THE THEORY & METHODOLOGY OF PERIODIZATION
by Matt Cole (1999)
Introduction
Many strength-training specialists subscribe to various periodization models for the long-term development of their athletes (Balyi, 1991; Bompa, 1994; Poliquin, 1992; Verhoshansky, 1992; Wilks, 1994). That is, through specific manipulations of training variables increases in performance from year to year may be systematically orchestrated through the enhancement of sport specific strength (Bompa, 1993). Periodization protocols are thought to optimize the development of sport specific strength over the long term for two reasons: (1) strategically coordinated regeneration or unloading periods allow cumulative fatigue to dissipate thereby reducing the potential for overtraining and fostering super-compensation (Banister & Calvert, 1981; Fry, Morton, & Keast, 1992b), and (2) the variation in training stimulus associated with periodization will yield greater and faster gains than training at the constant relative intensity associated with progressive overload training (Kukushkin, 1983; Poliquin, 1997; Sleamaker, 1989).
It should be noted, however, that periodization methodology is largely based on the beliefs of training theorists and the empirical observations of the specialists in the field, while much has yet to be scientifically validated. It is the purpose of this paper to examine the theory, methodology, physiological basis, and scientific validation of periodization designs and identify areas warranting further investigation.
Terminology
Due to a lack of consistency regarding the definitions and use of overtraining and periodization terminology in the literature, the following definitions will be applied to this discussion:
Stress: A host of non-specific physiological responses of an organism induced by exposure to one or more diverse stressors.
Stressor: One of many distinct agents that will elicit stress when exposed to an organism.
Overreaching: The practice and symptoms of the short-term use of excessive training loads. Decline in performance may or may not be accompanied by displaced physiological variables and/or psychological symptoms. Recovery will occur within 1-2 weeks of active rest.
Overtraining: The practice and symptoms of continuous use of excessive training loads. Decline in performance may or may not be accompanied by displaced physiological variables and/or psychological symptoms. Recovery will demand a number of weeks to months of active rest.
The Annual Plan: The periodization scheme encompassing the annual 12-month cycle.
Macrocycle: A period of the annual plan, generally 6-32 weeks[1] in length, dedicated to a particular strength goal. These objectives may reflect the development of sport specific strength, prerequisites, and/or their maintenance.
Mesocycle: A period of 2-6 weeks of overload training, usually followed by an unloading microcycle. These cycles are repeated across the macrocycle to facilitate super-compensation.
Microcycle: A one-week block of training comprised of one or more training sessions.
Physiological Basis of Periodization
The aspect of periodization believed to reduce the risk of overtraining is based on Hans Selye's general adaptation syndrome (Stone et al., 1991; Wathen, 1994). Selye (1976) demonstrated that an organism would react to a variety of diverse stressors, including muscular work, with a number of non-specific responses (stress). However, that is not to say that the stressors themselves would not induce specific responses as well. In fact, Selye states that these specific responses invariably modify the stress response, as do endogenous (i.e. athlete's genetics) and exogenous (i.e. hormone treatment) conditioning factors.
The general adaptation syndrome (GAS) may manifest in three stages (Selye, 1976). The first stage, referred to as the alarm reaction, is characterized by the discharge of catecholamines from the adrenal cortex, depleting its storage of secretory granules. Moreover, at the hypothalamus nervous stimuli induce the emission of corticotropic hormone releasing factor (CRF). CRF then elicits the release of adrenocorticotropic hormone (ACTH) at the anterior pituitary, which in turn induces the secretion of glucocorticoids, including cortisol, at the adrenal cortex (Selye). The discharge of sympathetic neurons and secretion of catecholamines is the more immediate response; the release of cortisol follows in later part of the alarm stage and may act to dampen the acute response (Standford & Salmon, 1993).
However, because the alarm state cannot be maintained indefinitely, a stage of resistance follows in which adaptation occurs and the organism re-establishes physiological homeostasis (Selye, 1976). Anabolism and an enlarged adrenal cortex rich in secretory granules characterize this stage. During this stage if continued exposure to the stressor is of relatively smaller amounts, resistance/adaptation will continue and the organs will return to normal (Selye). Yet, if the exposure to the stressor continues at the same high level over a prolonged period, the adaptation incurred will deteriorate after several months and symptoms of the alarm reaction stage will reappear (Standford & Salmon, 1993). This is the stage of exhaustion in which symptoms may become irreversible leading to pathology and even death of the organism (Selye).
