Exercise intensity during competition time trials in professional road cycling

Purpose: To estimate, upon competition heart rate (HR), exercise intensity during time trials (TT) in professional road cycling. Methods: Eighteen wor ld-class cyclists completed an incremental laboratory cycling test to asses s maximal power output (W-max), maximal HR (HRmax), onset of blood lactate accumulation (OBLA), lactate threshold (LT), and a HR-power output relation ship. An OBLA(ZONE) (HROBLA +/- 3 beats.min(-1)) and a LTZONE (HRLT +/- 3 b eats.min(-1)) were described. HR was monitored during 12 prologue (<10 km, PTT), 18 short (<40 km, STT), 19 long (>40 km, LTT), eight uphill (UTT), an d seven team (TTT) time trials. A HR-power output relationship was computed to estimate each cyclist's power output during TT racing from competition HR. Competition training impulse (TRIMP) values were estimated from HR and race duration. Results: %HRmax were 89 +/- 3%, 85 +/- 5%, 80 +/- 5%, 78 +/- 3%, and 82 +/- 2% in PTT, STT, LTT, UTT, and TTT, respectively. The amount of TRIMP were, respectively, 21 +/- 3, 77 +/- 23, 122 +/- 27, 129 +/- 14, and 146 +/- 6. Competition HR values relative to HROBLA and HRLT were, resp ectively, 100 +/- 3%, 114 +/- 8% in PTT, 95 +/- 7%, 108 +/- 9% in STT, 89 /- 5%, 103 +/- 8% in LTT, 87 +/- 2%, 101 +/- 5% in UTT, and 91 +/- 4%, 105 +/- 11% in TTT. Conclusions: %HRmax, TRIMP and time distribution around HRO BLA and HRLT reflected the physiological demands of different TT categories . HROBLA and HRLT were accurate intensity markers in events lasting, respec tively, less than or equal to 30 (PTT and STT) and greater than or equal to 30 min (LTT, UTT, TTT).