Cross-Validation of Ratings of Perceived Exertion Derived from Heart Rate Target Ranges Recommended for Pregnant Women.

Currently, there are no established evidence-based rating of perceived exertion (RPE) targets for physical activity (PA) in pregnant women. Yet, a set of target heart rate (HR) ranges have been recommended. Using the Borg Scale, we aimed to determine and validate the RPE target ranges for different PA intensities derived from the recommended HR ranges in the 2019 Canadian Guideline for PA throughout pregnancy. We assessed 13 pregnant women (age: 31.2 ± 3.5 years; gestational age: 20.5 ± 5.0 weeks) using the following three phases: 1) the incremental submaximal walking test to develop the linear regression equation; 2) establishment of the RPE targets for light- and moderate-intensity PA; 3) moderate-intensity exercise session aiming to cross-validate RPE targets in women whose HR ranges were within (Step 1; six participants; 36 RPE values) or outside (Step 2; seven participants; 42 RPE values) the guideline. Study Phase 1 showed a strong linear relationship between RPE x HR (RPE = -7.370 + 0.155*HR; R2 = 0.863). RPE targets for pregnant women aged ≤ 29 years are 8-12 (light-intensity) and 12-15 (moderate-intensity), respectively. For women aged ≥ 30 years, RPE targets are 8-11 (light-intensity) and 11-14 (moderate-intensity), respectively. The cross-validation suggested no differences between predicted (13.4 ± 0.7) vs. observed RPE (13.3 ± 1.4; p = 0.703) and a strong % agreement (Step 1 = 80.6%; Step 2 = 73.8%) between observed RPE and its predicted range. Thus, we have determined pregnancy-specific, evidence-based RPE targets. These RPE targets will help exercise professionals, other health care providers, and pregnant women to easily monitor exercise intensity during pregnancy to meet recommended Canadian PA Guideline.