UCLA

Introduction: Exercise intensity is a critical component of the exercise prescription model. Previous research suggests that the method of exercise intensity prescription may underpin the inter-individual variation in cardiorespiratory response (VO2) to exercise training. Past studies that employed several non-specific exercise intensity protocols have reported wide variability in participants’ VO2 measured after training. This suggests a present lack of consensus regarding the optimal heart rate training zones that will result in maximal athletic performance. Methods: Thirteen (males=4) UCLA club-level triathletes were recruited for 8 weeks of remote heart rate monitoring during all running and cycling sessions. Participants donned a forearm-worn optical heart rate sensor device (Scosche Rhythm+ TM) paired to a smartphone that remotely collected, stored and transferred heart rates. Results: Subjects were categorized into Low (94.2 � 3.0% in Zone 1) and High (64.2 � 9.4% in Zone 1) groups. The Low group spent significantly more time in Zone 1 (p=0.026). Significant increases were observed in absolute VO2max (P = 0.030, g = 0.29), relative VO2max (P = 0.007, g = 0.48), VO2θ (P = 0.018, g = 0.35), and VEθ (P = 0.030, g = 0.29) from baseline after eight weeks for both groups. Large and significantly greater changes in VO2θ were observed in the High group (0.37 � 0.15 L/min) compared to the Low group (0.17 � 0.14 L/min). Conclusion: Data show that no significant differences were observed in individuals who spent significantly more time training above MT. However, spending more time training above MT led to greater delays in VO2θ, which has proven to be a key measure in predicting aerobic performance. All subjects favored the polarized method of training compared to the threshold-based model.