Estimation of maximum oxygen consumption: reproducibility, validity and applicability of a test for non-expert adult swimmers

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UNIVERSIDADE DE TRÁS-OS-MONTES E ALTO DOURO

ESTIMATION OF MAXIMUM OXYGEN CONSUMPTION

Reproducibility, validity and applicability of a test for

non-expert adult swimmers

DOUTORAMENTO EM CIÊNCIAS DO DESPORTO

ADALBERTO VERONESE DA COSTA

Supervisors: Tiago Manuel Cabral dos Santos Barbosa, Ph.D.

Manoel da Cunha Costa, Ph.D. !

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UNIVERSIDADE DE TRÁS-OS-MONTES E ALTO DOURO

ESTIMATION OF MAXIMUM OXYGEN CONSUMPTION

Reproducibility, validity and applicability of a test for

non-expert adult swimmers

DOUTORAMENTO EM CIÊNCIAS DO DESPORTO

ADALBERTO VERONESE DA COSTA

Supervisors: Tiago Manuel Cabral dos Santos Barbosa, Ph.D.

Manoel da Cunha Costa, Ph.D. !

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Veronese da Costa, A. (2014). Estimation of maximum oxygen consumption: reproducibility, validity and applicability of a test for non-expert adult swimmers. PhD dissertation in the field of Sport Science, at Universidade de Trás-os-Montes e Alto Douro, Portugal

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This academic thesis was submitted with the purpose of earning a doctoral degree in Sport Sciences according to the provisions of the Portuguese Decree-Law n.er 107/2008 of June 25th.

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Dedicated to my son and friend, Arthur Borges Veronese da Costa

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ACKNOWLEDGMENTS

To the University Trás-Os-Montes and Alto Douro in the person of Victor Reis Machado, PhD who was able to make the exchange between Brazil / Portugal a reality, thus making possible the accomplishment of a quality work that will contribute to the improvement of health through physical activity.

To my advisor, Tiago Manuel Barbosa PhD. (Nanyang Technological University - Singapore), for the skill of being able to transmit his guidelines even if from a distance, and by enabling new knowledge that contributed to the completion of this thesis. His advice has provided the enthusiasm for pursuing further studies in the area of swimming after this thesis.

To my co-supervisor, Manoel da Cunha Costa PhD. (School of Physical Education, University of Pernambuco - Brazil), for his ability to direct the data collection for the research and for mediating the exchange between the universities (UTAD / PT and UPE / BR, UPE / BR and UERN / BR); he has my friendship and admiration.

To my family for having managed to "endure" all the building moments of this study, and particularly to my youngest son, Henrique de Oliveira Veronese da Costa, who has brought more joy into my life since his birth this year.

To the colleagues who were part of the published articles, for believing in our proposals which motivated the publication of these works.

To my colleague, Prof. Luis Marcos Medeiros Guerra PhD. for always being present not only in good but also in difficult times during all the years of study for the conclusion of this thesis. I also thank all the classmates that I met over these years.

To the Pro-Rectory for Extension and the Physical Education Faculty of the University of Estado Rio Grande do Norte that, even without clearance for this doctoral course, allowed for moments which conditioned the completion of this study.

To the FM University Radio of the University of Estado Rio Grande do Norte, for allowing the test’s audio recording, fundamental to the completion of this study.

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To all those who volunteered to participate in this research, their contributions have enabled the creation of a tool for a better monitoring of swimming lessons.

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RESUMO

A natação é uma forma popular de exercício para fins de saúde pelos participantes não expert. Na verdade, o corpo de conhecimento sobre nadadores não expert é muito reduzida em comparação com colegas especialistas envolvidos em esportes competitivos e de alta performance. O mesmo raciocínio pode ser usado para procedimentos validados de testes de campo para nadadores não expert. Desta forma, foi projetado e desenvolvido um teste de campo acessível e simples chamado Progressive Swim Test (PSwT), para estimar o VO2max de nadadores não expert. O

objetivo desta tese foi desenvolver e validar um teste para determinar o consumo de oxigênio máximo de nadadores não expert adultos. A tese foi dividida em três estudos que foram realizados para avaliar a reprodutibilidade (estudo n º 1), validade (estudo n º 2) e aplicação (estudo n º 3). As principais conclusões desses estudos foram as seguintes: (i) o PSwT participou de um alto nível de reprodutibilidade apresentando possibilidades de aplicação na avaliação indireta da resistência aeróbica (estudo n º 1), (ii) a equação de predição para determinar o VO2max do

PSwT foi validado apresentando evidências para seu uso em adultos nadadores não expert (estudo n º 2), (iii) o PSwT é uma ferramenta aplicável para nadadores adultos não expert, associada a um teste de natação (estudo n º 3). Assim, pode-se concluir que o teste de campo projetado é preciso, válido e apropriado para estimar o consumo máximo de oxigênio de forma acessível e direta para nadadores não expert adultos.

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ABSTRACT

Swimming is a popular form of exercise for health purposes by non-expert participants. In fact, the body of knowledge on non-expert swimmers is scarce when compared with competitive and high performance couterparts. The same reasoning can be exercised for validated field-tests procedures for non-expert swimmers. Hence, an afordable and straightforward field-test coined as Progressive Swim Test (PSwT) was designed and developed, in order to estimate the VO2max in non-expert

swimmers. The aim of this thesis was to develop and validate a test to determine the maximal consumption of oxygen of non-expert adult swimmers. The thesis was split into three original studies which were conducted to evaluate reproducibility (study n.er 1), validity (study n.er 2) and application (study n.er 3). The main conclusions of those studies were as follows: (i) PSwT achieved a high level of reproducibility presenting possibilities of application in indirect evaluation of aerobic endurance (study n.er 1), (ii) the prediction equation to determine the o VO2max of PSwT was validated

showing evidence to its use in non-expert adult swimmers (study n.er 2), (iii) PSwT is an applicable tool for non-expert adult swimmers, associated with a swimming test (study n.er 3). Thus, one can conclude that the field test designed is precise, valid and appropriate to estimate the maximal consumption of oxygen in an accessible and direct way to non-expert adult swimmers.

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ACKNOWLEDGMENTS!...!XI! RESUMO!...!XIII! ABSTRACT!...!XV! TABLE!OF!CONTENTS!...!XVII! FIGURES!INDEX!...!XXI! TABLE!INDEX!...!XXIII! LIST!OF!PUBLICATIONS!...!XXV! LIST!OF!ABBREVIATIONS!...!XXVII! GENERAL!INTRODUCTION!...!1! CHAPTER!1!–!PROBLEMS,!AIMS!AND!HYPOTHESES!...!7! CHAPTER!2!?!REPRODUCIBILITY!OF!AN!AEROBIC!ENDURANCE!TEST!FOR!NON?EXPERT!SWIMMERS!...!11! ABSTRACT!...!13! INTRODUCTION!...!14! MATERIALS!AND!METHODS!...!15! SUBJECTS!...!15! NEW*TEST*FOR*AEROBIC*ENDURANCE*WITH*NON2EXPERT*SWIMMERS*IN*THE*POOL*TO* REPRODUCIBILITY!...!16! VARIABLES*FOR*ANALYSIS!...!19! ETHICAL*ASPECTS!...!19! STATISTICAL*ANALYSIS!...!19! RESULTS!...!20! DISCUSSION!...!23! DISCLAIMER!...!25!