Overtraining
While the overtraining syndrome is generally not considered fatal or its symptoms irreversible, it is a stress response consistent to Selye's general adaptation syndrome (Kraemer, Bradley, & Nindl, 1998; Kuipers & Keizer, 1988; Stone et al., 1991). Moreover, muscular exercise should not be considered one type of stressor, but several. That is, overtraining symptoms will vary between aerobic endurance training and anaerobic training, and with respect to anaerobic training, periods of high volume training will produce different symptoms from those associated with high intensity training (Fry, 1998). Recall that the specific effects of the stressor are superimposed upon and invariably modify the non-specific stress response. Consequently when two different stressors are imposed upon an organism simultaneously their specific effects may interact upon the systemic stress response of the organism. Therefore, since strength-training sessions are comprised of both doses of volume and intensity (figure E1) their specific effects can be expected to interact in varying degree (Fry, 1998; Kraemer et al., 1998).
Figure E1. The relationship between relative training intensity (%1RM) and training volume (sets X repetitions = total repetitions) as they relate to resistance training overtraining (Fry, 1998).
While the specific and non-specific physiological and psychological consequences of overtraining stressors are beyond the scope of this paper[2], it is suffice to say that the imbalance between training and recovery results in neuroendocrine dysfunction localized at the hypothalamic level. This in turn can result in the compromise of the immune system, cardiovascular system, nervous system, the balance between anabolic and catabolic function, carbohydrate and lipid metabolism, as well as induce chronic fatigue (Budgett, 1998; Kreider et al., 1998; Kuipers & Keizer, 1988; Stone et al., 1991).
These medical consequences coupled with prolonged deterioration of performance may interrupt a competitive season, sacrifice an upcoming season, or worse, cause the premature termination of the athlete's career (Fry et al., 1992b; Kreider et al., 1998). Therefore, it is the design of periodization methodology to repeatedly cycle the athlete through the first two stages of the GAS, while avoiding the onset of the third (overtraining). Consequently, training sessions of overload training act as the initial stimulus (stressor) for adaptation while periods of rest or unloading facilitate restoration and adaptation, termed super-compensation in sport science literature (Banister & Calvert, 1981; Fry et al., 1992b; Gambetta, 1991).
Periodization Methodology
The annual plan (figure E2) for most athletic events is divided into three phases or macrocycles: the preparatory phase, the competitive phase, and the transition phase (Wilks, 1995). The preparatory phase is often further subdivided into the general preparatory phase and the specific preparatory phase, while the competitive phase is occasionally similarly subdivided into the pre-competitive phase and the main competitive phase (Bompa, 1994; Verhoshansky, 1992).
The Macrocycle
The preparatory phase marks the beginning of the annual plan. The role of the general preparatory phase is to establish a base or foundation of strength on which to build sport specific strength (Charnigra et al., 1994a; Matveyev, 1992). The focus should be on strengthening the connective tissue and the core stabilizer muscles as well as those of the limbs (Bompa, 1993). With the specific preparatory phase there is a shift toward the development of prerequisites for sport specific strength and sport specific strength itself (Bompa, 1994; Matveyev, 1992).
The competitive phase encompasses the annual competition calendar and, depending upon the nature of the sport, will either serve to forge a performance peak during the most important competitions or maintain the sport specific strength developed during the preparatory phase (Charnigra et al., 1994b). The pre-competitive phase is utilized when the event allows for exhibition competitions prior to main competitions (Bompa, 1994). In essence it is an extension to the specific preparatory phase in which the development of sport specific strength may be evaluated in a competition setting. The exact length of the competitive and preparatory phases are primarily determined by the competition schedule which, of course, is in turn determined by the event and the level of the athlete(s) (Bompa, 1993; Verhoshansky, 1992).
The transition phase follows the competitive phase and is a macrocycle of active rest (Charnigra et al., 1994a). That is, it is the role of the transition phase to allow recovery from fatigue that may have culminated over the preparatory and competitive phases as well as necessitate any biological regeneration from micro trauma that may have occurred (Charnigra et al., 1994b). Typically, both volume and intensity are dramatically reduced as well as any sport specific training, if not entirely eliminated. Active rest is characterized by low volume (moderate intensity) general conditioning work and recreational physical activity (Charnigra et al.).
Another objective of the transition phase, beyond the recovery from fatigue, is to have the athlete start off the forthcoming annual plan at a higher level of performance than the previous year (Charnigra et al., 1994a; Verhoshansky, 1992). Therefore, to avoid a stagnant type pattern in performance from year to year, the transition phase is much shorter than the preparatory and competitive macrocycles, typically lasting only 4 to 8 weeks. This time frame is thought to optimize recovery, while minimizing ay loss of the accumulated strength gains, ensuring observable performance enhancement from year to year (Bompa, 1993).
Figure E2. Training Phases of the Annual Plan (Modified from Bompa, 1994).
The Mesocycle
The mesocycle is a period of 2-6 weeks in which a number of microcycles of overload training are followed by an unloading microcycle in which both volume and intensity, and possibly frequency as well, are reduced (Bompa, 1993[3]; Banister & Calvert, 1981; Charnigra et al., 1994a; Fry et al. 1992b; Matveyev, 1992). The theory being that the overload training provided by the sessions within the initial microcycles provide a powerful stimulus for adaptation, while the unloading microcycle facilitates the adaptive process (Wenger, McFadyen, & McFadyen, 1996) by providing an interval in which the stress provided by the training is dramatically reduced. The mesocycle is then repeated over the length of the macrocycle to develop a particular strength quality. Table E1 reveals how a typical 4-week mesocycle might be structured.
