Quantifying Within-Individual Elbow Load Variability in Youth Elite Baseball Pitchers and Its Role in Overuse Injuries

Round 1

Reviewer 1 Report

My remarks:
PAGE_1_LINE_10:   a typo – pitchers
PAGE_2_LINE_89:   What does AAA pitcher mean? What is the difference between a typical AAA pitcher and the professional one?
PAGE_3_LINE_120: “Marker position data”: Could you clarify which data (x,y, z coordinates or only x,y, etc.)?
PAGE_3_LINE_124: If you have information about time of release and trajectory of the hand - why didn’t you use this data to calculate energy as the integral of power (by using the external valgus torque and kinematic data). This energy is responsible for the ball speed (in fact, its kinetic energy), not the torque itself.
PAGE_3_LINE_129: “participant eleven was not allowed” … Why?
PAGE_3_LINE_130: Was the time-space between 2 pitches kept the same for all participants and for all pitches? (viscoelastic properties of tissues, oxygen content in muscles, etc.)
PAGE_3_LINE_140: “where the ball mass linearly reduced by 10% over the last ten samples (0.025s) before ball release”- could you explain it?
PAGE_4_LINE_157: a table – Table 1.?
PAGE_4_LINE_178: Deviatio – n
PAGE_6_LINE_240: As I understood Figure 2 can be presented more clearly using only one graph (see the attached file)
PAGE_8_LINE_291: varus - a typo

Comments for author File: Comments.pdf

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

 

The study describes the within-individual external valgus torque variability and determines if the within-individual external valgus torque variability can be described by a Gaussian distribution. The authors concluded that the within-individual elbow load variability can be a useful variable as it might be related to overuse elbow injuries.

 

In my opinion, this paper is more suited to the journals specializing in health science research.

The limitation is the relatively small sample size consisting of 11 baseball pitchers. For this reason, these findings cannot be generalized to the broader community based on this study alone. 

There are minor concerns which should be addressed.

 

Please reformulate this sentence; “several studies” without relevant references should be removed.

L13-14: Several studies showed possible risk factors for medial elbow injuries, like the external valgus torque magnitude.

 

Reformulate also this sentence; the study does not address the aspect of injury prevention.

L25-27: Therefore, next to the elbow load magnitude also the load variability seems important towards injury prevention.

 

The authors should report whether the power analysis for estimating appropriate sample size was provided.

L89-90: Data were collected from eleven male Dutch AAA pitchers, at a mean age of 17.4 years …

 

Please, explain why this protocol including 25 pitches was designed.

L107-108: Once the pitchers were ready, they were instructed to throw 25 fastballs as fast and as accurately as possible.

L130-131: Altogether, 256 pitches of the in total 270 performed were used for analysis.

 

I would suggest removing this sentence from discussion.

L202-203: The aim of this study was to quantify the within-individual elbow valgus torque variability when pitching fastballs in elite youth baseball pitchers.

 

Please add references.

L208-210: As expected, and in line with other studies, the magnitude (average) of the elbow valgus torque was different between pitchers, showing the between-pitcher variability.

 

Please add references.

L212-213: Whereas the valgus torque magnitude differences between pitchers has been regularly reported …

 

Please add references.

L218-223: In general, it is known that within-individual variability is smaller compared to between-individual variability. The magnitude (average) external valgus torque between pitchers can be explained mainly by personal characteristics (body length, mass), motivation, well-being, fatigue, and technique (kinetic chain, energy flow), whereas the within-individual valgus torque variability can mainly be explained by motivation, technique, and fatigue.

 

I would suggest removing this part.

L311-314: Authors should discuss the results and how they can be interpreted from the perspective of previous studies and of the working hypotheses. The findings and their implications should be discussed in the broadest context possible. Future research directions may also be highlighted.

 

The discussion needs to present practical applications of findings with respect to youth elite baseball pitchers that are not currently addressed in the literature. 

Author Response

Please see the attachment

Author Response File: Author Response.docx