Drafting behind another cyclist reduces energy expenditure and oxygen uptake compared to riding alone at the same speed (McCole et al., 1990). This leads to a significantly faster subsequent running performance in triathlon (Hausswirth et al., 2001). When cyclists alternate between a draft / non-draft position, power output also alternates, since drafting allows ~30% power reduction without a concomitant decrease in speed (Kyle, 1979). The aim of the present study was to determine if the frequency of power output alternation during cycling would affect subsequent running performance. Methods: Eleven male triathletes completed a graded cycle test to determine power at 35% delta. Two performance tests were then conducted, each comprising of a thirty minute cycling protocol followed by a 5 km free pace run. Mean cycling power was equal for both trials; however the frequency of power alternations differed. In one trial cycling power output alternated every five minutes (CR5MIN), whereas in the other trial cycling power output alternated every one minute (CR1MIN). Power output was set to alternate 15% above and below the 35% delta value. Results: A significant difference was observed for mean heart rate between cycle trials (p = 0.045), however no significant difference was observed for mean oxygen uptake, minute ventilation, respiratory exchange ratio, blood lactate, rating of perceived exertion or pedal cadence (p > 0.05). No significant difference was found between trials for the subsequent running performance time or mean heart rate (p > 0.05). Discussion: The present results show that when utilising a power alternation strategy in cycling, the frequency of power alternation (maximum five minutes, minimum one minute) does not significantly affect subsequent running performance. The results of this study agree with Brickley et al. (2007) who suggest that when the average PO between two protocols is similar, variations in exercise intensity do not significantly affect muscle metabolism, demonstrated by the similar overall oxygen uptake and blood lactate values for both cycle protocols.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Published by Vrije Universiteit Brussel. All rights reserved.