Table E1.
A 4-Week Mesocycle Designed for Strength Development
|
Microcycle |
1 |
2 |
3 |
4 |
|
Intensity |
8RM |
6RM |
4RM |
10RM |
|
Sets/Muscle Group |
6 |
6 |
6 |
3 |
|
Frequency |
3 |
3 |
3 |
1 |
|
Volume |
144 |
108 |
72 |
30 |
Note. Volume is total repetitions for the microcycle (sets x repetitions x frequency). Intensity is progressively increased across the first three microcyles. The unloading microcycle is characterized by a reduction in intensity, volume, and frequency.
Beyond regeneration considerations and the goals and length of the macrocycles, another factor which will contribute to the form and sequencing of the mesocycles is the use of a particular periodization model. These schemes can be categorized as either linear or non-linear.
The Linear Model
Matveyev's original model of the annual training plan, what has since become to be known as the linear model, was first developed in the early 1960's (Wilks, 1995). The approach of the linear model is that of an initial onset of high volume training in the preparatory phase is followed by a progressive increase in intensity with sharper decrements in volume into the latter preparatory and competitive phases, working toward an eventual peak in intensity and performance (Wilks).
Matveyev's model has since been adapted specifically for the strength and power athlete (Stone, O'Bryant, & Garhammer, 1981). Figure E3 reveals the Stone et al. model. What has been labeled the first transition may be likened to the specific preparatory and pre-competitive macrocycles. The technique-training curve indicates sport specific training.
Figure E3. A Hypothetical Model for Strength Training (Stone et al., 1981).
Table E2.
Macrocycles Associated with Stone et al (1981) Model
General Specific Preparatory Competitive Transition
|
Macrocycle |
Hypertrophy |
Strength |
Power |
Peaking |
Active Rest |
|
Volume |
High |
Mod-Low |
Low |
Low |
Lowest |
|
Sets |
3-5 |
3-5 |
3-5 |
1-3 |
0-1 |
|
Intensity |
Low |
High |
High |
High |
Moderate |
|
Reps |
8-12 |
2-6 |
2-3 |
1-3 |
8-12 |
|
Specific Work |
Low |
Low-Moderate |
High |
High |
Low/ Nil |
Note. Volume refers to total reps, not sets. Set recommendations are per muscle group per training session.
The authors proposed four specific blocks or macrocycles of training contributing to the development of sport specific strength occurring across the preparatory and competitive phases: hypertrophy, strength, power, and peaking (table E2). Hypertrophy is the first block of mesocycles followed by the strength and power macrocycles. The hypertrophy macrocycle is positioned first because it is believed that hypertrophied muscle has a greater potential to increase strength and power than non-hypertrophied muscle (Bompa, 1993; Stone et al., 1981).
The objective of the strength phase is to develop the athlete's maximum or 1RM strength which is believed to be a prerequisite in the development of sport specific strength and power (Bompa, 1993). The power macrocycle follows in which the velocity and specificity of the exercises are increased and the raw ingredients, now developed, are transformed into sport specific forms of power (Willoughby, 1991).
The peaking block takes up the competitive phase (table E2) in which volume is further reduced in favor of intensity and specificity, building towards an eventual performance peak in the latter half of the competitive phase (Stone et al., 1981).
Both maximum strength and power training are thought act as a stimulus for adaptations to neural drive (Bompa, 1993; Fleck & Kraemer, 1997; Poliquin, 1997). Therefore, the theory is that the initial high volume training will stimulate the desired muscle hypertrophy and the later high intensity training will act as stimulus for neural adaptations[4] (Baker, 1993).
Like Stone et al. (1981), Bompa (1993) endorses similar block type training. However, Bompa has taken into consideration that not all events allow for hypertrophy. With weight class events the objective is to maximize sport specific strength and power without substantial lean tissue accretion, unless the athlete intends to move up a weight class. Therefore, the hypertrophy block is only inserted into the annual plan if it is warranted. However, all annual plans start off with a macrocycle[5] block Bompa refers to as anatomical adaptation.
The anatomical adaptation macrocycle and the hypertrophy macrocycle differ in several respects. The anatomical adaptation phase occurs during the early preparatory phase and is designed to lay the foundation on which future strength training can build (Bompa, 1994). The scope of this macrocycle then is to involve most, if not all the muscles groups, by utilizing a large amount of exercises (Bompa, 1993). The focus is to strengthen core muscles groups and develop joint and connective tissue strength as well as ideal muscle strength ratios between muscle groups.