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XVIII REFERENCES!...!26! CHAPTER!3!?!VALIDATION!OF!AN!EQUATION!TO!ESTIMATIE!VO2MAX!ON!NON?EXPERT!ADULT! SWIMMERS!...!31! ABSTRACT!...!33! INTRODUCTION!...!34! METHODOLOGY!...!36! SUBJECTS!...!36! DATA*COLLECTION!...!37! ETHICAL*ASPECTS!...!38! STATISTICAL*ANALYSIS!...!38! RESULTS!...!39! RELIABILITY*OF*THE*PROGRESSIVE*SWIM*TEST!...!39! MODEL*OF*THE*EQUATION*OF*VO2MAX*FOR*NON2EXPERT*ADULT*SWIMMERS!...!40! VALIDATION*OF*THE*EQUATION!...!40! DISCUSSION!...!42! REGARDING*THE*TRUSTWORTHINESS*OF*THE*PROGRESSIVE*SWIM*TEST*TO*800*METERS !...!42! REGARDING*THE*PROPOSED*EQUATION!...!42! REGARDING*THE*VALIDATION*OF*THE*PREDICTION*EQUATION*THROUGH*THE* PROGRESSIVE*SWIM*TEST!...!43! DISCLAIMER!...!44! REFERENCES!...!44! CHAPTER!4!?!APPLICABILITY!OF!AN!INDIRECT!VO2MAX!TEST:!ITS!ASSOCIATION!WITH!THE!400!METERS! FREESTYLE!PERFORMANCE!...!49! ABSTRACT!...!51! INTRODUCTION!...!52!

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! METHODS!...!53! SUBJECTS!...!53! DATA*COLLECTION!...!54! STATISTICAL*ANALYSIS!...!55! RESULTS!...!56! DISCUSSION!...!59! DISCLAIMER!...!62! REFERENCES!...!62! CHAPTER!5!–!GENERAL!DISCUSSION!...!67! CHAPTER!6!?!CONCLUSIONS!...!73! GENERAL!REFERENCES!...!77!

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FIGURES INDEX

Figure 1 - Schematic visual of Progressive Swim Test to non-expert swimmers ... 18 Figure 2 - Representation of the differences between paired measurements of before

heart rate (BHR), after heart rate (AHR), Rate of Perceived Exertion (RPE) and Number of Laps Performed (NLP) against their mean values. ... 23 Figure 3 - Comparison of average data, scatter plots and Bland Altman between

direct and estimated VO2max of non-expert adult swimmers ... 41

Figure 4 - Plot of the bias (average of differences) and agreement limits (± 1.96, IC95%) between the variables analysed between the simulation of the 400 meters freestyle test and the Progressive Swim Test, according to the Bland Altman analysis. Numbers between brackets represent the amount of

overlapping results. ... 58 Figure 5 - Correlation between the VO2max estimated through the Progressive Swim

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TABLE INDEX

Table 1 - Laps performed during the Progressive Swim Test for non-expert swimmers !...!17! Table 2 - Descriptive values of variables applied to non-expert swimmers!...!21! Table 3 - Paired differences between days of the variables applied to non-expert

swimmers!...!21! Table 4 - Values within and between classes of variables applied to non-expert

swimmers!...!22! Table 5 - Statistical analyses to reliability of progressive swim test to 800 meters!....!40! Table 6 - Models of equation for determination of VO2max for non-expert adult

swimmers!...!40! Table 7 - Descriptive data between the distance of the 400 meters freestyle and

Progressive Swim Test!...!56! Table 8 - Paired differences between 400 meters freestyle and Progressive Swim

Test of the variables applied to non-expert swimmers!...!57! Table 9 - Correlational values between 400 meters freestyle and Progressive Swim

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LIST OF PUBLICATIONS

The following parts of the present thesis are published:

VERONESE DA COSTA A, COSTA MC, CARLOS DM, GUERRA LM, SILVA AJ, BARBOSA TM (2012) Reproducibility of an aerobic endurance test for non-expert swimmers. Journal of Multidisciplinary Healthcare, 5(1):215-221.

VERONESE DA COSTA A, COSTA MC, OLIVEIRA SFM, ALBUQUERQUE FL, GUIMARÃES FJSP, BARBOSA TM (2013) Validation of an equation of estimating as VO2max of non-expert swimmers adults. Open Acess Journal of Sport Medicine,

4(1):19-25.

The following parts of the present thesis have been submitted for publication:

VERONESE DA COSTA A, COSTA MC, BARBOSA TM (2014). Applicability of an indirect VO2max test: it´s association with the 400 meters freestyle performance.

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LIST OF ABBREVIATIONS

(AHR) After Heart Rate

(AR) Analysis of Variance Regression (BHR) Before Heart Rate

(Bpm) beats per minute (BM) Body Mass

(CV) Coefficient of Variation

(CEP/UERN) Ethics Committee of the Rio Grande do Norte University, Brazil (CR-10) Borg's Category Ratio-scale

(DW) Durbin-Watson Test (ES) Effect Size

(HR) Heart Rate

(HRmax) Heart Rate maximum

(ICC) Intraclass Coefficient Correlation (km/h) kilometres per hour

(LC) Limit of agreement (m/s) meters per second (Mdif) Mean difference

(ml.kg-1.min-1) millilitres/kilograms/minute

(METs) resting energy expenditure equivalent to a 3.5 ml.min-1_.kg-1_{consumption of}

oxygen

(NLP) Number of Laps Performed

(PAR-Q) Questionnaire for Practice Physical Activity (PSwT) Progressive Swim Test

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XXVIII

(RPE) Rate of Perceived Exertion (R) Pearson’s Linear Correlation (R2) Coefficient of Determination

(R2a) Adjusted Coefficient of Determination (SEE) Standard Error of Estimate

(Sxy) Standard Error of Estimate

(SEM) Standard Error of Measurement (S) Standard Deviation

(SD) Standard Deviation (SL) Stroke Length

(T30) Continuous Test which measures the greatest distance swum in a given time

interval such as 30 minutes

(UM-TT) Université de Montréal Track Test (VO2) Oxygen Consumption

(VO2max) maximum oxygen consumption

(400MF) 400 Meters Freestyle (95% CI) 95% Confidence Interval

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GENERAL INTRODUCTION

GENERAL INTRODUCTION

ESTIMATION OF MAXIMUM OXYGEN CONSUMPTION

Reproducibility, validity and applicability of a test for non-expert adult swimmers

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GENERAL INTRODUCTION

Swimming is a physical activity or aquatic exercise practiced by non-expert participants for health purposes, although it presents itself in other contexts whether utilitarian, competitive, educational or recreational (1). Non-expert swimmers are persons who practice the sport regularly with the purpose of improving their physical conditioning. Thus, they are not included in the official competitive teams’ rosters of associations and federations (10). Unlike other aquatic programmes, the purpose of swimming is to improve the swim efficiency of its participants, improving their physical qualities, through involvement in this activity over a long period of time. As in any other physical conditioning programme performed on land, its efficacy depends on precision, conception, implementation and control. The monitoring of acute physiological responses of participants should be an obligation, in order to define realistic goals when prescribing exercises (2, 3). It is remarkable that studies conducted about non-expert swimmers are scarce when compared with expert couterparts (i.e. involved in competitive and high performance sports), as well as with participants involved in land-based fitness programmes. The same reasoning can be exercised to validate field test procedures in non-expert swimmers.

