Oxygen uptake and ratings of perceived exertion at the XXXX threshold and maximal fat oxidation rate in untrained adults.

@entity410 @entity880 @entity4962
The purpose of the study was to examine the relationship between VO(2) and RPE at the @entity880 threshold (LT) and maximal fat oxidation rate (FAT(MAX)) in untrained adults and determine the stability of the relationship across sex, age, and @entity410 status. A total of 148 untrained adults (mean age [year] = 30.5    13.9, height [m] = 1.72    0.08 m, body mass [kg] = 82.6    20.5, body fat [%] = 28.7    12.0) completed a continuous incremental VO(2) peak/LT protocol. Fat oxidation rates were determined using indirect calorimetry. The highest recorded fat oxidation rate was chosen as FAT(MAX). The breakpoint in the VO(2)-blood @entity880 relationship was chosen as LT. RPE was based on the Borg 6-20 scale. Bland-Altman plot analysis demonstrated that @entity4962 FAT(MAX) systematically preceded @entity4962 LT (mean bias = 1.3 ml kg(-1) min(-1)) with wide limits of agreement (+9.6 to -6.9 ml kg(-1) min(-1)). Multivariate ANOVA revealed a significant difference between @entity4962 FAT(MAX) (12.7    7.5 ml kg(-1) min(-1)) and VO(2) LT (14.1    5.9 ml kg(-1) min(-1)) in the total sample (p = 0.04). There were no differences between the intensities when the sample was divided into sex, age, and @entity410 comparison groups (p values >0.05). RPE FAT(MAX) (9.4    2.5) preceded RPE LT (10.4    2.0) in the total sample (p = 0.008), but was not different across comparison groups (p > 0.05). The present data indicate that the highest rate of fat oxidation slightly precedes the LT in untrained adults. For exercise prescription, a Borg-RPE of 9-12 identifies both FAT(MAX) and LT.
