Review Reports - Exploring the Influence of Acid-Base Status on Athletic Performance during Simulated Three-Day 400 m Race

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for giving me an opportunity to review the manuscript titled “Exploring the influence of acid-base status on athletic performance during three consecutive daily 400-m race of simulated competition”. Please find below my comments and suggestions for improvement.

Title: I would recommend the authors to modify the title of the manuscript. Instead of “…three consecutive daily 400-m race of simulated competition”, you should say “… during simulated three-day 400 m race”.

Line 22: PRAL has not been defined earlier.

Line 23: p<0.05

Line 25: Change 400-m to 400 m, without hyphen.

Keywords: Avoid using the same words here as you did in the manuscript title.

Table 1: Please modify the table to adhere to MDPI guidelines.

Line 178: Why squat jump, why not regular CMJ? Why did you eliminate the eccentric phase of the jumping movement?

Table 2 & Table 3: Same comment as Table 1.

Comment: I would suggest authors to separate the “conclusion” and “practical application sections”. Also, it would be beneficial if additional information could be included in the “practical application” section pertaining to how sports practitioners can implement these findings to improve athletes’ performance.

Comments on the Quality of English Language

N/A

Author Response

All changes made to the manuscript have been highlighted in yellow.

We would like to express our gratitude to the reviewers for their valuable feedback, availability, and the time devoted to the careful examination of this article. Their comments and suggestions have significantly contributed to enhancing the quality of our work. Following their suggestions, we have made direct modifications in yellow in the manuscript. We have also taken care to address a response to the reviewer regarding their suggestions (presented in red in the letter addressed to the reviewers).

Reviewer 1:

We would like to thank the reviewer for the time she/he gave us and for her/his valuable comments, which enabled us to make corrections to improve our article.

Thank you for your suggestion. We have taken your comment into account and changed the title on line 2 and text to make it more precise and consistent:

Line 2: “Exploring the influence of acid-base status on athletic performance during simulated three-day 400 m race”

Line 22: PRAL has not been defined earlier.

We apologize for this oversight. We have corrected this error by specifying the acronym PRAL (Potential Renal Acid Load) in the abstract to line 21.

Line 23: p<0.05

Thank you for your comment. This is an oversight on our part since the p-value corresponds to 0.05 (p<0.05). We have corrected it in the manuscript to line 24.

Line 25: Change 400-m to 400 m, without hyphen.

Thank you for that very precise comment. We have taken it into account in the manuscript by replacing 400-m by 400 m.

Keywords: Avoid using the same words here as you did in the manuscript title.

Thank you to the reviewer for this comment. We have replaced to the line 35 "acid-base balance" with "Sodium bicarbonate supplementation" and "anaerobic performance".

Table 1: Please modify the table to adhere to MDPI guidelines.

Thank you to the reviewer for this comment.

The table in the manuscript has been modified by the addition of a heading to each column in order to comply with the standards set out by MDPI. "All table columns should have an explanatory heading. To facilitate the copy-editing of larger tables, smaller fonts may be used, but no less than 8 pt. in size. Authors should use the Table option of Microsoft Word to create tables".

Line 178: Why squat jump, why not regular CMJ? Why did you eliminate the eccentric phase of the jumping movement?

We thank the reviewer for his/her comment.

The research team engaged in extensive deliberation before selecting the squat jump (SJ) as a test to indirectly assess neuromuscular fatigue following the 400 m. Komi and Bosco (1978) demonstrated that the difference between the SJ and the countermovement jump (CMJ) could be attributed to the storage and utilization of elastic energy during the countermovement, concluding that a greater difference between the CMJ and SJ suggests a better ability to store and utilize elastic energy. In addition, Squat jump performance has often been used as an independent muscular indicator to assess knee extensor fatigue separately from high intensity sprint exercise (White et al. 2014). As Skurvydas et al. (2002) demonstrated that sprinters exhibited a greater jump difference between performances in the SJ compared to the CMJ, we have chosen to use the SJ as a fatigue index. We also selected the SJ to align with our previous research (Thomas et al., 2022), which employed the SJ following maximal sprints performed by world-class cyclists to compare the effects of sodium bicarbonate supplementation vs placebo during repeated high-intensity exercises.

In view of your comment, we have added this element to the discussion section of lines 501 to 509.

