170 Journal of Exercise Physiology onli ne October 2018 Volume 21 Number 5 EditorOfficial- in Research- Chief Journal of JEP online Tommythe American Boone , PhD Society, MBA of ReviewExercise Board Physiologists Cardiorespiratory F itness of V isually I mpaired Todd Astorino, PhD Julien Baker,ISSN 1097 PhD - 9751 F ootballers through D irect and Indirect Methods: Steve Brock, PhD A Pilot Study Lance Dalleck, PhD Eric Goulet, PhD 1 , 2 3 Robert Gotshall, PhD Pablo R. O. Silva Míriam Mainenti , Lilian Felicio , Arthur Alexander Hutchison, PhD Ferreira 1 , Agnaldo Lopes 1 , Marcus Bernhoeft 4 , *Patrícia S. M. Knight - Maloney, PhD Vig ário 1 Len Kravitz, PhD James Laskin, PhD 1 Yit Aun Lim, PhD Postgraduate Program in Rehabilitation Sciences, Centro Lonnie Lowery, PhD Universitário Augusto Motta (UNISUAM), Rio de Janeiro, RJ, Derek Marks, PhD Brazil , 2 Physical Education Colleg e of the Brazilian Army , Rio Cristine Mermier, PhD de Janeiro, RJ, Brazil , 3 Faculty of Physical Education and Robert Robergs, PhD Physiothera py, Federal University of Uberlândia, Minas Chantal Vella, PhD 4 Dale Wagner, PhD Gerais, MG, Brazil , Institute of Pediatrics and Childcare Frank Wyatt, PhD Martagão Gesteira; Federal University of Rio de Jane iro, Rio Ben Zhou, PhD de Janeiro, RJ, Brazil ABSTRACT Official Research Journal Silva PRO, Mai nenti, M, Feli cio L, Ferreira A , Lopes A, of the American Society of B ernhoeft M, Vigário PS. Cardiorespiratory F itness of Exerc ise Physiologists V isually I mpaired F ootballers through D irect and I ndirect M ethods: A P ilot S tudy. JEP online 20 1 8 ; 21 ( 5 ): 170 - 183 . The ISSN 1097 - 9751 purpose of this study was to compare the cardiorespiratory fitness of visually impaired (VI) footballers with non - blind footballers and to examine the validity of the 20 - m shuttle run test in estimating cardiorespiratory fitness in VI footballers. A cross - sectional study was conducted with 8 VI football 5 - a - side players and 7 age - match ed non - blind futsal players. The groups performed the cardiopulmonary exercise testing (CPE T ) and the 20 - m shuttle run to obtain the maximal oxygen consumption (VO 2 max). The VI footballers presented a lower VO 2 max than the non - blind footballers on both the CPE T ( P = 0.04) and the 20 - m shuttle run ( P < 0.05). The 20 - m shuttle run test underestimated VO 2 max in the VI footballers ( P = 0.02). The agreement between the estimated and measured VO 2 max values were better among non - blind footballers (ICC 2,1 = 0.72) than the VI footballers (ICC 2,1 = 171 0.58), confirmed by Altman and Bland's graphical approach. The VI footballers presented a lower cardiorespiratory fitness than the non - blind footballers , which was observed through direct and indirect methods. The 20 - m shuttle run test underestimate d the VO 2 max and is not a valid method to assess cardiorespiratory fitness in VI footballers . Key W ords : F ootball, O xygen C onsumption , Visual Impairment INTRODUCTION The number of individuals with disability engaging in sports has e xponentially increas ed in recent years. In the Paralympic Summer Games, disabled individuals may compete in 22 sports modalities according to six main impairments types: visual impairment , cerebral palsy , intellectual impairment, limb deficiency or amputat ion, spinal cord - related disability, and les autre s (i.e., it includes those ones who do not fit into these five aforementioned categories) (29). For instance, football 5 - a - side is an adapted sport for people with visual impairments in which each team com prises four players who must have total vision loss ( i .e., a B1 level of visual impairment ) and one goalkeeper who can be either visually impaired or fully sighted. The rules of football 5 - a - side are similar to those of conventional futsal with some modifi cations such as the ball that makes noise when it moves and a guide is placed behind the opponent’s goal to orient the players at the time of the kick (20). This modality involves intermittent efforts that require both aerobic and anaerobic metabolic deman ds (8). Therefore, footballers should have well - developed aerobic and anaerobic fitness to achieve optimal performance in this modality (1). The maximal oxygen uptake (VO 2 max) during physical effort is the most commonly used measurement to describe an in dividual’s aerobic fitness (5) , and it can be obtained through direct and indirect methods (2,14). Cardiopulmonary exercise testing (CPET) is a noninvasive and direct method that evaluates the integrative response of the cardiovascular and respiratory syst ems during an effort through gas exchange analysis. Although CPET provides a valid and reliable measurement of VO 2 max , it requires specialized professionals and sophisticated equipment that is also a time consuming process (4). Indirect methods of VO 2 max estimation