The philosophy underlying linear periodization is that athletes need to build up some level of strength and endurance before they attempt high-intensity training; thus, they work on boosting their volume of training before initiating high-quality work. The problem with this is that the basic premise is wrong: Athletes are capable of carrying out reasonable amounts of intense training early in the training year, and there is no real reason why they should not do so. In fact, since competition requires intense effort, since efficiency during intense work can only be developed during intense exercise, and since intense work is the most potent advancer of fitness, it is possible to present a logical argument for introducing high-quality training as early as possible in the overall training schedule.

In contrast with linear periodization, the less-popular undulating periodization is marked by fairly frequent alterations in the intensity and volume of training (5). Instead of featuring changes in training which occur over a period of months, undulating training makes major changes on a weekly or even daily basis. Strength-trainers, for example, might move from high-volume, low-intensity work to low-volume, high-intensity lifting within the same week. A typical example of this would be the completion of sets of 12- to 15-repetition maxima on Monday ("12- to 15-repetition maxima" refers to using a resistance with which one could complete no more than 12 to 15 reps in any one set), sets of eight- to 10-repetition maxima on Wednesday, and sets of just three- to five-repetition maxima on Friday.

With undulating periodization, the so-called phases of training tend to be much shorter, compared with linear periodization. Exercise physiologists and some coaches have been attracted to undulating periodization, at least partially because of the belief that frequent changes in training stimuli are very conducive to gains in fitness. One physiological basis for the principle is that during undulating periodization the nervous system is forced to adapt to a wide variety of situations, including the elicitation of tremendous amounts of force (when resistance, i. e., intensity is high) and also the coaxing of very rapid rates of force application, as when resistance is low and reps are completed quickly. In theory, when these various stimuli are presented together in close temporal proximity, the neuromuscular system might adapt unusually quickly and develop an enhanced ability to respond with great force and great quickness.

Does undulating periodization really seem to work better than the classic, linear model? To find out, researchers in the Department of Exercise Science and Physical Education at Arizona State University recently divided 20 men, recruited from college physical-education classes, into two equal groups (6). All 20 individuals had been engaged in strength training for at least two years prior to the beginning of the study (the average training experience was five years). During the 12-week study, both groups performed abdominal crunches (three to four sets of 15 to 25 repetitions), biceps curls (three sets at eight- to 12-rep max), and lat pull-downs (three sets at eight- to 12-rep max) three times a week. Both groups also trained intensely with two key exercises, the bench press (performed on a standard free-weight bench-press station) and the leg press (carried out using a Cybex® incline leg-press machine), and the performance of these latter two exercises was completed in a linear-periodized or undulating-periodized way. Subjects were prohibited from carrying out any other strength-building exercises during the 12-week investigation.

For the bench press and leg press, the linear-periodization (LP) group performed three sets per workout at an intensity of eight-rep max for the first four weeks of the study, three sets per session at six-rep max for the next four weeks, and three sets per workout at four-rep max for the final four weeks. Thus, the LP group used a classic linear pattern, with total volume of training (weekly amount lifted) sliding and average intensity climbing from four-week block to four-week block.

The undulating-periodization group utilized daily undulating periodization (DUP), with workout patterns never repeating themselves from one workout to the next. For the DUP group, the first session of each week of the 12-week program consisted of three sets at eight-rep max, the second workout contained three sets at six-rep max, and the third session had three sets at four-rep max. As you can see, training volume and intensity were altered differently for the two groups, but total volume and intensity were absolutely equivalent (each group, for example, completed 12 total workouts using a resistance of eight-rep max, 12 workouts at six-rep max, and 12 sessions at four-rep max). The only difference between the LP and DUP programs was the order in which the athletes carried out the workouts.

Both LP and DUP groups increased strength significantly in both the leg and bench presses over the course of the 12-week training period, but the gains in strength were significantly greater for the DUP group. Specifically, the DUP group enhanced bench-press strength by 29%, compared with 14% for the LP athletes, and boosted leg-press strength by 56%, versus 26% for the DUP pressers. In the leg press, for example, DUP upped 1-RM from 230 kilograms at the beginning of the study to 350 kilograms after 12 weeks, while LP nudged leg-press 1-RM up from 267 kilograms to just 331 kilos in the same time period.

What was going on? Why did the rearrangement of sessions corresponding with DUP have such a pronounced effect on strength gain? The Arizona-State study, which is the first to investigate differences between linear and undulating periodization in experienced athletes in situations in which the volume and intensity of training are held constant, suggests that the nervous system may be the key player involved in producing the differing upswings in strength. In theory, the nervous system may adapt less readily to training if it is exposed to a single type of training for an extended period of time (for example, for the four-week blocks of time used in the LP plan in this research) and might respond more effectively if the volume and intensity of training are adjusted frequently (as they were with DUP).

As we have implied earlier, pointing a finger at the nervous system is a reasonable thing to do, and such finger-pointing is supported by the fact that in the Arizona-State study there were no significant changes in body composition or muscle circumference in the two groups over the 12-week period! Thus, the greater strength displayed by the DUP group was not due to thicker muscles or leaner physiques but must have been related to the way in which the nervous system was controlling the sinews.

