野球　遠投シリーズ２　英文論文まとめ　つづき

さっそくですが、前回の続きを書いていきます。
(Updated Oct/4/2020 I added English after Japanese for English readers)

3. 肘の負荷と球速、投手間の信頼性

Variability in Baseball Throwing Metrics During a Structured Long-Toss Program: Does One Size Fit All or Should Programs Be Individualized? - PubMed

高校・大学ピッチャー60人を対象にした遠投の論文です。27m、36m、 45m、 54m、マウンドから全力投球時、それぞれで肘の負荷と球速を計り、どんな違いがあるのかを探ったものです。

Motusスリーブを使い、他にも測っています。重要なところは、この論文も山なりではなくon a lineで、またcrow-hopはなしで投げたところではないでしょうか。

結果と研究者の見解

球速は距離が遠くなるにつれて上がりましたが、肘にかかる負荷は36m以上の距離とマウンドからの全力投球では増加は見られませんでした。

またピッチャー間(A君 vs B君 vs C君 vs D君...)の球速と肘負荷の信頼性(Interthrower reliability)も載せてあります。球速に関しては91％と、距離が遠くなるにつれて、ほとんどの投手が同じように球速が上がるが、肘の負荷は79％と一貫性が少し欠けます。その為、スピードガンで球速を測って肘の負荷がこれくらいだろうと予測するのは注意しましょうとの見解です。

個人的な見解

この研究でもon a lineで投げた場合、36m以上の距離とマウンドからの投球では肘の負荷の増加は見れなかったですね。これは前回の記事の高校野球選手95名を対象にした論文でも似たような結果でした。面白いですね。球速は上がるが、肘の負荷はある一定の距離からは頭打ちするということでしょうか。

しかし、投球時の平均球速が124kmhとエリートとは言い難い数字ではありました。150kmh前後が平均のメジャーやマイナーのピッチャーではどんな結果が出るのでしょうか。やはり、肘のリハビリでのスローイングプログレッションでは投手自身の感覚を重要視することは当然ながら、Motusスリーブのような客観的に肘の負荷を数値化できるものを併用できれば負荷のコントロールがしやすいのですね。

4. 全力の７５％・５０％の感覚で投げると、球速も肘の負荷も同じ割合で減るのか？

Baseball Pitchers' Perceived Effort Does Not Match Actual Measured Effort During a Structured Long-Toss Throwing Program - PubMed

こちらの論文は遠投とはちょっとずれていますが、面白い論文です。
高校・大学ピッチャー60人にMotusスリーブを着けてもらい、”36mをそれぞれ全力、75％の力、50％の力で５球ずつ投げて下さい。”という指示に従い投げた時、肘にかかる負荷、腕の速度、アームスロット、肩の回旋を測りました。また球速はスピードガンを使っての計測です。

そしてどのカテゴリー(全力、75％、50％)でもon a lineで、またcrow-hop無しで投げるよう指示がありました。この論文の目的は、投手の主観75％と50％の力で投げた時に、本当に球速と肘の負荷も全力時と比べ75％と50％の値に減少するのか、アームスロットなどに違いが出るのか調べることです。

結果

- 全力（100％）と比べ75％の力で投げた時 - 
肘にかかる負荷は93％、腕の速度は91％、アームスロットは96％、肩の回旋は100％、球速は86％でした。

- 全力時（100％）と比べ50％の力で投げた時 -
肘にかかる負荷は86％、腕の速度は83％、アームスロットは95％、肩の回旋は100％、球速は78％でした。

アームスロットに関しては、それぞれ４％・5％低い位置で投げていた、という意味です。

研究者たちの解釈

つまりピッチャーの主観の75％の力・50％の力で投げても、肘への負荷はそれぞれ7％・14％減、球速は14％・22％減に留まり、それぞれ25％・50％減には程遠い結果となり、口頭による指示とピッチャーの主観にはズレがあるということが分かりました。

個人的な見解

この論文から言えることは、あるピッチャーが80％で投げたと言ったとしても球速や肘の負荷などは20％減ではないということですね。またMotusスリーブが測るものは、骨や軟部組織など体内で実際にかかる負荷と同じではないので注意が必要ですね。選手の感覚はとても大事です。

5. まとめ

遠投に関しての論文はまだまだ少ないですし、実際現場でみる山なりで投げるのとは違い、on a lineで投げさせたものばかりでした。おそらく研究デザインの観点からon a lineの方が一定に揃えやすいのでしょうか。”山なりで投げる”の定義も決めずらいですしね。

noteを始めて最初の記事でした。これからも記事を書いていって徐々に上手くなれればと思います。

次回は遠投の論文シリーズの延長で、周りのマイナーリーグ選手やコーチ達から遠投について意見や感覚を聞いたり、自分が見てきたものをまとめた記事にしようと思っています。

よろしくお願いいたします！

Baseball, summary of long-toss researches Vol 2

Following is in English. I apologize in advance for any grammatical error!

