The Impact of the Weight Status on Cardiovascular Parameters Related to Physical Effort in Young Athletes

Round 1

Reviewer 1 Report

The authors sought to investigate the impact of weight status on cardiovascular responses to a maximal volitional graded exercise test, in a cohort of your athletes. For this purpose, they conducted a retrospective analysis of the data from the pre-participation sport screening, in a period of twenty years. Overall, the results of the present study are interesting and can provide important insights on the field. Indeed, one of the major strength of the present manuscript is the very large cohort and the comparison of overweight/obese children/adolescents with normal weight individuals, an aspect that has been previously investigated only in small laboratory-based studies. Thus, the present study can clarify some contrasting results arising from previous studies with smallest samples and without a sufficient number of overweight/obese individuals. Notwithstanding, there are a number of aspects that need consideration:

Whole manuscript

terminology is not uniform throughout the text. Relative to exercise test (line 38, 43, 67,98,...) I suggest using maximal volitional graded exercise test (GXTmax) when describing exercise test in a general way, and adopting maximal cycle ergometer exercise test or treadmill maximal cycle ergometer exercise test when appropriate. Relative to the populations described here and in cited studies (line 59, 199, 210, 211), I suggest to use athletic and non-athletic children/subjects. 

Introduction

The authors stated that the aim of the study was to investigate the impact of weight status on cardiovascular responses to a maximal volitional graded exercise test, in a cohort of young athletes. However, they should also declare their hypothesis based on scientific background (they think weight status influence or not some/all parameters investigated?) and better focus scientific gaps in literature. In particular, at line 52-53 they should define the relationship between body weight and HR response, as well as at line 54 they should also define how age and BMI are related with exercise duration (BMI and exercise duration are inversely related? Both on treadmill and cycle-ergometer). Furthermore, the influence of BMI on recovery is still not clear. Can authors better define inconsistency in literature? Indeed, the majority of the studies with a large sample presented in the background did not examined the role of weight status (Lintu 2014 e 2015, Szmigielska 2016, Singh 2008) while studies that did it involved just a small sample (Cooper 1984), populations different from reference population (Easley 2018), and different protocols (1, 4, or 5 minutes of recovery). All this aspect should be better explained to focus aim and hypothesis of the study. 

At line 46 authors describe HR recovery as an index of athletic performance. However, the cited study describe HR recovery as an index of pathological condition rather than a athletic performance.

Moreover, the following sentences should be rephrased for a better comprehension:

line 35-37

line 40-42

line 51-52

line 98-100

Results

The sentences starting at line 174, line 178, and line 184 should be rephrased because they infer the role of weight status while they should just describe the difference between groups. Any consideration should be done in the discussion section.

Table 1 and 2 are large and quite dispersive. Maybe, highlighting the significant results in bold may help readers.

Moreover, at line 163-164 and 168-169 the sentence "between normal weight and overweight and obese" is confusing. Between normal weight and overweight/obese or between normal weight vs. overweight and obese are more understandable.

Discussion

The sentence at line 218 is somehow contradictory: while results show that HR in O&O subject is higher at rest in that study, authors speculate that sport practice reduce resting HR. They infer this speculation comparing these data with other studies? Could authors better explain this point?

At line 228-230 Authors describe SBP max-rest behavior.Can they also describe what can be deduced from this data?

What authors mean with protective at line 244?

Moreover, the following sentences should be rephrased for a better comprehension:

line 219-222

line 227-232

Author Response

The authors thank for the work done by the reviewer in order to improve their manuscript.

Replies to comments are highlighted in red below.

The authors sought to investigate the impact of weight status on cardiovascular responses to a maximal volitional graded exercise test, in a cohort of your athletes. For this purpose, they conducted a retrospective analysis of the data from the pre-participation sport screening, in a period of twenty years. Overall, the results of the present study are interesting and can provide important insights on the field. Indeed, one of the major strength of the present manuscript is the very large cohort and the comparison of overweight/obese children/adolescents with normal weight individuals, an aspect that has been previously investigated only in small laboratory-based studies. Thus, the present study can clarify some contrasting results arising from previous studies with smallest samples and without a sufficient number of overweight/obese individuals. Notwithstanding, there are a number of aspects that need consideration:

The authors thank the reviewer for the appreciation for our work.

Whole manuscript

terminology is not uniform throughout the text. Relative to exercise test (line 38, 43, 67,98,...) I suggest using maximal volitional graded exercise test (GXTmax) when describing exercise test in a general way, and adopting maximal cycle ergometer exercise test or treadmill maximal cycle ergometer exercise test when appropriate.

Thank you for the comment. The terminology about Exercise test has been modified as graded exercise test (GXT) throughout the text. In addition, the terminology related to cycle ergometer and treadmill exercise test has been modified as treadmill GXT and cycle ergometer GXT.

However, the authors not use "maximum volition" because the tests were carried out according to the Italian protocol that provides the interruption at 85% of the predicted HR max; which may not coincide with the maximal volitional.

