Validity of a perceptually-regulated step test protocol for assessing cardiorespiratory fitness in healthy adults.

PURPOSE

To determine whether maximal oxygen uptake (VOmax) could be predicted accurately and reliably from a 2-step, perceptually-regulated exercise test (PRET) in healthy adults.

METHODS

Sixteen participants (31.7 ± 11.3 years, 3 females) completed three PRETs (separated by 24-72 h) and one maximal, perceptually-regulated, graded exercise test (PRETmax) on a motorized treadmill. Oxygen uptake (VO) and heart rate (HR) were recorded during each test. VO values for RPE range 9-15 were extrapolated to RPE 20 and age-predicted maximal HR (HRmax) using individual linear regression analysis to predict VOmax values compared to measured VOmax.

RESULTS

VO and HR values were consistent between each of four RPE levels of the PRET. ICC values ranged between 0.76 and 0.85. Predicted VOmax from both methods were lower than measured VOmax (p < 0.01). Limits of agreement (LoA) for measured (41.4 ± 5.3 ml kg min) versus predicted VOmax from each of the three PRETs using RPE20 were -1.2 ± 15.6, -1.0 ± 7.2 and -2.1 ± 5.5 and for HRmax were -1.8 ± 4.2; -2.6 ± 4.2 and -2.4 ± 4.4 ml kg min for PRET 1, 2 and 3, respectively.

CONCLUSIONS

The step PRET elicited significant and reliable increases in VO across the four RPE levels, but under-estimated treadmill VOmax. However, there was better agreement between measured and predicted VOmax when extrapolated to HRmax. As evidence indicates the underestimation of VOmax is explained by the difference in the mode of exercise, the step PRET provides a simple and convenient test of cardiorespiratory fitness.