Most swimming research is done on high-performance subjects, relating their performance to biomechanics and energetics (4). For both swimmers (expert and non-expert), the cardiorespiratory is a key-factor, whether for health or performance-driven (5-8). Although there are cutting edge high-tech procedures to evaluate the cardiorespiratory responses of swimmers, these procedures are usually applied to high performance swimmers (expert), namely in research environments (6,7,9). These same procedures can be used on non-expert swimmers, as long as these participants are aware that the control of exercise and evaluation with testing procedures must be a daily practice. However, some limitations should be considered when it comes to their application in the field (for example, the logistics used to assemble the equipment is time consuming, the time spent on manpower training for the handling of the equipment, several dozens of participants being evaluated in a short period of time, etc.).

We observed that there are few studies focused on non-expert swimmers, on top of which, although it is a standard practice to use field test procedures on

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land-GENERAL INTRODUCTION

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based exercises to estimate previously validated cardiorespiratory responses, there is an absence of these same field tests for swimming, despite the fact that any test should be done within the reality of each sport, aiming for more accurate results (1,10).

The few works on this subject were conducted in a unsystematic way (10–13). Thus, as a reference for these thesis, we used the Université de Montréal Track Test (UM-TT), which is an indirect protocol that estimates the VO2max of

young and middle-aged men, as well as women (14). UM-TT is a multistage continuous running field test, determined by the recorder through progressive beeps, which tell us the moment in which a runner should be passing alongside each of the markings placed every 50 meters. The first stage is defined at a walking velocity of 5 METs (6 km/h) where the speed is increased by one MET every two minutes. The test ends when the runner is late to consecutive markings and can’t catch up, that is, when they hit their VO2max. The test has proven valid when they had their VO2max

predicted with UM-TT and measured directly with a treadmill multistage running test, presenting the statistical values r=0.96, S=0.09 ± 2.90ml of O2.kg-1.min-1 and Syx=2.81ml of O2.kg-1.min-1. The same occurred when evaluating its reproducibility,

for repeating the test twice in 60 individuals reaching the following values r=0.97, S=0.11 ± 1.92 of O2.kg-1.min-1 and Syx=1.92 of O2.kg-1.min-1. The test was also

considered applicable due to the fact that it was designed for runners within the reality of their performances and associated with the Cooper 12 minutes test, presenting a r=0,84.

In this sense, we intended to design an adaptation of the Université de Montréal Track Test for swimming (which we coined as “Progressive Swim Test”), to estimate the VO2max of non-expert adult swimmers.

The thesis was brokendown into the following chapters: • Chapter 1 presents the problem, aims and hypothesis;

• The purpose of Chapter 2 (study #1) was to verify the reproducibility of the Progressive Swim Test;

• The objective of Chapter 3 (Study #2) was to validate the Progressive Swim Test;

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• The objective of Chapter 4 (study #3) was to estimate the VO2max

through the Progressive Swim Test and determining its relation to the 400 meters freestyle;

• In Chapter 5 we present a general discussion which displays the connections between the three studies.

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CHAPTER 1 – PROBLEMS, AIMS AND HYPOTHESES

CHAPTER 1 PROBLEMS, AIMS AND HYPOTHESES

Reproducibility, validity and applicability of a test for non-expert adult swimmers

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CHAPTER 1 – PROBLEMS, AIMS AND HYPOTHESES

Based on the difference in the amount of research and the reasoning stated in the general introduction, the main scientific problem was:

Is it possible to design a precise, comprehensive and simple procedure to estimate the maximum oxygen consumption in non-expert adult swimmers?

Main aim:

• To develop and validate the precision of a field test to determine the maximum oxygen consumption in non-expert adult swimmers.

Specific aim:

• To verify the reproducibility of a field test to determine the maximum oxygen consumption in non-expert adult swimmers (study #1);

• To validate an equation to estimate the maximum oxygen consumption in non-expert adult swimmers (study #2);

• To evaluate the maximum oxygen consumption with the validation procedure and establish its connection to a swimming performance test (study #3)

The hypothesis of this thesis were as follows:

• H0 – There is no high reproducibility intra and inter evaluators in PSwT for non-expert adult swimmers (study #1);

• H1 – There is high reproducibility intra and inter evaluators in PSwT for non-expert adult swimmers (study #1);

• H0 – There is no validation between the direct VO2max and the

estimate equation of VO2max determined by PSwT for non-expert adult

swimmers (study #2);

• H1 – There is validation between the direct VO2max and the estimate

equation of VO2max determined by PSwT for non-expert adult

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• H0 – There is no connection between the VO2max estimated by the

PSwT and the performance of a swimming test (study #3);

• H1 – There is a connection between the VO2max estimated by the

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CHAPTER 2 - REPRODUCIBILITY OF AN AEROBIC ENDURANCE TEST FOR NON-EXPERT SWIMMERS

CHAPTER 2 REPRODUCIBILITY OF AN AEROBIC ENDURANCE

TEST FOR NON-EXPERT SWIMMERS

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CHAPTER 2 - REPRODUCIBILITY OF AN AEROBIC ENDURANCE TEST FOR NON-EXPERT SWIMMERS

CHAPTER 2 - REPRODUCIBILITY OF AN AEROBIC ENDURANCE

TEST FOR NON-EXPERT SWIMMERS

ABSTRACT

Background: this study aimed to verify the reproducibility of an aerobic test to determine the non-expert swimmers´ resistance.

Methods: The sample consisted of 24 male swimmers (age: 22.79 ± 3.90 years; weight: 74.72 ± 11.44 kg; height: 172.58 ± 4.99 cm; and fat percentage: 15.19% ± 3.21%), who swim for 1 hour three times a week. A new instrument was used in this study (a Progressive Swim Test): the swimmer wore an underwater MP3 player and increased their swimming speed on hearing a beep after every 25 meters. Each swimmer’s heart rate was recorded before the test (BHR) and again after the test (AHR). The rate of perceived exertion (RPE) and the number of laps performed (NLP) were also recorded. The sample size was estimated using G*Power software (v 3.0.10; Franz Faul, Kiel University, Kiel, Germany). The descriptive values were expressed as mean and standard deviation. After confirming the normality of the data using both the Shapiro–Wilk and Levene tests, a paired t-test was performed to compare the data. The Pearson’s linear correlation (r) and intraclass coefficient correlation (ICC) tests were used to determine relative reproducibility. The standard error of measurement (SEM) and the coefficient of variation (CV) were used to determine absolute reproducibility. The limits of agreement and the bias of the absolute and relative values between days were determined by Bland–Altman plots. All values had a significance level of P < 0.05.

Results: There were significant differences in AHR (P = 0.03) and NLP (P = 0.01) between the 2 days of testing. The obtained values were r > 0.50 and ICC > 0.66. The SEM had a variation of ±2% and the CV was <10%. Most cases were within the upper and lower limits of Bland–Altman plots, suggesting correlation of the results. The applicability of NLP showed greater robustness (r and ICC > 0.90; SEM < 1%; CV < 3%), indicating that the other variables can be used to predict incremental changes in the physiological condition of swimmers.

Conclusion: The Progressive Swim Test for non-expert swimmers produces comparable results for non-competitive swimmers with a favourable degree of

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reproducibility, thus presenting possible applications for researching the physiological performance of non-expert swimmers.

