The Effect of Static and Dynamic Stretching Exercises on Sprint Ability of Recreational Male Volleyball Players
, Ioannis Gissis 1, Georgios Komsis 1, Stergios Komsis 1, Angelos Kyranoudis 3, Beat Knechtle 4,* and Pantelis T. Nikolaidis 5Round 1
Reviewer 1 Report
This paper attempts to verify the findings on stretching required by the teaching site and can be evaluated. However, the following information is not sufficient, and significant changes are required to make this paper evaluable.
Major changes
1. Subjects' information (sex, volleyball level, usual training menu etc)2. Where and when did the subject go stretching?
3. Did you check the implementation status of the stretching?
Minor change
1. Line 197 (funding acquisition, P.T.N. and B.K.) and line 198 (This research recieved no external funding.) are not correct.
Author Response
Comments and Suggestions for Authors
This paper attempts to verify the findings on stretching required by the teaching site and can be evaluated. However, the following information is not sufficient, and significant changes are required to make this paper evaluable.
Answer: We agree with the expert reviewer and made all suggested changes.
Major changes
1. Subjects' information (sex, volleyball level, usual training menu etc)2. Where and when did the subject go stretching?
Answer: We agree with the expert reviewer and added detailed information about subjects (“Among them, complete data of demographic characteristics and sprint ability were available for 27 participants (Table 1), who were included in the present analysis.” & “The study was conducted from the middle of February 2015 till the end of March 2015. Both testing and stretching exercise sessions were performed in the indoors court of School of Physical Education and Sport of Aristotle University of Thessaloniki. All stretching exercise sessions of both static and dynamic group were supervised by the principal investigator of this study (F.A.).”).
3. Did you check the implementation status of the stretching?
Answer: We agree with the expert reviewer and added this information (see previous comment: the principal investigator supervised all sessions).
Minor change
1. Line 197 (funding acquisition, P.T.N. and B.K.) and line 198 (This research received no external funding.) are not correct.
Answer: We agree with the expert reviewer and corrected it (deleted the part from the authors’ contribution).
Reviewer 2 Report
The authors have done a great job, although I observe some limitations that are important to solve.
Table 1 is complicated to understand. The authors should show in each sprint test the values of the 3 groups both at the beginning and at the end of the study. Likewise, it would be interesting to know if there was an interaction between the duration of the study (time) and the stretching protocol (group). For this, it is necessary to perform a 2-way ANOVA. The authors indicate that they have used the time * group but in table 1 none of that is seen. They should clarify it.
On the other hand, it would be interesting for the authors to show the anthropometric data of the different groups before and after the study to determine if this could have an influence, as Mielgo-Ayuso et al. in 2015 (https://0-www-ncbi-nlm-nih-gov.brum.beds.ac.uk/pubmed/25617573).
Likewise, it would be interesting to know the diet and the supplementation that the different groups had during the study, as well as what they took in the previous moments of the physical tests.
The authors do not indicate the sex of the athletes. It would be convenient for the authors to indicate it in all places where volleyball players are mentioned.
Author Response
Comments and Suggestions for Authors
The authors have done a great job, although I observe some limitations that are important to solve.
Answer: We agree with the expert reviewer and addressed these issues.
Table 1 is complicated to understand. The authors should show in each sprint test the values of the 3 groups both at the beginning and at the end of the study. Likewise, it would be interesting to know if there was an interaction between the duration of the study (time) and the stretching protocol (group). For this, it is necessary to perform a 2-way ANOVA. The authors indicate that they have used the time * group but in table 1 none of that is seen. They should clarify it.
Answer: We agree with the expert reviewer and totally revised the results section. We deleted the table 1 of the original version and created two new figures. In addition, we added two panels of figures describing individual values and percentage changes from pre- to post-test.
On the other hand, it would be interesting for the authors to show the anthropometric data of the different groups before and after the study to determine if this could have an influence, as Mielgo-Ayuso et al. in 2015 (https://0-www-ncbi-nlm-nih-gov.brum.beds.ac.uk/pubmed/25617573).
Answer: We agree with the expert reviewer and added the aspect of anthropometry as limitation before conclusions - “Moreover, further research could examine the relationship of longitudinal changes in sprinting ability and anthropometric characteristics since it has been shown that physical performances in volleyball were related with anthropometric characteristics [36].” - (anthropometric characteristics were tested only at baseline since we could not support an hypothesis for changes in body mass due to a stretching program; however, we performed additional analyses to examine the relationship of demographic characteristics and changes in sprint ability “With regards to the relationship of changes in sprint ability from pre- to post-test with demographic characteristics of participants, a moderate negative correlation of percentage change in 4.5 m sprint with sport experience was observed, i.e. the longer the sport experience, the largest the improvement in 4.5 m sprint (Figure 6). The percentage change in 4.5 m sprint correlated largely with the percentage change in 9 m. No relationship was observed in the relationship of age, weight, height and body mass index with percentage changes in sprint ability (p>0.05).” and created figure 6).