When the hypertrophy block is included, focus is on enlarging the prime movers, thus fewer exercises are prescribed. However, there are exceptions to this. Bodybuilders, shot putters, and offensive and defensive linemen will benefit from more broad hypertrophy (Bompa, 1993). Figure E4 reveals annual plans with and without a hypertrophy block.
Figure E4. The Annual Plan With and Without a Hypertrophy Block.
Criticism of the monocyclic linear model and the impracticality of peaking once a year for many events led to the implementation of bi-cyclic (figure E5) and tri-cyclic annual plans (Wilks, 1995; Fleck & Kraemer, 1997). These models repeat the original linear model two or three times within the annual plan by shortening the length of each of the macrocycles[6] (Fleck & Kraemer, 1997). For example a 100-meter sprinter who peaks in the summer for his event may which to peak as well during the winter to compete in the 60-meter sprint during the indoor season.
These bi-cycle and tri-cycle models have shown a trend to produce greater gains than the monocycle (Balyi, 1995; Bompa, 1993). Therefore, athletes competing in one-peak or competitive phase events have adopted them as well. Fleck and Kraemer (1997) have proposed that the superiority of these designs may be due to their variation of training stimulus believed to be essential for optimal and continuous gains (Poliquin, 1997).
Moreover, these models provide for more individual and sport specific training for elite athletes who will not benefit from a prolonged general preparatory phase at the beginning of each annual cycle (Balyi, 1991; Balyi & Hamilton, 1996).
Figure E5. A Typical Bi-Cyclic Annual Plan (Balyi and Hamilton, 1996).
Note. GPP = general preparatory phase; SPP = specific preparatory phase; PCP = Pre-competitive phase; CP = Competitive phase; TP = transition phase. Note the very short transition phase separating the two cycles and that the second preparatory phase is entirely specific in nature.
As a general rule with bi-cycle and tri-cycle designs the first preparatory phase is the longest and therefore typifies the highest volume of training (Bompa, 1994). Furthermore, subsequent preparatory phases should be solely of a specific nature (figure E5) for experienced athletes since they already possess a foundation of physical conditioning optimized during the initial general preparatory phase (Balyi & Hamilton, 1996).
With multiple competitive phases, it is common that the first peak is a lesser peak and occurs during the least important competitive phase (Bompa, 1994).
Non-Linear Models
Non-linear or undulating designs are characterized by short periods of high volume training alternated with shorts periods of high intensity training (Baker, 1993). This type of periodized loading is thought to optimize strength gains by regularly employing training protocols thought to favor both hypertophic adaptations (high volume training) and neural activation (high intensity training) enhancement (Baker, 1995; Poliquin, 1992). The specific manipulations of intensity and volume of the non-linear model can vary widely and in its various forms has been referred to as undulating, wave like, accumulation-intensification, and multiple periodization (Baker, 1993, Balyi, 1991; Poliquin). The reader should, however, not let these terms confuse the issue here. These schemes are all essentially the same thing: non-linear designs that alternate between periods of high volume and high intensity. If they differ, it is only in how the periods of high volume and high intensity training are manipulated.
The most common non-linear variations alternate periods of high volume and high intensity training within the mesocycle or between mesocycles. Poliquin (1992) has successfully applied a 2:1 ratio of high volume microcycles to high intensity microcycle, while 3:3 and 4:4 ratios have also been reported by Baker (1993). Depending upon the phase of training, volume may be highest in the first microcycle and decline across the mesocycle as intensity increases or vice versa. Moreover, volume or intensity may peak in the middle of the mesocycle or volume may increase while intensity is held constant across the mesocycle (Baker). These manipulations coupled with a possibility of sequencing mesocycles varying in length from 2-6 weeks allows for tremendous variation and flexibility to suit the needs of numerous competition schedules.
Figure E6 reveals an 18-week undulating model designed by Poliquin (1992) for hammer thrower, Judson Logan who thereafter set an indoor world record. 3-week mesocycles are employed with a 2:1 ratio of accumulation (high volume) microcycles to intensification (high intensity) microcycles. Intensity is increased linearly over the 3-week cycle while volume is decreased, substantially (by 30-40%) in the third microcycle.
Figure E6. Undulating Model Developed for Hammer Thrower, Judson Logan (Poliquin, 1992).
It should also be noted that Poliquin's design (1992) periodized exercise selection, rest intervals, and contraction velocity or tempo as well as intensity and volume. During the general preparatory phase contraction tempo was slow to moderate; the specific preparatory placed an emphasis on quick contraction velocities. And during the final weeks leading up to the major competition contraction tempo was gradually increased as volume was tapered.
Bompa (1993) has advocated the use of the 3:3 accumulation-intensification microcycle ratio during long preparatory phases and for power dominant events. Figure E7.a shows 3-week hypertrophy cycles been alternated with 3-week maximum strength cycles following larger blocks of hypertrophy and maximum strength training during a lengthy preparatory phase. Figure E7.b reveals alternating 3-week cycles of maximum strength with power training.