Keywords: Swimming, Physic Evaluation, Resistance Training, Health.

INTRODUCTION

The assessment of cardiorespiratory fitness has been very useful for diagnosing the health and fitness in a variety of populations (e.g., types of physical activity or age), assuming that a favourable heart condition is related to performance improvement and longevity (1,2). The evaluation of sports performance by researchers generally uses methodology designed for elite athletes. Our study was limited by the absence of new methodologies designed for the general public practicing the sport for a better lifestyle (3). This study outlines a new aerobic endurance test for non-expert adult swimmers who can perform swimming techniques, especially freestyle (front-crawl), and who are not affiliated with the national swimming organization nor are former participants in regional, national, and international championships (4).

Specific sports utilize laboratory tests under controlled temperature, relative air humidity, intensity of treadmill exercise, and cycle ergometers to determine the maximal and submaximal level of relative oxygen consumption (VO2). This controlled

environment is a test “field” that approaches the conditions of a real situation in a specific sport (5,6). In swimming, it is possible to identify specific tests for aerobic endurance that are valid for athletes (7–9).

Recent research relating to competitive swimming has produced data on the performance, energetics, and biomechanics of athletes that can be used to answer questions about the effects of exercise intensity (10,11). However, these variables need to be assessed in the fitness levels of non-expert swimmers (3,12), as the biomechanics of the physical patterns become more efficient through regular exercise and practice, less energy is spent on the activity and the swimmers become healthier (2,4,13,14).

Aerobic swimming tests were traditionally designed to control the intensity of exercise, using either the time or distance to be executed by the swimmer (15,16). Thus, there are testing intervals (those in which the intensity of the exercise is

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performed at a moderate or strong pace, with rest breaks between one repetition and another as in the two Mader test speeds) (8) and continuous tests (which measure the greatest distance swum in a given time interval such as 30 minutes [T30]) (17).

However, it is believed that the most suitable type of test when working with non-expert swimmers is a progressive test, or one in which every lap swum with the front-crawl technique increases in swimming intensity in relation to the execution time (18). Studies aimed at demonstrating this progressive method are best measured within a competitive environment (18–20), which facilitates the execution of a water test by non-expert swimmers without concern for mistakes regarding the pace of a specific swimmer – a factor that might limit continuous tests and intervals for all these swimmers. Thus, this study questioned the reliability of a new progressive test, on the basis that evaluating its effectiveness will enable further research to be conducted to validate the test by direct methods (21).

In view of the fact that some water tests are outside commercial reality in many swimming schools, this study resorted to new alternative methods that evaluate swimmers through indirect tests. An adaptation of the water progressive running test as proposed by Léger and Boucher (22), allowed this study to conduct a low-cost, easily applicable aerobic test to evaluate the exertion of non-expert swimmers. It was possible to assess the ability of the swimmers through the largest number of laps swum. Therefore, this study aimed to verify the reproducibility of a test for aerobic endurance by non-expert swimmers. The hypothesis is that the results are highly replicable.

MATERIALS AND METHODS

SUBJECTS

This comparative descriptive study comprised 24 non-expert male swimmers in the town of Mossoró, Rio Grande do Norte, northeast of Brazil, aged from 18 to 30 years (age: 22.79 ± 3 90 years, weight: 74.72 ± 11.44 kg, height: 172.58 ± 4.99 cm, body fat percentage: 15.19 ± 3.21%). Swimmers with good technique who used the front-crawl swimming style attended lessons at least three times a week and swam for at least 1 hour per session over a distance of approximately 800 meters. Those included in the criteria did not take any food supplements or conduct any type of

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physical activity 24 hours before the tests. The exclusion criteria for the study included swimming athletes affiliated to the Brazilian Confederation of Aquatic Sports, athletes who had been affiliated to this federation 3 years before the survey, or non-expert swimmers or participants who indicated any type of debilitating illness (e.g., flu, fever, or any type of injury). The health care professionals who evaluated the tests were two swimming teachers with an academic background in physical education who had a minimum of 3 years of professional experience, together with a less-experienced assistant teacher. Not unlike many swimming schools around the world, the schools that agreed to participate in the survey had a higher number of adults in learning phase for this research program, unlike those who met the inclusion criteria of this study. Thus, this study did not prevent quantitative reproduction of a new test for this category of swimmers, which can be observed in other studies (15,23–25).

NEW TEST FOR AEROBIC ENDURANCE WITH NON-EXPERT SWIMMERS IN THE POOL TO REPRODUCIBILITY

The Progressive Swim Test corresponds to a series of 400 meters in a 25-meter pool, based on the world record for men (03´32″57; www.fina.org/H2O/) at this distance in a short-course pool. The world-record time was registered by the International Federation of Amateur Swimming in Berlin, Germany in 2009. A beeping sound indicates the swimming rhythm, occurring at a decrease in partial time of 1 second for each performed lap, with a beep given at the end of the first lap at the time of 28″30 (i.e., a rate of 0.88 m/s) and for the 16th at 13″30; (i.e., a rate of 1.88 m/s) (Table 1):

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Table 1 - Laps performed during the Progressive Swim Test for non-expert swimmers

Lap Time m/s km/h Lap Time m/s km/h

1 28”30 0.88 3.18 9 20”30 1.23 4.43 2 27”30 0.92 3.30 10 19”30 1.30 4.66 3 26”30 0.95 3.42 11 18”30 1.37 4.92 4 25”30 0.99 3.56 12 17”30 1.45 5.20 5 24”30 1.03 3.70 13 16”30 1.53 5.52 6 23”30 1.07 3.86 14 15”30 1.63 5.88 7 22”30 1.12 4.04 15 14”30 1.75 6.29 8 21”30 1.17 4.23 16 13”30 1.88 6.77

Note: This table will serve to monitor the swimmers by the evaluators during the execution of the Progressive Swim Test

Abbreviation: m/s – meters per second; km/h – kilometres per hour

The start of each progressively more intense lap was indicated by MP3-format sound signals, using the subaquatic device SwiMP3 v2 (Finis Inc., Livermore, CA) attached to the silicon strip of the swimmer’s goggles. The direct transfer of sound vibrations from the swimmer’s jaw bone to their ear provided exceptional sound clarity. The sounds were also played through a microsystem outside the pool, synchronized with the subaquatic MP3, as an aid to the evaluators monitoring the tests. The beeps increased in frequency for each 25 meters swum, causing an increase in speed during a repetition of 400 meters using the front-crawl swimming technique.

One week before testing, the evaluators familiarized the swimmers with the procedures that would be implemented by providing an illustrative video on how the test would be conducted. After week 1, the tests were initiated. Each swimmer, before starting the test, performed between 50 and 100 meters with the equipment, as a warm-up exercise.

The swimmer remained in the pool until the synchronization of the MP3 and the microsystem was made by the main evaluator. Following an announcement (“Attention swimmer, prepare for the test”), a short beep sounded, accompanied by a visual signal from the hands of the evaluator to mark the beginning of the test. To facilitate the identification of the correct rhythm for every lap swum, a longer beep of

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a different type was heard by the swimmer to indicate that he should be near the middle of the pool. After completing each lap, another short beep was given to indicate the start of the next lap. The swimmer was instructed to try to keep to the rhythm sounded by the MP3 v2 so as to always be within the beginning/ending 5-meter zone when the short beep was heard.

