IJCS | Volume 32, Nº4, July/August 2019

339 Araújo et al. CLINIMEX aerobic fitness questionnaire Int J Cardiovasc Sci. 2019;32(4):331-342 Original Article found non-significant associations (r values > -0.1 and < 0.1; p > 0.05) with age and the anthropometric variables studied — height, weight, waist and body mass index (these last two not represented in figure 2). The r-values between deltaMETs with other non-aerobic components of physical fitness, as assessed by SRT scores andmaximal muscle power were, respectively, -0.09 and -0.04, also suggesting no clinical relevance or implications. The small but significant and positive associations found between delta METs and measured METs — r = 0.09 (p < 0.001) — and measured METs expressed as % sex- and age-predicted METs — r = 0.15 (p < 0.001), but not with sex- and age-predicted MET — r = -0.04 (p = 0.55), indicated that the delta METs slightly tends to increase for those subjects at an upper range of measured aerobic fitness. Median [percentiles 25–75] CPET duration was 11 [8–12] minutes with 75%of all 1,000 CPETs lasting between 8 and 15 minutes. Discussion This study proposed the C-AFQ, a new assessment tool for non-exercise estimation of aerobic fitness, and also validated it against the gold standard and criterion measurement of VO 2 max obtained during a maximal CPET. In addition, it explored the potential influence of several other variables in the magnitude of the delta METs between estimated (C-AFQ) and measured (CPET) VO 2 max. The rationale for proposing the C-AFQwas primarily based on two major needs: a) to have a simple and valid tool for estimating VO 2 max for the Brazilian population when CPETwas not feasible or desirable to be carried out; and b) to obtain subsidies for a better and more precise planning of an individual CPET ramp protocol. Regarding the main variable of the study, a small yet statistically significant difference was found between both means and medians of estimated and measured VO 2 max, being, respectively, 0.38 and 0.2 METs. However, considering the minimal interval of 0.5 MET in the C-AFQ scale, these small differences were likely to be clinically irrelevant and acceptable. It should also be recognized that in some subjects that were more used to running than to cycling exercises, the clinical option (i.e., need for a more precise measurement of exercise blood pressure) of cycling rather than treadmill CPET might have produced some overestimation of estimated VO 2 max when the C-AFQ was applied, and therefore, contributed to themodest yet significant difference found between the means andmedians. Additionally, it should also be mentioned that in some cases, the use of C-AFQ was limited either by not contemplating some specific regular exercises, such as primarily swimming and rowing, or by not being able to offer adequate options and adjustments for those presenting major motion deficits or limitations, such as subjects that are wheelchair- dependent or that have severely limiting arthrosis. The correlation coefficient of 0.91 observed between estimated (C-AFQ) and measured (CPET) VO 2 max in our 1,000 subjects was quite impressive and higher than the one reported — r = 0.79 — in the 212 subjects in the VSAQ’s original paper. 19 Using linear regression analysis, it was possible to show that C-AFQ explained 83% of the variation in the measured VO 2 max. However, it should be pointed out that the standard error of the estimate was 1.54 METs and that, according to our data (Figure 2), the error of estimate was ±1 and ±2 METs for, respectively, 50% and 78% of the subjects. It is also relevant to emphasize that, since the C-AFQ values are based on the subjects’ self-report, it was always likely that some of these individual differences could be explained either by self-misevaluation or due to purposeful misinformation—under or overestimation. So, while, in general, aerobic fitness assessed by C-AFQ was a quite good estimator of measured VO 2 max, at an individual level, delta METs could be quite high in a relatively large portion of the subjects, with relevant clinical implications, especially when it is known that detraining and training interventions or conditions would rarely be able to producemore than 2METs changes inmeasuredVO 2 max and, therefore, within this margin of error of estimate. The application of C-AFQ and its use in planning the individual ramp protocol seemed to have been successful as shown by the profile of CPET duration in which a median value of 11 minutes was observed and the large majority of tests ended after 8 to 15 minutes. An interesting point to comment in our results was the fact that the mean values for sex- and age-predicted and measured (CPET) VO 2 max were quite similar, which may reinforce the merit in using Jones’ equation 29 to CLINIMEX’s population. However, it is worth noting the huge inter-individual variability that ranged from -9.6 to 8.3 METs or from 28.8% to 236% of sex- and age- predicted VO 2 max in the 1,000 subjects studied, which clearly indicates the limitation of using sex- and age- predicted VO 2 max values for planning individual ramp protocols, much differently thanwhat was observedwith the estimated aerobic fitness obtained by C-AFQ.