1. Sadowsky, H. Steven PT, RRT, MS, CCS

Article Content


Although a number of tools exist for the purpose of modulating or prescribing exercise intensity, there are numerous reasons why each is less than ideal for many portions of the exercising public. Alternatively, the ventilatory response index (a relative measure of one's ability to breathe during exercise) is a simple, "no instruments required" clinical tool that can be used to modulate or prescribe exercise intensity.



Examinations of concurrent and construct validity of the ventilatory response index were made using apparently healthy adults.



Concurrent validity was determined for the ventilatory response index (VRI) by assessing its correlation with oxygen consumption (VO2), heart rate (HR), venous lactate concentration ([La]), and rating of perceived exertion (RPE, Borg's 6-20 scale) responses to speed- and grade-incremented treadmill tests. Because VO2 and VRI involve mutually exclusive determinations (one with expired gas analysis; one without), the order of the two testing conditions was randomly determined in an a priori manner. Heart rate, [La], and RPE were measured during each stage of both tests. Construct validity was established by assessing differences between values of VO2, HR and RPE obtained during steady-state exercise at VRI level 2 with those corresponding with VRI level 2 during the incremental tests.



Repeated measures ANOVA showed no differences between the two test conditions for HR, [La], RPE, or exercise duration. Correlation/regression analyses showed the VRI to be a positive linear function of VO2, HR, [La], and RPE (r = 0.96, 0.92, 0.89, and 0.77; P <.01, respectively). Paired t-tests showed no significant differences between VRI level 2 values for VO2, HR, or RPE obtained during incremental or steady-state exercise.



These results provide concurrent and construct evidence to support the use of the VRI to modulate or prescribe exercise for apparently healthy adults.