Physiological Profiles of Recreational Runners and Cyclists Aged 20 to 60 Years
Round 1
Reviewer 1 Report
The manuscript provides population data that may be beneficial for future investigations. However, the methods require more detail to ensure that scientific rigor was adhered to when assessing these athletes for the outcomes of interest.
Lines 44-47: This statement should be refined as it is a run-on sentence that is difficult to follow.
How was the sample size chosen? Provide power analysis information.
Provide more detail regarding the VO2max criteria. For example, what length of time was the minimal criteria to be considered a plateau? Were any other markers considered when determining VO2max? Was rating of perceived exertion used? Were the subjects fasted or what instructions were they provided before testing? Were any dietary and fluid intake instructions provided prior to testing?
What was the rationale for waiting three minutes after recovery to collect blood lactate concentrations? Blood lactate will substantially rise with exercise, but it can quickly recover as well. Justify this method of waiting for three minutes with references to the literature, as there are concerns that this is too far after the completion of the test to obtain an accurate measurement of maximal blood lactate values.
Author Response
Response to Reviewer 1 Comments
Point 1: Lines 44-47: This statement should be refined as it is a run-on sentence that is difficult to follow.
Response 1: The text was refined as follows: In adolescents and young adults, there is strong evidence for improved cardiorespiratory endurance and muscular fitness, favorable body composition, improved bone health, and improved cardiovascular and metabolic health biomarkers with physical activity and training [6]. In older adults, however, it still remains unclear to what extent may recreational physical activities, such as running and cycling affect or slow physiological changes with increasing age. From these age-related changes, a decreased of fat-free mass, lung function and decreased work capacity are frequently discussed [7, 8].
Point 2: How was the sample size chosen? Provide power analysis information.
These recreational athletes were selected from a wider range of people examined over the last few years in the Biomedical Laboratory, Faculty of Physical Education and Sport, Charles University. Subjects were eligible if they met all of the following inclusion criteria: (1) adhered to the regular recreational activities at least for three years, (2) provided written informed consent before being involved to the study, (3) were over 20 years of age. Subjects were excluded if they: (1) were beginners or adhered to the regular recreational activities less than five years, (2) were high performance cyclists or runners, i.e. organized in sports clubs and results-oriented in sports competitions, (3) had acute or chronic health problems that may alter their adherence to regular cycling or running.
Power analysis: The power of a statistical test depends on several factors, including effect size, the variability of the measure, the predetermined level of significance, directionality, and sample size. For parameters analysed in separate age groups the sample size at effect size 0.78 and power 0.80 reached n= 40 to 50. Thus the comparisons at the highest age groups (50 to 60 years) both in males and females did not correspond to the desired or staisfactory sample size needed to reject the null hypothesis. This fact is now also mentioned in the limitations of the study.
Point 3: Provide more detail regarding the VO2max criteria. For example, what length of time was the minimal criteria to be considered a plateau? Were any other markers considered when determining VO2max? Was rating of perceived exertion used? Were the subjects fasted or what instructions were they provided before testing? Were any dietary and fluid intake instructions provided prior to testing?
Response 3: We will explain in the text VO2max criteria used in the test. A plateau in VO2 was defined as any two 30-s VO2 values in which the second was not higher that the first, provided increase in ventilation at maximal effort. In addition, standard criteria of maximum physiologic effort, as RER values > 1.00, 85% to 100 % of the age-predicted HRmax, Borg scale6-20 rating ≥ 17 RPEmax and ≥ 8 mmol.l-1 for maximum blood lactate were also used.
Dietary and fluid intake instructions provided prior to testing wew as follows:
Subjects were instructed to eat a light breakfast at least 3 hours before the stress test. They were also instructed not to drink tea or coffee on the day of testing and to limit their drinking regimen prior to testing.
Point 4: What was the rationale for waiting three minutes after recovery to collect blood lactate concentrations? Blood lactate will substantially rise with exercise, but it can quickly recover as well. Justify this method of waiting for three minutes with references to the literature, as there are concerns that this is too far after the completion of the test to obtain an accurate measurement of maximal blood lactate values.
Response 4: Investigators have assumed various times post exercise as appropriate to measure peak blood lactate concentrations following maximum exercise, e.g. within the first minute (McGrail et.al, 1978), at 2 minutes (Hermansen and Svensvold, 1972), between 1 and 5 minutes (Hermansen and Vaage, 1977) between 2 and 5 minutes (Freund and Gendry, 1978) or at 3 minutes (Tamir et ale, 1988) Our own older study (Heller et al. Lactate kinetics during exercise and recovery: A comparison of ear lobe, fingertip, and toe tip capillary levels. In: Sports, Medicine and Health, Hermans, G.P.H., Morsted, W.I. (Eds.). Excerpta Medica, Amsterdam-New York-Oxford, 1990, s. 609-614) also showed peak blood lactate concentrations in samples taken between 1 and 5 minutes after maximum exercise. More recently some authors recommend - if repeated blood draws are not performed in the first minutes after maximum exercise – the 3rd minute after exercise as a suitable compromise that takes into account the time of lactate leaching from muscle tissue into the blood, but at the same time minimizes the disappearance of lactate concentration from blood during recovery (Smith et al. Blood lactate profile after two different arm crank ergometry tests. J Sports Sci, 2002, 20.1: 58-59; Janssen, P. Lactate threshold training. Elsevier, 2001; Shephard, R.J. Anaerobic metabolism and endurance performance. Oxford, UK: Blackwell Science LTD, 2000.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
General Comments: the majority of cited literature was published 10-15 years ago. I would strongly recommend reviewing and citing current literature on the topic.
