The subjects of this study were 18 professional road cyclists. The cyclists collaborated voluntarily in our research. The study was approved by the ethical committee of Oviedo University. The subject pool included the top ranked cyclist in the world and several others ranked in the top 10. In addition, the pool also contained single-stage and overall event winners. The total training performed during a year by these cyclists ranges from 30,000 to 35,000 km.
Two weeks before each race subjects reported to laboratory to have their body fat measured according to Jackson and Pollock (7). Next, the subjects completed an incremental exercise test on a modified and very specific cycle electromagnetically-braked ergometer (Orion S.T.E., Toulouse, France). The test began at 100 W and intensity was increased 50 W every 4 min until exhaustion. The highest V̇O2 obtained during 30 s was considered the V̇O2max. Subjects chose their own cadence, which was generally between 90 and 105 rpm. HR via telemetry (Sport tester PE 4000, Polar, Kempele, Finland) and V̇O2 via expired gas were monitored every 5 s by a gas analyzer calibrated before and after each incremental test (Vmax 29, Sensormedics, Yorba Linda, CA). Capillary blood, from a hyperaemized ear lobe for lactate concentration, was collected every 4 min and subsequently analyzed in duplicate by an electro-enzymatic method (Analox GM7, London, UK). Blood lactate data were used to determine each rider’s individual lactate threshold (IAT) according to the techniques of Stegmann et al. (16). All the aforementioned data were used to establish four heart zones that corresponded to the following intensities of exercise: anaerobic (AN), which was over the individual anaerobic threshold (this IAT was around 90% of V̇O2max); intense aerobic (IA), which was between 70 and 90% of max; moderate aerobic (MA), which was between 50 and 70% of max; and recovery (RE), which was under 50% of V̇O2max.
Field testing was conducted in the 1995 Vuelta and the 1996 Tour. The 22-d Vuelta covered 3725.6 km, 3635.6 km in 19 IL, and 89.6 km in 3 ITT stages. The combined mean stage length was 191 km. The 22-d Tour covered 3899.4 km, 3796 km in IL, and 103.4 km in ITT stages. The combined mean stage length was 199.8 km. Table 1 shows the characteristics of the races. In each stage HR was recorded every 15 s, via telemetry (Fig. 1). HR data were then downloaded and subsequently analyzed by a specific software (Polar HR analysis 5.03, Polar, Kempele, Finland). From this analysis we determined the total stage exercise time (TT) and time and percentage of total time in minutes that the cyclists spent in the four heart zones during each stage.
Data are reported as mean ± SD. To study the differences between Tour and Vuelta, because different subjects ran in each race, a Mann-Whitney test was applied for each exercise intensity (AN, IA, MA, and RE) during each type of stage (flat, mountain, and ITT). For studying differences between the types of stages in each race (Tour and Vuelta separately) and because the same subjects performed the three types of stages and because they were performed on different days, a nonparametric Friedman test was used for the mean of each subject for the different type of stages. After that, Wilcoxon matched-pairs test was used to test whether there are differences between flat-mountain, mountain-ITT, and flat-ITT. Significance level was set at P < 0.05. A SPSS+ Vers. 4.0 statistical software ( Chicago, IL) was used.
The riders’ physical characteristics are listed in Table 2.
Vuelta a España
During the Vuelta a España, cyclists carried out a mean + SD exercise intensity, expressed as the stage mean heart rate (mHR) for the overall race, of 133.8 ± 17.9 beats·min−1. The mean total time of each stage was 269.6 ± 122 min. The mean stage time over IAT was 17.5 ± 15.7 min, the IA time was 75.2 ± 47.6 min, the MA was 97.2 ± 57.4, and the RE time was 79.6 ± 60.5 min. The percentage of participation related to total time of the race was 12.99 in AN exercise intensity, 29.5 in IA, 32.4 in MA, and 25.1 in RE (Table 3).
During the flat stages cyclists reached a mean heart rate of 126.5 ± 10 beats·min−1. The mean total time of flat stages was 278.4 ± 68.1 min. The mean stage time over IAT was 15.5 ± 15.2 min, the IA time was 67.6 ± 38.5 min, the MA was 108.2 ± 39.4, and the RE time was 87 ± 56 min (Fig. 2). The percentage of participation related to total time was 5.3 in AN exercise intensity, 24.4 in IA, 39.7 in MA, and 30.4 in RE.