E7.a
E7.b
Figure E7. 3:3 Undulating Models for the Long Preparatory Phase and Power Development (Bompa, 1993).
Note. Subscript numbers in the upper right corner of each mesocycle refer to the number of microcycles within it. AA = anatomical adaptation; MxS = maximum strength; P = power; Hyp = hypertrophy; Comp = compensation training or active rest.
The noteworthy distinction with undulating mesocycles is that that volume and intensity are not simultaneously unloaded. With respect to Selye's GAS, one stressor is traded off for another. Thus, while the specific effects of one stressor are removed, the athlete would still theoretically be experiencing systemic stress. One could speculate that loading muscle in such a manner over the long term would lead to overtraining.
More aggressive undulating approaches has also been structured within the microcycle sequencing heavy and light days (Fleck & Kraemer, 1997) and even within the daily training session incorporating high intensity low volume sets and moderate intensity high volume sets (Wilks, 1995). Table E3 presents an undulating microcycle in which a high intensity day is centered within the week, with high volume days positioned on Monday and Friday, the Friday being of higher volume and lesser intensity.
Table E3. An Undulating Microcycle (Fleck & Kraemer, 1997)
|
|
Monday |
Wednesday |
Friday |
|
Intensity (RM) |
8-10 RM |
3-5RM |
12-15RM |
|
Sets |
3-4 |
4-5 |
3-4 |
|
Rest Interval |
2 min |
3-4 min |
1 min |
While periodization designs as a whole are believed to be superior to non-periodized prescriptions in developing strength and power gains (Baker, 1993; Poliquin, 1997), undulating models are thought to be superior to the linear model. The rationale being that prolonged high intensity periods within the linear model may contribute to neural fatigue (Baker; Bompa, 1993).
Maintenance vs. Peaking
For events with many competitions within the competitive phase, a maintenance program will be utilized rather than working toward a performance peak (Charnigra et al., 1994b). Fleck and Kraemer (1997) have therefore deemed the undulating model appropriate for events in which the athlete will be competing on a weekly or bi-weekly basis while the linear model is appropriate for peaking once or several times a year. However, the bi-cycle should also be considered a viable alternative for team sports with a long preparatory phase (Bompa, 1993).
A further distinction can be made between events with shorter competitive phases and weekly competitions, such as football, and those events with longer competitive phases and multiple weekly competitions (Charnigra et al., 1994b).
While the latter events'competitive phases will exclusively include maintenance and restorative mesocycles, events with shorter competitive phases and weekly competitions may allow for more intense training earlier in the week (Charnigra et al, 1994b).
Events focused on peaking will select a limited number of competitions to peak for and train through the minor competitions (Charnigra et al, 1994b). Moreover, in the weeks preceding a major competition the mesocycles should be shorter, competition specific, and include a taper to maximize the distance between performance and fatigue (Bansiter & Calvert, 1981; Balyi & Hamilton, 1996; Charnigra et al). The taper differs from unloading in that only volume is reduced while intensity is maintained (Bansiter & Calvert). However, in specific reference to strength training, a complete cessation of 5-10 days prior to the major competition has been prescribed (Bompa, 1993; Ruisz, 1987).
Scientific Support
While the body of experimental research into the periodization as a whole is extremely small, the majority of these investigations have focused on the linear model (Herrick & Stone, 1996; Stone et al., 1981; Kraemer, 1997; Willoughby, 1992, 1993). Stone et al. (1981) investigated the effects of both a linear and non-periodized (3 X 6RM) design among 20 college-aged males. The experiment was 6 weeks long in which both groups trained three days a week. Monday and Friday exercises included squats, bench press, and one set of leg curls. Wednesday's exercises were made up of pulls (mid thigh), pulls (floor), and behind the neck press. The linear group performed 5 X 10RM for the first three weeks, 5 X 5RM in the fourth week, 3 X 3RM in the fifth week, 3 X 2RM in the sixth week. Measures of 1RM strength, power, and body composition were taken at weeks 0, 4, and 6. Results showed significant differences in power, 1RM strength and relative strength favoring the linear group. Overall body weight did not change, however LBM was up and %F was down with the linear group and significantly different from the non-linear group at T2 and T3.
Further observation by Stone et al. (1981) noted greater 1RM and relative strength gains over 5.5 months among Olympic lifters using a linear design compared with those using a non-linear high intensity (2-3RM) model. Similarly, in a 12 week study with high school football players greater gains in 1RM squat, bench press, power clean and power were associated with the linear model over those resulting from a non-periodized (3 X 6RM) design (Stone et al.). However, with all these experiments the subjects utilizing the linear model were subject to greater volume in terms of total repetitions. Therefore, it is difficult to conclude if the superior gains are attributable to the greater volume or the design itself, or both.
