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  • Author: Jürgen M. Steinacker x
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Gunnar Treff, Kay Winkert, Katja Machus, and Jürgen M. Steinacker

Purpose: Ramp tests are continuously increasing exercise tests used for the determination of maximal oxygen uptake (V˙O2max), which is identifiable by a plateau in oxygen uptake despite increasing mechanical power output (LOAD). On wind-braked rowing ergometers (RowErg), it is hardly feasible to ensure a continuous increase in LOAD until test termination, as neither resistance nor stroke frequency is externally adjustable but depends on the rower. To enable ramp tests on RowErg, the authors produced visual stroke-by-stroke feedback showing target and actual LOAD to the rower. The software supports automatic test termination (TERMauto) if LOAD ceases to increase. The authors aimed to evaluate linearity of the LOAD increment and calculate the difference between TERMauto and test duration at subjective exhaustion. Materials: Twenty-eight highly trained male rowers performed a ramp test until subjective exhaustion on RowErg, targeting an increment of 35 W·min−1. LOAD was measured as work per time via external force and position sensors and visualized on a computer screen. TERMauto was deactivated, but all data were logged. Test duration at subjective exhaustion was subsequently compared with virtual test duration at TERMauto calculated from the log files. Results: Regression between time and LOAD was y = 167 + 34.6 W (r = .99). Individual correlations ranged from .97 to 1.0. TERMauto caused 12- to 35-s-shorter test durations than subjective exhaustion in 4 rowers, leading to an underestimation in V˙O2max not higher than 1.2% or 3.7%. Conclusion: This setup allows one to perform ramp tests on RowErg with continuously increasing LOAD until TERMauto. In particular cases V˙O2max might be slightly underestimated at TERMauto.

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Kay Winkert, Johannes Kirsten, Rupert Kamnig, Jürgen M. Steinacker, and Gunnar Treff

Purpose: Automated metabolic analyzers are frequently utilized to measure maximal oxygen consumption (V˙O2max). However, in portable devices, the results may be influenced by the analyzer’s technological approach, being either breath-by-breath (BBB) or dynamic micro mixing chamber mode (DMC). The portable metabolic analyzer K5 (COSMED, Rome, Italy) provides both technologies within one device, and the authors aimed to evaluate differences in V˙O2max between modes in endurance athletes. Methods: Sixteen trained male participants performed an incremental test to voluntary exhaustion on a cycle ergometer, while ventilation and gas exchange were measured by 2 structurally identical COSMED K5 metabolic analyzers synchronously, one operating in BBB and the other in DMC mode. Except for the flow signal, which was measured by 1 sensor and transmitted to both devices, the devices operated independently. V˙O2max was defined as the highest 30-second average. Results: V˙O2max and V˙CO2@V˙O2max were significantly lower in BBB compared with DMC mode (−4.44% and −2.71%), with effect sizes being large to moderate (ES, Cohen d = 0.82 and 1.87). Small differences were obtained for respiratory frequency (0.94%, ES = 0.36), minute ventilation (0.29%, ES = 0.20), and respiratory exchange ratio (1.74%, ES = 0.57). Conclusion: V˙O2max was substantially lower in BBB than in DMC mode. Considering previous studies that also indicated lower V˙O2 values in BBB at high intensities and a superior validity of the K5 in DMC mode, the authors conclude that the DMC mode should be selected to measure V˙O2max in athletes.