Title: The Effect of Menstrual Cycle on Inter-Joint Coordination Variability during Roundhouse
Kicks in Taekwondo
Version: 1 Date: 28 May 2024
Reviewer's report:
Firstly, congratulations for the well written manuscript. This is an interesting study which
investigates the effect of the menstrual cycle on the coordination variability of the lower-limb
joints during the taekwondo roundhouse kick in professional athletes. However, to enhance the
quality of the manuscript, revise suggestions are given below.
1. Line 66, I don’t agree with that the primary distinction between men and women lies in the
menstrual cycle. The differences between men and women are diverse and complex, authors
please treat them with rigor.
2. Line 107, the sample size is small, and there is no mention of a power analysis. Please conduct
and report a power analysis to justify the sample size and discuss its potential impact on the
study's findings and conclusions.
3. Line 108, how to define “professional” players? Professional players are also divided into
levels, and there are great differences in performance and skills between athletes at different
levels.
4. Line 151, why only calculate the range of motion (ROM) of the lower limb joints in the sagittal
plane? The range of motion in the coronal and transverse planes is also meaningful.
5. Line 152, the manuscript does not mention if the data were tested for normality before
conducting the repeated-measures ANOVA. Please include a section that describes the normality
tests performed (e.g., Shapiro-Wilk test) and provide the results to ensure the validity of the
ANOVA assumptions.
6. Figure 1-3, although the authors state that there is no difference in SPM analysis, the results
of SPM analysis still need to be presented in the figure section.
7. Line 173, since there is no significant difference in the data and the number of subjects is
not large, the slightly higher ROM in the ankle and knee joints during the ovulation phase may
not be meaningful and is more likely due to chance. I do not think it indicates that the knee and
ankle are at a higher risk of acute injuries during the ovulation phase. The author should treat
this matter with caution. Furthermore, a larger ROM is not always associated with injuries, as
there is considerable debate on this issue in many biomechanical studies.
8. Line 176, I believe this manuscript did not study knee-joint laxity, ACL injury, and knee
valgus. So why does it say, 'our results were inconsistent with those of previous studies showing
that the ovulation phase of the menstrual cycle could affect knee-joint laxity, ACL injury, and
knee valgus and that they correlated with changes in the knee joint loads'? This confuses me.
Where does the term 'inconsistent' come from when the research content is different? The author
should treat this matter with caution and provide a thorough explanation.
9. Line 178, the term 'knee-joint laxity' appears many times in the text. What exactly is 'laxity'?
I don't quite understand this term. Is it defined by ROM, or by CRP or CRPV? I have also
researched literature on ROM and CRP or CRPV, and at least in the popular literature I have
seen, these parameters are not directly linked to 'laxity.' Could the author please explain?
10. Line 183, what is 'out-of-phase'?
11. The discussion of coordination patterns is unclear and lacks detail. I strongly suggest that the
authors should thoroughly describe what CRP is, its underlying meaning, and how the phases
of CRP are defined and interpreted in the introduction, methods, or discussion sections of the
manuscript. I have read other articles related to CRP, and they all provide detailed descriptions
and interpretations of CRP. The authors present the results of CRP directly in the discussion
section, making it difficult for readers to relate these results to the explanations and discussions
provided by the authors. I recommend that the authors carefully consider this issue.
12. The manuscript speculates on injury risk without sufficient evidence. Similar to the question
I raised earlier, without statistical differences, the authors analyze the likelihood or risk of injury
based solely on the raw data differences. I believe this is neither rigorous nor well-considered.
13. Although the authors mentioned in the limitation section that they only performed the tests
based on the days of the menstrual cycle, I still have to say that incorporating hormonal assays to
confirm the menstrual cycle phases would strengthen the reliability of the phase classification.
14. Please do check the language and writing mistakes throughout the whole article to further
improve clarity. In summary, please make sure that your manuscript is properly prepared and
formatted before submitting a revision.