In a 12 week study using trained college aged males Willoughby (1992) reported significantly superior 1RM strength gains in both the squat and bench press with the use of a linear program over two non-periodized models (3 X 10 RM & 3 X 6-8RM). However, like Stone et al. (1981) the subjects within the linear group were subject to a greater volume of training, in this case 3-4 times a greater volume.
In two separate studies Kraemer (1997), using NCAA division III football players as subjects, investigated a linear variation and an undulating design along with single set circuit training protocols of lesser volume. Both periodization models produced superior gains in vertical jump, anaerobic power, and 1RM strength compared to the single set circuit training programs. Although, it is difficult to extract any sound knowledge regarding periodization design from these studies since volume, as well as exercise type, rest interval, and in one case, frequency were not controlled for.
Herrick & Stone (1996) trained 22 untrained college aged females for 15 weeks complying with either a non-periodized (3 X 6RM) or linear model. The linear model was characterized by hypertrophy (3 X 10RM) training during the first 8 weeks followed by strength training (3 X 4RM) for 2 weeks and a peaking/maximum strength phase (3 X 2RM) in the final 2 weeks. And following each phase, before the commencement of the next phase, was a microcycle of active rest (low intensity aerobic training). Volume was not equated, however similar in terms of total reps per exercise: linear = 552 reps, non-periodized = 540 reps.
Results showed no significant difference between the two groups regarding 1RM strength in both the bench press and the squat. However, the authors did note a consistent improvement in performance with the periodized group during the last 9 weeks of the study, while the non-periodized group appeared to be plateauing near the end of the study.
In a review by Baker (1993) it was concluded that when intensity was equated higher volume training would yield greater gains and when volume was equated higher intensity would yield greater gains. However, Willoughby (1993) in a 16 week study utilizing 92 trained males showed greater gains in 1RM strength (squat & bench press) with a linear design of reduced volume in the last 8 weeks. The study equated volume for the first 8 weeks among two non-periodized groups (5 X 10RM & 6 X 8RM) and a linear periodized group. The periodized group was subject to 4 weeks of training according to each of the following protocols: 5 X 10RM, 6 X 8RM, 3 X 6 RM, and 3 X 4RM. At weeks 8, 12, and 16 the periodized group differed significantly from the other groups in the squat. At weeks 4, 8, and 12, the periodized group and the 6 X 8RM non- periodized group differed from the 5 X 10RM non-periodized group and the control group regarding 1RM strength on the bench press. At week 16 the periodized 1RM bench press strength differed significantly from all other groups.
It should be noted that Willoughby's (1993) method of equating volume was not in terms of total repetitions, but total mass lifted per week. It was calculated as reps per set x number of sets per session x mass lifted per set x sessions per week. Nonetheless, in terms of total repetitions per exercise the volume was similar between the three groups during the first 8 weeks: non-periodized (5 x 10RM) = 1200, non-periodized (6 x 8RM) = 1152, and linear periodized = 1176. Volume for the non-periodized groups was identical in the second 8 weeks of training while the linear group's volume was reduced to a total of 360 repetitions per exercise.
The non-linear design has been the focus of few investigations (Baker, Wilson, & Carlyon, 1994; Baker, 1995; Kraemer, 1997). Baker (1995) investigated an undulating variation in a 9-week study utilizing 5 trained males as subjects. Microcycles were either predominately high volume or high intensity arranged in a 2:1 fashion respectively. However, manipulation of volume and intensity also occurred within the microcycle with heavy days on the first and third training days and day 2 characterized by more moderate intensity. Results showed a significant increase in both squat and bench press 1RM strength as well as an increase in body mass attributed to an increase in LBM.
Unfortunately, this study offered no other experimental or control group e.g. linear or non-periodized in which a comparison of effectiveness could be made. Any program of sufficient volume and intensity will induce strength gains over the short term. The goal of periodization research is to unearth the most effective design for a particular sport specific strength or prerequisite, which may be applied to the long-term development of the athlete.
Perhaps the best-designed study to date is Baker et al. (1994), in which a linear, undulating, and non-periodized models were studied over a 12-week period. Both volume and intensity were equated in terms of total reps per exercise and RM respectively. IEMG, 1RM strength (bench press & squat), %F, and body mass were all recorded at regular intervals. Results indicated that all three groups increased their vertical jump, LBM, bench press and squat 1RM similarly. IEMG and %F remained unchanged.
Thus, in considering the limited experimental research, it appears that when both volume and intensity are equated, enhancement of strength and power in the first 12 to 15 weeks of training will be similar despite program design. However, there is some indication that strength and power gains maybe enhanced by periodized designs beyond 15 weeks (Herrick & Stone, 1996; Willoughby, 1993).
Sequencing of Training Sessions
The sequencing of training sessions within the microcycle to optimize super-compensation is an aspect of periodization in which not all sport scientists agree, and of which the knowledge base is largely theory.