Although we have not given you a periodization plan which you can immediately incorporate into your own training, there are a number of practical applications which emerge from the Texas-A-&-M and Arizona-State investigations. First, it seems obvious that athletes should probably not plan extended (several-weeks-or-longer) "blocks" of training during which workouts are relatively uniform, since fitness progressions may be slower during such periods, compared to time frames in which training is more variable. Thus, the familiar pattern of speed on Tuesday, tempo training on Thursday, and a long effort on the weekend may make a nice training week, but it is not a building block in a great training month, and it is a crumbly foundation for a six-month preparation for a major event.

Along these lines, it also makes sense for athletes to diverge from traditional patterns of "base-building" and carrying out "recovery training." For example, at the beginning of a training year, many athletes try to lay a foundation for what lies ahead by working at low to moderate intensities while gradually building up their total volume of training. During this base-building period, the quality of training is generally low, in part because it is believed that the musculoskeletal system is not yet strong enough to handle higher-intensity work. There is really little justification for this practice, however. As long as intense efforts are attempted reasonably, the risk of injury should be no greater than it is with augmentations in volume. In addition, the whole idea of training is to progressively and steadily move one's fitness to higher and higher levels; it makes little sense to devote significant blocks of time to exertions which will fail to do this or which will move fitness upward more slowly than other forms of training. Thus, varied training, with an adequate inclusion of quality, is preferred over uniform, mediocre-intensity training during base-building periods.

The avoidance of "all-one-thing" training would also be important during recovery periods (for example, during the month following a major competition, during a week of "easy" training within a strenuous training period, etc.). Recovering is not the same as training easily all the time; one can still recover while utilizing a varied program into which some quality has been inserted, and the quality, of course, will prevent plunges in fitness which might occur while an athlete's mind and body are getting a chance to obtain some much-needed rest.

While these periodization pointers should help you, bear in mind that knowledge concerning the proper periodization of training is extremely "light-weight" at this point in time. In addition to the fact that most periodization studies have been constrained by time (and, to some extent, by the researchers' imaginations), there have essentially been no studies carried out with female athletes, masters athletes, or children, and the periodization models utilized in existing research projects have been quite limited. Periodization work has also been biased towards strength trainers, with little emphasis on endurance athletes. In one of the very few studies in which endurance activity was even mentioned, an effort was made to assess the impact of various types of strength training on endurance performance, with three different strength-training programs being utilized (7). One strengthening program featured one set at 8- to 12-RM per workout, another had three sets at 10-RM, and a third consisted of a periodized plan for advancing strength and power (seven different exercises were used in each program). In the periodized plan, volume steadily decreased and intensity was augmented from 10-RM to 3-RM over the course of the study. At the end of seven weeks, resistance to fatigue during back squatting was measured (the squatting was carried out with a 60-kilo weight and a cadence of one squat per six seconds, with the mass squatted increasing by 2.5 kilos per minute), and so was endurance while cycling at an intensity of 265 Watts. As it turned out, only the 3 X 10 and periodized groups displayed improvements in both tests over the seven-week period. In addition, there was a strong trend for the improvement in cycling endurance time (while cycling at 265 Watts) to be greater in the periodized group, compared with the other two groups of exercisers.

So what are the bottom lines about periodization? As the renowned running coach Arthur Lydiard once said, "Athletes tend to repeat their basic training patterns over and over again, yet with each repetition of the basic plan they expect different (i. e., better) results." A properly periodized program prevents the performance plateaus which are inevitable with training which is too repetitive. As you construct your overall program, you should be certain to include variety in your training, not just from month to month but also from week to week and even from day to day; the limited periodization research which is available suggests that such variety can be quite conducive to fitness gains. You should also be sure to include those workouts in your program which have the greatest chance of optimizing the physiological variables which are crucial for success in your event, and you should "mix" such workouts over time, instead of hammering away at just two or three different types of exertion.

One of the interesting periodization schemes which will be looked at closely in the future is something called skill-strength periodization. Once the linchpin of the former-Soviet-Union's track-and-field-teams' preparations for the Olympic games, skill-strength periodization SSP) calls for athletes to spend an extensive amount of time perfecting their technical skills during the preparatory phase of training, prior to embarking on the development of strength, power, and endurance. The idea is that once athletes are skilled (for example, once they are technically proficient jumpers, stroke-perfect swimmers, or economical runners), they can then optimally use their increasing strength to boost performance, because the increased strength that they subsequently gain is not "wasted" on inefficient movements but is channeled directly into proper patterns of motion. Of course, this is the opposite of many traditional schemes, which mindlessly crank up the volume of training as the first step in the periodized plan in order to "to build strength."

    
 References

(1) Stress without Distress.  New York: J. B. Lippincott, 1974
(2) Journal of Sports Medicine, Vol. 21, pp. 342-351, 1981
(3) Journal of Strength and Conditioning Research, Vol. 7(1), pp. 2-8, 1993 
(4) Journal of Strength and Conditioning Research, Vol. 13(1), pp. 82-89, 1999 
(5) National Strength and Conditioning Association Journal, Vol. 10, pp. 34-39, 1988
(6) Journal of Strength and Conditioning Research, Vol. 16(2), pp. 250-255, 2002
(7) Journal of Applied Sports Science Research, Vol. 6, pp. 92-95, 1992 

By Owen Anderson, Ph. D.

Copyright © 1998-2004 by Running Research News

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