The energetics of competitive road race cycling.

Abstract:

One of the roles of the sport scientist is to ascertain the demands of a competitive event, and establish training regimes for success in the chosen event. The aim of this thesis was to establish the relative demands, and establish the physiological responses to road race cycling.

Study 1 - Physiological Responses of Competitive Road Race Cyclists.

Research has shown that the Kingcycle (EDS Portaprompt Ltd, High Wycombe, UK.) maximal minute power (MMP) test correlates strongly to performance during endurance time trial cycling events (Davison et al., 1997). The aim of this study was to evaluate the test as a method of ascertaining a relative exercise intensity in a homogenous population of racing cyclists. Eleven male trained cyclists consented to participate in this study. Following familiarisation, subjects underwent two MMP tests, followed by a further six 10-minute submaximal Kingcycle trials at relative exercise intensities (60, 65, 70, 75, 80, 85% MP). The coefficient of variation for maximal minute power output between MMP tests was 1.72% (SEE 2.6%). Submaximal test data revealed that subjects had similar lactate inflection point (68.9 ± 2.2% MMP). Thus it appears the figures derived from MMP are reliable, and the figures attained reflect lactate kinetics thus explaining the high correlation between MMP and performance.

Study 2 - Data Collection from Competitive British Cycling Federation Events.

Previous research has used heart rate data to assess the demands of road cycling by establishing a heart rate:power relationship in the laboratory and extrapolating the laboratory data to heart rate data recorded in the field (Palmer et al., 1994). The development of a portable powermeter (SRM, Julich, Welldorf, Germany.) allows for the simultaneous recording of power and heart rate in the field. The aim of this study was to use the SRM powermeter to evaluate this method of heart rate analysis during competitive cycling competition. Nine male subjects participated in this study. Following familiarisation, subjects underwent MMP testing ± 7 days of a road race in which subjects competed and recorded the race with an SRM powermeter. Power output, pedal cadence, heart rate and speed/distance were recorded from the competitive races at 1 second resolution. Five subjects also underwent Wingate testing in the laboratory during the same time period. Mean power output from the races was 264 watts, mean heart rate was 169 beats min'1, which was significantly higher (11 beats.min'1, p<0.05) than the predicted heart rate from laboratory tests similar to Palmer et al. (1994). The data also revealed road race cycling to be highly intermittent in nature, with high power outputs (>MMP) recorded during hill climbing. The findings therefore question i) the methods used by Palmer et al., (1994), and, ii) the ecological validity of the previous studies that have attempted to simulate road race cycling (Brouns et al., 1989, Palmer et al., 1997).

Study 3 - Correlates of Cycling Hill Climb Ability.

Study 2 revealed the importance of hill climbing to the road race cyclist. Hill climbing during road race cycling generally involves seated and standing cycling, the aim of this study was to evaluate the simulated hill climbing ability of competitive cyclists relative to standard stationary seated ergometer testing (Kingcycle). Following familiarisation, eight trained cyclists undertook Kingcycle MMP, Wingate and simulated climbing (Woodway treadmill, Guhb, Germany.) tests. Two simulated climbs were conducted, the first at a 6% gradient for 6 km, and the second at a 12% gradient for 1 km. Subjects sustained 92.6 % of MMP during the 6 km climb, despite recording the same % of maximum heart rate, and lower blood lactate concentration (BfLac'j) than when exercising at 85% in study 1. MMP test data and Wingate mean power both significantly correlated to performance time when data were expressed relative to body mass (r2 >0.79). These findings indicate that seated stationary ergometer testing can predict hill climb ability, and that when riding on a gradient the relationship between power, heart rate, and B[Lac ] is different when compared to level cycling.

Study 4 - The Effect of Gradient on Cardio Respiratory Measures during Submaximal Cycling.

Study 3 revealed that riders can sustain higher power outputs on a gradient than when compared to level cycling, this could be attributed to the changes in cycling position during hill climb performance testing. The aim of this study was to evaluate the submaximal cardio respiratory responses to level and graded seated cycling. ii Six trained cyclists undertook MMP testing followed by two submaximal trials at (60% of MMP) on a motorised treadmill (Woodway). Submaximal trials consisted of a level (0%) and graded (6%) condition. There was no significant difference for power output, heart rate, RER and gross mechanical efficiency between level and graded cycling (p>0.05). Significantly lower oxygen consumption (V02), Ventilation (VE), and carbon dioxide production (VC02) values were recorded during graded cycling. These results indicate that respiratory measures during submaximal cycling are lower during graded cycling, possibly explaining the high power outputs sustained during field and laboratory hill climb performance.

Study 5 - The Effect of Glucose Polymer Supplementation on Simulated Road Race and Even Power Cycling.

The data from study 2 indicates potential limitations with the method of evaluation of road cycling by Palmer et al. (1994), and the previous attempts to simulate road race cycling (Brouns et al., 1989, Palmer et al., 1997). The aim of this study was to construct a valid road race laboratory simulation protocol, and compare the effects of glucose polymer ingestion and the physiological responses to even power and simulated road race cycling. Six male trained cyclists undertook MMP testing followed by two even power, and two simulated road race trials. Each condition consisted of a glucose polymer (Tekno fuel, Medway, UK) and a placebo trial. The trials were two hours in duration. The mean power output equated to 60% of MMP. The trials were followed by a 2 km hill climb performance test at a 6% gradient. A fresh performance test was also completed by all subjects. There were no significant differences between even power and simulated road race cycling for mean power, heart rate, V 02, ammonia (NH3), urea, economy, or efficiency values during the trials (p>0.05). Significantly higher B[Lac ], and VC02 production were observed during simulated road race cycling (p<0.05). Glucose polymer ingestion improved post even power (5.3%) and post simulated road race (6.01%) cycling performance. Power output sustained during the performance test was significantly lower following the simulated road race trial when compared to fresh and even power trials. Better relative performance following simulated road race cycling was found in riders with lower plasma NH3 and urea concentrations (r>0.81), and in those riders with the higher B[Lac'] following the performance test (r=-0.81). These factors did not significantly correlate to post even power performance. These results indicate there are specific physiological demands of intermittent road race cycling when compared to performance following even power cycling.

The findings from this study highlight the specific demands of road race cycling, the potential problems of interpreting heart rate data in the field, and the physiological responses of trained cyclists during hill climbing in the field or simulated in the laboratory.