Komi, PV and Bosco, C. Utilization of stored elastic energy in leg extensor muscles by men and women. Med Sci Sports 10: 261–265, 1978.
Skurvydas, A, Dudoniene, V, Kalvenas, A, and Zuoza, A. Skeletal muscle fatigue in long-distance runners, sprinters and untrained men after repeated drop jumps performed at maximal intensity. Scand J Med Sci Sports 12: 34–39, 2002.
Thomas, C., Delfour-Peyrethon, R., Dorel, S., & Hanon, C. (2022). Positive effects of pre-exercise metabolic alkalosis on perceived exertion and post-exercise squat jump performance in world-class cyclists. The Journal of Strength & Conditioning Research.
White GE, Rhind SG, Wells GD. The effect of various cold-water immersion protocols on exercise-induced inflammatory response and functional recovery from high-intensity sprint exercise. Eur J Appl Physiol 114: 2353–2367, 2014.

Table 2 & Table 3: Same comment as Table 1.

Thank you to the reviewer for this comment.

We have indeed modified the tables 2 and 3 in the manuscript by adding a heading to each column so that the tables comply with MDPI standards:

MDPI instruction for author: "All table columns should have an explanatory heading. To facilitate the copy-editing of larger tables, smaller fonts may be used, but no less than 8 pt. in size. Authors should use the Table option of Microsoft Word to create tables".

We would like to thank the reviewer for this comment. We have now clearly separated the "practical application" section from the "conclusion" to facilitate better readability and understanding for the reader. Additionally, we have specified concrete recommendations in the "practical application » section to the line 570 to 583, providing guidance for readers, particularly coaches or athletes, who wish to test this nutritional strategy.

We have therefore changed the paragraph.

Many athletes use sodium bicarbonate supplements to enhance their body's buffering capacity in sports where the anaerobic lactic energy system plays a significant role. However, taking sodium bicarbonate in capsule form could cause gastrointestinal disturbances (McNaughton et al., 2016; Ragone et al., 2020), particularly under the stress of an upcoming international competition, which can impair performance. Additionally, some coaches and athletes may be hesitant to use bicarbonate supplementation in capsule form. As an alternative reported in this study, athletes seeking a more natural and ecological approach can be advised to follow an alkalizing diet (with a negative PRAL value) focused on vegetables and legumes, while limiting animal products, and ensuring a balanced intake of carbohydrates. This should be combined with consuming 1.5 to 2 liters of bicarbonate-rich water daily for 3 to 5 days before the event. Based on our previous work (23), we can assert that this nutritional strategy chosen for this study does not cause digestive issues. Nevertheless, to prevent any adverse effects during competition, this should first be tested during training before being applied in a competitive setting.

Reviewer 2 Report

Comments and Suggestions for Authors

The paper considers a very significant topic related to anaerobic metabolism during the 400m sprint. In my opinion the classification into an elite group of 400m sprinters is questionable, as in male sprinters elite senior athletes may be considered with results below 47.0s. For senior sub – elite athletes we can qualify sprinters that perform in the 48-49s range, while above 50s is a result for youth athletes or an recreational result for seniors. There is a substantial difference in energy metabolism and physiological reactions in world class 400m sprinters (44-45s) and those of average national status (48-49s). so I think that you need to rethink the selection of these people for the experiment. Moreover, how do you evaluate the way of motivating to run as fast as you can? How would you comment on the time drop in the BIC group between 2 and 3 400m? Moreover, Figure 2 shows that individual differences are very large, both in terms of gender and the method of performing the exercise. Moreover, the competitors from the BIC group have been running faster from the very beginning. How does this affect the experiment? It is possible that these are people with better personal records. The analysis of mean results in such a case and for such SD is unreliable. First of all, there is a lack of dependency assessment. There are no cause-and-effect relationships here.

Consider making the below suggested changes to improve the style.

Line 112 - how people were assigned to groups - how many men and how many women were in them.

Line 118 - why was the Hungarian table of World Athletic Quotation Table (W) for the 400-m race or 800-m race chosen to evaluate the results?

Line 157 - how time was measured and what the simulated race was like. Starting from the block does not mean a simulation of the competition. Why was the measurement performed with a stopwatch and then corrected this time using an iPhone and iPad? Why did the warm-up take an hour? What it consist of?