Likewise, it would be interesting to know the diet and the supplementation that the different groups had during the study, as well as what they took in the previous moments of the physical tests.
Answer: We agree with the expert reviewer and added this aspect in the methods (“During the 6-week period of the study, participants had been strictly instructed to maintain their regular physical activity and nutritional habits.”) and limitations section.
The authors do not indicate the sex of the athletes. It would be convenient for the authors to indicate it in all places where volleyball players are mentioned.
Answer: We agree with the expert reviewer and added this information in title, abstract and text.
Round 2
Reviewer 1 Report
I feel that it has been improved compared to the previous paper. However, I think there are still some issues to be solved.
1. You should describe how many people originally assigned 45 subjects to 3 groups. And you should write in detail why 45 people were reduced to 27 for reasons.
2. I can not understand what players "recreational volleyball players" are. Did you gather 50 physical education students who are good at exercise and let volleyball go for six weeks and then take part in this experiment?
3. Have you done one by one subject doing stretching? Isn't it time fixed to decide the time to carry out the stretch?
4. Does the sporting experience include volleyball? Please describe what item the subjects were experiencing.
Author Response
Comments and Suggestions for Authors
I feel that it has been improved compared to the previous paper. However, I think there are still some issues to be solved.
Answer: We agree with the expert reviewer and addressed these issues according to his suggestions. Please, see our detailed answers to each comment below. All changes are presented in the text highlighted in blue.
You should describe how many people originally assigned 45 subjects to 3 groups. And you should write in detail why 45 people were reduced to 27 for reasons.Answer: We agree with the expert reviewer and added this information in the methods section (“...and were randomly assigned into three groups (static, n=17; dynamic, n=17; control group=16).”; “...(age, body mass, height, sport experience)”; “...(4.5 and 9m sprint times)”).
I can not understand what players "recreational volleyball players" are. Did you gather 50 physical education students who are good at exercise and let volleyball go for six weeks and then take part in this experiment?Answer: We agree with the expert reviewer and clarified this aspect in the methods (“The term “recreational” denoted that participants were volleyball players of teams competing at regional level.”; “Their sport experience was defined as the years they had been practicing volleyball.”).
Have you done one by one subject doing stretching? Isn't it time fixed to decide the time to carry out the stretch?Answer: We agree with the expert reviewer and added this information in the methods section (“…and were administered individually, i.e. one-by-one”). Information on time can be found below table 1.
Does the sporting experience include volleyball? Please describe what item the subjects were experiencing.Answer: We agree with the expert reviewer and added this information in the methods section (“Their sport experience was defined as the years they had been practicing volleyball as members of sport clubs that involved three to four training units during weekdays and an official match during weekend.”).
Round 3
Reviewer 1 Report
I saw this paper and confirmed that it was further improved. But I think that one more point should be added regarding a limitation of the present study.
In the dynamic stretching group of this study, it decreased from the initial 17 subjects to 7 subjects finally, and only about 40% remained. I should mention the reason why about 60% dropped out in the dynamic stretching group and the possibility that the completion rate decreased in the results of this study.
Finally, I think sports experience may be simpler if written as volleyball experience.
Author Response
I saw this paper and confirmed that it was further improved. But I think that one more point should be added regarding a limitation of the present study.
Answer: We agree with the expert reviewer and addressed these concerns. In addition, we revised the last sentence of the conclusions in order to be specific to the results of the study. Please, find our answers to the specific comments below and the changes in the text highlighted in green colour.
In the dynamic stretching group of this study, it decreased from the initial 17 subjects to 7 subjects finally, and only about 40% remained. I should mention the reason why about 60% dropped out in the dynamic stretching group and the possibility that the completion rate decreased in the results of this study.
Answer: We agree with the expert reviewer that this issue needs clarification and added in the limitations (“...- using larger sample sizes -...”); however, it was question of availability of data rather than drop out. Although, there were complete data on pre- and post-test sprint performances for the whole initial sample (n=50; based on these we had performed the initial analyses in the first submitted version), we had been asked in the first revision round to perform additional analyses with regards to demographic characteristics. Such data were available only for 27 participants and this is the reason that we reduced the sample from 50 to 27 in the first revision. We reported this in the methods section. Furthermore, it should be highlighted that the findings with regards to the effect of stretching exercise on sprint ability in both samples were similar.
Finally, I think sports experience may be simpler if written as volleyball experience.
Answer: We agree with the expert reviewer and changed it accordingly both within text and in the x axis of figure 6 (left and centre graph).