As identifiers for both the swimmers and the evaluators, cones were placed along the edge of the testing lane, and 4 kg rings inside the pool, to mark the initial and final 5 meters and 12.5 meters (half-distance) (Figure 1). During the test, while the main evaluator counted the number of laps (Table 1), the evaluator’s assistant monitored the swimmer, giving verbal and visual signals of the progressive test pace.

Figure 1 - Schematic visual of Progressive Swim Test to non-expert swimmers

The test ended when the swimmer didn’t reach the 5-meter zone preceding the edge of the pool two laps in a row. At this point, the main evaluator immediately measured the heart rate of the swimmer, while the assistant evaluator presented a rate of perceived exertion (RPE). Then, the two evaluators registered the number of laps performed by the swimmer. If any swimmer, for any reason, were to stop during the test, their test would be aborted and not counted in the results.

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VARIABLES FOR ANALYSIS

For result analysis, it was decided to measure the resting heart rate 30 minutes before the start of the test (before heart rate [BHR]) and after the end of the test (after heart rate [AHR]) with a heart rate monitor (Polar Model FT1; Polar Electro Oy, Kempele, Finland) (26,27). These measurements were taken inside the pool at the swimmer’s chest level. At the end of the test, a Borg’s RPE score (scale from 1 to 10) was presented to the swimmer, but the number of laps performed (NLP) was registered by the evaluators. The swimmers were evaluated on different days, in the same order, on their same respective day each week and at their same respective time, with a main and assistant evaluator present at each test. Before each test the water temperature was measured in order to identify any difference in swimmers’ environmental conditions (Bestway® Floating Pool Thermometer, accurate to 1°C; Bestway Inflatables North America Inc., Mississauga, ON, Canada); the temperature in the two days of testing was 28°C.

ETHICAL ASPECTS

All the procedures adhered to the guidelines of the Declaration of Helsinki (www.wma.net/e/policy/b3.htm). This study was approved by the Ethics Committee of the Rio Grande do Norte University, Brazil – CEP/UERN, protocol 070/2011. All participants, including swimmers, teachers, evaluators, and assistants, signed an Informed Consent.

STATISTICAL ANALYSIS

The sample size was estimated by the software G*Power 3.0.10 (Franz Faul, University of Kiel, Kiel, Germany), considering the effect size 0.75, the minimum power 0.80, and α = 0.05, resulting in 13 swimmers (28). However, it was possible to evaluate 24 swimmers. Atkinson and Nevill (21), believed that statistical methods are necessary in order to quantify the results substantially. From this perspective, the descriptive values were expressed as mean and standard deviation. After testing the normality of the data through the Shapiro–Wilk and Levene tests, a paired t-test was performed for comparison between the days. To analyse the reliability, the r-test was used (Pearson’s linear correlation), classified according to da Silva et al (29), as very

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low (<0.20), low (0.20–0.39), moderate (0.40–0.59), high (0.60–0.79), and very high (0.80–1). In analysing the consistency among the variables, intraclass correlation coefficient (ICC) was used, as categorized by Santos et al (30) and Sánchez and Echeverry (31): not acceptable (<0.70), acceptable (0.70–0.79), good agreement (0.80–0.89), and excellent agreement (>0.90). The coefficient of variation (CV) was used to ascertain absolute reproducibility as:

CV = Standard Deviation / mean x 100 (1)

First the equation was applied in each subject between the days of testing to calculate the general CV average. Limits of agreement and bias of the absolute and relative values between the days were evaluated with Bland–Altman analysis:

LC = (1.96 x SD) ± Mdif, and LC = Limit of agreement (95%), SD = standard

deviation and mean difference = Mdif. (2)

All statistics were considered significant at P < 0.05. Data were analysed using the statistical packages SPSS for Windows (v 20; IBM Corporation, Armonk, NY) and MedCalc for Windows (v 12.3.0; MedCalc Software bvba, Mariakerke, Belgium).

RESULTS!

Table 2 shows the descriptive values of the BHR, AHR, RPE, and NLP variables between the days.

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Table 2 - Descriptive values of variables applied to non-expert swimmers

Variables Days Mean Standard Deviation

BHR (bpm) 1 80.09 7.32 2 79.26 6.45 AHR (bpm) 1 173.82 9.79 2 178.44 6.77 RPE 1 8.40 0.78 2 8.25 0.72 NLP 1 6.86 1.36 2 7.50 1.79

Abbreviation: BHR - Before Heart Rate; AHR - After Heart Rate; RPE - Rate of Perceived Exertion; NLP - Number of Laps Performed; bpm - beats per minute.

Table 3 shows the mean and standard deviation of the differences between test days, the standard errors of measurement, and the significant differences found between the AHR and NLP.

Table 3 - Paired differences between days of the variables applied to non-expert swimmers

Variables Mean SD SEM CI95% t-test p value

Lower Upper

BHF 2.56 6.31 1.49 -0.58 5.69 1.72 0.10

AHF -4.50 7.64 1.91 -8.57 -0.43 -2.36 0.03*

RPE 0.05 0.78 0.18 -0.32 0.43 0.29 0.77

NLP -0.48 0.68 0.15 -0.77 -0.17 -3.21 <0.01*

Note: * Significant Difference (p≤0,05)

Abbreviation: SD - Standard Deviation; SEM – Standard Error Measurement; CI95% – Confidence Interval; BHR - Before (test) Heart Rate; AHR - After (test) Heart Rate; RPE - Rate of Perceived Exertion; NLP - Number of Laps Performed; bpm - beats per minute.

Table 4 shows the reproducibility on the Pearson’s linear correlation values of r>0.50, the consistency between variables at ICC>0.66, and an absolute CV<6%.

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Table 4 - Values within and between classes of variables applied to non-expert swimmers

Variables r p CCI (CI95%) p CV

BHF (bpm) 0.55 0.02* 0.706 (0.214 / 0.890) <0.01* 5.06% AHF (bpm) 0.51 0.04* 0.674 (0.067 / 0.886) 0.02* 3.07% RPE 0.50 0.03* 0.665 (0.129 / 0.871) 0.01* 5.14% NLP 0.92 <0.01* 0.948 (0.872 / 0.979) <0.01* 2.35%

Note: * Significant difference (p ≤ 0.05)

Abbreviation: r - Pearson linear correlation; ICC - Intraclass Coefficient Correlation (CI95% - Confidence Interval); BHR – Before (test) Heart Rate; AHR – After (test) Heart Rate; RPE - Rate of Perceived Exertion; NLP - Number of Laps Performed; bpm - beats per minute.

Figure 2 shows the absolute values of bias and limits of agreement (LC 95%) for BHR, AHR, RPE, and NLP between the days.

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Figure 2 - Representation of the differences between paired measurements of before heart rate (BHR), after heart rate (AHR), Rate of Perceived Exertion (RPE) and Number of Laps Performed (NLP) against their mean values.

DISCUSSION

This study aimed to verify the reproducibility of an aerobic test for non-expert swimmers and presented favourable conditions for the implementation of the Progressive Swim Test to assess the fitness level by increasing the load beep frequency with the number of laps performed. The results shown for BHR, AHR, RPE, and NLP by r, ICC, SEM, and CV demonstrated that this new test was stable across the inter-day and inter-rate variations found. According to Barbosa et al (23), the consistency of a test becomes greater as training adaptation occurs. As the

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Progressive Swim Test was directed at non-expert swimmers, the stability was analysed with caution due to the few studies testing non-expert swimmers (3,12) so as not to overstate their results given the amount of research conducted with expert swimmers (4,6,8,15,16).

