As discussed in the previous article, training isn't anything more than a continuous process of adaptation. Every training session, exercise, set, rep, and so on serves as a stimulus that can lead to a training effect. The purpose of this article is to examine how to alter the stimulus to provide the desired adaptations.

Three general factors

According to Zatsiorsky, there are three general factors of adaptation—stimulus magnitude, specificity, and accommodation. The stimulus magnitude is quite simply the actual volume, intensity, and choice of exercises. The specificity of the training load is how well the actual tasks performed in training will transfer to the competitive event. Finally, accommodation is the actual adjustment that has been made that results in an increase in the potential of work and a decrease in reaction to the physical load applied. From here, we will further examine these factors.

Stimulus magnitude

As stated above, the stimulus magnitude revolves around the following three factors:

  • Volume of load—total amount of all work performed
  • Intensity of load—effort calculated either as a percentage of a maximum, heart rate response, or rate of exertion
  • Exercises selected—actual movements being used to bring about a training effect

The three factors above have to be adjusted to provide a stimulus above the current level. This is the principle of overload that has been discussed many times, but it is the basis of how the process works. There are various ways to modify each of these, and this is what needs to be looked at in order to further the process of adaptation.

Volume considerations:

One of the simplest ways to manipulate loading is volume. Many times people only think of volume in terms of the total amount of work in each session. While adding a few sets or reps here will add some volume, many people neglect volume in the big picture. It needs to be looked at from a perspective of the sum of all training performed. The reasoning for this is because in each session, only so much work can be done. Fatigue will set in, and at some point, more work will become counterproductive. After a certain point, in order to overload but still provide quality stimulus, more workouts in a given time period will need to be included.

The issue that needs to be looked at here is that while workouts are being added, it needs to be done gradually. This may mean initially decreasing some volume from certain sessions but adding it in the form of an additional session. While each session may have slightly less volume, the total sum of all volume will be greater. This process can be repeated when an additional session may be needed in order to create or provide a greater stimulus.

The problem is that people are always on opposite sides of the fence, and no one looks at the underlying issue. You either have the guys who train two to three times a week and hit just enough to barely create any overload and eventually stall, but keep doing the same thing without any results for the fear of overtraining or the guys who train haphazardly and add work on top of work without any tracking or consideration to what the total sum is or what effect they're trying to achieve.

The key here is to track the volume from session to session. When it appears that a trend of decreased stimulation may be surfacing, slowly accumulate more volume either by way of small additions to each session or by adding an additional session. The key is to do this slowly and only once it becomes clear that this is the missing variable. Don't be the moron who goes from three sessions a week to twelve sessions a week split over six days two weeks later and think that a desired effect will come out of this.

While in some cases volume may be one of the most important and simplest modifications to make, it has its limitations. When adding volume in each session, attention has to be paid to the quality of work. Once fatigue sets in and the desired form of work can't be maintained, it is time to shut it down and move on. In a given session, like stated before, the volume can only be so high before fatigue sets in and there isn't any positive outcome by adding more.

Also, when adding sessions, the practicality has to be looked at as well as the ability to recover. While it would be great if we all could train two to three times a day, six to seven days a week, the reality is that those of us with full-time jobs, school, families, and other responsibilities run out of time.

Additionally, in the case of athletes, there are limitations placed by governing bodies such as the NCAA or similar organizations. It is important to remember that attention has to be paid to recovery, and by piling more and more volume, there can be the issue of impeding recovery and diminishing the quality of work. While gradually increasing volume and correctly structuring training can lessen the chances of negative effects, it still has to be a consideration. Sometimes the old saying of “more isn't more” is true.

Intensity considerations:

Another variable that can be manipulated to produce training effects is intensity. Basically, intensity can be looked at as a percentage of the maximum, a rate of perceived exertion (RPE)/intensity zone (IZ), or measure of physiological responses such as heart rate.

