Quantifying Training Load: A Comparison of Subjective and Objective Methods

Purpose: To establish the relationship between a subjective (session rating of perceived exertion [RPE]) and 2 objective (training impulse [TRIMP]) and summated-heart-rate-zone (SHRZ) methods of quantifying training load and explain characteristics of the variance not accounted for in these relationships. Methods: Thirty-three participants trained ad libitum for 2 wk, and their heart rate (HR) and RPE were recorded to calculate training load. Subjects were divided into groups based on whether the regression equations over- (OVER), under- (UNDER), or accurately predicted (ACCURATE) the relationship between objective and subjective methods. Results: A correlation of r = .76 (95% CI: .56 to .88) occurred between TRIMP and session-RPE training load. OVER spent a greater percentage of training time in zone 4 of SHRZ (ie, 80% to 90% HRmax) than UNDER (46% +/- 8% vs 25% +/- 10% [mean +/- SD], P = .008). UNDER spent a greater percentage of training time in zone 1 of SHRZ (ie, 50% to 60% HRmax) than OVER (15% +/- 8% vs 3% +/- 3%, P = .005) and ACCURATE (5% +/- 3%, P = .020) and more time in zone 2 of SHRZ (ie, 60% to 70%HR(max)) than OVER (17% +/- 6% vs 7% +/- 6%, P = .039). A correlation of r = .84 (.70 to .92) occurred between SHRZ and session-RPE training load. OVER spent proportionally more time in Zone 4 than UNDER (45% +/- 8% vs 25% +/- 10%, P = .018). UNDER had a lower training HR than ACCURATE (132 +/- 10 vs 148 +/- 12 beats/min, P = .048) and spent more time in zone 1 than OVER (15% +/- 8% vs 4% +/- 3%, P = .013) and ACCURATE (5% +/- 3%, P = .015). Conclusions: The session-RPE method provides reasonably accurate assessments of training load compared with HR-based methods, but they deviate in accuracy when proportionally more time is spent training at low or high intensity.