By comparing the results between the days and different evaluators, a decrease in BHR and RPE (P > 0.05) and an increase in AHR and NPP (P < 0.05) were observed, which showed improvements in the physical conditioning that did not interfere with the variable results. The use of heart rate and RPE parameters gave the possibility of controlling the intensity of aerobic exercises both in research tests and in training (32,33). The results obtained in this study of non-expert swimmers were similar to those observed in water running tests in deep-water pools (25,34). The calculation of maximum heart rate, estimated by Karvonen (i.e., 220 – age) (35), may also be useful in predicting if the swimmer, at the end of the Progressive Swim Test, was within the zone of maximum effort training; AHR in the first and second day was 88% and 89% maximum, respectively, showing that such a test required a performance of intense form by the swimmer seeking to keep up with the speed controlled by progressively more frequent beeps in each lap.

Relative reproducibility was considered to be moderate for the BHR, AHR, and RPE (r > 0.50, P < 0.04), and very high for the NLP (r > 0.90, P < 0.01). The consistency of the results of AHR and RPE were considered not acceptable (ICC < 0.70, P < 0.02), BHR acceptable (ICC > 0.70, P < 0.01), and NLP excellent (ICC > 0.90, P < 0.01). The absolute reproducibility in all variables was regarded as acceptable (CV < 6%), being less than 10% (21) and the SEM, (95% CI) showed ±2% actual change in the values of variables (23). The absolute values of the mean difference and limits of agreement (95% CI) were shown graphically in Bland–Altman plots, confirming that there were no heteroscedastic errors. However, one swimmer in the RPE and two in the NLP data were outside the limits of acceptance; in other words, the RPE confirmed a low reproducibility and the NLP reliability was not lost, since the values of Pearson’s r and ICC were presented as excellent. The variables in this study require attention for the use of the Progressive Swim Test, because of the low relative reproducibility values. This attention does not apply to NLP, which showed robustness of the results for its applicability.

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The variability of these results can be found in swimming studies that deal with reproducibility. Barbosa et al (23), in a strength test through tied swimming, found high scores on the values of Pearson’s r and ICC and low scores for most of the results of SEM and CV. The same was observed by Albert et al (15), in the execution of three types of swimming tests, and by Martin and Thompson (24), in the reproducibility of diurnal variation in submaximal swimming. It is likely that the results of these studies have shown significant values because the tests were conducted with athletes and were moderated by the same appraiser (15,23,24). However, Barbosa et al (3) and Zamparo (12) confirmed that NLP for non-expert swimmers are lower than for elite swimmers and that high anthropometric and biomechanical factors are highly associated with performance.

In this way, NLP was a predictor of physical conditioning of the non-expert swimmers due to the distances of a predetermined time, since studies with continuous testing, intervals testing, and progressive testing use time and distance as criteria of exercise intensity (8,15–18). This new test may also be applied to swimming lessons, due to the progressive requirements of each lap, and the variables of HR and RPE may be useful in the prediction of the physiological conditions of non-expert swimmers.

There were a number of limitations to the reproducibility of this study: (i) the evaluation of response rate and/or psychophysiological factors only: in the future, selection of other physiological variables (e.g., VO2, energy cost, lactate) might give

a more detailed answer; (ii) it was unable to evaluate the biomechanical responses of the non-expert swimmers; and (iii) the study included only non-expert swimmers, who were not compared with elite swimmers.

In conclusion, the Progressive Swim Test for non-expert swimmers suggests a favourable level of reproducibility, with possible application in the indirect assessment of aerobic fitness for the prescription of non-competitive swimming for fitness.

DISCLAIMER!

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!

26 REFERENCES

1. Agarwal SK. Cardiovascular benefits of exercise. Int J Gen Med. 2012;5:541– 5.

2. Balsamo S, Tibana RA, Nascimento DDC, De Farias GL, Petruccelli Z, De Santana FDS, et al. Exercise order affects the total training volume and the ratings of perceived exertion in response to a super-set resistance training session. Int J Gen Med. 2012;5:123–7.

3. Barbosa TM, Lima V, Mejias E, Costa MJ, Marinho DA, Garrido N, et al. Propulsive efficiency and non- expert swimmers performance. Motricidade. scielopt; 2009;5:27–43.

4. Barbosa TM, Fernandes RJ, Keskinen KL, Vilas-Boas JP. The influence of stroke mechanics into energy cost of elite swimmers. Eur J Appl Physiol. 2008;103(2):139–49.

5. Schnitzler C, Heck G, Chatard J-C, Ernwein V. A simple field test to assess endurance in inexperienced runners. J Strength Cond Res. 2010;24(8):2026– 31.

6. Wakayoshi K, Yoshida T, Udo M, Kasai T, Moritani T, Mutoh Y, et al. A simple method for determining critical speed as swimming fatigue threshold in competitive swimming. Int J Sports Med. 1992;13(5):367–71.

7. Gayda M, Bosquet L, Juneau M, Guiraud T, Lambert J, Nigam A. Comparison of gas exchange data using the Aquatrainer® system and the facemask with Cosmed K4b2 during exercise in healthy subjects. Eur J Appl Physiol. Springer; 2010;109(2):191–9.

8. Olbrecht J, Madsen O, Mader A, Liesen H, Hollmann W. Relationship between swimming velocity and lactic concentration during continuous and intermittent training exercises. Int J Sports Med. 1985;6(2):74–7.

9. Toussaint HM, Meulemans A, De Groot G, Hollander AP, Schreurs AW, Vervoorn K. Respiratory valve for oxygen uptake measurements during swimming. Eur J Appl Physiol Occup Physiol. 1987;56(3):363–6.

(55)

10. Reis JF, Alves FB, Bruno PM, Vleck V, Millet GP. Effects of aerobic fitness on oxygen uptake kinetics in heavy intensity swimming. Eur J Appl Physiol. 2012;59(4):1104–9.

11. Barbosa TM, Bragada J a, Reis VM, Marinho D a, Carvalho C, Silva AJ. Energetics and biomechanics as determining factors of swimming performance: updating the state of the art. J Sci Med Sport. 2010 Mar;13(2):262–9.

12. Zamparo P. Effects of age and gender on the propelling efficiency of the arm stroke. Eur J Appl Physiol. 2006;97(1):52–8.

13. Honda T., Kamioka H. Curative and health enhancement effects of aquatic exercise: evidence based on interventional studies. Open Access J Sport Med. 2012;3(1):27–34.

14. Resnick B, Galik E, Gruber-Baldini AL, Zimmerman S. Perceptions and Performance of Function and Physical Activity in Assisted Living Communities. J Am Med Dir Assoc. 2010;11(6):406–14.

15. Alberty M, Sidney M, Huot-Marchand F, Dekerle J, Bosquet L, Gorce P, et al. Reproducibility of performance in three types of training test in swimming. Int J Sports Med. Stuttgart, New York, Thieme.; 2006;27(8):623–8.

