Heart Rate Acquisition and Threshold-Based Training Increases Oxygen Uptake at Metabolic Threshold in Triathletes: A Pilot Study.

Exercise intensity is a critical component of the exercise prescription model. However, current research employing various non-specific exercise intensity protocols have reported wide variability in maximum oxygen uptake (VO) improvement after training, suggesting a present lack of consensus regarding optimal heart rate (f) training zones for maximal athletic performance. This study examined the relationship between percentage of time (%time) spent training between the metabolic (VOθ) and ventilatory thresholds (Vθ), and the resultant change in markers of aerobic performance. Thirteen (6 males) collegiate club-level triathletes were recruited for eight weeks of remote f monitoring during all running and cycling sessions. Participants donned a forearm-worn optical f sensor paired to a smartphone that collected and stored fs. Subjects were categorized into Low and High groups based on %time spent training between the VOθ and Vθ. Significant increases were observed in relative VO ( = 0.007, g = 0.48), VOθ ( = 0.018, g = 0.35), and Vθ ( = 0.030, g = 0.29) from baseline after eight weeks for both groups. A 95% bootstrapped confidence interval that did not include zero (-0.38, -0.03; g = 1.26) revealed a large and significantly greater change in VOθ in the High group (0.37 ± 0.15 L/min) versus the Low group (0.17 ± 0.14 L/min). No significant differences were observed in other variables between groups. Increasing triathletes' %time spent exercising between VOθ and Vθ may optimize increases in VOθ after eight weeks of training.