title: Effect of sodium citrate on performance and metabolism of human skeletal muscle during supramaximal cycling exercise.
abstract: The aim of this study was to examine whether the alkalosis-induced improvement in supramaximal performance could be explained by a less-altered muscle metabolic status. Eight subjects first performed exhausting exercise at 120% peak oxygen uptake after ingesting either a placebo (PLC) or sodium citrate (CIT) at a dose of 0.5 g.kg-1 body mass to determine exhaustion time (texh). They then, performed exercise (Lim-EX) at the same relative intensity lasting PLCtexh minus 20 s in both treatments. Samples were taken from vastus lateralis muscle at rest (90-min after the ingestion) and at the end of Lim-EX. Arterial blood samples were obtained at rest (immediately prior to and 90 min after ingesting the drug) and during the 20-min post-exercise recovery. The texh was significantly increased by CIT [PLC 258 (SD 29) s, CIT 297 (SD 45) s]. The CIT raised the rest [citrate] in blood [PLC 0.11 (SD 0.01) mmol.l-1, CIT 0.34 (SD 0.07) mmol.l-1] and in muscle [PLC 0.78 (SD 0.23) mmol.kg-1 dry mass, CIT 1.00 (SD 0.21) mmol.kg-1 dry mass]. Resting muscle pH and buffering capacity were unchanged by CIT. The same fall in muscle pH was observed during Lim-EX in the two conditions. This was associated with similar variations in both the cardio-respiratory response and muscle energy and metabolism status in spite of a better blood acid-base status after CIT. Thus, CIT would not seem to allow the alkalinization of the muscle cytosolic compartment. Though sodium citrate works in a similar way to NaHCO3 on plasma alkalinization and exercise performance, the exact nature of the mechanisms involved in the delay of exhaustion could be different and remains to be elucidated.
authors.affiliation: Laboratoire de Physiologie, GIP Exercise, Faculté de Médecine Saint-Etienne, France.
authors.forename: M T
authors.initials: MT
authors.lastname: Linossier
authors.forename: D
authors.initials: D
authors.lastname: Dormois
authors.forename: P
authors.initials: P
authors.lastname: Brégère
authors.forename: A
authors.initials: A
authors.lastname: Geyssant
authors.forename: C
authors.initials: C
authors.lastname: Denis
mesh_terms: D000328:Adult; D000471:Alkalosis / Q000378:metabolism; D002951:Citrates / Q000494:pharmacology*; D019343:Citric Acid / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism*; D000077559:Sodium Citrate; D013647:Task Performance and Analysis
chemical_list: D002951:Citrates; D000077559:Sodium Citrate; D019343:Citric Acid