16. Zacca R, Wenzel BM, Piccin JS, Marcilio NR, Lopes AL, de Souza Castro FA. Critical velocity, anaerobic distance capacity, maximal instantaneous velocity and aerobic inertia in sprint and endurance young swimmers. Eur J Appl Physiol. Springer; 2011;110(1):121–31.

17. Deminice R, Papoti M, Zagatto AM, Prado MV do. Validity of 30 minutes test (T-30) in aerobic capacity, stroke parameters and aerobic performance determination of trained swimmers. Rev Bras Med do Esporte. scielo; 2007;13:195–9.

18. Figueiredo P, Zamparo P, Sousa A, Vilas-Boas JP, Fernandes RJ. An energy balance of the 200 m front crawl race. Eur J Appl Physiol. 2011;111(5):767– 77.

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!

28

19. Zamparo P, Lazzer S, Antoniazzi C, Cedolin S, Avon R, Lesa C. The interplay between propelling efficiency, hydrodynamic position and energy cost of front crawl in 8 to 19-year-old swimmers. Eur J Appl Physiol. Springer; 2008;104(4):689–99.

20. Zamparo P. Energy cost of swimming of elite long-distance swimmers. Eur J Appl Physiol. 2005;97(1):697–704.

21. Atkinson G, Nevill AM. Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine. Sport Med. Adis International; 1998;26(4):217–38.

22. Léger L, Boucher R. An indirect continuous running multistage field test: the Université de Montréal track test. Can J Appl Sport Sci J Can Des Sci Appl Au Sport. Can J Appl Sports Sci, (5), 77-84; 1980;5(2):77–84.

23. Barbosa AC, Andrade RM, Moreira A, Serrão JC, Andries Junior O. Reliability of front-Crawl’s force-time curve in a short duration protocol. Rev Bras Educ Física e Esporte. scielo; 2012;26:37–45.

24. Martin L, Thompson K. Reproducibility of diurnal variation in sub-maximal swimming. Int J Sports Med. 2000;21(6):387–92.

25. Silva IRS, Oliveira LS, Berenguer MF, Sousa AVF, Nascimento JA, Costa MC. Reproducibility of an effort protocol during deep-water running. Motricidade. 2010;6(4):47–54.

26. Spence AL, Naylor LH, Carter HH, Buck CL, Dembo L, Murray CP, et al. A prospective randomised longitudinal MRI study of left ventricular adaptation to endurance and resistance exercise training in humans. J Physiol. Blackwell Publishing Ltd; 2011;589(22):5443–52.

27. Laukkanen RMT, Virtanen PK. Heart rate monitors: State of the art. J Sports Sci. Routledge; 1998;16(4):3–7.

28. Faul F, Erdfelder E, Lang A-G, Buchner A. G*Power 3: a flexible statistical power analysis program for the social, behavioral, and biomedical sciences. Behav Res Methods. Psychonomic Society Publications; 2007;39(2):175–91.

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29. Silva CD da, Natali AJ, Lima JRP de, Bara Filho MG, Garcia ES, Marins JCB. Yo-Yo IR2 test and margaria test: validity, reliability and maximum heart rate in young soccer players. Rev Bras Med do Esporte. scielo; 2011;17:344–9. 30. Santos MM, Silva MPC, Sanada LS, Alves CRJ. Photogrammetric postural

analysis on healthy seven to ten-year-old children: interrater reliabilit. Brazilian J Phys Ther. scielo; 2009;13:350–5.

31. Sánchez R, Echeverry J. Validating scales used for measuring factors in medicine. Rev Salud Pública. scieloco; 2004;6:302–18.

32. Graef, Fabiane Inês; Kruel LFM. Heart rate and perceived exertion at aquatic environment: differences in relation to land environment and applications for exercise prescription - a review. Rev Bras Med do Esporte. scielo; 2006;12(4):221–8.

33. Perez AJ, Dias KD, Carletti L. Aerobic exercise intensity can be controlled by palpation of the radial artery. Brazilian J Kinanthropometry Hum Perform. scielo; 2010;12(3):186–94.

34. Rodriguez D, Silva V, Prestes J, Rica RL, Serra AJ, Bocalini DS, et al. Hypotensive response after water-walking and land-walking exercise sessions in healthy trained and untrained women. Int J Gen Med. Dove Medical Press; 2011;4:549–54.

35. Karvonen, M. J., Kentala, E., & Mustala O. The effects of training on heart rate. A longitudinal study. Ann Ned Exp Biol Fenn. 1957;35(3):307–15.

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CHAPTER 3 - VALIDATION OF AN EQUATION TO ESTIMATIE VO2MAX ON NON-EXPERT ADULT SWIMMERS

CHAPTER 3 VALIDATION OF AN EQUATION TO ESTIMATIE VO2MAX ON

NON-EXPERT ADULT SWIMMERS

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CHAPTER 3 - VALIDATION OF AN EQUATION TO ESTIMATIE VO2MAX ON NON-EXPERT ADULT SWIMMERS

CHAPTER 3 - VALIDATION OF AN EQUATION TO ESTIMATIE

VO2MAX ON NON-EXPERT ADULT SWIMMERS

ABSTRACT

Background: To validate an equation to estimate the maximal oxygen consumption (VO2max) of non-expert adult swimmers.

Methods: Participants were 22 non-expert swimmers, male, aged between 18 and 30 years (age: 23.1 ± 3.59 years; body mass: 73.6 ± 7.39 kg; height 176.6 ± 5.53 cm; and body fat percentage: 15.9% ± 4.39%), divided into two subgroups: G1 – eleven swimmers for the VO2max oximetry and modelling of the equation; and G2 – eleven

swimmers for application of the equation modelled on G1 and verification of their validation. The test used was the adapted Progressive Swim Test, in which there occurs an increase in the intensity of the swim every two laps. For normality and homogeneity of data, Shapiro-Wilk and Levene tests were used, the descriptive values of the average and standard deviation. The statistical steps were: (1) reliability of the Progressive Swim Test – through the paired t-test, intraclass correlation coefficient (ICC), and the Pearson linear correlation (R) relative to the reproducibility, the coefficient of variation (CV), and standard error measurement (SEM) for the absolute reproducibility; (2) in the model equation to estimate VO2max, a relative VO2

was established, and a stepwise multiple regression model was performed with G1 – so the variables used were analysis of variance regression (AR), coefficient of determination (R2), adjusted coefficient of determination (R2a), standard error of estimate (SEE), and Durbin–Watson (DW); (3) validation of the equation – the results were presented in graphs, where direct (G1) and estimated (G2) VO2max were

compared using independent t-test, linear regression (stressing the correlation between groups), and Bland–Altman (the bias agreement of the results). All considered a statistical significance level of P < 0.05.

Results: On the trustworthiness of the Progressive Swim Test adapted presented as high as observed (R and ICC > 0.80, CV < 10%, and SEM < 2%). In the equation model, VO2max has been considered the third model as recommended due to the

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2.06). Upon validation of the equation, no significant differences occurred between G1 and G2 (P > 0.01), linear regression stressed a correlation between the groups (R > 0.80, P < 0.01), and Bland–Altman Plot of the results was within the correlation limits of 1.96 (95% confidence interval).

Conclusions: The estimating equation for VO2max for non-expert swimmers is valid

for its application through the Progressive Swim Test, providing to contribute in prescribing the swimming lessons as a method of evaluating the physical condition of its practitioners.

Keywords: Swimming, VO2max, Regression Equation, Health.

