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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 variation in gross efficiency (GE) over the day of cyclists (a) and non-cyclists (b). The broken lines are the variation in GE within day 1, 2, and 3. The solid line is the average of all 3 days
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Fig5: The variation in gross efficiency (GE) over the day of cyclists (a) and non-cyclists (b). The broken lines are the variation in GE within day 1, 2, and 3. The solid line is the average of all 3 days

Mentions: All subjects were physically active and engaged in regular sport activities at least two times per week (7.25 ± 5.6 h/week). Eleven of the subjects were cyclists, they had at least 2 years of cycling experience and cycled minimally 3,000 km per year. The remaining subjects engaged in divergent sport activities. There was a significant difference in GE between cyclists and non-cyclists (F = 6.97, p < 0.05), with the cyclists having a higher mean GE (20.7% ± 0.93%) than the non-cyclists (19.4% ± 1.71%) (Fig. 5a, b). There was no significant interaction effect between time of day and cyclist versus non-cyclist (F = 1.56, p = 0.17). Thus, even well trained cyclists do not show a circadian rhythm in GE.Fig. 5


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 variation in gross efficiency (GE) over the day of cyclists (a) and non-cyclists (b). The broken lines are the variation in GE within day 1, 2, and 3. The solid line is the average of all 3 days
© Copyright Policy
Related In: Results  -  Collection

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

Fig5: The variation in gross efficiency (GE) over the day of cyclists (a) and non-cyclists (b). The broken lines are the variation in GE within day 1, 2, and 3. The solid line is the average of all 3 days
Mentions: All subjects were physically active and engaged in regular sport activities at least two times per week (7.25 ± 5.6 h/week). Eleven of the subjects were cyclists, they had at least 2 years of cycling experience and cycled minimally 3,000 km per year. The remaining subjects engaged in divergent sport activities. There was a significant difference in GE between cyclists and non-cyclists (F = 6.97, p < 0.05), with the cyclists having a higher mean GE (20.7% ± 0.93%) than the non-cyclists (19.4% ± 1.71%) (Fig. 5a, b). There was no significant interaction effect between time of day and cyclist versus non-cyclist (F = 1.56, p = 0.17). Thus, even well trained cyclists do not show a circadian rhythm in GE.Fig. 5

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