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Practical Applications of Muscle Physiology 101 - Introductory Microcycles and the Repeated Bout Effect

Posted on mars 26 2018

Michael C. Zourdos, Ph.D., CSCS 

1. Prepare for success by implementing an introductory training week to acclimate to the training stimulus and avoid excess fatigued and missed repetitions.

2. An introductory week is designed to elicit the repeated bout effect (RBE) which is the protection or attenuation of muscle damage.

3. Basic guidelines for an introductory week are to train at a lower percentage (5-10%) of 1RM and lower total volume than the first week of the training block, thus rating of perceived exertion (RPE) will be about 2-3 values lower in the intro week vs. main training block.

4. It is easy to lift heavy and jump into a high volume or intensity block, but it is hard to have the discipline to consistently run introductory weeks. Be disciplined enough to make the correct choice and set yourself up for success. 

Countless times we have all setup a training program and calculated the load we will be utilizing in the latter weeks.  We might say something like, “Wow, as I keep adding 10lbs. per week that’s going to translate to a 40lb. rep PR, which will be a 50lb. squat PR after I taper.  I am finally going to squat 500lbs.”  Despite our unrealistic optimism, many of us have found ourselves unable to maintain the planned progression or too fatigued (i.e. excess muscle damage) to complete the volume in the first week of the training block.  Often this inability to recover in the initial week of training is due to the lack of acclimatizing to a new training stimulus, which can be avoided with an introductory week.

Specifically, when an unaccustomed exercise (1) or stimulus, such as significantly increased volume or intensity, is introduced significant muscle damage will occur.  This is problematic because training in a state of significant damage will compromise performance (2), thus limiting the ability to sustain planned progressions and nullifying progressive overload in the short term.  However, when repeatedly training an exercise, muscle group, (3) or stimulus, muscle damage in subsequent weeks will be attenuated and this is known as the repeated bout effect (RBE).  This can also be thought of as a ‘protective effect’ against muscle damage, so targeting the protective effect by gradually increasing training volume and intensity will improve feasibility of sustaining planned progressions.  Therefore, utilizing an ‘introductory week’ or ‘microcycle’, which is designed to elicit the RBE, prior to a volume or intensity block is invaluable to protect against excess damage and avoid the resulting consequences.  This strategy will set you up to meet or even exceed the appropriate progressions.  Indeed, recent literature has utilized an intro week in experienced lifters and almost all individuals went on to complete the planned load progressions over 8 weeks (4).

For experienced lifters, an introductory microcycle is typically one week, however, this is not a fixed time frame.  If transitioning from low volume training (i.e. end of a macrocyle) to a volume-focused block, an introductory microcycle may last up to four weeks to gradually increase volume and acclimate to higher repetitions.  Similarly, when moving from low intensity to an intensity-focused block an introductory microcycle might gradually build up intensity for a few weeks to acclimate the neuromuscular system to heavier loads. Specifically, general guidelines for construction of an introductory week might include using a percentage of one-repetition maximum (1RM) to prescribe load, which is 5-10% lower than the planned percentage in week 1 also leading to lower total volume during the intro week.  The difficulty per set would likely result in a target rating of perceived exertion (RPE) 2-3 values lower than the goal for week 1.  An example intro week for a volume block can be seen in Table 1, while an intensity block example is displayed in Table 2.


Table 1: Introductory Microcycle Preceding 4-Week Volume Block






2 X 8 @60%

3X6 @65%

4X4 @70%


3 X 8 @70%

4X6 @75%

5X4 @80%


3 X 8 @WK.1 +5kg

4X6 @WK.1+5kg

5X4 @WK.1+5kg


3 X 8 @WK.2 +2.5kg

4X6 @WK.1+2.5kg

5X4 @WK.1+2.5kg


3 X 7 @WK.2 +2.5kg

4X5 @WK.1+2.5kg

5X3 @WK.1+2.5kg

Note: The introductory week is 10% less than the recommended percentages in week 1.  For a volume block the RPE per set should fall between the range of 5-8 (i.e. 2-5 repetitions in reserve); thus the RPE in the intro week will likely be <5 and will not exceed 7.  Therefore, construction (i.e. sets, reps, and intensity) of a volume block are contingent upon the actual training block.