Continuing from the previous article...

3. Elbow load and ball velocity, interthrower reliability 

60 high school and collegiate pitchers participated in this long-toss study. They measured load to the elbow and ball velocity from 90ft, 120ft, 150ft, 180ft, and max effort pitching off mound to find out what the differences and any trend.

They used the Motus sleeve and also measure other metrics like arm slot, arm velocity, and shoulder rotation. The important point is that this study also instructed to throw "on a line", not "arc", and without a crow-hop.

Results and researchers' views

The ball velocity increased as the distance increased, but the elbow load did not increase at a distance of 120ft or more and with max effort pitching off mound.

In addition, they measured reliability of ball velocity and elbow load between pitchers (pitcher A vs. B vs. C vs. D ...). The ball velocity was 91%, which means that velocity increased in most pitchers as the distance increased, but the elbow load was 79%, which was found to be a bit inconsistent. Therefore, they caution you for measuring the ball velocity with a speed gun to predict the amount of elbow load at a given distance. 

Personal view

Also in this study, there was no increase in the elbow load when throwing on a line at 120ft or more and pitching off mound. It was a similar result from Dowling et al's article. It is interesting. Does it mean that as ball velocity  increases, elbow load would level off from a certain distance?

However, the average pitching velocity in this study was 77.8mph, which was hard to say as an elite. What kind of results could we see if it was major or minor league pitchers whose average would be around 94mph-ish? 

After all, although pitchers' subjective feeling is important in throwing progression during elbow rehab, we could use device, such as a Motorus sleeve, that objectively quantifies the elbow load in real-time to manage the load. 

4. Does throwing at 75% and 50% intensity actually reduce the ball velocity and elbow load at the same rate?

This paper is a little different from other long-toss study, but it is interesting.

They asked 60 high school and college pitchers to wear the Motus sleeve and throw at 120ft with full intensity, 75% intensity, and 50% intensity. Then they measured elbow load, arm velocity, arm slot, and shoulder rotation. The ball velocity was measured using a radar gun.

And they were instructed to throw on a line in any category (full intensity, 75%, 50%) and without crow-hop. The purpose of this study was whether the pitcher's perceived 75% and 50% intensity throwing would really reduce the ball velocity and elbow load to 75% and 50% compared to full intensity, and if there would be any difference in arm slots, etc. 

Results

― When throwing with 75% intensity compared to full intensity (100%) ―
The elbow load was 93%, the arm velocity was 91%, the arm slot was 96%, the rotation of the shoulder was 100%, and the ball velocity was 86%.

― When throwing with 50% intensity compared to full intensity (100%) ―
The elbow load was 86%, the arm velocity was 83%, the arm slot was 95%, the rotation of the shoulder was 100%, and the ball velocity was 78%.

Regarding the arm slot, it means that they threw at 4% and 5% lower slots, respectively.

Researchers' conclusion and views

In other words, even if the pitcher throws at 75% and 50% of perceived intensity, the elbow load is reduced by 7% and 14%, and the ball velocity is reduced by 14% and 22%, respectively. The result was far from 25% and 50% reduction. They found that there was a discrepancy between the verbal instructions and the pitcher's perceived intensity.

Personal view

What we can tell from this study is that the ball velocity and elbow load would not be reduced by 20% even if a pitcher says throwing at 80% intensity. Also, we need to be aware that what the Motus sleeve measures is not the actual load being applied to the inside of the body, such as bones and soft tissues. Therefore, we also need to respect player's subjective information.

5. Summary

There are only a few papers on long-toss, and all of them were thrown "on a line" unlike the "arc" that we often see on the field. Perhaps throwing "on a line" is easier to control from a research design perspective. It is probably difficult to define what throwing in the "arc" is.

It was the first article since I started writing here. I hope I gradually improve in writing as I continue.

Next time, I will extend this series of long-toss, and I will ask about opinions and feelings about long-toss from the minor league players and coaches around me, and write an article that summarizes what I have seen.

Thank you for reading!