When it comes to intensity, there are some things to consider. We all know that if you want to get stronger, you need to lift heavy weights at some point. It also isn’t out of the question to say that if you want to get faster, you will have to sprint, or if you want to become more skilled in a sporting movement at the speed you will perform it, at some point you will need to perform it at that rate. All of these are examples of high intensity. While all these produce strong effects on the body and there are benefits, they also have to be looked at within the limitations.

If we are to look at the benefits of high-intensity work (and in the realm of lifting weights, we would be talking about maximal lifts), the following benefits can be seen. Zatsiorsky states that the central nervous system uses three options that occur for varying muscle force production. These are recruitment (activation of motor units for the given task), rate coding (the actual rate at which motor units fire), and synchronization (motor units being activated at the same time as opposed to separately. During maximal efforts, the most motor units are recruited along with the fastest motor units at the highest rates, and the activity is synchronous.

While this looks as if all training should be high intensity, there are some limitations that need to be examined. A true maximal effort will mean that less volume will need to be performed in each session. While this isn't necessarily a bad thing on its own, if you just work up to one heavy max in each training session, you don’t really accumulate volume. Over time, the cumulative loading won’t be enough to produce a stimulus. Additionally, in each session, the intensity will be finite. At some point, you won’t be able to go any further.

Additionally, if we're looking at trying to induce metabolic reactions, simply going up to a heavy single won’t do much. Let’s use a max of 500 pounds. If this is a max and you work up to it for a single, the breakdown of protein is high, but the total amount of work is small (only 500 lbs of work, not including warm ups, but we're just talking work sets here). This won’t produce much stimulus for muscle growth (granted that caloric surplus is in place). If you were to do 12 reps split into sets of 3–6 at 75 percent of that weight, which would be 375 pounds X 12 reps, you would have a total work amount of 4,500 lbs. Not only does this produce more of a stimulus for increased cross-sectional areas of muscle fiber, which can lead to more growth, but it also increases the total amount of work performed, which can be a factor in the cumulative loading.

To an extent, it is true that during submaximal efforts, the maximal amount of motor units aren't recruited. However, what is often forgotten is that as fatigue sets in, muscle tension increases and maximal available motor units are now being recruited. So over multiple repetitions and multiple sets, more motor units are recruited. This needs to be considered because rarely do people lift a submaximal weight one time for one set in a workout. Think of other sports such as sprinting in track and field. Sprinters may compete in the 100-meter but at times run distances shorter than this. Even though this is run at maximal intensity, the shortened distance makes it a lower intensity than the 100-meter.

Of course, someone will bring up the Bulgarians and how they “maxed out” in every workout multiple times a day, multiple days a week. First, what needs to be acknowledged is that they went to a training max, which is different than a competition max (meaning they didn’t snort ammonia, jump around like idiots, slap the shit out of each other, or make sure their favorite song was played on repeat twenty times before attempting these weights in training).

These “maxes” were done without any arousal and oftentimes weren't in line with what their competition max was. Many people get caught up with trying to set a PR in every workout when using an intensity-based approach. This wasn't the basis of the system used in Bulgaria. Also, they had low volume in each session (i.e. they didn’t do 9,000 other exercises after these movements), and many aspects of their lives were controlled so that outside stressors weren't as much of a factor.

Exercise selection considerations:

Exercise selection is another way to vary the stimulus. With our exercises, we're looking at the particular movements that we will use, and we attempt to vary these to continue to produce a disruption of homeostasis.

One method here is varying the actual exercise. If we're talking about lifting, this could be switching the bar or stance, using a box for squatting, changing up the grip, adding bands or chains, or lifting in supportive gear. All these will vary the movement. In other sports, this could be using a resisted sprint for a sprinter, throwing with heavier or lighter implements or using modified techniques for throwers, or using specialized drills for positional players of team sports. In this case, the actual exercise itself is modified.

Another method is changing the muscle work regime that an exercise is performed with. This could involve slow yield/eccentrics, isometric holds either in a position or against a fixed apparatus, overspeed yield/eccentrics, and so on. By altering these regimes, the exercise is in effect a different movement. All these regimes will have different effects on the body, which will lead to different adaptations.

