Medicine & Science in Sports & Exercise:
G-15T Free Communication/Poster Protein Metabolism
1Louisiana State University, Baton Rouge, LA; Brigham Young University —Hawaii, Laie, HI; Kent State University, Kent, OH; and Xavier University, New Orleans, LA
Blood ammonia [NH3] concentration is a marker for the assessment of training status. However, concerns arise as to the intra-subject reproducibility of the blood [NH3] assay across high-intensity exercise sessions. Although an inverse relationship exists between blood [NH3] and training status (Graham et al. MSSE 29:646), the reproducibility of the ammonia assay is unknown.
To investigate the reliability of the blood [NH3] assay across high-intensity exercise sessions.
Fifteen recreationally upper body trained (e.g. weight training, surfing, swimming) college-age male (n = 11) and female (n = 4) students were ramp-tested via incremental (25W.30 second-1) arm ergometry to RPE 17 on three occasions (S1, S2, S3). Total time, power output, cadence (100rpm), and stage completion were constant per subject across sessions. A 48h-72h washout separated each session. Antecubital venous blood samples were drawn at 3-minutes postexercise (subject seated and resting), immediately chilled, centrifuged, with harvested serum frozen (−20 degrees C) immediately. Subsequent batch analysis for [NH3] used a multi-layered urease/colorimetric slide technique (Kodak@ Ektachem DT Analyzer).
One-way repeated measures ANOVA revealed no significant (p > .05) differences (x ± SE) in blood ammonia [uM/L] across S1 (180 ±13), S2 (190 ±14), and S3 (184 ±13). Secondly, the intraclass correlation coefficient was highly significant, r = .92, p < .0000, as were the correlations between the individual sessions (S1 vs. S2, r =.94, p < .0000; S2 vs. S3, r =.90, p < .0000; S1 vs. S3, r = .90, p < .0000).
These results suggest that blood [NH3] post-exercise is highly reliable in moderately trained college age subjects. However, additional work is needed to ascertain whether the effects of 1) training status (e.g. in-season training, progression, and taper) and 2) arm vs. leg activity can influence the reliability of blood [NH3].