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.
- AMP deaminase
- Ammonia concentration
- Muscle energetics
- Oxygen uptake kinetics
ASJC Scopus subject areas
- Orthopedics and Sports Medicine
- Physical Therapy, Sports Therapy and Rehabilitation