Plasma ammonia concentrations and the slow component of oxygen uptake kinetics during cycle ergometry

Moh H. Malek, Terry J. Housh, Larry D. Crouch, Glen O. Johnson, C. Russell Hendrix, Travis W. Beck, Michelle Mielke, Richard J. Schmidt, Dona J. Housh

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

Malek, MH, Housh, TJ, Crouch, LD, Johnson, GO, Hendrix, CR, Beck, TW, Mielke, M, Schmidt, RJ, and Housh, DJ. Plasma ammonia concentrations and the slow component of oxygen uptake kinetics during cycle ergometry. J Strength Cond Res 22(6): 2018-2026, 2008-The purposes of this study were to 1) compare the patterns of responses for plasma ammonia concentration ([NH3]) during moderate- vs. heavy-intensity cycle ergometry, and 2) examine the relationship between the V̇o2 slow component (V̇o2Sc) and plasma [NH3]. Thirteen healthy, untrained men (mean ± SEM age = 24.8 ± 0.6 years) performed a total of eight constant power output exercises (7 minutes in duration) at two different intensities (moderate, 60% gas exchange threshold [GET] = 60% of the gas exchange threshold; and heavy, Δ50% = 50% of the difference between GET and V̇o2max). Blood was collected from an antecubital vein before the exercise, during the last 3 minutes of the 6-minute warm-up, and during each minute of the 7-minute constant power output workbout. The time course of changes in plasma [NH 3] and V̇o2 during the two constant power output exercise intensities were assessed separately using 2 (intensity) × 7 (time) repeated-measures analyses of variance. For 60% GET, there were no significant differences in the mean normalized plasma [NH3] during the 7-minute workbout. For Δ50%, there was a significant increase in the mean normalized plasma [NH3] during the 7-minute workbout. These findings suggest a potential relationship between exercise-induced hyperammo-nemia and the V̇o2SC during heavy-intensity exercise.

Original languageEnglish (US)
Pages (from-to)2018-2026
Number of pages9
JournalJournal of strength and conditioning research
Volume22
Issue number6
DOIs
StatePublished - Nov 2008

Keywords

  • AMP deaminase
  • Ammonia concentration
  • Bioenergetics
  • Muscle energetics
  • Oxygen uptake kinetics

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

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