In the mountain stages cyclists reached a mean heart rate of 129.6 ± 7.8 beats·min−1. The mean total time of flat stages was 356.2 ± 84.5 min. The mean stage time over IAT was 21.1 ± 16.3 min, the IA time was 111.6 ± 41.6 min, the MA was 121.3 ± 52.9, and the RE time was 102.3 ± 53.1 min (Fig. 2). The percentage of participation related to total time was 6.2 in AN exercise intensity, 32.4 in IA, 34.1 in MA, and 27.3 in RE.
In individual time-trial stages, cyclists reached a mean heart rate of 171.2 ± 10.7 beats·min−1. The mean total time of ITT stages was 38.4 ± 20.5 min. The mean stage time over IAT was 16.7 ± 15.3 min, the IAe time was 21.1 ± 20.4 min, the MA was 0.6 ± 1.2, and the regeneration time was 0 min (Fig. 2). The percentage of participation related to total time was 57.1 in AN exercise intensity, 41.7 in IA, 1.2 in MA, and 0 in RE.
Tour de France.
During the Tour cyclists achieved a mean heart rate for the overall race of 134 ± 18.6 beats·min−1. The mean total time of each stage was 259.4 ± 119.9 min. The mean stage time over IAT was 24.7 ± 26 min, the IA time was 79.6 ± 48.3 min, the MA was 89.5 ± 54.9, and the RE time was 65.4 ± 69.7 min. The percentage of participation related to total time of the race was 16.8 in AN exercise intensity, 29.2 in IA, 31.9 in MA, and 25.2 in RE (Table 4).
During the flat stages cyclists reached a mean heart rate of 125.7 ± 13.7 beats·min−1. The mean total time of the in-line stage was 298.1 ± 64.3 min. The mean stage time over IAT was 20.6 ± 23.8 min, the IA time was 82 ± 34.8 min, the MA was 106.3 ± 35.6, and the regeneration time was 89 ± 78.4 min (Fig. 2). The percentage of participation related to total time was 7.5% in AN exercise intensity, 29.4 in IA, 36.1 in MA, and 26.9 in RE.
In the mountain stages cyclists reached a mean heart rate of 134.6 ± 9.9 beats·min−1. The mean total time of mountain stages was 300.2 ± 120.6 min. The mean stage time over IAT was 35.1 ± 30.6 min, the IA time was 106.9 ± 58.4 min, the MA was 106.3 ± 56.9, and the RE time was 52.1 ± 30.5 min (Fig. 2). The percentage of participation related to total time was 14.8 in AN exercise intensity, 36 in IA, 33.1 in MA, and 16.1 in RE.
In individual time-trial stages, cyclists reached a mean heart rate of 165.5 ± 11.68 beats·min−1. The mean total time of ITT stages was 52.2 ± 29.8 min (Fig. 2). The mean stage time over IAT was 23.07 ± 22.6 min, the IA time was 27.25 ± 31.8 min, the MA was 1.86 ± 2.73, and the RE time was 0 min. The percentage of participation related to total time was 54.6 in AN exercise intensity, 38.9 in IA, 6.2 in MA, and 0 in RE.
Differences between races and type of stages.
There are statistical differences in RE between the Tour and Vuelta during mountain stages and TT time during mountain and ITT stages, without there being differences in the other intensities.
In the Vuelta we found significant differences in IA, TT, and mHR between flat and mountain stages. Also there are differences in IA, MA, RE, TT, and mHR between mountain and ITT stages and between flat and ITT stages
In the Tour there are significant differences in AN, RE, and mHR between flat and mountain stages. Also there are differences in IA, MA, RE, TT, and mHR between flat and ITT stages. Finally, there are differences in AN, IA, MA, RE, TT, and mHR between mountain and ITT stages.
Our study is one of the first to evaluate HR response during two professional multi-stage road cycling races involving top level cyclists. The data support the idea that professional cycling is a long-duration, high intensity sport, with a high participation of aerobic metabolism (time at IA was 75.2 ± 47.6 and 79.6 ± 48.3 min daily for the Vuelta and the Tour, respectively, and MA were 97.2 ± 57.4 and 89.5 ± 54.9 min), as well as of anaerobic metabolism, with cyclists spending nearly 20 min over IAT.
Based on these HR responses and our laboratory tests, we found that each cyclist spent about 93 min in flat stages and 123 min in mountain stages (32% of the total stage time in flat and 40% in mountain stages) riding at an intensity greater than 70% of V̇O2max, and between 18 and 27 of these minutes, moreover, were at an intensity greater than 90% of V̇O2max, depending on the type of stage. In all, nearly 75% of each stage was spent above 50% of V̇O2max.