Introduction: I would recommend updating references, for example in the first sentence: Oja P, Titze S, Bauman A, de Geus B, Krenn P, Reger-Nash B, Kohlberger T. Health benefits of cycling: a systematic review. Scand J Med Sci Sports. 2011 Aug;21(4):496-509. doi: 10.1111/j.1600-0838.2011.01299.x. Epub 2011 Apr 18. PMID: 21496106.
Methods: men and women were investigated separately, I would recommend the analysis of sex differences for these age categories in order to better portray the study population
Results: I would recommend varying the display of results
Discussion: an update of references is again strongly recommended here. Please proved more details when physiological mechanisms are described
a spell and grammar check is strongly recommended
Author Response
Response to Reviewer 2 Comments
Point 1: General Comments: the majority of cited literature was published 10-15 years ago. I would strongly recommend reviewing and citing current literature on the topic.
Response 1: Many thanks for the comment, the literature was updated, approximately one third of all the literature sources.
Point 2: Introduction: I would recommend updating references, for example in the first sentence: Oja P, Titze S, Bauman A, de Geus B, Krenn P, Reger-Nash B, Kohlberger T. Health benefits of cycling: a systematic review. Scand J Med Sci Sports. 2011 Aug;21(4):496-509. doi: 10.1111/j.1600-0838.2011.01299.x. Epub 2011 Apr 18. PMID: 21496106.
Response 2: The literature in the Introduction was updated, including the recommended source.
Point 3: Methods: men and women were investigated separately, I would recommend the analysis of sex differences for these age categories in order to better portray the study population
Response 3: The recommended analysis of sex differences was added into Discusssion.
Regarding sex differences, VO2max values for female cyclists of the three younger age categories corresponded to approximately 81 to 84% those of male cyclists, but in the highest age category, VO2max values for female cyclists corresponded to 97% of their male counterparts. Similarly to this, values of maximum power output and maximum blood lactate in female cyclists of the three younger age categories corresponded to approximately 78 to 83% and 86 to 91 % those of male cyclists, respectively. In the highest age category, the values of maximum power output and maximum blood lactate in female cyclists corresponded to 98% and 96 % of their male counterparts, respectively. VO2max values in female runners across all the age categories corresponded to approximately 90 to 99 % those of male runners. The values of maximum power output and maximum blood lactate in female runners corresponded to 85 to 90 % and 81 to 101 % of their male counterparts, respectively. In the adult population, it is well established that physical activity participation decreases significantly as age increases and motivation for physical may also vary with age [26]. One possible explanation for the above findings in female cyclists may be the assumption that recreational female cyclists over the age of 50 may attain different adherence and motivation for regular training and health outcomes than women of younger age categories [27].
Trujillo K, Brougham R, Walsh D. Age differences in reasons for exercising. Curr Psychol. 2004, 22(4): 348–367. https://doi.org/10.1007/s12144-004-1040-z
Molanorouzi, K., Khoo, S., Morris, T. Motives for adult participation in physical activity: type of activity, age, and gender. BMC Public Health, 2015, 15, 66. https://doi.org/10.1186/s12889-015-1429-7
Point 4: Results: I would recommend varying the display of results.
Response 4: Thank you for the proposal better resp. clearer presentation of results. However, the results are organized by age group and gender into four clear tables. The graphical presentation of the data could be illustrative, but the use of the study results for comparison with the results of similar research studies will require specific numerical values of the monitored parameters according to gender and age. Therefore, the authors believe that the current form of presentation of results is appropriate to the intent of the cross-sectional study.
Point 5: Discussion: an update of references is again strongly recommended here. Please proved more details when physiological mechanisms are described
Response 4: The literature in the Discussion was updated and the text was improved.
Point 6: A spell and grammar check is strongly recommended
Response 6: Thank you for pointing out the need for a language check. The authors carefully made spell and grammar check.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Thank you for the considerate responses. All concerns have been addressed, but the limitation of power not being reached needs to be more explicitly stated in the manuscript as to let the reader understand what conclusions can be formed. Please add the power analysis detail to the manuscript.
Author Response
Response to Reviewer 1 Comments (2)
Point 1: Thank you for the considerate responses. All concerns have been addressed, but the limitation of power not being reached needs to be more explicitly stated in the manuscript as to let the reader understand what conclusions can be formed. Please add the power analysis detail to the manuscript.
Response 1: Power analysis detail was added in the Methods and is also mentioned in the Limitation of the study.