20. Biffi, A.; Delise, P.; Zeppilli, P.; Giada, F.; Pelliccia, A.; Penco, M.; Casasco, M.; Colonna, P.; D’Andrea, A.; et al. Italian cardiological guidelines for sports eligibility in athletes with heart disease: Part 1. J. Cardiovasc. Med. 2013, 14, 477–499.

Relative to the populations described here and in cited studies (line 59, 199, 210, 211), I suggest to use athletic and non-athletic children/subjects.

Thank you for the comment. The terminology has been modified accordingly.

Introduction

The authors stated that the aim of the study was to investigate the impact of weight status on cardiovascular responses to a maximal volitional graded exercise test, in a cohort of young athletes. However, they should also declare their hypothesis based on scientific background (they think weight status influence or not some/all parameters investigated?) and better focus scientific gaps in literature. In particular, at line 52-53 they should define the relationship between body weight and HR response, as well as at line 54 they should also define how age and BMI are related with exercise duration (BMI and exercise duration are inversely related? Both on treadmill and cycle-ergometer).

The sentence about body weight has been modified as: “The impact of body weight is well establish on HR response to exercise in children, particularly during an incremental test, the increase in peripheral oxygen demand increases the HR in direct proportion to body weight”.

While the sentence about age and BMI has been modified as: “Similarly, age and BMI are related to exercise duration in both boys and girls; age has a direct correlation, while BMI has an inverse relationship.”

Furthermore, the influence of BMI on recovery is still not clear. Can authors better define inconsistency in literature? Indeed, the majority of the studies with a large sample presented in the background did not examined the role of weight status (Lintu 2014 e 2015, Szmigielska 2016, Singh 2008) while studies that did it involved just a small sample (Cooper 1984), populations different from reference population (Easley 2018), and different protocols (1, 4, or 5 minutes of recovery). All this aspect should be better explained to focus aim and hypothesis of the study.

The authors agree with the reviewer. The sentence has been moved from line 66 to line 62 and it has been modified from:

“Currently the influence of body weight on cardiovascular performance in young people has been studied mainly on small samples size or in non-athletic subjects.”

To:

“Currently the influence of body weight on cardiovascular performance in young people has been studied mainly on small samples size, in non-athletic subjects and using different protocols. In addition, most studies with a large sample size did not examine the role of weight status on cardiovascular response to exercise.”

At line 46 authors describe HR recovery as an index of athletic performance. However, the cited study describe HR recovery as an index of pathological condition rather than a athletic performance.

Thank you for the comment. The sentence has been modified as: “The speed in reduction of HR after termination of the GXT, termed HR recovery, currently is considered as an index of cardiorespiratory fitness and is associated with the mortality risk”

Moreover, the following sentences should be rephrased for a better comprehension:

line 35-37

The sentence has been modified as: “The main hemodynamic changes in obese youth are an increase in resting blood pressure and resting heart rate and an increase in peak heart rate during exercise tests compared to lean controls”

line 40-42

The sentence has been modified as: “In normal subjects, during exercise there is an increase in muscle work, which leads to an increase in oxygen demand. To meet these growing requirements, the cardiovascular system applies a gradual increase in cardiac output.”

line 51-52

The sentence has been modified as “The interpretation of GXT data in pediatric subjects requires special considerations; these results may have different connotations based on the age, size and sex of the child”

line 98-100

The sentence has been modified as “The GXT is performed by increasing the speed and/or the grade of the treadmill or by increasing the work on the cycle ergometer with the same pedalling frequency.”

Results

The sentences starting at line 174, line 178, and line 184 should be rephrased because they infer the role of weight status while they should just describe the difference between groups. Any consideration should be done in the discussion section.

At line 174, the sentence has been modified as: “These values show a high statistical difference (p <0.001) in ΔHR max-rest and ΔSBP max-rest, a statistical difference (p <0.05) in ΔHR max-rec and ΔSBP max-rec, and finally no difference on the ΔDBP max - rec. between athletic subjects NW and O&O.”

At line 178 the sentence has been modified as:” In particular, in Figure 1 it is shown that from the 3rd stage the are no differences in HR in male subjects who perform cycle ergometer GXT”

At line 184, the sentence has been modified as:” The differences in cardiovascular parameters between NW and O&O appear greater in males and with increasing age. However, the differences already begin in the age group of 8-10 years: resting BP is greater in O&O males. From the age group 12-14 years onwards, all parameters analysed (except HR max) show higher values in males. In contrast, O&O athletic females show higher BP values in comparison with NW athletic females.”

Table 1 and 2 are large and quite dispersive. Maybe, highlighting the significant results in bold may help readers.

Thank you for the suggestion. Significant differences in Table 1 and 2 has been highlighted accordingly.

Moreover, at line 163-164 and 168-169 the sentence "between normal weight and overweight and obese" is confusing. Between normal weight and overweight/obese or between normal weight vs. overweight and obese are more understandable.

