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The between and within day variation in gross efficiency.

Noordhof DA, de Koning JJ, van Erp T, van Keimpema B, de Ridder D, Otter R, Foster C - Eur. J. Appl. Physiol. (2010)

Bottom Line: PI was calculated by multiplying VO2 with the oxygen equivalent.The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of approximately 0.6% can be reliably detected.Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO(2) and RER <1.0 are applied.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Movement Sciences, VU University-Amsterdam, Van Der Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands. d.noordhof@fbw.vu.nl

ABSTRACT
Before the influence of divergent factors on gross efficiency (GE) [the ratio of mechanical power output (PO) to metabolic power input (PI)] can be assessed, the variation in GE between days, i.e. the test-retest reliability, and the within day variation needs to be known. Physically active males (n = 18) performed a maximal incremental exercise test to obtain VO2max and PO at VO2max (PVO2max), and three experimental testing days, consisting of seven submaximal exercise bouts evenly distributed over the 24 h of the day. Each submaximal exercise bout consisted of six min cycling at 45, 55 and 65% PVO2max, during which VO(2) and RER were measured. GE was determined from the final 3 min of each exercise intensity with: GE = (PO/PI) x 100%. PI was calculated by multiplying VO2 with the oxygen equivalent. GE measured during the individually highest exercise intensity with RER <1.0 did not differ significantly between days (F = 2.70, p = 0.08), which resulted in lower and upper boundaries of the 95% limits of agreement of 19.6 and 20.8%, respectively, around a mean GE of 20.2%. Although there were minor within day variations in GE, differences in GE over the day were not significant (F = 0.16, p = 0.99). The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of approximately 0.6% can be reliably detected. Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO(2) and RER <1.0 are applied.

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The increase in gross efficiency (GE) with exercise intensity (%PVO2max). Each data point represents the mean GE of 3 days for each individual. Data points were only displayed when RER did not exceed 1.0. Cross mark the overall mean GE. The highest intensity with valid data was selected for each subject
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Fig1: The increase in gross efficiency (GE) with exercise intensity (%PVO2max). Each data point represents the mean GE of 3 days for each individual. Data points were only displayed when RER did not exceed 1.0. Cross mark the overall mean GE. The highest intensity with valid data was selected for each subject

Mentions: All subjects completed the three experimental testing days. One exercise intensity was selected for GE analysis, based on the mean RER during the final 3 min of the submaximal exercise steps. The highest exercise intensity for each individual with a mean RER <1, during the final 3 min, was chosen for the GE analysis. In this way, the highest possible GE was selected for every individual, because GE increases when exercise intensity rises, as can be seen in Fig. 1. The data of one of the subjects was excluded, because his mean RER during the final 3 min of the first submaximal exercise step (45% PVO2max) already exceeded 1, which makes it impossible to calculate GE.Fig. 1


The between and within day variation in gross efficiency.

Noordhof DA, de Koning JJ, van Erp T, van Keimpema B, de Ridder D, Otter R, Foster C - Eur. J. Appl. Physiol. (2010)

The increase in gross efficiency (GE) with exercise intensity (%PVO2max). Each data point represents the mean GE of 3 days for each individual. Data points were only displayed when RER did not exceed 1.0. Cross mark the overall mean GE. The highest intensity with valid data was selected for each subject
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908447&req=5

Fig1: The increase in gross efficiency (GE) with exercise intensity (%PVO2max). Each data point represents the mean GE of 3 days for each individual. Data points were only displayed when RER did not exceed 1.0. Cross mark the overall mean GE. The highest intensity with valid data was selected for each subject
Mentions: All subjects completed the three experimental testing days. One exercise intensity was selected for GE analysis, based on the mean RER during the final 3 min of the submaximal exercise steps. The highest exercise intensity for each individual with a mean RER <1, during the final 3 min, was chosen for the GE analysis. In this way, the highest possible GE was selected for every individual, because GE increases when exercise intensity rises, as can be seen in Fig. 1. The data of one of the subjects was excluded, because his mean RER during the final 3 min of the first submaximal exercise step (45% PVO2max) already exceeded 1, which makes it impossible to calculate GE.Fig. 1

Bottom Line: PI was calculated by multiplying VO2 with the oxygen equivalent.The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of approximately 0.6% can be reliably detected.Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO(2) and RER <1.0 are applied.

View Article: PubMed Central - PubMed

Affiliation: Department of Human Movement Sciences, VU University-Amsterdam, Van Der Boechorststraat 9, 1081 BT, Amsterdam, The Netherlands. d.noordhof@fbw.vu.nl

ABSTRACT
Before the influence of divergent factors on gross efficiency (GE) [the ratio of mechanical power output (PO) to metabolic power input (PI)] can be assessed, the variation in GE between days, i.e. the test-retest reliability, and the within day variation needs to be known. Physically active males (n = 18) performed a maximal incremental exercise test to obtain VO2max and PO at VO2max (PVO2max), and three experimental testing days, consisting of seven submaximal exercise bouts evenly distributed over the 24 h of the day. Each submaximal exercise bout consisted of six min cycling at 45, 55 and 65% PVO2max, during which VO(2) and RER were measured. GE was determined from the final 3 min of each exercise intensity with: GE = (PO/PI) x 100%. PI was calculated by multiplying VO2 with the oxygen equivalent. GE measured during the individually highest exercise intensity with RER <1.0 did not differ significantly between days (F = 2.70, p = 0.08), which resulted in lower and upper boundaries of the 95% limits of agreement of 19.6 and 20.8%, respectively, around a mean GE of 20.2%. Although there were minor within day variations in GE, differences in GE over the day were not significant (F = 0.16, p = 0.99). The measurement of GE during cycling at intensities approximating VT is apparently very robust, a change in GE of approximately 0.6% can be reliably detected. Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO(2) and RER <1.0 are applied.

Show MeSH
Related in: MedlinePlus