The cycle section in triathlon is influenced by race tactics, terrain and coursetechnicality often resulting in a pattern of highly variable power output. The extent to which these factors affect the subsequent running performance is unclear. We aimed to determine how a 1 h triathlon-specific cycling trial (with a highly variable power distribution) affects subsequent run performance and how an individual`s cycling power profile relates to any decrement in run performance after variable power cycling. Methods: After ethical approval was obtained, twelve well-trained male triathletes (age 28 ± 5 y; peak 4.9 ± 0.5 L/min; body mass 73.5 ± 7.7 kg, mean ± SD) performed an initial incremental cycle ergometer test to determine their maximal aerobic power (MAP). Subjects also completed a series of six maximal effort cycling intervals (6 s, 15 s, 30 s, 1 min, 4 min, and 10 min) to establish their power/duration relationship (power profile). Subsequently, each subject performed two experimental 1 h cycle-run trials on different days at either triathlon-specific variable (VAR) or constant (CON) power (both equivalent to 65% of MAP) followed by a 9.3 km run at race-pace (four laps of a road course). Subjects also completed a control 9.3 km run with no preceding exercise (NO-EX). Blood lactate (BLa), rating of perceived exertion (RPE) and heart rate (HR) were measured at 20, 40 and 60 min during the cycle trials. The split and total times for the 9.3 km run were also recorded. Results: The overall 9.3 km run time was substantially slower (42 ± 37 s, mean ± 90% confidence limits (CL); standardised difference 0.21 ± 0.19) after VAR (35:39 ± 3:19 min:s, mean ± SD) compared with CON (34:57 ± 2:50 min:s). The decrement after VAR appeared primarily in the early stages of the run (35 ± 20 s, mean ± 90% CL slower after 2 laps). Both runs after the cycle exercise were substantially slower than NO-EX (33:49 ± 2:33 min:s). During the 1 h cycling mean BLa (8.2 ± 2.6 vs. 3.3 ± 1.5 mM), HR (159 ± 15 vs. 155 ± 13 bpm) and RPE (6.9 ± 1.1 vs. 6.2 ± 1.5 units) were substantially higher after VAR compared with CON. Subjects with higher peak power output during the 6 and 15 s efforts, and higher mean power in the 1 and 4 min efforts, had the lowest reduction (0.32-0.39 ±~0.45, r-value ± 90% CL) in run time after VAR. Discussion: Cycling courses with a variable power profile are likely to result in an impaired ability to maintain performance during a subsequent run. Triathletes should aim to improve short-term peak power and medium length mean power to minimise the impact of variable power cycling, and limit the decrease in running ability during the early stages of the subsequent run at race-pace.
© Copyright 2012 17th Annual Congress of the European College of Sport Science (ECSS), Bruges, 4. -7. July 2012. Veröffentlicht von Vrije Universiteit Brussel. Alle Rechte vorbehalten.