The Difference Between Pitching Stress and Training Stress

Last week I posted a visual on Twitter illustrating the interactions between pitching stress, training stress, and recovery. The purpose of this drawing was to create an analogy that would help a player or coach understand that not all physical stressors are created equal, as each unique stress will elicit its own specific adaptation within the body.


Despite my terrible artistic skills and penmanship, I hope that this drawing accomplished that goal. But, today I wanted to take some time to give an elaborated explanation to further illuminate the concept being shown in this analogy.

Understanding the S.A.I.D Principle

In terms of human performance and performance training, there are a handful of principles which govern how we go about coaching and periodizing training. These principles also provide us with the why as well – meaning, they are the foundation behind our rationale.

While all of the principles are equally important, there is one that I believe is vital for all players, coaches, and those involved with baseball to understand, and that is the S.A.I.D Principle – Specific Adaptation to Imposed Demands.

Much like the Principle of Specificity – which states that, in order to develop a certain physical or motor quality, you must train specifically for that quality – the SAID Principle explains that the body, physiologically and anatomically, will develop and adapt according to the demands posed on it.

Two crude and remedial examples to explain this principle:

Example A) Loading a muscle through resistance training leads to physiological and cellular changes in that muscle which will increase strength and lean muscle mass.

Example B) A lack of loading of a muscle – say, through immobilization such as casting a limb after breaking a bone – will lead to a loss of strength and muscle mass (atrophy).

As the two opposite examples above show, the body will specifically adapt according to the demands that are imposed upon it. Thus, the the inverse of the situations above will not occur; the body will not build muscle (naturally) without any loading, and the body will not atrophy without significant disuse relative to its normal workload.

This is the premise in which the bucket full of rocks and water analogy, pictured above, stems from:

  • Your body is going to adapt specifically to demands you impose upon it.
  • Not all imposed demands are created equal in terms of the adaptations that they elicit.
  • Therefore, not every adaptation is beneficial, or can be easily “recovered” from. 

Now that we have gone over the main concept of the SAID Principle, let’s look at the adaptations that we incur from general physical training, followed by the adaptations that we see in response to pitching, and discuss the differences and implications of both.

General Training Stressors and Adaptations


There are many different ways to go about training, with many different training and performance goals in mind, leaving us with a litany of adaptations that can be experienced by the athlete’s body. For the sake of this topic, though, let’s cover some of the predominant adaptations we are seeking when we train for baseball.

The goal of strength training is to induce cellular and neurological changes within the body to elicit an increase in lean body mass, muscular strength and power.

From a cellular standpoint – and in the most basic terms – loading of the tissues through resistance training causes microtrauma within the muscle. In other words, muscle fibers tear. Microtrauma in the muscle, followed by adequate rest and the necessary nutrient intake, can be recovered from in 48-72 hours. After the proper recovery period the muscle can be re-stressed and “damaged” in subsequent training sessions. Depending on the type of training being used, this process can lead to an increase in both strength and lean muscle mass.

From a neurological standpoint, loading of the tissues through resistance training taxes and stresses the nervous system. Especially when multiple muscle groups are used at once (compound, multi-joint movements seen in most performance training), and when they are performed at high intensities (heavy loads) or fast speeds. These circumstances require that the nervous system recruit as many motor units (the unit composed of a muscle fiber and the nerves that attach to it) as possible to create the strongest or fastest muscular response. Ultimately, the neurological goal of resistance training is to elicit an adaptation of more rapid and synchronous nerve impulses to the muscle (hence why you can still get stronger without getting bigger). Neurological fatigue exists, and can be recovered from in a relatively short amount of time if training and recovery are administered properly.


Additionally, training for baseball may seek to enhance mobility of specific joints (such as the hips) or stability in other joints (such as the trunk) in order to create a more efficient and safe platform to project the baseball. While some athletes may be more “lax” or stiff in their joints than others thanks to passive structural qualities (“loose” joint capsules and ligaments), the mobility and stability we are after in training is that of dynamic mobility and stability, whereby we are looking to create adaptations to the active structures (i.e. muscles and tendons). Again, much like the cellular and neurological adaptations above, these stresses can be recovered from relatively easily with rest and unloading at the appropriate times.

This is the big takeaway that is being stressed – general training stressors (if applied right) can be recovered from simply by “unloading” or “deloading”. It is the supercompensation effect that we are after. In other words, if done right, the body will be stressed by training, break down, and then supercompensate to enhanced levels.


This process can be repeated many times throughout the annual training plan without too much worry of a negative impact on health.

