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Conducting Maximal and Submaximal Endurance Exercise Testing to Measure Physiological and Biological Responses to Acute Exercise in Humans
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Published on: October 17, 2018

Systemic acid load from the diet affects maximal-exercise RER.

Katherine Niekamp1, Gerald S Zavorsky, Luigi Fontana

  • 1Department of Nutrition and Dietetics, Doisy College of Health Sciences, Saint Louis University, St. Louis, MO, USA.

Medicine and Science in Sports and Exercise
|September 14, 2011
PubMed
Summary
This summary is machine-generated.

Dietary acid load influences respiratory exchange ratio (RER) during maximal exercise. An alkaline diet may lead to falsely high RERmax, suggesting maximal effort was achieved when it wasn't.

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Measurement and Analysis of Extracellular Acid Production to Determine Glycolytic Rate
06:47

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Published on: December 12, 2015

Area of Science:

  • Exercise Physiology
  • Nutritional Science
  • Sports Medicine

Background:

  • Respiratory exchange ratio (RER) is a key indicator for assessing maximal oxygen uptake (V˙O(2max)).
  • RERmax is influenced by CO2 production from acid buffering during intense exercise.
  • Dietary acid load may contribute to variability in RERmax.

Purpose of the Study:

  • To investigate if a diet promoting systemic alkalinity increases RERmax during V˙O(2max) testing.
  • To explore the relationship between habitual dietary acid load and RERmax.

Main Methods:

  • 57 sedentary adults (47-63 yrs) underwent maximal graded treadmill tests.
  • Indirect calorimetry measured V˙O(2max) and RERmax.
  • Potential renal acid load (PRAL) was calculated from food diaries to assess habitual diet.

Main Results:

  • Participants with the lowest PRAL (alkaline diet) exhibited higher RERmax (1.21 ± 0.01) compared to higher PRAL groups.
  • No significant differences in RER were observed at submaximal intensities (70-90% V˙O2max).
  • PRAL explained 19% of the variability in RERmax (r = -0.43, P = 0.001); lower PRAL was associated with higher RERmax.

Conclusions:

  • Diets promoting systemic alkalinity may facilitate achieving the RERmax criterion (≥ 1.10).
  • This could lead to overestimation of maximal effort and V˙O(2max) in graded exercise tests.
  • Dietary factors should be considered when interpreting RERmax during exercise testing.