In addition to changing the actual exercise or the muscle work regime that is emphasized, rest intervals in relation to the volume and intensity of work will greatly alter the training effect. For example, let's take the squat. If we use 80–100 percent for 1–3 reps for 4–8 sets with a rest interval of 3–4 minutes, we are training for maximal strength and explosive strength against a significant external resistance. Say that we decide to use the same movement, but we keep the weight around 70–80 percent for 3–6 sets of 6–12 reps with a rest interval of 1–2 minutes between sets. This changes the effect to maximal strength and hypertrophy. Now let’s say that we use a weight of 30–60 percent and perform 2–4 sets of 30–50 repetitions with rest intervals of 45–90 seconds. Now, we are working muscular endurance against a moderate external resistance. Keeping the bar weight in a similar range of 30–60 percent but with 4–6 sets of 10–15 reps with a rest interval of 3–4 minutes produces a different effect of high speed movements against a low external resistance.

So even though this movement is the same, the adaptation achieved is very different. Rest intervals should be closely monitored to ensure the correct training effect of any movement used whether it is in the weight room, on the field, or in sport practice. Look at it this way—think of the exercise as a drill and the rest interval, volume, and intensity as the bit. The training effect is the hole that will be left by the drill and the bit. If the bit is the wrong size, the hole will be too small or too large to actually fasten. This is the same as using a movement that makes sense but using poorly planned volumes, intensities, and rest intervals. It won’t produce an effect that fits the nature of the sport.

One last thing to touch on is what can be referred to as exercise novelty. Issurin defined this as an exercise having unknown details or a new combination of known elements. This is an important variable because new exercises or combinations of movements need to be introduced, especially in sports with complex motor structures such as team games. However, these exercises need to have logical application. It isn’t hard to come up with goofball shit that no athlete has done before. If you go on YouTube and take a look through various private training facilities, you'll find some rather intriguing exercises that truly deserve the title of novelty. You can also see many strength athletes adding bands, chains, reverse bands, and other contraptions and coming up with some reverse kneeling Zercher lunge. While these movements may make someone sore or feel different and be different than what the training center down the street is doing, therefore getting parents to spend money, it really doesn’t matter if they don’t produce a relevant adaptation in relation to the competitive movements.

Training specificity

When it comes to the specificity of the training load, there are two factors at hand—whether or not the exercises are being used to improve motor abilities or whether or not they're being used to improve actual sport form through technique. Motor abilities are attributes such as speed and strength that contribute to the sport. Technical skill involves the actual movements that are used during the sport. For example, let's look at football for this. In football, the motor abilities that are desirable are maximal strength, explosive strength, reactive ability, alactic power, alactic capacity, and aerobic capacity. Technical skills will vary by position but examples include correct tackling for defensive players, correct technique when running, or pass blocking for linemen.

For lower level athletes, simply increasing the motor abilities will have a positive transfer to their sport. Low level lifters will get a lot out of general accessory movements. Low level athletes will get a lot out of sprints, jumps, throws, weights, and tempos. In the case of athletes, this is because they make gains in the motor abilities that are used in their actual sport and allow them to perform at a faster rate of movement, develop more force, and so on. After a certain point, just becoming stronger or more explosive will be too general to have transference.

Technical skill includes exercises that are either the actual movement or closely related in the neuro-muscular sense. In order to have a high positive transfer, these exercises will have to either be a technical part of the actual exercise broken down or be a correction and practice of the exercise itself. Some specialized movements may have some transfer, such as the pushing of a weighted sled for a lineman. However, some movements may become detrimental to the competitive movements. This can be seen with excessively weighting a sprint with a sled or weighting a ball that would be thrown by a pitcher or quarterback. The neuro-muscular coordination of these movements becomes too different, which produces undesirable movement patterns. This can negatively impact the technique once the weight is removed.

