Effects Of Ammonium Chloride Ingestion On Phosphocreatine Recovery Following Heavy-intensity Plantar Flexion Exercise
Bibliographic record
Abstract
Intracellular acidosis has been shown to increase the time constant and/or rate constant of the phosphocreatine (PCr) kinetic response during recovery from exercise, supporting the notion that mitochondrial respiration is reduced under low pH conditions. The slowed PCr recovery in the presence of intracellular acidosis has also been attributed to an increased ATP consumption by cellular ion pumps, and/or to a pH-induced shift in the creatine kinase (CK) equilibrium. However, during this recovery period, [PCr] often rises transiently above resting values before returning to pre-exercise values. This phenomenon has been named the PCr recovery overshoot, and the mechanisms responsible for it remain unknown. PURPOSE: To examine the effects of ammonium chloride (NH4Cl) ingestion on PCr recovery and the magnitude of PCr overshoot following heavy-intensity plantar flexion (PF) exercise. METHODS: Eight untrained male subjects performed isotonic PF exercise in a control (CON) and NH4Cl ingestion (ACID) trial (0.3g/kg oral dose of NH4Cl, over 3 hrs prior to exercise). PF exercise (contraction rate, 0.5 Hz) was performed for 9 min each during moderate- (MOD: 75% of intracellular pH threshold, TpHi) and heavy-intensity exercise (HVY: 125% TpHi), and was followed immediately by 15 min resting recovery. 31phosphorus magnetic resonance spectroscopy was used to non-invasively monitor changes in intracellular pH (pHi), [PCr], and [ATP]. RESULTS: End HVY exercise pHi was lower (P<0.05) in ACID (6.61 (0.07); mean (SD)) than CON (6.69 (0.06)). During recovery the PCr time constant (tPCr) was greater (P<0.05) in ACID (45 s (16)) than CON (33 s (10)). The magnitude of [PCr] recovery overshoot, as a percentage of the pre-exercise resting value, was greater (P<0.05) in ACID than CON during the following recovery periods: 3-6 min (ACID, 110% (3); CON, 107% (3)); 6-9 min (ACID, 110% (3); CON, 106% (4)); 9-12 min (ACID, 108% (3); CON, 105% (3)); and 12-15 min (ACID, 108% (3); CON, 105% (4)). CONCLUSION: A greater intracellular acidosis at the end of HVY was seen in ACID vs. CON. This was associated with a longer time constant describing PCr recovery kinetics and a greater magnitude of [PCr] overshoot above baseline values.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".