The interval-training paradox: Physiological responses vs. subjective rate of perceived exertion

The purpose of the present study was to compare the physiological and perceived exertion responses of two different interval-training protocols - decreasing- and increasing-distance, matched for total distance, throughout a six-week training period.

Forty male physical education students (23 ± 1.3 years) were randomly assigned to either the increasing- or decreasing-distance interval-training group (ITG and DTG). The ITG performed increasing-distance interval training (100-200-300-400-500 m) and the DTG performed decreasing-distance interval training (500-400-300-200-100 m), twice a week for each. Heart rate (HR) and rate of perceived exertion (RPE) responses were monitored in each of the six-week training program sessions.

Mean HR values were significantly higher (p = .00) in the DTG (181 ± 2.8 bpm) compared with the ITG (163 ± 10.4 bpm). Mean RPE values were significantly higher (p = .00) in the ITG (7.5 ± 0.3 a.u.) compared with the DTG (5.8 ± 0. 6 a.u.). The percent change in RPE responses throughout the six-week training program was significantly greater (p = .00) in the DTG (50% ± 0.7) compared with the ITG (25% ± 0.7).

The findings demonstrated that physiological responses may not necessarily match the participant's perceived exertion, and that in addition to training physical load, a sensation of relief from the achievement is probably a significant factor to be considered during training.