Thank you for the suggestion. The legend has been modified accordingly (also legend of figure 1 and 2)

Discussion

The sentence at line 218 is somehow contradictory: while results show that HR in O&O subject is higher at rest in that study, authors speculate that sport practice reduce resting HR. They infer this speculation comparing these data with other studies? Could authors better explain this point?

Yes, thanks for the comment. That sentence is a speculation referring to the previous paragraph with reference 26.Norman, A.C.; Drinkard, B.; McDuffie, J.R.; Ghorbani, S.; Yanoff, L.B.; Yanovski, J.A. Influence of excess adiposity on exercise fitness and performance in overweight children and adolescents. Pediatrics. 2005;115(6):e690–e696. doi:10.1542/peds.2004-1543

Resting heart rate and recovery HR results in that study are greater than the results obtained in the present study.  Therefore, do not start a new paragraph, but continue the concept in the previous point.

At line 228-230 Authors describe SBP max-rest behavior. Can they also describe what can be deduced from this data?

A sentence has been added: “This lower Δ SBP max-rest value obtained by young athletic subjects suggests a better relationship between cardiac output and the response of the vascular endothelium.”

What authors mean with protective at line 244?

The term “protective” has been changed with “promotes”

Moreover, the following sentences should be rephrased for a better comprehension:

line 219-222

The sentence has been modified as “Furthermore, the differences between NW and O&O about HR can be shown early through physical exertion. In fact, the GXT results show these differences in a previous age group compared to those shown in resting conditions.”

line 227-232

The sentence has been modified as: “The analysis of the Δ SBP max-rec results show less significant differences, therefore the SBP has slightly higher values but the effort in excess weight conditions has a reduced effect on the recovery of blood pressure in young athletes.”

Author Response File: Author Response.pdf

Reviewer 2 Report

Very well presented

Author Response

The authors thank for the work done by the reviewer in order to improve their manuscript.

Very well presented

The authors thank the reviewer for the appreciation for our work.

Author Response File: Author Response.pdf

Reviewer 3 Report

This is an interesting research which give a new information about exercise physiology response in young athletes. Results showed the importance of implementing and active life and training in young age, appropriate to physiological and physiological demands of actual social life. The sample was appropiate and the results showed similar to previously researches which evaluated the exercise physiology response. The rational of this study is clear. Methodological issues are clear. However, I offer the following suggestions for improvement

-Please explain the criteria to determine the test finished and to determine if the test was a valid VO2max test. 

-Authors must include the number of test performed in treadmill or in a cycloergometer. 

-Improve participants description, previous training and experience

-Explain training application of the results obtained for young athletes

Author Response

The authors thank for the work done by the reviewer in order to improve their manuscript.

Replies to comments are highlighted in red below.

This is an interesting research which give a new information about exercise physiology response in young athletes. Results showed the importance of implementing and active life and training in young age, appropriate to physiological and physiological demands of actual social life. The sample was appropiate and the results showed similar to previously researches which evaluated the exercise physiology response. The rational of this study is clear. Methodological issues are clear. However, I offer the following suggestions for improvement

The authors thank the reviewer for the appreciation for our work.

-Please explain the criteria to determine the test finished and to determine if the test was a valid VO2max test.

Thank you for the comment. The termination criteria has been reported in discussion section:

“Italian guidelines declare that the achievement of 85% of age-predicted maximal HR is a main criterion to define a sufficient effort during GXT and generally, it is used in combination with other parameters to termination the evaluation”.

However, a sentence has been added in methods section at line 103: “up to 85% of age-predicted maximal HR [20].”

The Italian protocol for sport eligibility does not provide a GXT with a metabolimeter, therefore the GXT conducted in the present study is only a part of the methodology used for the evaluation of VO2 max. This parameter could possibly be obtained through an indirect evaluation with mathematical algorithms. However, the purpose of the study does not provide for an evaluation of VO2 max and therefore VO2 max has not been reported.

-Authors must include the number of test performed in treadmill or in a cycloergometer.

Each subject carried out only one test: on the cycle ergometer or on the treadmill.

This aspect can be verified:

- In the exclusion criteria "they had already made the same visit and had already been included in the study sample at a younger age"

- In the results section " from 8307 subjects that were included in the study, 3075 males and 1299 females carried out the cycle ergometer GXT and 2503 males and 1430 females carried out the treadmill GXT."

-Improve participants description, previous training and experience

Thank you for the comment. The authors agree with the reviewer on the interest of this possible variable.

However, the retrospective nature of the study does not allow for this investigation. Data recorded over 10 years ago cannot provide this information. For this reason, the authors believe that they maintain this structure in order to ensure the large sample size that appears to be a strength of the study.

-Explain training application of the results obtained for young athletes

The results of this study cannot provide methodological indications on training. However, from a public health point of view, they highlight how sport can be an effective resource of controlling cardiovascular parameters during youth. A sentence has been added at the end of the conclusion section: “This once again highlights the effectiveness of during youth from a public health perspective”.

Author Response File: Author Response.pdf