Date Published: February 7, 2019
Publisher: Public Library of Science
Author(s): Liliana Pereira Lima, Hércules Ribeiro Leite, Mariana Aguiar de Matos, Camila Danielle Cunha Neves, Vanessa Kelly da Silva Lage, Guilherme Pinto da Silva, Gladson Salomão Lopes, Maria Gabriela Abreu Chaves, Joyce Noelly Vitor Santos, Ana Cristina Resende Camargos, Pedro Henrique Scheidt Figueiredo, Ana Cristina Rodrigues Lacerda, Vanessa Amaral Mendonça, Gustavo Batista Menezes.
Preliminary studies have showed that the Incremental Shuttle Walking Test (ISWT) is a maximal test, however comparison between ISWT with the cardiopulmonary exercise test (CEPT) has not yet performed in the healthy woman population. Furthermore, there is no regression equation available in the current literature to predict oxygen peak consumption (VO2 peak). Thus, this study aimed to compare the ISWT with CEPT and to develop an equation to predict peak oxygen uptake (VO2 peak) in healthy women participants.
First, the VO2 peak, respiratory exchange ratio (R peak), heart rate max (HR max) and percentage of predicted HR max (% predicted HR max) were evaluated in the CEPT and ISWT (n = 40). Then, an equation was developed to predict the VO2 peak (n = 54) and its validation was performed (n = 20).
There were no significant differences between the ISWT and CEPT of VO2 peak, HR max and % predicted HR max values (P>0.05), except for R peak measure in the ISWT (1.22 ± 0.13) and CEPT (1.18 ± 0.1) (P = 0.022). Therefore, both tests showed a moderate positive correlation of VO2 peak (r = 0.51; P = 0.0007), HR max (r = 0.65; P<0.0001) and R peak (r = 0.55; P = 0.0002) and the Bland-Altman analysis showed agreement of VO2 peak (bias = -0.14). The distance walked on ISWT and age explained 36.3% (R2 Adjusted = 0.363) of the variance in VO2 peak. The equation developed was VO2 peak (predicted) = 19.793 + (0.02 x distance walked)—(0.236 x age). There was no statistically significant difference between the VO2 peak measured directly and the predicted, and the Bland-Altman analysis showed agreement (bias = 1.5 ml/kg/min). ISWT is a maximal test showing similar results compared to the CEPT, and the predicted equation was valid and applicable for VO2 peak assessing in young adult healthy women.
Cardiorespiratory fitness (CRF) is defined as the ability to sustain dynamic exercise by large muscle groups over time at moderate to high intensity levels . Furthermore, CRF has been used to measure exercise capacity and provide information about physical limitation, morbidity prognosis, and responsiveness to treatment . The current gold standard for the evaluation of CRF is the direct measurement of maximal oxygen uptake (VO2max) which represents the maximal achievable level of oxidative metabolism involving large muscle groups . However, in clinical testing situations, the exercise usually is limited by symptoms before the individual achieve the VO2max. Consequently, VO2 peak is often used as an estimate for VO2max and they are used interchangeably .
In the present study it was observed that the direct VO2 peak measurement was concordant between the CEPT and the ISWT and that ISWT was a maximum test in the young healthy women population. Considering that the direct analysis of VO2 is not feasible for clinical practice, an equation was elaborated and validated to estimate this measure. The distance walked on ISWT and age were the variables that composed the equation. Furthermore, there was agreement between VO2 peak measured directly and that estimated by the elaborated equation, indicating its validity and applicability in this population.
The Incremental Shuttle Walking Test was concordant with the CEPT, requiring maximum effort in young health women. The elaborated equation is valid and applicable, being a simple and inexpensive tool to evaluate the cardiorespiratory fitness in the study population.