PADILLA, S., I. MUJIKA, J. ORBAÑANOS, and F. ANGULO. Exercise intensity during competition time trials in professional road cycling. Med. Sci. Sports Exerc., Vol. 32, No. 4, pp. 850–856, 2000.
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 OBLAZONE (HROBLA ± 3 beats·min−1) and a LTZONE (HRLT ± 3 beats·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 HROBLA and HRLT 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 HROBLA and HRLT reflected the physiological demands of different TT categories. HROBLA and HRLT were accurate intensity markers in events lasting, respectively, ≤30 (PTT and STT) and ≥30 min (LTT, UTT, TTT).
In3-wk professional road cycling stage races, performance in the time trials (TT) is of paramount importance to the final overall standings of the race. This racing format, in which the cyclist most often races individually and attempts to achieve the shortest possible time to cover a fixed distance, has often been simulated under laboratory conditions (4,5,8,13,19,20,22), usually with the aim of predicting cycling performance in the field. However, there are very few reports on the intensity of actual road cycling competition in general, and the TT in particular (23). This lack of data is mainly due to the technical difficulties of determining oxygen uptake (V̇O2) and blood lactate concentration ([La]) during competition, which are two of the main methods used by exercise scientists to quantify exercise intensity (14). In this past decade, the advent of accurate portable telemetric heart rate (HR) monitors (18) has made it possible to estimate exercise intensity both during training and competition by relating individual HR values measured in the field with those previously obtained in a laboratory setting (9,10,23).
In contrast with most laboratory simulations, TT cycling competition represents a unique experience during which the athlete’s power output (i.e., exercise intensity) is freely chosen. Although several methods based on HR values have been described to quantify the load undertaken by athletes during training (1,16), the principle of training specificity with regard to the intensity at which a cyclist trains cannot be met unless the intensity and physiological demands of competition are determined. The aim of the present study was therefore to estimate, using competition HR data, exercise intensity during the TT in professional cycling, and to compare the cyclists’ physiological responses to the different competition TT categories and formats.