IJCS | Volume 32, Nº4, July/August 2019

DOI: 10.5935/2359-4802.20190058 374 ORIGINAL ARTICLE International Journal of Cardiovascular Sciences. 2019;32(4):374-383 Mailing Address: Ricardo Stein Hospital de Clínicas de Porto Alegre (HCPA), Universidade Federal do Rio Grande do Sul (UFRGS) - Largo Eduardo Zaccaro Faraco, Rua Ramiro Barcelos 2350 - Serviço de Fisiatria,Térreo. Postal Code: 90035-903, Porto Alegre, RS - Brazil. E-mail: rstein@cardiol.br Speed and Grade Increment During Cardiopulmonary Treadmill Testing: Impact on Exercise Prescription Karlyse C. Belli, 1 Paula F. Da Silva, 1 Leandro T. Franzoni, 2 J onathan Myers, 3,4 Ricardo Stein, 2, 5 J orge P. Ribeiro† 5 Hospital de Clínicas de Porto Alegre, 1 Porto Alegre, RS - Brazil Study Group in Exercise Cardiology (CardioEx), 2 Porto Alegre, RS - Brazil Stanford University, 3 Palo Alto, California - USA VA Palo Alto Health Care System, 4 Palo Alto, California - USA Federal University of Rio Grande do Sul, 5 Porto Alegre, RS - Brazil Manuscript received April 01, 2019; revised manuscript May 06, 2019; accepted May 22, 2019. Abstract Background: Maximal oxygen uptake (VO 2 max) and both first (VT 1 ) and second (VT 2 ) thresholds have been used as reference points for exercise prescription in different populations. Objective: We aimed to test the hypothesis that exercise prescription, based on VTs determined by treadmill cardiopulmonary exercise testing (CPET), is influenced by the rate of increase in treadmill workload. Methods: Nine healthy individuals underwent two CPETs, followed by two sessions of submaximal exercise, both in randomized order. For the “speed” protocol, there was an increment of 0.1 to 0.3 km.h -1 every 15s. The “grade” incremental protocol increased 1% every 30s and 0.1 km.h -1 every 45s. This was followed by submaximal exercise sessions lasting 40min at an intensity corresponding to heart rate (HR) between the VT 1 and VT 2 . Results: The “speed” protocol resulted in higher VT 1 (p = 0.01) and VT 2 (p = 0.02) when compared to the “grade” incremental protocol, but there was no effect on VO 2 max. The target HR for the submaximal exercise sessions was higher in the “speed” protocol compared to the “grade” incremental protocol (p < 0.01) and remained stable during the two steady-state exercise sessions. Blood lactate remained stable during the submaximal exercise sessions, with higher values observed during the “speed” protocol than those “grade” incremental protocol (p < 0.01). Conclusions: Compared to a grade-based protocol, a speed-based protocol resulted in higher VT 1 and VT 2 , which significantly affected cardiorespiratory and metabolic responses to prescribed exercise intensity in healthy young adults. (Int J Cardiovasc Sci. 2019;32(4):374-383) Keywords: Cardiovascular Diseases; Exercise Test; Exercise Tolerance; Oxygen Consunption. Introduction Cardiopulmonary exercise testing (CPET) provides valuable diagnostic and prognostic information for healthy subjects and patients with cardiovascular disease 1,2 and has long been used in the assessment of athletic performance, as well as for various research applications. 3 CPET responses have also been extensively used for the prescription of exercise intensity during aerobic training. 4 In this context, maximal oxygen uptake (VO 2 max) and, both first (VT 1 ) and second (VT 2 ) thresholds, have been used as reference points for Ricardo Stein, PhD Professor Adjunto da Faculdade de Medicina da UFRGS Coordenador do CardioEx-HCPA rstein@cardiol.br † Note: Deceased on August 23, 2012.