Publication

The between and within day variation in gross efficiency

Noordhof, D., de Koning, J., van Erp, T., van Keimpema, B., de Ridder, D., Otter, R. & Foster, C., 2010, In : European Journal of Applied Physiology. 109, 6, p. 1209-1218 10 p.

Research output: Contribution to journalArticleAcademicpeer-review

  • Dionne Noordhof
  • Jos de Koning
  • Teun van Erp
  • Bart van Keimpema
  • Daan de Ridder
  • Ruby Otter
  • Carl Foster
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 VO2 and RER were measured. GE was determined from the final 3 min of each exercise intensity with: GE = (PO/PI) × 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 ~0.6% can be reliably detected. Lastly, GE does not display a circadian rhythm so long as the criteria of a steady-state VO2 and RER <1.0 are applied.
Original languageEnglish
Pages (from-to)1209-1218
Number of pages10
JournalEuropean Journal of Applied Physiology
Volume109
Issue number6
Publication statusPublished - 2010

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