One thing that is looked over here is that technical skill should also work the appropriate motor abilities and energy systems. We can probably go and look at any football practice in America and see an example of the wrong energy systems being taxed through something in a lactic zone, drills being conducted without enough repetition to produce enough loading in a desired movement, and parts of practice that should be at game speed being stopped to “walk and talk.” On one hand, errors need to be corrected, but on the other, practices need to be structured to not just work technical and tactical preparation, but also physical preparation in the actual sporting movement.


When accommodation has occurred, the stimulus will no longer be causing as great of a reaction. There will also be an ability to tolerate an increase in the amount of work that can potentially be performed. To view the levels of accommodation that have occurred, one can use either objective or subjective measures. In general, the objective measures will be more valid. This doesn’t mean that subjective measures should be disregarded though because a lot can be found out by communicating with the right athletes.

An example of an objective measure is using a blood sample to determine the blood lactate level in response to prolonged moderate exercise. Another example is having an athlete perform a set of 5 reps in the squat at a given weight at RPE9 in the first week and, by the second or third week, seeing an RPE7 in video analysis and bar speed. These show that the stimulus is having less of a reaction and has become “easier” to perform.

A subjective measure is something like an athlete saying that everything felt light or easy or that the movement has become more effortless and he has a greater level of relaxation while performing it. Some may say that this isn’t an accurate way to view accommodation, but in reality, a coach should always look for ways to communicate with athletes about this. Most of us don’t have the massive budgets or time available to purchase an Omega Wave, run blood work, or do any of the other more in-depth tests to view this. Communicating with athletes can be a simple way of finding out how they feel in regards to training. This all comes down to knowing your athletes and knowing which ones to talk to (i.e. don’t talk to the slapdicks who will jerk you around). It also comes down to monitoring which athletes respond better or worse and taking note of this.

In the thoughts of some, accommodation is something bad that should be avoided at all costs. While it is true that we strive to keep hitting the body with an overload to produce a reaction, at some point, there has to be a decrease in the reaction to that stimulus. The body must be able to restructure (i.e. adapt) to be able to handle this stimulus. If all you do is just throw random shit at the body, it doesn’t really necessarily know what to accommodate to. This is where the standardization of training loads from the last article comes into play. Like I said before, changes need to be made to keep producing training effects, but they don’t have to be made in every single session.

Volumes and intensities also need to be tracked to make sure a decrease in reaction to the stimuli is being observed. This is the problem with many practices in team sport. Many coaches don’t track reps or the intensities that the reps are being performed at. Because of this, it can vary from day to day. One day you might have a massive load (think of the “fuck it, run it again” mentality of many football coaches in drills and team offense and defense periods) and another, for whatever reason, you might have the volume/intensity swing to the opposite end in an incredibly low amount (think of days when a coach might say “hold on, slow it down" and "let’s walk and talk here”). While coaches need to do both repetition and “walk and talk” to reinforce technical and tactical skills, it should be programmed and tracked rather than arbitrarily going with the “fuck it, we run it until I’m happy with it” or “let’s slow it down and talk a minute” mentalities. Standardization will help lead to better training effects, which in turn will lead to accommodation and adaptation.


When looking at creating adaptations, the stimulus magnitude will play a part in what effect is gained. By manipulating volume, intensity, exercise selection, and specificity, vastly different training effects can be reached. Coaches and athletes have to track the variables so that any positive or negative effects are noted and the process that brought them on is documented.

Accommodation should not be something that is constantly avoided by randomly rotating movements in training/practice and hoping for the best. Training isn’t a process that should be equated to randomly throwing shit at the wall to see what sticks. In order for a restructuring to occur, there must be some kind of standardization to guide the process.


Issurin V (2008) Principles and Basics of Advanced Athletic Training. Ultimate Athlete Concepts: Michigan.
Zatsiorsky VM (1995) Science and Practice of Strength Training. Human Kinetics: Champaign, IL.
Zatsiorsky VM. Intensity of Strength Training Facts and Theory: A Russian and Eastern European Approach. At: