Validity and Reliability of the Axiom Powertrain Cycle Ergometer When Compared with an SRM Powermeter

Abstract

The purpose of this study was to determine the validity and the reliability of a stationary electromagnetically-braked cycle ergometer (Axiom PowerTrain) against the SRM power measuring crankset. Nineteen male competitive cyclists completed four tests on their bicycle equipped with a 20-strain gauges SRM crankset: a maximal aerobic power (MAP) test and three 10-min time trials (TTs) with three different simulated slopes (0, 3, and 6 %). The Axiom ergometer overestimated (p < 0.05) the SRM power output during the last stage of the MAP test and during TTs, by 5 % and 12 %, respectively. Power output (PO) of the Axiom ergometer drifted significantly (p < 0.05) with the time during TT. These findings indicate that the Axiom ergometer does not provide a valid measure of PO compared with SRM. However, the small coefficient of variation (2.2 %) during the MAP test indicates that the Axiom provides a reliable PO and that it can be used e.g. for relative PO comparisons with competitive cyclists during a race season.

Key words

Power output - SRM system - Axiom PowerTrain - accuracy

References

• 1 Atkinson G, Nevill A M. Statistical methods for assessing measurement error (reliability) in variables relevant to sports medicine.  Sports Med. 1998;  26 217-238
• 2 Balmer J, Davison R C, Coleman D A, Bird S R. The validity of power output recorded during exercise performance tests using a Kingcycle air-braked cycle ergometer when compared with an SRM powermeter.  Int J Sports Med. 2000;  21 195-199
• 3 Balmer J, Davison R C, Bird S R. Reliability of an air-braked ergometer to record peak power during a maximal cycling test.  Med Sci Sports Exerc. 2000;  32 1790-1793
• 4 Bland J M, Altman D G. Statistical methods for assessing agreement between two methods of clinical measurement.  Lancet. 1986;  1 307-310
• 5 Candau B, Grappe F, Ménard M, Barbier B, Millet G Y, Hoffman M, Belli A, Rouillon J D. Simplified deceleration method for assessment of resistive forces in cycling.  Med Sci Sports Exerc. 1999;  31 1441-1447
• 6 Coyle E F, Feltner M E, Kautz S A, Hamilton M, Montain S, Baylor A, Abraham L, Petrek G. Physiological and biomechanical factors associated with elite endurance cycling performance.  Med Sci Sports Exerc. 1991;  23 93-107
• 7 Finn J P, Maxwell R, Withers R T. Air-braked cycle ergometers: Validity of the correction factor for barometric pressure.  Int J Sports Med. 2000;  21 488-491
• 8 Grappe F, Candau R, Barbier B, Hoffman M, Belli A, Rouillon J D. Influence of tyre pressure and vertical load on coefficient of rolling resistance and simulated cycling performance.  Ergonomics. 1999;  10 1361-1371
• 9 Hickey M S, Costill D L, McConee G K, Widrick J J, Tanaka H. Day to day variation in time trial cycling performance.  Int J Sports Med. 1992;  13 467-470
• 10 Hopkins W G, Hawley J A, Burke L M. Design and analysis of research on sport performance enhancement.  Med Sci Sports Exerc. 1999;  31 472-485
• 11 Jones S M, Passfield L. Dynamic calibration of bicycle power measuring cranks. Haake SJ The Engineering of Sport. Oxford; Blackwell Science 1998: 265-274
• 12 Lawton E W, Martin D T, Lee H. Validation of SRM Power Cranks Using Dynamic Calibration. Fifth IOC World Congress, Oct 31 - Nov 5, 1999. Sydney; International Olympic Committee 1999
• 13 Martin J C, Milliken D L, Cobb J E, McFadden K L, Coggan A R. Validation of a mathematical model for road cycling power.  J Appl Biomech. 1998;  14 276-291
• 14 Millet G P, Tronche C, Fuster N, Bentley D J, Candau R. Validity and reliability of the Polar®S710 mobile cycling powermeter.  Int J Sports Med. 2003;  24 156-161
• 15 Nevill A. Why the analysis of performance variables recorded on a ratio scale will invariably benefit from a log transformation.  J Sports Sci. 1997;  15 457-458
• 16 Nevill A M, Atkinson G. Assessing agreement between measurements recorded on a ratio scale in sports medicine and sports science.  Br J Sports Med. 1997;  31 314-318
• 17 Paton C D, Hopkins W G. Tests of cycling performance.  Sports Med. 2001;  31 489-496
• 18 Perrey S, Grappe F, Girard A, Bringard A, Groslambert A, Bertucci W, Rouillon J D. Physiological and metabolic responses of triathletes to a simulated 30 min time trial in cycling at self-selected intensity.  Int J Sports Med. 2003;  24 138-143
• 19 Reiser M, Meyer T, Kindermann W, Daugs R. Transferability of workload measurements between three different types of ergometer.  Eur J Appl Physiol. 2000;  82 245-249
• 20 Vandewalle H, Peres G, Heller J, Panel J, Monod H. Force-velocity relationship and maximal power on a cycle ergometer.  Eur J Appl Physiol. 1987;  56 650-656
• 21 Van Praagh E, Bedu M, Roddier P, Coudert J. A simple calibration method for mechanically braked cycle ergometers.  Int J Sports Med. 1992;  13 27-30