In the same way we found that during ITT cyclists performed a mean of 20 min over 90% of V̇O2max (16.7 min during the Vuelta and 23 min in the Tour). Lucia et al. (9) studied the global intensity of exercise during a Tour of France, calculating the percentage of time over ventilatory thresholds (VT1 and VT2). They reported a contribution about 7% over the 87.5% of V̇O2max, and 23% between 71.2 and 87.5% of V̇O2max. We found a greater contribution (12.9% during the Vuelta and 16.7 during the Tour) over 90% of V̇O2max and between 70 and 90% of V̇O2max (29.4 and 29.1%). In addition, Lucia et al. (9) reported a greater percentage of participation at an intensity of exercise over 90% of V̇O2max during ITT versus flat, high mountain, and medium mountain stages; however, we found that if this percentage of participation is expressed in absolute time (minutes), it is quite similar (20 min in ITT, 18 min in flat, and 27 min in mountain stages of the Vuelta and Tour together) in spite of the percentage differences.
One of the reasons that the mountain stages are considered harder than flat stages by coaches and cyclists could be the tendency (Fig. 2) of the former to have longer time periods at IA intensity than flat stages both in the Vuelta and Tour. It should also be pointed out that the time expended in AN intensity has a tendency to be longer in the Tour than in the Vuelta.
These data confirm the observation that professional stage racing is a long-duration, high intensity sport (Neumann (12)) that requires participants to possess high V̇O2max and lactate thresholds. Indeed, our subjects had a mean V̇O2max of 73.5 mL·kg−1·min−1 and lactate thresholds that were reached at 90% of max. These data are similar to previously reported findings (2,3,8,14).
The HR data support findings from another study in which the HR response during an amateur stage race that consisted of two IL and TT stages was recorded (13). In contrast to a conclusion from that study, we found that the HR response was related to course profile rather than being stochastic (Fig. 1). We also noted that the time spent at AN was roughly 20 min regardless of stage type, which may mean that anaerobic capacity could be limited and/or limits performance, as previously suggested (14,17).
Collectively our data quantitatively describe the varying intensity of professional stage racing, which should help coaches design proper exercise regimens. These data may be more useful for the construction of training programs than previously reported data on the intensity of professional cycling (1,15). In these studies the intensity of effort was either determined indirectly from distance, time, velocity, and change in altitude or from a race simulation. Because of methodological constraints in these studies, the authors were unable to account for the variance in intensity that occurs during a race.
We realize that our methodology also had some limitations. Specifically, several factors affect the HR response to exercise, such as temperature, hydration status, glycogen depletion, and adaptation to training (6,10,11,19). High temperature and dehydration elevate the HR response, for example, whereas glycogen depletion and adaptation to training lower it. Consequently, it is possible that we either underestimated or overestimated the time spent at each exercise intensity. The magnitude of our error was probably small, since cyclists are generally adept at maintaining proper levels of hydration during a race (15), which minimizes increases in body temperature, and HR (5,18). Similarly, professional cyclists are also adept at maintaining a good nutritional profile (4), thereby minimizing glycogen depletion. Lastly, it is unlikely that our cyclists realized a significant training effect from their race participation since they were experienced cyclists who typically ride over 30,000 km·yr−1. Possible interpretive errors caused by the aforementioned factors that affect the HR response to exercise may have also been minimized by our large sample size. Overall, there were 658 HR response profiles, since each of the 18 subjects completed nearly 44 stages during the course of both races.
Overall, our study is the first to quantify the daily varying intensity of professional cyclists during two long-stage races. Our data confirm the observation that professional cycling is an arduous sport because approximately 93 min in flat and 123 min in mountain stages were performed above 70% of V̇O2max. In addition, the time spent over IAT was roughly 20 min regardless of stage type, suggesting that the anaerobic capacity limits performance during road cycling competition.
We gratefully acknowledge the efforts of the cyclist participants in this investigation and the staff of 1995 Mapei-GB and ONCE professional cycling teams for technical support. We thank Robin Walker for the final revision of the manuscript and Norberto Corrales, Professor of Statistics, and Pablo Rodriguez-Camblor for statistical assistance.
This manuscript is part of the Ph. D. dissertation: “Parameters related to acute and chronic fatigue during competition, in professional road cycling,” presented at the Oviedo University, Spain, in September, 1998.
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