In fact, certain methods and modalities can actually help improve – and possibly expedite – the recovery process.

As long-winded as this segment has been, it is all to thoroughly explain why general training stressors are analogous to the water in the below illustration, and why a “Recovery Release Valve” can empty the bucket of these stressors:


Pitching adaptations, on the other hand, are quite different.

Pitching Stressors and Adaptations

First, understand that pitching does have cellular and neurological components that, when stressed, lead to similar adaptations as general training.

For example, the high eccentric (deceleration) that occurs in the pitching motion, along with the great deal of throwing volume seen in pitching leads to microtrauma at the cellular level. This is why many pitchers often have hypertrophy (an increase in muscle mass) of certain muscles used in throwing. These stresses can be adequately recovered from with rest, proper nutrient intake, and management of throwing volume.

Baseball strength

There are, however, many different adaptations that more commonly occur due to pitching stress than general training stress, and are a lot harder to (or impossible to) recover from, hence the likening of pitching stressors to rocks in the bucket analogy. These adaptations, specific to highly repetitive and rapid movements, include osseous and ligamentous changes.

Osseous adaptations (i.e. changes to the bones) occur in response to the highly stressful nature of throwing a baseball, as well as the way in which we subject ourselves to high throwing volumes. For the sake of this post, let’s discuss the arm:


When a child begins throwing early and often in life their body is subjected to stresses that will impact their arm differently than they will the arm of a pitcher who has reached physical maturity. That is because, before reaching physical maturity, their bones are still growing and are susceptible to change. While strength training at an older age can help build resilience of the skeleton, the bones should not morph easily once they have finished growing. Contrarily, the developing skeletal system that is exposed to rapid and repetitive movements can morph to meet the demands of those stresses.

Thus, at an early, an adaptation known as humeral retroversion is often accrued. Essentially, this is a twisting of the upper aspect of the arm bone, causing the shoulder to sit in a more externally rotated position. This undoubtedly is a specific adaptation to the imposed demand of “lay-back”, or the great external rotation seen at the shoulder during the late cocking phase of pitching.

LaybackWhat makes an “osseous adaptation” – such as humeral retroversion – a rock in the bucket analogy? Well, quite simply because there isn’t much anything that recovery can do to change it once it has developed. You can hit the “release valve” as much as you want, but the bone is not going to morph back to its original position.

Similarly, ligamentous and capsular adaptations (changes to ligaments and joint capsules) are hard to reverse or offset as well. And, over time with chronic loading of the shoulder and elbow, these static stabilizers of the shoulder will adapt to throwing by stretching out and tightening according to the demands placed on them. For example, pitchers generally experience a tightening of the posterior (back side) of the shoulder, and a loosening of the anterior (front side) of the shoulder, which can create anterior instability, and possibly shoulder pain. And, these adaptations aren’t as easy to recover from as those seen in the muscles – like those incurred during strength training). More so, they are just “worked around”, as the muscles surrounding the joint are strengthened to dynamically stabilize it.


It’s important to note, though, that these adaptations occur for a reason: the body is attempting to put itself in the best position to handle the stressors imposed upon it. Thus, when great external rotation is demanded at a young age, the body responds with humeral retroversion. In fact, these adaptations aren’t all bad. Typically, these very adaptations are what help promote successful pithing or the exceptional velocity it takes to throw a baseball, even at a marginal level.

Think about it… Even if you’re an average high school pitcher throwing 80 mph, this is still exceptionally faster than most your age can throw a baseball. Imagine trying to teach someone who has never played baseball to pitch. Even as they improve their motor skills through hours and hours of practice, they may never throw as hard as you because they don’t have the adaptations that you occurred from throwing early and often as a kid.

This is the paradox that is pitching. The same adaptations we incur from throwing that lead us to be successful in the sport are the same ones that predispose us to injury.


That’s why, when I share this illustration of the bucket, water, and rocks, I am not suggesting that you never fill your bucket with rocks – in other words, I am not suggesting that you don’t throw, long-toss, partake in weighted baseball throwing, throw bullpens, etc. Because, while the best way to avoid baseball-related throwing injuries is to avoid throwing, that’s the very same way you avoid becoming any good at pitching at all…

What I am suggesting though, is that you manage all of your baseball activities and throwing volumes to prolong the amount of time it takes before your bucket becomes “full”.

Because, for all of the throwing you do, and any damage you incur from overdoing and overusing, you cannot simply recover your way back from those adaptations like you can from general training stress.



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