Super-compensation
Figure E8 reveals the classic model of super-compensation. Following a series of training impulses over a training session physiological homeostasis is disrupted and fatigued is induced. During a period of recovery homeostasis is re-established and regeneration is such that over compensation occurs resulting in enhanced performance (Bompa, 1994). However, if subsequent training impulses are not administered the acquired adaptation and enhanced performance will eventually degrade.
Figure E8. The Super-Compensation Model (Modified from Bompa, 1994).
Banister and Calvert (1981) theorized that a training session would induce twice as much fatigue as it does fitness (the training effect). Although, the length of the residual effect of fatigue, termed the time constant, is much shorter than that of the training effect[7] (figure E9). Therefore, appropriately timed subsequent training sessions will build upon the residual training effect, yet not that of fatigue. On the contrary, subsequent training sessions imposed too soon will contribute to cumulative fatigue (Wenger et al., 1996) and overreaching (Fry, Mortan, & Keast, 1992a) and eventually overtraining and a decline in performance (Banister & Calvert, 1981). Conversely, training sessions imposed too far apart will not optimally build upon the strength residue because some detraining has been allowed to occur (Bompa, 1994; Kukushkin, 1983). In fact if the training sessions are far enough apart no apparent performance gain will be observed at all.
Figure E9. The growth and decay of the residual effects of fatigue and fitness (i.e strength) (Bansiter & Calvert, 1981).
The question then arises, what is the time constant for fatigue/recovery following a strength training session? And what then is the number of training sessions that can be scheduled across the microcycle for the same muscle groups? In the past a period of 48 hours of recovery has been prescribed (Atha, 1981; Bompa, 1993) and adopted as the standard. However, this may be inadequate and a 72-hour recovery period may be more appropriate (Fleck & Kraemer, 1997; Poliquin, 1997; Wilson, 1996).
Logan and Abernethy (1995) measured urinary 3-methylhisidine[8] (3MH), IEMG, 1RM strength (leg press) among 19 trained males following an intensive training session. The training protocol included five sets of both the squat and leg press exercises with intensities ranging from 2-6RM
(2X6RM, 2X4RM, & 1X2RM). Three sets (1x8RM + 2X6RM) of leg
extensions were also employed. Thirteen sets in all with intensities ranging from 2-8RM constitutes a high volume and reasonably high intensity training session and the authors found full recovery occurred within 72 hours.
Eccentric training on the other hand appears to require a lengthier recovery. Clarkson, Nosaka, & Braun (1992) presented data on 109 subjects (up to five days after) and 15 subjects (up to 10 days after) following an eccentric resistance training session. The loading protocol included two sets of 35 maximal eccentric repetitions. One repetition was performed every 15 seconds and there was a five-minute rest interval between sets. Maximal isometric force was impaired greater than 50% immediately afterward and gradually recovered yet was still depressed after 10 days. Serum creatine kinase had a delayed rise (48 hours) and did not peak until four days afterward. Both muscle soreness and swelling (circumference) were reported to be still evident 8-10 days afterward. Fry (1998) notes, however, that excessive eccentric loading, which the above protocol might be considered, can cause considerable muscle damage.
Overreaching
It has been suggested by some (Harre, 1982; Kukushkin, 1983; Sleamaker, 1989) that complete recovery between training sessions and microcycles is not necessary within the mesocycle. In fact these authors (Councilman, 1968; Kukushkin, 1983; Sleamaker, 1989) have suggested that incomplete recovery between training sessions provides a more powerful stimulus for adaptation by progressively increasing the degree to which homeostasis is displaced (Councilman, 1968), while still allowing partial recovery. The key point advocated by these theorists is that the subsequent mesocycle is not commenced until super-compensation and full recovery has been demonstrated and therefore overtraining is averted (Bompa, 1994; Harre, 1982; Kukushkin, 1983).
The extreme of this type of training is the intentional use of overreaching to precipitate a training effect has been reported elsewhere (Kraemer et al., 1998; Stone & Fry, 1998; Stone et al., 1991) and has been suggested to induce a delayed performance gain several weeks after returning to normal training loads (Stone & Fry). One way this is done is to "superload" the microcyle immediately preceding the unloading microcyle (Wenger et al., 1996). Such microcycles have been referred to in the literature as shock or crash microcyles and can be characterized by sharp increases the volume and/or intensity of training (Councilman, 1968; Harre, 1982; Kukushkin, 1983; Sleamaker, 1989).
The superior gains achieved through the use of periodic overreaching, however, is speculation and not an opinion shared by all. Wilson (1996) recommends complete recovery between training sessions and therefore microcycles, contending that incomplete recovery between sessions will lead to reduced performance gains. Furthermore, large increments in training loads should be avoided (Bompa, 1994). More gradual progressions and variation will increase the stability of the pituitary-adrenocortical system and therefore elevate the training level at which abnormal adrenocortical activity would occur (Kuipers & Keizer, 1988).