Line 165 - if the race was aimed at achieving the best possible result, as if they qualified for the next round, why are the results far from the real results of people at the elite level?

Line 176 - since in the experimental phase athletes in the 400 m race achieved on average 98% of the best results in the season, they are not elite athletes in this sports competition.

Line 177 to 188 - for what purpose were SJ jumps performed - this is not a jump related to the tested effort. Similarly, the compression force test – what was it used for? These tests add nothing to the article.

Table 3B what do p values of 0 mean?

Author Response

All changes made to the manuscript have been highlighted in yellow.

We would like to thank the reviewer for highlighting this point. Following this remark, we have revised the manuscript by replacing the designation "elite" with "highly trained" in accordance with the classification established by McKay et al., 2022. The participants in our study correspond to athletes at the interregional to national level, training 6 to 8 times per week, with some participating in various National Championships. These "highly trained" athletes align with the population studied by Mastalerz et al., 2024, categorized as a sub-elite athlete population.

Additionally, the metabolic responses observed in our study following the 400 m races are comparable to the metabolic stress highlighted in previous works such as Hanon et al., 2010, and Lacour et al., 1990.

McKay, A. K., Stellingwerff, T., Smith, E. S., Martin, D. T., Mujika, I., Goosey-Tolfrey, V. L., ... & Burke, L. M. (2021). Defining training and performance caliber: a participant classification framework. International journal of sports physiology and performance, 17(2), 317-331.
Mastalerz, A., Johne, M., Mróz, A., Bojarczuk, A., Stastny, P., Petr, M., ... & Maculewicz, E. (2024). Changes of Anaerobic Power and Lactate Concentration following Intense Glycolytic Efforts in Elite and Sub-Elite 400-meter Sprinters. Journal of Human Kinetics, 91(Spec Issue), 165.
Hanon, C., Lepretre, P. M., Bishop, D., & Thomas, C. (2010). Oxygen uptake and blood metabolic responses to a 400-m run. European journal of applied physiology, 109(2), 233-240.
Lacour, J. R., Bouvat, E., & Barthelemy, J. C. (1990). Post-competition blood lactate concentrations as indicators of anaerobic energy expenditure during 400-m and 800-m races. European Journal of Applied Physiology and Occupational Physiology, 61(3), 172-176.

Moreover, how do you evaluate the way of motivating to run as fast as you can?

We thank the reviewer for this remark, which is a crucial element in our study to ensure that the athletes were giving 100% effort during their performance.

We have added this part to explain the way to motivate the athletes to run as fast as they can (line 182 to 201).

Warming up the athletes lasted one hour and was individualized so that each could warm up as in competition. Tactically, the athletes were specifically trained to make a fast and effective start by utilizing their phosphocreatine stores (34) to gain an early advantage. As 400m specialists, they have also learned to manage their effort with a quick start and to maintain resistance to the inevitable decline in speed that occurs in the final 100m (2). Additionally, participants engaged in direct 1 vs. 1 competition with instructions to win the race and achieve the best possible performance, as if they were qualifying for the next round.

Throughout all the tests, the athletes received verbal encouragement and support, similar to a competitive environment, to ensure they felt supported and motivated. Combining these strategies has helped the athletes stay motivated for the three tests and perform at their best in the three 400m races.

In this context, we measured participants' motivation both before and after each effort to ensure full engagement. Additionally, the athletes were also motivated to achieve the best possible performance as they were promised a voucher for the new competitive carbon spikes at the end of the study.

In the discussion to the line 426 to 428, we have also specified the results relating to motivation data to make it easier for the reader to understand the importance of this parameter in interpreting the results.

How would you comment on the time drop in the BIC group between 2 and 3 400m?

We thank the reviewer for this comment. We have tried to improve the paragraph and comment this observation:

The 3rd 400m was significantly faster on average for the athletes in the BIC group. it was observed that the BIC group athletes slowed down less during the 2^nd 200 meters of the 3^rd 400 m race compared to the 1^st (2^nd 200m of the 3^rd 400m: 28.40 ± 2.75 s vs 2^nd 200m of the 1^st 400m: 28.96 ± 2.80 s; p = 0.01). Therefore, the BIC group exhibited a faster completion time in the second half of the race, corresponding to the final 200 m, during the third 400-metre race. Additionally, it is important to note that the subjects served as their own controls, and the study was conducted in a double-blind manner. It could therefore be postulated that the observed improvement in performance exhibited by the BIC group between the second and third 400-meter races may be attributed to the alkalizing diet in conjunction with bicarbonate-rich water, which may delay the negative effects of metabolic acidosis on muscle performance. We have included this paragraph in the discussion (line 464 to 475).

