Carmichael, R. D., Heikkinen, D. J.,& Mertens, E. (2013). Impact of cycling intensity on cycle-run transition. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 608.

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This study determined the impact of intensity during the final km of a cycling bout on subsequent run performance and overall cycle-run performance in well-trained female triathletes N = 9). Ss completed two cycle-run sessions (20 km cycle, 5 km run) separated by a minimum of seven days. The intensity of the first 19 km of the cycling bouts was equivalent to peak power at 70% of VO2max and the final 1 km varied between power achieved at 95% of VO2max (high intensity) and power achieved at 50% of VO2max (low intensity). The 5 km run was completed as fast as possible. Blood lactate concentration was measured before the run and after each km of the run was completed.

Mean blood lactate concentration was significantly higher following the cycling bout ending with a high-intensity effort rather than a low-intensity effort. Run performance was not significantly different between high and low cycling intensities. As well, no significant differences were found between the two overall cycle-run sessions.

Implication. Despite increases in blood lactate concentration, cycling intensity during the final stages of a 20 km cycling bout does not impact run or cycle-run performance in well-trained female triathletes. The improvements in lactate clearance via oxidation and gluconeogenesis that are characteristic of endurance trained athletes may have offset any negative consequences of the high lactate concentrations during the run following the high intensity cycle. Taken at face value, the running performance in a triathlon is independent of the intensity of effort involved in the cycling leg of the event.

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