A laboratory and field comparison of gross efficiency at an absolute, relative and performance intensity
Saunders, S., Brown, M. and Coleman, D. 2014. A laboratory and field comparison of gross efficiency at an absolute, relative and performance intensity.
|Authors||Saunders, S., Brown, M. and Coleman, D.|
Gross efficiency is a measure of the ability to convert stored energy into power and is included as an important element in the majority of performance models. Currently, gross efficiency measured in a laboratory is assumed to be representative of outdoor cycling, despite limited empirical research in the field. PURPOSE: To investigate gross efficiency in an outdoor environment and explore the relationship between laboratory testing at an absolute, relative and Time-Trial (TT) performance intensity. METHODS: 18 trained male cyclists (age 40.6±9.4 yrs, mass 82.7±13.7 kg, maximum minute power MMP370.4±43.8 W.min-1, VO2max 45.3±24.1 ml.kg-1.min-1) completed a VO2max test inthe laboratory prior to efficiency measurement. Participants cycled at 150W, 60%MMP and completed a 16.109 km TT both in a laboratory and at a closed road circuit. Laboratory (L) and field (F) based tests were randomised and the same portable gas analysis device used for both conditions. Laboratory testing was performed on a stationary ergometer and field testing on the participants’ road bicycle fitted with a power wheel device. RESULTS: Gross efficiency was significantly lower in the field compared to laboratory testing; 150W (L: 20.4%, F: 18.4%), 60% MMP (L: 23.2%,F: 21.3%) and during TT performance (L: 24.5%, F: 21.7%), (p<0.001 in all cases).There was a significant positive relationship between laboratory and field based gross efficiency when measured at 60% MMP (r=0.61, p=0.008) and TT performance intensity (r=0.65, p=0.005), but not at 150W (p>0.05). CONCLUSION: This study provides evidence to support the measurement of gross efficiency at performance intensities in the laboratory. These results demonstrate that the measurement of gross efficiency in a field based environment is significantly lower than laboratory measures. These novel findings could be used to optimise outdoor training intensities which otherwise would not have accounted for the observed reductions in gross efficiency. Furthermore these results show the possibility for the underestimation of energy expenditure whilst cycling outside as opposed to a laboratory environment.
|Publication process dates|
|Deposited||16 Sep 2014|
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