Moreover, Figure 2 shows that individual differences are very large, both in terms of gender and the method of performing the exercise. Moreover, the competitors from the BIC group have been running faster from the very beginning. How does this affect the experiment? It is possible that these are people with better personal records. The analysis of mean results in such a case and for such SD is unreliable. First, there is a lack of dependency assessment. There are no cause-and-effect relationships here.

We thank the reviewer for this remark.

We have therefore added the following section explaining this standard deviation in the discussion section from Line 451 to 458. “the large standard deviation (SD) among the subjects could be explained by the fact that the average performances reported after the 400 m races include both male and female athletes. If we consider only the performances of male athletes, the intra-group standard deviation would be, on average, 2.66 seconds for the PLA group and 1.64 seconds for the BIC group. This is comparable to the performance variability reported in previous studies (Hanon et al., 2010 and Lacour et al., 1990), and it could be assumed that this will have no impact on blood metabolic responses, which do not differ between sexes from the age of 14 onwards (Bardin et al., 2023). “

Furthermore, the slight performance improvement observed in the BIC group during the third 400m race does not impact the validity of our results. Indeed, this improvement is within the BIC group itself, not between different groups, ensuring that our statistical analysis remains uncompromised

Bardin, J., Maciejewski, H., Diry, A., Droit‐Volet, S., Thomas, C., & Ratel, S. (2023). Sex‐and age‐related differences in the rating of perceived exertion after high‐intensity rowing exercise during childhood and adolescence. Psychophysiology, 60(8), e14296.

Line 112 - how people were assigned to groups - how many men and how many women were in them.

The protocol used in our study was randomized and double-blind. Of the 22 participants, 7 were female and 15 male.

Line 118 - why was the Hungarian table of World Athletic Quotation Table (W) for the 400-m race or 800-m race chosen to evaluate the results?

According to the classification by McKay et al., 2022 (32), these highly trained athletes had achieved personal best (PB) performances that met the criteria for Performance level 4 (National 4) as outlined in the Hungarian table of World Athletics Quotation Table (W) for the 400 m race or 800-m race. The Hungarian table is an internationally recognized reference, certified by World Athletics, for classifying athletes based on their performance levels.

We have introduced these informations lines 123-129 à vérifier.

https://worldathletics.org

We appreciate the reviewer’s comment, which prompted us to take a closer look. Our simulated competition was meticulously designed to replicate real competition conditions as closely as possible. During the test period, which was structured to mimic the characteristics of an actual competition, we included a specific warm-up, a call room, a direct confrontation race, a start from starting blocks, and three consecutive races within 24 hours, effectively emulating the format of heats, semi-finals, and finals.

We have changed the paragraph by:

For performance measurements (400 m and the 200 m split times (in seconds), we used video recordings captured by an iPhone 11 (1080p HD at 60 frames per second, Apple, Cupertino, CA, USA) and an iPad Pro (1080p HD at 60 frames per second, Apple, Cupertino, CA, USA). The footage was analyzed using software to obtain measurements accurate to the hundredth of a second. Furthermore, a manual stopwatch was employed to provide a backup measurement in the event of any failure in the primary method. (Line 169 to 178).

With regard to the one-hour warm-up phase, athletes were obliged to adhere to their customary competition routine, which included mobilization, jogging, stretching, technical exercises, sprints, and starts, prior to entering the call room. We have added these information lines 187.

Line 165 - if the race was aimed at achieving the best possible result, as if they qualified for the next round, why are the results far from the real results of people at the elite level?

The sub-elite athletes were competitors who trained at a national or interregional level, typically training 5 to 6 times per week. This training frequency distinguishes them from elite athletes who train between 8 to 12 times weekly. Regarding qualification for the next round, athletes were encouraged to finish in first place each time, as if their ranking would influence their participation the following day.

Line 176 - since in the experimental phase athletes in the 400 m race achieved on average 98% of the best results in the season, they are not elite athletes in this sports competition.

