Relative Running Intensity and Pacing During an Official HYROX PRO MEN Competition: The HYScience Study.

PURPOSE: This study quantified running pace and relative exercise intensity during a HYROX PRO MEN event by integrating laboratory-derived aerobic markers with competition data. METHODS: Twenty-four male HYROX PRO MEN athletes (race time: 69:58 [5:05] min:s) completed a maximal incremental treadmill test to determine second ventilatory threshold (VT2), maximal aerobic speed (vVO2max), and maximal oxygen uptake (VO2max). Within 10 days, participants competed in the official HYROX Madrid 2025 event. Running speed was calculated for each of the eight 1-km segments and the Roxzone, as well as for the total running component, defined as the combined distance of run 1 to 8 and the Roxzone (8.70 km), and expressed in absolute terms (kilometers per hour) and relative to VT2 and vVO2max. RESULTS: During laboratory testing, athletes reached a VO2max of 51.56 (5.00) mL·kg-1·min-1 (95% CI, 49.56 to 53.56), with VT2 and vVO2max occurring at 16.41 (0.87) km·h-1 (95% CI, 16.06 to 16.76), and 18.08 (0.81) km·h-1 (95% CI, 17.76 to 18.40), respectively. Competition running speed declined from 16.13 (0.97) km·h-1 (95% CI, 15.74 to 16.52) in run 1 to 13.58 (1.02) km·h-1 (95% CI, 13.17 to 13.99) in run 8, with the lowest speed in the Roxzone (10.52 [1.18] km·h-1; 95% CI, 10.05 to 10.99). Mean intensity, calculated across the 8 running segments and the Roxzone, corresponded to 84.13% (5.54%) of VT2 (95% CI, 82.66 to 87.10) and 76.33% (4.05%) of vVO2max (95% CI, 75.31 to 78.55). CONCLUSIONS: Running in HYROX PRO MEN is performed at submaximal intensities relative to VT2 and vVO2max and declines progressively across segments. Sustaining a higher relative intensity appears central to shorter total running time.