Table 2: Introductory Microcycle Preceding 4-Week Intensity Block






3X5 @70%

3X3 @75%, 1X1 @80%

3X2@80%, 2X1@85%/90%


4X5 @80%

4X3 @85%, 1X1 @87.5%

4X2 @90%, 1X1 @92.5%


3X5 @WK.1 +2.5kg

3X3 @WK.1+2.5kg, 1X1 @90%

X2 @9RPE, 2X3 @80% of double


3X5 @WK.2+2.5kg

3X3 @WK2+2.5kg, 1X1 @90%

X2 @9.5RPE, 2X2 @85% of double


3X4 @WK.3+5kg

4X2 @WK.3+5kg

X1 @9.5RPE, 1X2 @87.5% single

Note: The introductory week is about 10% less than the recommended percentages in week 1.  For an intensity block the RPE per set should fall between the range of 7-10 (i.e. 0-3 repetitions in reserve); thus the RPE in the intro week will likely be <7 and will not exceed 8.5.  Therefore, construction (i.e. sets, reps, and intensity) of an intensity block are contingent upon the actual training block.  Finally, take note that relative volume (total sets and repetitions) decreases as the block continues and the heaviest day (Friday) is gradually improving neuromuscular capabilities as the competition approaches.


Additionally, in novice lifters taking advantage of the RBE is also of paramount importance.  As a coach, you may have had an experience where a beginning trainee has skipped a session due to lingering fatigue.  Importantly, this can be mitigated, as training with as little as 10% of 1RM in the initial training week can confer the protective effect against muscle damage (5).  Ultimately, if the RBE is elicited the individual will be able to increase adherence to training, thus increasing training frequency and volume, subsequently leading to greater adaptations. 

Ultimately, this is an easy concept to understand, however, we have all fallen victim to impatience causing us to skip an intro week and move straight into the high volume or intensity training.  Often, we equate more difficulty per set or per session with working harder, however, this is far from reality.  Part of working hard and being dedicated is making the right decisions, which includes utilizing introductory microcycles when you already believe that you can crush the first official week of training.  While this is the correct course of action, it is still a difficult decision for most.  Take a step back and think logically for a moment: “Will I get weaker by simply taking one week to prepare with low stress/RPE per set before jumping into this volume block?”  The answer is of course: NO.  If you truly work hard and if you are truly dedicated, you will take a week to utilize an introductory microcycle and set yourself up for success.


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  1. Hyldahl RD, Chen TC, Nosaka K. Mechanisms and Mediators of the Skeletal Muscle Repeated Bout Effect. Exercise and Sport Sciences Reviews. 2017 Jan 1;45(1):24-33.
  1. Clarkson PM, Nosaka K, Braun B. Muscle function after exercise-induced muscle damage and rapid adaptation. Medicine and science in sports and exercise. 1992 May;24(5):512-20.
  1. Zourdos MC, Henning PC, Jo E, Khamoui AV, Lee SR, Park YM, Naimo M, Panton LB, Nosaka K, Kim JS. Repeated bout effect in muscle-specific exercise variations. The Journal of Strength & Conditioning Research. 2015 Aug 1;29(8):2270-6. 
  1. Klemp A, Dolan C, Quiles JM, Blanco R, Zoeller RF, Graves BS, Zourdos MC. Volume-equated high-and low-repetition daily undulating programming strategies produce similar hypertrophy and strength adaptations. Applied Physiology, Nutrition, and Metabolism. 2016 Feb 16;41(7):699-705.
  1. McHugh MP, Connolly DA, Eston RG, Gleim GW. Exercise-induced muscle damage and potential mechanisms for the repeated bout effect. Sports Medicine. 1999 Mar 1;27(3):157-70.








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