We would like to thank the reviewer for this important comment.

We have introduced this sentence in the discussion now. The sub-elite athletes demonstrated performances at 98% of their optimal capacity, with a mere difference of a few tenths of a second between their best and their performance in the 400-meter race. Furthermore, the experimentation was conducted either immediately before the outdoor or indoor competitive season (in May and December). Consequently, although the performances recorded during this experimental protocol are not identical to their best performances, they nevertheless correspond to acceptable standards for an experiment involving sub-elite athletes.

We thank the reviewer for this comment.

The research team engaged in extensive deliberation before selecting the squat jump (SJ) as a test to indirectly assess neuromuscular fatigue following the 400 m. Komi and Bosco (1978) demonstrated that the difference between the SJ and the countermovement jump (CMJ) could be attributed to the storage and utilisation of elastic energy during the countermovement, concluding that a greater difference between the CMJ and SJ suggests a better ability to store and utilise elastic energy. In addition, Squat jump performance has often been used as an independent muscular indicator to assess knee extensor fatigue separately from high intensity sprint exercise (White et al. 2014). As Skurvydas et al. (2002) demonstrated that sprinters exhibited a greater jump difference between performances in the SJ compared to the CMJ, we have chosen to use the SJ as a fatigue index. We also selected the SJ to align with our previous research (Thomas et al., 2022), which employed the SJ following maximal sprints performed by world-class cyclists to compare the effects of sodium bicarbonate supplementation vs placebo during repeated high-intensity exercises.

In view of your comment, we have added this element to the discussion section of lines 456 to 462.

Komi, PV and Bosco, C. Utilization of stored elastic energy in leg extensor muscles by men and women. Med Sci Sports 10: 261–265, 1978.
Skurvydas, A, Dudoniene, V, Kalvenas, A, and Zuoza, A. Skeletal muscle fatigue in long-distance runners, sprinters and untrained men after repeated drop jumps performed at maximal intensity. Scand J Med Sci Sports 12: 34–39, 2002.
Thomas, C., Delfour-Peyrethon, R., Dorel, S., & Hanon, C. (2022). Positive effects of pre-exercise metabolic alkalosis on perceived exertion and post-exercise squat jump performance in world-class cyclists. The Journal of Strength & Conditioning Research.
White GE, Rhind SG, Wells GD. The effect of various cold-water immersion protocols on exercise-induced inflammatory response and functional recovery from high-intensity sprint exercise. Eur J Appl Physiol 114: 2353–2367, 2014.

We have added this element to the discussion section of lines 505 to 509.

However, if the reviewer wishes for us to remove these results from the article, we will do so in the next version.

Table 3B what do p values of 0 mean?

Thank you to the reviewer for this precise comment. Indeed, the table had rounded the number to two decimal places. A p-value of 0 corresponds to a p < 0.001. We have included this results in Table 3B.

Reviewer 3 Report

Comments and Suggestions for Authors

I want to thank you for the opportunity to review this manuscript. In general, this is in advance, an interesting research about acid-base status on athletic performance. Still, after a careful analysis, I believe that this paper, in my opinion, must be modified before publication. Therefore, I hope my recommendations will help you improve the manuscript.

Title

Clear and well-constructed.

Abstract

Line 22: PRAL index is an acronym (Potential Renal Acid Load), first time using, please explain the meaning.

Line 23: what means (p < 0,5)?

Lines 25-26: Authors wrote “Athletes experienced similar levels of metabolic perturbations during the three 400-m races, with improved lactate clearance 20 minutes after the third race compared to the first two (p < 0,05)” Is now well explained. Lactate differences happens in both, PLA and BIC groups, and show higher values in BIC group.

Introduction

Bicarbonate concentration, blood pH, base excess, and Lactate are measured and these topics are included in the introduction chapter. Well structured.

Maybe authors can explain about simulated competition concept and the possible differences with real competition.

Materials and methods

Line 113: The predetermination of the sample size is not defined in the study. The authors include 22 male and 7 female athletes, but the physiological responses to high-intensity exercise are different between sexes. Is it a good idea to mixture males and females in the sample?

In Table 1, bicarbonate levels in BIC water are 14.27 higher than in PLA water, and it is the only highlighted point. But sodium levels in BIC water are 194.09 higher than in PLA water. Something similar happens with potassium. Why is this not important in the study?