INTRODUCTION

The evaluation of the Maximum Oxygen Consumption (VO2max) has been

used as a parameter to determine the intensity of physical activity during the aerobic exercises (1,2). In swimming, the direct test that presents the conditions to analyse the VO2max is the aquatic ergospirometry (3), which enables quantification of the

respiratory capacity due to the swimmer’s ability to maintain a maximum rate of muscle work during swimming (4,5). Therefore, some direct methods have been used to assess the distance travelled during swimming; Castro et al (3) highlights the swim flume, tethered swimming, back extrapolation from recovery, and with collection during swimming, as the methods most frequently used to evaluate the VO2max.

With this technology, assessments have been performed at the pool approximating them to the sport reality, as the conditions of real life can substantially influence the answers of the cardio respiratory exercise, becoming the direct methods of assessment in the aquatic environment ideals for a better accuracy in swimming (6– 8).

The assessments performed by direct measurement of oxygen consumption present disadvantages and advantages to be considered. The disadvantages are at a high financial cost due to the sophistication of the equipment and some limitations in the biomechanical aspect (i.e., absence of side breathing and the, impossibility of running the Olympic turn, for front crawl, as well as the drag of the equipment used where the swimmer performs the swim with a valve which captures the air through the system breath-by-breath). Its advantages are the possibility of the direct analysis

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to validate new assessment tools in the aquatic environment through the respiratory exchange required in the tests (9). With this perspective, several measures have been taken to verify the effectiveness of new equipment for oximetry (10–12), analysis of energy expenditure in competitive swimming (1), comparing the performance of elite swimmers with non-expert swimmers (8) and to validate the prediction equations. The prediction equations resulting from the direct test results have contributed as a valuation method of low cost and applicability. With swimming, it is possible to identify these equations from the anthropometric viewpoint (13), estimating the propulsive force of swimming (14), at the critical speed (15), as well as validating tests to determine the aerobic capacity (16). Therefore, the determination of an equation is linked to the type of test to be performed. In this case, the tests that are fit to be applied in non-expert swimmers are those that enable the intensity of swimming to be controlled. It is believed that the progressive tests would be ideal for assessing the VO2max due to controlling the rate of stroke without intervals, which

would gradually increase the intensity and duration through sounds and signals, mainly because these swimmers do not have the expertise to properly control their rhythm during swimming, as do elite swimmers (17,18).

It is also worth mentioning that the execution time of swimming at a speed that matches the maximum oxygen uptake for non-expert swimmers is between 310 and 325 seconds (19,20), which requires attention to the duration of test execution for these swimmers.

When dealing with the studies which involve non-expert swimmers, verified results focus on propulsive efficiency of swimming and the changes that occur at different levels of performance for certain distances, as it is common to consider that when a particular subject is experiencing changes in mechanical efficiency this factor is being related to the efficiency of motion due to the process of physical training and thus enables swimming a progressively greater distance (21,22). In this regard, the intensity of the activities proposed in swimming lessons needs further discussion, especially when it comes to people who practice regular non-competitive physical activity, since the number of studies that evaluate the performance in elite swimming athletes is greater than those for non-expert swimmers, and it seems that there is no equation for determining the level of VO2max for swimmers of this level (17,21,22).

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Therefore, this study aimed to validate an equation for estimating the VO2max

of non-expert adult swimmers. The hypothesis is that there is a high correlation between the direct VO2max and the equation for estimating VO2max.

METHODOLOGY

SUBJECTS

The study included 22 non-expert male swimmers, aged between 18 and 30 years (age: 23.1 ± 3.59 years; body mass: 73.6 ± 7.39 kg; height 176.6 ± 5.53 cm; and body fat percentage: 15.9% ± 4.39%). These swimmers were divided into two subgroups: G1, in which eleven swimmers were evaluated through direct VO2max for

modelling the equation; and G2, in which eleven swimmers were used for application of the equation modelled on G1, aiming to verify its validation.

The following inclusion criteria were defined: swimmers with accurate technique for front crawl; they practice swimming lessons three times a week with a duration of 1 hour per session, swimming about 800 meters; they have not taken any kind of dietary supplementation; and have not done any physical activity 24 hours before the test. The following exclusion criteria were applied: elite swimmers affiliated with the national federation for swimming or athletes who had been affiliated 3 years before the survey; non-expert swimmers who had responded negatively to one of the questions in the Readiness Questionnaire for Practice Physical Activity (23), had executed the test in under 4 minutes (19,20,24); or visibly presented any kind of illness that would limit the study (e.g., flu, fever, or any type of injury).

Regarding the experimental design in dealing with quantitative non-expert swimmers, despite swimming schools that agreed to participate in the survey presented a number of people who were in the learning phase of the swimming strokes or of non-expert swimmers who were outside the required age, the quantitative subject to the completion of this study has become feasible in accordance with other studies in the area(8,25–27).

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DATA COLLECTION

The test used for the validation of the equation for estimating VO2max was the

Progressive Swim Test proposed by Veronese da Costa et al (17). This protocol corresponds to a progressive series of front crawl in a 25 m pool and includes the use of a recording of beeps that enable the swimmer to keep the correct swimming rhythm; there is a decrease of the partial times of 1 second for each lap completed (number of laps performed [NLP]). The test ends when the swimmer twice followed fails to be within 5 meters that precede the edge of the pool. Studies have shown that VO2max in a swimming test is obtained above the 4 minutes to meet the criteria for

verification of VO2max (an increase of 45 ml.kg-1.min-1; rate of perceived exertion of

seven, classified as “very hard;” 90% maximum heart rate) (28,29). The protocol of Veronese da Costa et al was adapted to extend the time of exercise and verification of all the criteria for reaching VO2max (17,19,24,29). Accordingly, the adaptation has

doubled the maximum distance from 400 to 800 m, with the goal of increasing the intensity of the test with the reduction of 1 second for every two laps completed. In the first two laps of 25 m, the swimmer executed the test with the proposed time of 28″30 (0.88 m/s or 18.3 km/h) and a total time until the second round of 56″36; the next two laps were performed with a time of 27″30 (0.92 m/s or 30.3 km/h) and a total time up to the fourth round of 01′51″00, and so on. It was observed that the minimum time was about four minutes between the ninth and the tenth lap (time 24″30, 1.3 m/s or 3.70 km/h), confirming the criteria used in this study. Heart rate was checked before the test to identify the swimmer’s resting conditions, so it was used as criteria to start the test (heart rate below 90 bpm), and after the test (AHR) to verify that the maximum heart rate reached. During the test, the swimmer used an underwater MP3 device which was attached to the silicon strip of the swimmer’s goggles (SwiMP3 V2, Finis Inc., Livermore, CA), and the evaluators had a microsystem of 50–60 Hz (18 W). Thus, both the swimmer and the evaluators followed the beeps during the test. The oxygen consumption, as well as other respiratory and metabolic variables, was assessed by a metabolic card (K4b2, Cosmed®, Rome, Italy) being connected to a snorkel (Aquatrainer®, Cosmed®, Rome, Italy) fixed in the mouth of the swimmer (7,25–27). To control the cardiovascular response, a heart rate monitor (Polar FT1 Model, Polar Electro Oy, Kempele, Finland) was used. To analyse the perceived exertion, Borg’s category-ratio scale was used at the end of the protocol (28,30).