The effect of citrate loading on exercise performance,acid-base balance and metabolism |
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Authors: | John M Kowalchuk Stephen A Maltais Keiji Yamaji Richard L Hughson |
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Institution: | (1) Department of Kinesiology, University of Waterloo, N2L 3G1 Waterloo, Ontario, Canada;(2) Present address: Faculty of Education, Toyama University, Toyama City, Japan |
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Abstract: | Summary Nine subjects (
65±2 ml·kg−1·min−1, mean±SEM) were studied on two occasions following ingestion of 500 ml solution containing either sodium citrate (C, 0.300
g·kg−1 body mass) or a sodium chloride placebo (P, 0.045 g·kg−1 body mass). Exercise began 60 min later and consisted of cycle ergometer exercise performed continuously for 20 min each
at power outputs corresponding to 33% and 66%
, followed by exercise to exhaustion at 95%
. Pre-exercise arterialized-venous H+] was lower in C (36.2±0.5 nmol·l−1; pH 7.44) than P (39.4±0.4 nmol·l−1; pH 7.40); the plasma H+] remained lower and HCO
3
−
] remained higher in C than P throughout exercise and recovery. Exercise time to exhaustion at 95%
was similar in C (310±69 s) and P (313±74 s). Cardiorespiratory variables (ventilation,
,
, heart rate) measured during exercise were similar in the two conditions. The plasma citrate] was higher in C at rest (C,
195±19 μmol·l−1; P, 81±7 μmol·l−1) and throughout exercise and recovery. The plasma lactate] and free fatty acid] were not affected by citrate loading but
the plasma glycerol] was lower during exercise in C than P. In conclusion, sodium citrate ingestion had an alkalinizing effect
in the plasma but did not improve endurance time during exercise at 95%
. Furthermore, citrate loading may have prevented the stimulation of lipolysis normally observed with exercise and prevented
the stimulation of glycolysis in muscle normally observed in bicarbonate-induced alkalosis. |
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Keywords: | Citrate Alkalosis Buffering Performance Lactate Glycerol Free fatty acids |
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