In general, the methods chapter is extensive and well structured. The statistical procedure is correct and well explained.

Results

Results chapter is extensive and detailed.

Discussion

Complete and well-structured.

Conclusions

Lines 499-501: Authors wrote “The implementation of a nutritional strategy combining the consumption of bicarbonate-rich water with an alkalizing diet may thus potentially substitute the supplementation of bicarbonate capsules often associated with gastrointestinal disturbances”. It is a surprise authors argue about gastrointestinal disturbances. Maybe it can be included as an aim. Included as in the introduction as in discussion chapters.

Author Response

All changes made to the manuscript have been highlighted in yellow.

I want to thank you for the opportunity to review this manuscript. In general, this is in advance, interesting research about acid-base status on athletic performance. Still, after a careful analysis, I believe that this paper, in my opinion, must be modified before publication. Therefore, I hope my recommendations will help you improve the manuscript.

We would like to express our gratitude to the reviewer for their valuable contribution in reviewing our manuscript and providing us with constructive feedback. We have implemented the necessary corrections to the manuscript based on the reviewer’s comments to ensure that this version more closely meets the desired requirements.

Line 22: PRAL index is an acronym (Potential Renal Acid Load), first time using, please explain the meaning.

We extend our apologies for this error. We have rectified this omission by including the acronym PRAL (Potential Renal Acid Load) in the abstract. We have also clarified the meaning of this term on line 23.

Line 23: what means (p < 0,5)?

We would like to thank you for your comment. We acknowledge that this is an oversight on our part, given that the p-value corresponds to 0.05 (p < 0.05). We have corrected this in the manuscript, on line 24.

Lines 25-26: Authors wrote “Athletes experienced similar levels of metabolic perturbations during the three 400-m races, with improved lactate clearance 20 minutes after the third race compared to the first two (p < 0,05)” Is now well explained. Lactate differences happen in both, PLA and BIC groups, and show higher values in BIC group.

Maybe authors can explain about simulated competition concept and the possible differences with real competition.

We would like to express our gratitude to the reviewer for their observation. We have clarified in the method and discussion what we consider a simulated competition.

Line 405 : “During a test period designed to replicate the characteristics of a competition, this simulated competition involved a specific warm-up, a call room, a direct confrontation race, a start from starting blocks, and three consecutive races within 24 hours, mirroring the format of heats, semi-finals, and finals”

Additionally, the details of the context in which the 400 m races were conducted are specified in the methodology section ("400 m race test") starting from line 171:

During the testing phase (Day 3, Day 4, and Day 5), participants completed a daily 400 m race. These races served as simulated competitions, with a specific warm-up, a call room, a direct confrontation race, a start from starting blocks. Performance were initially recorded through manual double timing. For performance measurements (400 m and the 200 m split times (in seconds), we used video recordings captured by an iPhone 11 (1080p HD at 60 frames per second, Apple, Cupertino, CA, USA) and an iPad Pro (1080p HD at 60 frames per second, Apple, Cupertino, CA, USA). The footage was analyzed using software to obtain measurements accurate to the hundredth of a second. Furthermore, a manual stopwatch was employed to provide a backup measurement in the event of any failure in the primary method. The 400 m races were conducted on an indoor track with a length of 340 meters (Maigrot Hall at the Institute of Sport Expertise and Performance, Paris, France) to ensure highly reproducible conditions (the temperature was maintained at a constant level and there was no wind).

As before each competition, the athletes were encouraged to visualize their perfect race, imagining themselves successfully completing each stage and achieving their goals. They prepared as if for a real competition, using techniques to stay calm and focused. The athletes were conditioned by their coaches similarly to a real competition setting. The training load was adjusted and reduced in the days preceding the tests to ensure they were in optimal shape and motivated to perform. Warming up the athletes lasted one hour as in competition. Athletes were obliged to adhere to their customary competition routine, which included mobilization, jogging, stretching, technical exercises, sprints, and starts, prior to entering the call room. Tactically, the athletes were specifically trained to make a fast and effective start by utilizing their phosphocreatine stores (Nummela et al., 1992) to gain an early advantage. As 400m specialists, they have also learned to manage their effort with a quick start and to maintain resistance to the inevitable decline in speed that occurs in the final 100m (Hanon et al., 2010). Additionally, participants engaged in direct 1 vs. 1 competition with instructions to win the race and achieve the best possible performance, as if they were qualifying for the next round, with their ranking influencing their participation the following day.

