Reliability and Validity of Physiological Data Obtained Within a Cycle-Run Transition Test in Age-Group Triathletes

摘要

This study examined the validity and reliability of a sequential “Run-Bike-Run” test (RBR) in age-group triathletes. Eight Olympic distance (OD) specialists (age 30.0 ± 2.0 years, mass 75.6 ± 1.6 kg, run VO2max 63.8 ± 1.9 ml· kg^-1· min^-1, cycle VO2peak 56.7 ± 5.1 ml· kg^-1· min^-1) performed four trials over 10 days. Trial 1 (TRVO2max) was an incremental treadmill running test. Trials 2 and 3 (RBR1 and RBR2) involved: 1) a 7-min run at 15 km· h^-1 (R1) plus a 1-min transition to 2) cycling to fatigue (2 W· kg^-1 body mass then 30 W each 3 min); 3) 10-min cycling at 3 W· kg^-1 (Bsubmax); another 1-min transition and 4) a second 7-min run at 15 km· h^-1 (R2). Trial 4 (TT) was a 30-min cycle - 20-min run time trial. No significant differences in absolute oxygen uptake (VO2), heart rate (HR), or blood lactate concentration ([BLA]) were evidenced between RBR1 and RBR2. For all measured physiological variables, the limits of agreement were similar, and the mean differences were physiologically unimportant, between trials. Low levels of test-retest error (i.e. ICC <0.8, CV<10%) were observed for most (logged) measurements. However [BLA] post R1 (ICC 0.87, CV 25.1%), [BLA] post Bsubmax (ICC 0.99, CV 16.31) and [BLA] post R2 (ICC 0.51, CV 22.9%) were least reliable. These error ranges may help coaches detect real changes in training status over time. Moreover, RBR test variables can be used to predict discipline specific and overall TT performance. Cycle VO2peak, cycle peak power output, and the change between R1 and R₂ (deltaR₁R₂) in [BLA] were most highly related to overall TT distance (r = 0.89, p < 0. 01; r = 0.94, p < 0.02; r = 0.86, p < 0.05, respectively). The percentage of TR VO_2max at 15 km· h^-1, and deltaR₁R₂ HR, were also related to run TT distance (r = -0.83 and 0.86, both p < 0.05).Key points class="unordered" style="list-style-type:disc">It is extremely important to ensure that the measurements made as part of research or athlete support work are adequately reliable and valid.The modified Millet triathlete “Run-Bike-Run” (RBR) test allows both for important physiological variables that are normally obtained from isolated tests (such as cycle VO_2peak and peak power output) to be determined, and for measurement of the extent to which an athlete adapts to a cycle-run transition (T2).The data reported in this paper regarding the test-retest reliability of the modified RBR, and its validity relative to cycle-run time-trial performance in male age-group triathletes, may help coaches determine the extent to which changes on test measures are likely due to training adaptation rather than to measurement error. class="kwd-title">Key words: Multi-discipline, reproducibility, time-trial, test, adaptation class="head no_bottom_margin" id="sec1-1title">IntroductionCoaches require a reasonable degree of confidence that the changes in test measures that are obtained by their athlete(s) are due to training adaptations rather than due to measurement error (Atkinson and Nevill, ). The scores that are obtained on a laboratory test must also adequately reflect the needs of the sport. Therefore, the physiological measures that are obtained within any “sport specific test” should be shown to be reliable, and to be relevant to performance in that sport.Although triathlon involves a sequential swim, cycle and run; swim test results have been shown not to be significantly related to triathlon performance (Millet et al., ). In contrast, physiological data obtained from both isolated (maximal incremental and submaximal) cycle or run tests have successfully predicted triathlete race or time trial performance (Hue, ; Schabort et al., ; Zhou et al., ). Schabort et al., , for example, found cycle and run blood lactate concentration ([BLA]) at 4 W· kg^-1 and 15 km· h^-1, respectively; cycle peak oxygen uptake (VO_2peak); and peak treadmill running velocity (TRV_max) to be the best predictors of Olympic distance (OD) (1.5 km swim, 40 km cycle, 10 km run) triathlon performance in South African National Squad triathletes. End cycle [BLA] and total distance run within a 30-min cycle-20-min run combined laboratory time trial were also shown to account for 93% of the variation in draft-legal OD triathlon finishing times of Elites (Hue, ). However, time trials do not provide the scientist or coach with information regarding peak workload or the anaerobic threshold - both of which measures can be important for training prescription and analysis.As adaptation to the cycle-run transition has been shown to affect both triathlon run pacing and, therefore, finishing position (Vleck et al., ), assessment of the ability to run after cycling (Millet and Vleck, ) is also an important and sports specific component of the analysis of a triathlete (Vleck and