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Carnot Cycle and Efficiency01:26

Carnot Cycle and Efficiency

The Second Law of Thermodynamics asserts that it's impossible for any heat engine to achieve 100% efficiency. While contemplating the maximum possible efficiency, Nicolas Sadi Carnot conceptualized an ideal heat engine. This engine gets its energy from a high-temperature reservoir. It then performs some work and releases the remaining energy into a low-temperature reservoir.The Carnot cycle, named after Sadi Carnot, is fully reversible. The cycle consists of four distinct stages. In the first...
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Updated: May 21, 2026

Determining and Controlling External Power Output During Regular Handrim Wheelchair Propulsion
08:55

Determining and Controlling External Power Output During Regular Handrim Wheelchair Propulsion

Published on: February 5, 2020

Factors affecting gross efficiency in cycling.

J J de Koning1, D A Noordhof, A Lucia

  • 1Research Institute MOVE, VU University Amsterdam, Amsterdam, The Netherlands.

International Journal of Sports Medicine
|June 19, 2012
PubMed
Summary
This summary is machine-generated.

Standardizing cycling gross efficiency (GE) measurements is crucial. This study found GE is reliable with steady-state exercise and a respiratory exchange ratio (RER) below 1.0, with minimal impact from stage duration or prior maximal tests.

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Last Updated: May 21, 2026

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A Rapidly Incremented Tethered-Swimming Maximal Protocol for Cardiorespiratory Assessment of Swimmers
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Published on: January 28, 2020

Area of Science:

  • Exercise Physiology
  • Sports Science
  • Biophysics

Background:

  • Cycling gross efficiency (GE) measurement lacks standardization.
  • Variability in GE assessment methods affects data reliability.
  • Understanding factors influencing GE is key for accurate physiological assessment.

Purpose of the Study:

  • To evaluate the impact of stage duration on GE.
  • To determine the effect of relative exercise intensity on GE.
  • To assess the influence of work capacity and prior maximal testing on GE.

Main Methods:

  • Trained cyclists (n=28) underwent incremental tests with varying stage durations (1, 3, 6 min).
  • GE was measured at different relative exercise intensities, including 50% peak power output (PPO).
  • The effect of a prior maximal incremental test was examined in a separate group (n=9).

Main Results:

  • GE was similar for 3- and 6-min stages but higher for 1-min stages.
  • GE increased with relative intensity up to the ventilatory threshold, then plateaued.
  • No correlation was found between work capacity and GE; prior maximal exercise slightly reduced GE.

Conclusions:

  • Robust GE measurement requires steady-state exercise and a respiratory exchange ratio (RER) ≤ 1.0.
  • Stage duration and prior maximal exercise have minimal impact under these conditions.
  • Standardized protocols ensure reliable GE data for exercise physiology research.