Unquestionably, the use of overreaching protocols within the mesocycle is a controversal methodology that must be either validated or discredited since their employment will initially impair performance regardless of what later gains are or not achieved. Future studies might examine the effectiveness of mesocycles utilizing such protocols by comparison to those with a more conservative, yet equated[9], distribution of training loads.
Conclusions & Recommendations
Periodization methodology should not be viewed as rigid training architecture, but rather a flexible framework that may be adapted for the development of sport specific performance attributes for any event. Factors to consider when designing and implementing a periodization scheme for a particular athlete or group of athletes include: the training age of the athletes, the specific demands of the event in terms of sport specific performance attributes sought, the length and competition frequency of the competitive phase, and the adoption of a particular periodization model.
Clearly, however, there is an immense need for equated investigations between linear, non-linear, and non-periodized designs 15 weeks or more in length. For when training volume is equated, there appears to be no superiority to either linear or undulating designs over a non-periodized approach when training is confined to a 12-week period (Baker et al., 1994). However, at 15-16 weeks periodization designs have shown significantly superior gains (Willoughby, 1993) or a trend for greater gains (Herrick & Stone, 1996).
The use of periodic unloading microcycles appears theoretically sound and in line with Selye's general adaptation syndrome and accordingly may effectively curb overtaining by providing regular interval periods in which the athlete is not under continuous demand to adapt. However, long-term studies (>15 weeks) are required to test their effectiveness compared to non-periodized regimes and undulating mesocycles which do not simultaneously unload volume and intensity. In addition, such studies would be complemented by further investigations of resistance training induced overtraining (volume vs. intensity) and identification of appropriate physiological markers.
What should also be of particular interest for researchers is the length of the mesocycle, or rather the frequency of unloading. The literature indicates that a common length of the mesocycle is 4 weeks (Bompa, 1993; Mateveyev, 1992; Wenger et al., 1996). However, as indicated earlier, the mesocycle length can vary from 2-6 weeks (Bompa, 1994; Fry et al., 1992a; Wilks, 1995). And while the total number of weeks allocated to a particular macrocycle can partially determine the length of its mesocyles, the length of the mesocycle is still largely dictated by the intuition of the coach or trainer. Therefore, a series of well-controlled studies is warranted in determining the optimal length of the mesocycle or unloading frequency with respect to different prescriptions of volume and intensity of training.
Not all sport scientists agree on what the optimal strategy is for the sequencing of strength training sessions. Some propose that complete neuromuscular recovery between training sessions would be best (Banister & Calvert, 1981; Wilson, 1996), while others (Harre, 1982; Kukushkin, 1983; Slemaker, 1989) have theorized that partial, yet incomplete neuromuscular recovery acts as a greater stimulus for adaptation by progressively displacing homeostatsis over a number of training sessions (Councilman, 1968) within the microcycle and mesocycle. Overtraining is thought to be prevented because full neuromuscular recovery occurs during the unloading microcycle. Hence, no cumulative fatigue is carried over into the next mesocycle and therefore not allowed to build over the macrocycle[10] (Bompa, 1994; Harre, 1982; Kukushkin, 1983).
The standard recovery time prescribed between strength training sessions for the same muscle groups has been 48 hours (Atha, 1981; Bompa, 1993) yet the time course for complete muscular recovery following a resistance training session appears to be 72 hours (Logan & Abernathy, 1995). However, this time course can be increased considerably with the inclusion of eccentric resistance training (Clarkson et al., 1992). Therefore, before researchers can investigate whether complete neuromuscular recovery or partial, yet incomplete neuromuscular recovery is optimal within the microcycle and mesocycle, the time course for complete neuromuscular recovery must be documented for a variety of interacting prescriptions of volume and intensity (RM) as well as exercise type i.e. conventional resistance training, plyometrics, submaximal and subra-maximal eccentric resistance training.
Nevertheless, It should be noted that even if complete
recovery were to take place between training sessions and microcycles, the periodic unloading of the mesocycle structure would still be theoretically sound and in line with Selye's general adaptation syndrome. Recall that even though an organism has demonstrated adaptation to a stressor, if exposure to that stressor is continued to the same degree over a prolonged period, the "adaptive energy" of that organism will become exhausted and adaptation that has occurred will begin to deteriorate (Selye, 1976). Unloading microcycles, provide regular interval periods in which the athlete is not continuously challenged to adapt.
The idea that short-term overreaching protocols may induce a banked accumulation effect positively benefiting performance (Kraemer et al., 1998, Stone & Fry, 1998) is intriguing, however, it may be misguided and more conservatively distributed, yet equated, training loads within the mesocycle may induce superior gains. Overreaching protocols may only appear to induce great gains because they diminish performance initially. Direct comparisons between equated mesocycles are required to validate or discredit these protocols. This may be done be equating the volume of two mesocycles of the same length, yet varying their distribution of training volume so that one mesocyle represents an overreaching approach while the other has the training volume more uniformly dispersed across the length of the mesocycle.
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