Journal of Clinical and Diagnostic Research. 2018 Jun, Vol-12(6): YC01-YC04 1 1 DOI: 10.7860/JCDR/2018/28692.11626 Original Article Physiotherapy Section Can the Six-Minute Step Test Predict the VO 2 Peak in Healthy Young Men? INTRODUCTION Regular physical activity and exercise is associated with numerous physical and mental health benefits and a delay in mortality from all causesin both healthy individuals and patients with cardiovascular disease [1-3]. For the exercise to be performed safely, a prior full assessment of maximum oxygen consumption (VO 2max ) is recommended, and the gold standard test is the Cardiopulmonary Exercise Test (CPX) [4,5]. However, CPX requires specific equipment, a suitable place, and trained personnel [4], in addition to being relatively expensive and time consuming [3]. In terms of practical application, when only an estimate of VO 2max is required, the use of simpler tests, applicable on a large scale, may be a viable strategy [6]. For example, step tests are low cost, can be easily transported, require little practice to perform, and usually have a short duration [7-9]. There are several step test protocols, with differences in the height of the step, test duration, frequency of cadence, and number of stages [9]. In patients with chronic diseases, a six-minute step test has been used, self- cadenced with a step height of 20 cm (6MST) [10-17]. On the other hand, in healthy individuals, the scientific literature demonstrates a predominance of the use of step tests with a pre- set cadence [9]. However, the self-cadenced test model, in the 6MST, may also be useful for healthy individuals, as it allows the frequency of the cadence to be individually adjusted during the total test time, so there is no need to choose a single step test protocol which may not promote the best work intensity, especially when evaluating individuals with different levels of physical fitness [9,18]. Nevertheless, further information on the applicability of the 6MST in healthy individuals can be obtained by comparing performance in the step test with direct oxygen consumption measured in a progressive test. To our knowledge, this information is not available in the literature and could allow VO 2 peak prediction through 6MST performance in healthy young people. Thus, the objective of the present study was to verify the correlation between VO 2 peak obtained in the CPX and performance in the 6MST in a group of healthy young men, and analyse the power of the 6MST to predict VO 2 peak. MATERIALS AND METHODS Following a transversal design, this study was conducted during spring/summer (September-December of south hemisphere) of 2013 after being approved by the Ethics Committee on Human Research of the State University of Londrina, Brazil (243/2013). All subjects agreed to participate and all signed a written informed consent in accordance with Helsinki Declaration. The calculation of sample size (two-tailed alpha = 0.05, beta = 0.20, and expected correlation of 0.50) showed requirement of a minimum of 29 subjects. For the sample selection, graduate students of Londrina State University, aged 18 to 27 years were invited. In total, 34 young males (healthy, normotensive and recreationally active) were included, not undergoing any drug treatment and without orthopedic or equilibrium alterations or any other conditions that could limit the tests. Experimental Procedure The tests were performed in a climatized laboratory (22°C to 24°C), in the evening to avoid alterations in circadian rhythm. The participants were instructed not to perform physical exercise in the 24 hours prior to the test, not to smoke or drink caffeine for three hours before the collections, not to drink alcohol for a period of 48 hours before testing and to wear sportswear and sneakers [7]. Participants attended the laboratory on two separate days with an interval of 72 hours between the applied exercise tests to allow relaxation of the muscles. On the first day, the subjects were instructed on how to respond to modified Borg CR10 scales on perceived exertion and fatigue of the lower limbs [19], they answered CRISTIANE TRAVENSOLO 1 , WALACE MONTEIRO 2 , TAINAH LIMA 3 , ROBERTA PINTO 4 , PAULO FARINATTI 5 , MARCOS POLITO 6 Keywords: Cardiorespiratory fitness, Exercise test, Peak oxygen consumption, Physical effort, Regression analysis ABSTRACT Introduction: The six-minute step test can estimate the oxygen consumption in patients with chronic obstructive pulmonary disease. However, the literature is scarce regarding to six- minute step test application to health and young subjects. Aim: To correlate peak oxygen consumption (VO 2 peak) obtained in a Cardiopulmonary Exercise Test (CPX) with performance in the 6-Minute Step Test (6MST) in a group of healthy young men. Materials and Methods: In a prospective observational cross- sectional study, thirty-one young healthy men (22.3±2.2years) were volunteers. The study was conducted during two non- consecutive days. On the first day, the VO 2 peak was obtained using CPX on a treadmill. After 72 hour, the 6MST (20 cm of height) was performed at a self-selected cadence. The reproducibility of the 6MST was tested in 14 subjects, 30 minute after the first 6MST. Results: The 6MST demonstrated reproducibility (ICC=0.977; 95%CI 0.932 to 0.992). There was a significant correlation between the total number of steps and heart rate in the 6th minute of the 6MST (r=0.794; p<0.001). The multiple regression did not identify variables that could be associated with the VO 2 peak. Conclusion: The 6MST has no power to estimate the VO 2 peak in healthy young men.