Title: Effects of backhand stroke styles on bone mineral content and density in postmenopausal
recreational tennis players – a cross-sectional pilot investigation
Version: 1 Date: 25 Apr 2021
Reviewer's report:
General comments
Thank you for providing me with the opportunity to review this work. Although this work tries to
answer an important research question a lot of methodological shortcomings and inconsistencies
are apparent which need to be addressed. In addition, several sentences need to be corrected to
reach the required grammatical level.
Major comments
ABSTRACT
L28; What about the backhand slice? Was this considered in this research project?
L33; Which statistical methods were used?
L36-41; The representation of the results is not clear. Please re-write this section.
INTRODUCTION
L65-66; I do not agree that tennis is a unilateral type of upper limb exercise. I would like to
argue that tennis is a (mostly) unilateral sport for the upper extremity and that the trunk and
lower extremities are loaded also. Please correct this sentence.
L76-78; Please clarify in what way the tennis players are benefited from a two-handed backhand.
Also, what about the backhand slice? Was this considered?
L80-81: What is being meant by the rear legs? Also, please clarify when there are larger axial
torques during the execution the two-handed backhand stroke.
L71-83; The rationale to study the difference in bone responses between a one and two-handed
backhand is not sufficiently referenced. The authors should elaborate more (1) on the difference
between the one and two-handed backhand and (2) on the implications this will have one bone
responses.
METHODS
L92; The sample size is small. Was a sample size calculation provided?
L96-97; Why was the reference population swimmers? The rationale for this decision is missing.
L99; A very important thing to consider is whether the tennis players started to play tennis before
puberty was reached. The authors should clearly mention whether tennis play was initiated
before puberty.
L115-119; is it unclear which regions were specifically examined. Was it the right or left hip
and/or distal radius? Also, were the players right or left-handed (this is up to this point unclear).
This is an important point to consider as there is evidence of a cross-asymmetry in female
tennis players (Chapelle, L., Rommers, N., Clarys, P., & D’Hondt, E. (2020). Whole-body
morphological asymmetries in high-level female tennis players: A cross-sectional study. Journal
of Sports Sciences, 1-6).
L117-119; How was bone health in the hands examined? Also, the authors mention that whole-
body bone health was assessed. This is the first time the author mentions this. In addition, only
specific regions were examined (L116-117).
L122; Why was the left hip examined as opposed to the right hip or both hips?
L125; Why was the radius divided into three parts?
L131: Why was muscle strength assessed? What is the rationale for this?
L143; Overall, the statistical analysis section is insufficiently described and unclear. As a result,
it is unclear how the collected data was analysed.
L149; Again, what is being meant by “hands”?
RESULTS
Table 2; here the tennis players (one and two-handed backhand tennis players) are being
compared to the reference population. However, this is not described as being a specific aim
of this study.
Table 3; specific hip regions are described here (e.g., Ward’s triangle). These regions were not
mentioned in the methods section. Please clarify.
DISCUSSION
L249-250; I do not agree with the statement as this study did not directly examine the influence
of backhand technique on “tissue strength”. This statement should be adapted and correctly
referenced.
L269-271; This statement is not supported by the data as no significant difference was found in
BMC and BMD in the spine and hip region.
L275-286; This part of the discussion is speculative and under-referenced. Please re-write this
part of the discussion based on the analysed data and references.
Minor comments
ABSTRACT
L30; Please clarify what is being meant by “the rear leg”.
L34; write DEXA in full as this is the first time it is being mentioned.
L42; Please clarify “within the core”.
INTRODUCTION
L54-57; I suggest re-writing these two sentences as the word “inpatients” could generate some
confusion. In addition, the last sentence is not very clear.
L59-61; Please re-write this sentence due to grammatical inconsistencies.
L65-66; Please add a reference to this sentence.
L73-74; Please add a reference to this sentence.
METHODS
L95-97: this sentence needs re-writing.
L97: I would suggest using another word for “cardiometabolically”.
RESULTS
Table 4; Non-dominat should be changed to non-dominant.
Figure 1; Please find another word for ‘swimmer”.
DISCUSSION
L250-252; Please re-phrase this sentence.
L260-263; Please re-phrase this sentence.
L271; please be consistent when describing a one-handed or single-handed backhand.
L290-292; Please add a reference to this sentence.