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 In previous articles, we debunked the lactic acid myth. I decided to dig out this paper and write the article for those of you who wanted to learn more about why lactic acid is NOT the cause of arm soreness.

For something to make sense in science, a term must be definable, measureable, and evaluable. For example, take muscle soreness. What is it?

Well, we tend to define it as an aching, sometimes debilitating feeling when we lengthen the affected area. It can be measured and evaluated by the presence of specific enzymes within the tissues themselves: Creatine Kinase (CK) and Lactate Dehydrogenase (LDH).

If you missed my previous article, we know that when a muscle lengthens this produces the greatest amount of stress, and therefore the most amount of soreness.

Being that pitching is a high-intensity activity, is lactic acid the cause of this soreness?


 Previous research reported that eccentric muscle actions produce the greatest amount of CK and LDH in the blood.

The amount of rest taken between high-intensity bouts of exercise (like baseball pitching) may alter these levels of CK and LDH in the blood.

However, the researchers in this present study wanted to determine if different recovery periods (between simulated games of baseball pitching) would yield different values of enzyme levels within the blood.

10 males, with “prior experience to baseball pitching”, were used in the study. It is important to note that the researchers did not define what “prior experience” meant. For all we know, they could’ve been washed up little leaguers! This is definitely a huge limitation in my eyes.

Training status, pitching experience in this example, has a very important impact on how the body responds to high-intensity exercise, which in turn will impact the amount of enzyme release in the blood.

These participants took part in an 18-day pitching program to ensure that they would all be on the same “training status”. On alternating days, they threw a specific amount of pitches at a predetermined percentage of their maximum velocity (starting at 55% and progressing up to 100%).

After this specific warmup, they threw 14 pitches per inning, with 20 seconds of rest between each pitch, and a 6-minute rest between innings.

However, the amount of pitches thrown per inning is almost never consistent throughout a game. For the purposes of conducting research, this amount had to be same for everyone in the study to limit the amount of variation in data collection.

The participants then threw 3 simulated games, labeled A, B, and C.

Between Games A and B, they had 4 days of rest.

Between Games B and C, they had 2 days of rest.

To allow for the volume of pitches to be controlled, participants could have up to 45 warm-up pitches before each game, and 5 warm-up pitches before the start of each inning.

To measure performance, the researchers wanted to use throwing velocity, which seems to be one of the most important variables in baseball pitching.

At each blood-draw time point (there were multiple in this study, but the details are not too important for this post), participants were asked to rate their perceived soreness levels on a scale from 0-3 (Abraham scale for muscle soreness).

The Results

 After the study, all 3 games produced a significant increase in CK levels. These enzymes were greatest at 24-hours after exercise for games A and B, and 6-hours after game C.

For all 3 games, it took 72 hours for CK levels to get down to baseline measures.

As for LDH levels, there were significant increases after each game. However, these enzymes were greatest at 6-hours after each game.

Interestingly, none of the participants reported to have any soreness in the legs after any of the games. My guess is that this must do with the participants’ prior experience” to baseball pitching. Perhaps, 90% of their throwing velocity could have been coming straight from their throwing arm for all we know.

Pitching velocity was not significantly different between any of the games, but there was a slight decrease in game C. This is most likely because there was only 2 days of rest prior to this game.

However, the participants were able to maintain their pitching velocity throughout each game.

Discussion and Practical Applications

 As stated before, when our body is put under an unaccustomed stress, it will adapt over time. The reason why the researchers used a general 18-day “on ramp” program was to get all the participants towards the same baseline levels (as well as protecting individuals from getting injured).

What’s interesting was that the amount of CK and LDH release in the blood was not significantly different from a 2-day or 4-day rest between games. This specific enzymatic response tells us that baseball pitching is surely a high-intensity activity.

The only limitation with using enzymes to measure muscle damage is that you cannot determine WHERE these enzymes are specifically coming from. Were these enzymes released from the throwing arm? The legs? We cannot answer that question by simply drawing blood.

Once we have a way to specifically measure where these enzymes are coming from, we could potentially monitor our pitchers for overtraining. Further down the road, we could possibly correlate these measures with high pitch counts!

Although the amount of soreness was not different between groups, the researchers did see a difference in velocity. There was a trend for velocity to decrease in Game C (2.7%), most likely due to the short amount of rest between Games B and C.

If you start to see your velocity die down over the course of a few games, this may be one sign of chronic fatigue.

These results are certainly promising for starting pitchers, relievers, and closers in the game of baseball, since rest days are different between these types of pitchers.

For example, let’s say your team is on a tough road trip and the games have been very close coming down to the last few innings.

Should you use your closer earlier in the game, and possibly increase the risk of him throwing more than usual? Or, should you use multiple pitchers later in the game to cover the same number of innings?

If you have one pitcher who, chronically, has adapted to throw a decent amount of pitches in a game, then this could be an option. Therefore, it is important to always track the amount of pitches each pitcher throws in a game!

Lastly, while tracking pitch counts, also keep track of subjective information: how is the pitcher feeling during the game? After the game? The day after the game? We can use these data to create a bigger picture for our athletes.

To sum it all up, this study adds to the body of literature stating that baseball pitching is highly anaerobic and high in intensity.


Keep adapting,


Jarad Vollkommer, CSCS






Potteiger, J.A., Blessing, D.L., & Wilson, G.D. (1992). Effects of varying recovery periods on muscle enzymes, soreness, and performance in baseball pitchers. Journal of Athletic Training 27(1), 27-31.

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