Cardiorespiratory and metabolic responses and reference equation validation to predict peak oxygen uptake for the incremental shuttle waking test in adolescent boys

Cross-Validation of Predictive Equation for Cardiorespiratory Fitness by Modified Shuttle Walk Test in Adults with Schizophrenia: A Secondary Analysis of the CORTEX-SP Study

Cardiorespiratory fitness (CRF) can be direct or estimated from different field tests. The Modified Shuttle Walk Test (MSWT) is suitable for all levels of function, allowing a peak response to be elicited. Therefore, we aimed (1) to validate the equation presented in the original study by Singh et al. for evaluating the relationship between MSWT with peak oxygen uptake (VO_2peak) in adults with schizophrenia (SZ), (2) to develop a new equation for the MSWT to predict VO_2peak, and (3) to validate the new equation. Participants (N = 144, 41.3 ± 10.2 years old) with SZ performed a direct measurement of VO_2peak through a cardiopulmonary exercise test and the MSWT. A new equation incorporating resting heart rate, body mass index, and distance from MSWT (R² = 0.617; adjusted R² = 0.60; p < 0.001) performs better than the Singh et al. equation (R² = 0.57; adjusted R² = 0.57; p < 0.001) to estimate VO_2peak for the studied population. The posteriori cross-validation method confirmed the model’s stability (R² = 0.617 vs. 0.626). The findings of the current study support the validity of the new regression equation incorporating resting heart rate, body mass index, and distance from MSWT to predict VO_2peak for assessment of CRF in people with SZ.

Adapted Chester Step Test Can Have Maximal Response Characteristics for the Assessment of Exercise Capacity in Young Women

Chester step test (CST) estimates the exercise capacity through a submaximal response, which can limit its application in the prescription of exercise. This study aimed to assess whether an adaptation of the CST (with a progressive profile) can have maximal response characteristics in young women and compare it to the incremental shuttle walk test (ISWT). Another aim was to determine its within-day test–retest reliability. A cross-sectional study was conducted with 25 women (20.3 ± 1.5 years) who performed the field tests twice on two different days (48 h apart). The maximal effort attainment was assessed by the heart rate (HR), perception of exertion (Borg scale), and blood lactate concentration. For the performance variables, Pearson’s correlation and intraclass correlation coefficient (ICC_2,1) were used. In the best test, mean values of maximal response were observed in the adapted CST (94.0 ± 6.5% of age-predicted HR_max, 11.3 ± 4.5 mmol/dl of blood lactate, and 18.4 ± 1.5 of Borg rating). The correlations between the adapted CST and the ISWT were weak to moderate (0.38 ≤ r ≤ 0.55; p < 0.05). Fair to good reliability was found for the adapted CST (ICC_2,1 = 0.48–0.61). The adapted CST showed mean values of maximal response, weak to moderate association with the ISWT, and low within-day test–retest reliability in young women.