Alves, ). Millet et al. (Millet et al., ; Millet and Bentley, ) were the first to assess the relationship between triathlete race performance and physiological variables obtained from a sequential, laboratory-based, “run-bike-run” (RBR) test. The latter comprises submaximal running, maximal and then submaximal cycling, followed by an additional submaximal running bout. The test is unique in so far as it allows both for important physiological variables that are normally obtained from isolated tests (such as cycle VO_2peak and peak power output [Schabort et al., ]) to be determined, and measurement of the extent to which the athlete adapts to a cycle-run transition (T2). As both running bouts during the sequential RBR are conducted at the same speed, the first run (R₁) of the test acts as a control to which physiological data from the second, post-cycle, run (R₂) (such as running economy) can be compared, and this allows for the efficiency of running after cycling to be established.Both cycle VO_2max (r = -0.80, p < 0. 001) and cycle peak power output (W_peak) (r = -0.85, p < 0.001), obtained within the Millet RBR test, have been found to be significantly related to the OD performance times of French National Squad triathletes. However, certain aspects of the test are open to modification. Firstly, both runs are conducted at a speed corresponding to the subject’s current personal best OD triathlon run time, although set workloads are usually used to measure running economy (Saunders et al., , ). Secondly, the protocol that is used to determine cycle VO_2max and W_peak within the incremental “bike” of the RBR (i.e. 3-minute increments of 70 W from an initial workload of 70 W until 280 W, and then 35 W increases every 2 minutes until exhaustion) has not been validated for that purpose. Thirdly, the submaximal cycle is conducted at 80% of the W_peak that was arrived at within the preceding incremental cycle section. The physiological responses to cycling at said workload has not yet been specifically related to cycling and overall triathlon performance, as has power output standardised to body mass (Schabort et al., ). Power output standardised to body mass may in itself be an easier measure than power at 80% W_peak to use for tracking changes in cycling economy over time.Moreover, although prior cycling appears to have more of an adverse affect on subsequent running in middle-level, “age-group", triathletes than in elite triathletes (Millet et al., href="#ref24" rid="ref24" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380331">2001), almost all of the cycle-run transition test research to date (see Vleck and Alves [href="#ref39" rid="ref39" class=" bibr popnode">2011] for bibliography) has involved National Squad athletes.The focus of this study, therefore, was to investigate the reliability and validity of a version of the Millet laboratory-based sequential “Run-Bike-Run” (RBR) transition test (Bentley et al., href="#ref5" rid="ref5" class=" bibr popnode">2005), that has been modified so as to address some of the aforesaid limitations, in well trained age-group male triathletes. The modified RBR test incorporates aspects of both Millet et al.’s and Schabort et al. ‘s approach (Millet et al., href="#ref23" rid="ref23" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380335">2000href="#ref23" rid="ref23" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380315">; href="#ref24" rid="ref24" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380302">2001; href="#ref25" rid="ref25" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380359">2003; Millet and Bentley, href="#ref26" rid="ref26" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380362">2004; Schabort et al., href="#ref32" rid="ref32" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380340">2000). It still involves submaximal running, maximal then submaximal cycling, and an additional submaximal running bout. However, both runs are conducted at a standardised speed of 15 km· h^-1 - the [BLA] after which was shown by Schabort et al., href="#ref32" rid="ref32" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380351">2000 to be related to OD performance time. Moreover, the protocol of the incremental cycle section of the RBR has been amended to one that has been previously validated for the determination of W_peak in cyclists (Bentley and McNaughton, href="#ref4" rid="ref4" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380347">2003) (i.e. to one with 30 W increments every 3 min). Additionally, the submaximal cycle section has also been standardised relative to body mass - but to 3 W· kg^-1 rather than the 4 W· kg^-1 the [BLA] after which was demonstrated to be related to OD performance (Schabort et al., href="#ref32" rid="ref32" class=" bibr popnode tag_hotlink tag_tooltip" id="__tag_331380314">2000) because 4 W· kg^-1 may prove too demanding for age-group athletes.