Materials and methods

We thank the reviewer for their valuable input. In the manuscript, we have specified the requisite sample size for the reliability of this study.

Line 119: “Based on previous studies (20 and 23) and to achieve 95% power with a 5% statistical risk, we will include 22 participants in our experimental protocol.”

With regard to the analysis of results for men and women, it is our opinion that the formation of two distinct groups would have been optimal for the performance of appropriate statistical analyses. However, the low number of female participants necessitates the collective treatment of the results. Furthermore, it appears that physiological responses following high-intensity exercise are more influenced by the participants' fitness level than by their sex. Previously, our team demonstrated that physiological responses to high-intensity exercise and bicarbonate supplementation were comparable between participants of different sexes, with only performance differing (5 and 16) from 14 years old (46)

In order to address your comments and those of reviewer 2, we have introduced the following paragraph.

Line 450 Furthermore, the large standard deviation (SD) among the subjects could be explained by the fact that the average performances reported after the 400 m races include both male and female athletes. If we consider only the performances of male athletes, the intra-group standard deviation would be, on average, 2.66 seconds for the PLA group and 1.64 seconds for the BIC group. This is comparable to the performance variability reported in previous studies (Hanon et al., 2010 and Lacour et al., 1990), and it could be assumed that this will have no impact on blood metabolic responses (Thomas et al. 2016 et 2022) , which do not differ between sexes from the age of 14 onwards (Bardin et al., 2023).

Thomas C, Delfour-Peyrethon R, Bishop D, PerreyS, LeprêtrePM, DorelS, Hanon C. Effets of pre-exercise alkalosis on the decrease in VO₂ at the end of all-out exercise. European Journal of Applied Physiology. 116 : 85-95. 2016.

Bardin J, Maciejewski H,Diry A,Armstrong N,Thomas C, Ratel S. Authors' Reply to Dotan: "Sex-related differences in accumulated O ₂ deficit incurred by high-intensity rowing exercise during childhood and adolescence. European Journal of Applied Physiology. 121(9):2651-2652, 2021.

Bardin J, Maciejewski H,Diry A,Armstrong N,Thomas C, Ratel S. Sex-related differences in accumulated O₂ deficit incurred by high-intensity rowing exercise during childhood and adolescence. European Journal of Applied Physiology. 121(6):1641-1651 2021.

Thomas C, Delfour-Peyrethon R, Dorel S, Hanon C. Positive effects of pre-exercise metabolic alkalosis on perceived exertion and post-exercise squat-jump performance in world-class cyclists Journal of Strength and Conditioning Research. 36(9):2602-2609. 2022.

We would like to express our gratitude to the reviewer for bringing this point of concern to our attention. Indeed, the composition of the two types of water used in our experimental protocol differs, particularly in terms of bicarbonate and sodium content. However, the supplementation with alkalising agents is typically carried out using sodium bicarbonate (NaHCO3-): https://doi.org/10.1186/s12970-021-00469-7. Therefore, it appears that the higher sodium concentration in the BIC water may not pose an issue in the interpretation of the results. Nevertheless, it is important to remain vigilant in specifying this point in the discussion and limitations of the study.

Line 498: “Finally, future studies should take into account sodium supplementation, which could also have an impact on anaerobic performance (43).”

Grgic, J., Grgic, I., Del Coso, J., Schoenfeld, B. J., & Pedisic, Z. (2021). Effects of sodium bicarbonate supplementation on exercise performance: an umbrella review. Journal of the international society of sports nutrition, 18, 1-13.

We would like to thank the reviewer for this point of vigilance.

We have therefore changed the paragraph for the practical applications (line 569 to 583).

Ragone, L., Guilherme Vieira, J., Camaroti Laterza, M., Leitão, L., da Silva Novaes, J., Macedo Vianna, J., & Ricardo Dias, M. (2020). Acute Effect of Sodium Bicarbonate Supplementation on Symptoms of Gastrointestinal Discomfort, Acid-Base Balance, and Performance of Jiu-Jitsu Athletes. Journal of Human Kinetics, 75, 85–93. https://doi.org/10.2478/hukin-2020-0039