have been developed, which are simple to perform, have low financial cost, and can be applied to large and varied populations in different places. For instance, the Léger Shuttle Run Test , also called the 20 - m shuttle run (22,23) is a maximal m ultistage exercise test largely used to estimate the VO 2 max of different populations, including athletes (9,26). The measurement and estimation of variables, however, are susceptible to some degree of error (24). Therefore, it is very important to determi ne to which extent indirect methods truly provide reliable measures of the phenomenon that is being investigated. Otherwise, daily clinical and practical decisions may be made with potential biases, which in the case of sports may directly influence the pe rformance of athletes. Despite its popularity among adapted sports, football 5 - a - side has rarely been the object of scientific investigations. To date, little is known about the aerobic fitness parameters of blind footballers (7), and yet this information could be useful for maximizing training program periodization and perfo rmance. Moreover, to the author s ’ knowledge, no previous study has investigated the validity of an indirect test to estimate the VO 2 max of blind footballers. Thus, the aims of this st udy were to investigate the cardiorespiratory fitness of blind footballers 172 comparing them with non - blind footballers, and to examine the validity of the 20 - m shuttle run test in estimating the cardiorespiratory fitness of blind footballers. METHODS Stud y and S ample A cross - sectional, pilot study was conducted with 8 football 5 - a - side line players, who were all classified in the B1 visual class and who competed on a second division team in the Brazilian National Championship of Football 5 - a - side. A group of 7 age - matched futsal players (Rio de Janeiro, Brazil, second division) with no visual impairments was also included in the study as the control group. During the study, both groups of footballers were in the specific preparatory phase of their training periodization. The inclusion criteria were: (a) male aged >18 y rs ; (b) practice of competitive football 5 - a - side or futsal for at least 1 yr ; and (c) regularly trained at least 3 times ·w k - 1 . Goalkeepers, beta - blocker users, smokers, and subjects with any muscle or joint injuries that could limit the test performance were excluded from the study. The study was submitted to and approved by the local ethical committee (CAAE: 17691113.1.0000.5235) , and all subjects gave their written consent before study entry . Direct M easurement of C ardiorespiratory F itness All subjects were submitted to symptom - limited CPET performed on a treadmill, using the ramp protocol proposed by Silva and Torres (27) in a study conducted on Brazilian Paralympic athletes. The protocol c onsisted of 5 min of warm - up at a velocity of 5.0 km·h - 1 and successive increases of 1.0 km·h - 1 during each minute of testing. Respiratory gas exchange was sampled from a facemask connected to a flow meter and a metabolic gas analyzer (FitMate PRO, Cosme d, Italy). The ventilation flow and expired oxygen fraction were measured and recorded breath - by - breath during exercise. A 12 - lead electrocardiogram (WinCardio, Micromed, Brazil) was continuously monitored during exercise and recovery. During every 3 min of the test, the systolic and diastolic blood pressure (SBP and DBP, respectively) values were measured ( using a mercury sphygmomanometer, Narcosul, 1400 - C), and the subjects were questioned about their perception of fatigue using the Borg Scale of Perceiv ed Exertion. The subjects were encouraged to perform using their maximal effort. The CPET was considered maximal when one or more of the following parameters were obtained: a VO 2 plateau, maximum heart rate (HR max ) > 180 beats · min - 1 (bpm), or a rating on the Bor g Scale of Perceived Exertion > 18 (19). The t est interruption criteria were based on the American College of Sports and Medicine recommendations (3). The following variables were considered for statistical analysis: oxygen uptake ( VO 2 max ; mL · kg - 1 · min - 1 ), minute ventilation (VE; L · min - 1 ), heart rate (HR; b eats·min - 1 ), S BP and D BP (mmHg), velocity (km · h - 1 ), and total test duration (min: sec ). 173 Indirect E stimation of C ardiorespiratory F itness Blind and non - blind footballers performed the 20 - m shut tle run test (22) with a mean interval of 1 w k after CPET. Both CPET and the 20 - m shuttle run test were performed at the same time of day. All subjects continuously ran back and forth betwee n two points that were 20 m apart. The runs were synchronized wit h a “ beep ” sound from a prerecorded compact disc. As the test proceeded, the interval between each “ beep ” decreased, requiring the athletes to increase their speed over the course.