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 world-class cyclists completed an incremental laboratory cycling test to assess maximal power output (Wmax), maximal HR (HRmax), onset of blood lactate accumulation (OBLA), lactate threshold (LT), and a HR-power output relationship. An OBLA(ZONE) (HR(OBLA) +/- 3 beats x min(-1)) and a LT(ZONE) (HR(LT) +/- 3 beats x 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), and 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 HR(OBLA) and HR(LT) were, respectively, 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 HR(OBLA) and HR(LT) reflected the physiological demands of different TT categories. HR(OBLA) and HR(LT) were accurate intensity markers in events lasting, respectively, < or =30 (PTT and STT) and > or =30 min (LTT, UTT, TTT).