High Intensity Exercise Performance and Acid-Base Balance: The Influence of Diet and Induced Metabolic Alkalosis

Given the ergogenic properties of β-alanyl-L-histidine (carnosine) in skeletal muscle, it can be hypothesized that elevated levels of circulating carnosine could equally be advantageous for high-intensity exercises. Serum carnosinase (CN1), the enzyme hydrolyzing the dipeptide, is highly active in the human circulation. Consequently, dietary intake of carnosine usually results in rapid degradation upon absorption, yet this is less pronounced in subjects with low CN1 activity. Therefore, acute carnosine supplementation before high-intensity exercise could be ergogenic in these subjects. In a cross-sectional study, we determined plasma CN1 activity and content in 235 subjects, including 154 untrained controls and 45 explosive and 36 middle- to long-distance elite athletes. In a subsequent double-blind, placebo-controlled, crossover study, 12 men performed a cycling capacity test at 110% maximal power output (CCT 110%) following acute carnosine (20 mg/kg body wt) or placebo supplementation. Blood samples were collected to measure CN1 content, carnosine, and acid-base balance. Both male and female explosive athletes had significantly lower CN1 activity (14% and 21% lower, respectively) and content (30% and 33% lower, respectively) than controls. Acute carnosine supplementation resulted only in three subjects in carnosinemia. The CCT 110% performance was not improved after carnosine supplementation, even when accounting for low/high CN1 content. No differences were found in acid-base balance, except for elevated resting bicarbonate following carnosine supplementation and in low CN1 subjects. In conclusion, explosive athletes have lower serum CN1 activity and content compared with untrained controls, possibly resulting from genetic selection. Acute carnosine supplementation does not improve high-intensity performance.

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Influence of plasma bicarbonate concentration and pH on citrate excretion

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1964.206.4.875 ◽

1964 ◽

Vol 206 (4) ◽

pp. 875-882 ◽

Cited By ~ 21

Author(s):

David P. Simpson

Keyword(s):

Linear Relationship ◽

Metabolic Alkalosis ◽

High Plasma ◽

Alkaline Ph ◽

Acid Base Balance ◽

Bicarbonate Concentration ◽

Acid Base ◽

Plasma Bicarbonate ◽

Close Relationship ◽

Base Balance

Citrate excretion has been studied in dogs under various conditions of acid-base balance in order to determine which factors are responsible for the increased citrate clearance present in metabolic alkalosis. A close relationship, significantly modified by systemic pH, was found between plasma bicarbonate concentration and citrate clearance. In the presence of an alkaline plasma pH, there was a linear relationship between changes in plasma bicarbonate concentration and changes in citrate clearance. Other experiments also demonstrated the influence of plasma bicarbonate concentration on citrate clearance at alkaline pH. Under acidotic conditions citrate clearances were low and changes in plasma bicarbonate concentration had little effect on citrate excretion. A change in plasma pH from an acidotic to an alkalotic state, with a constant plasma bicarbonate concentration, produced an increase in citrate clearance. Thus the coexistence in metabolic alkalosis of high plasma bicarbonate concentration and high plasma pH results in a markedly increased citrate clearance.

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ACUTE PROTEIN SUPPLEMENTATION DOES NOT ALTER POWER OUTPUT, PLASMA AMMONIA CONCENTRATION AND ACID-BASE BALANCE DURING HIGH INTENSITY INTERMITTENT EXERCISE 1097

Medicine & Science in Sports & Exercise ◽

10.1097/00005768-199705001-01096 ◽

1997 ◽

Vol 29 (Supplement) ◽

pp. 192

Author(s):

J. A. Potteiger ◽

B. A. Dolezal ◽

K. S. Almuzaini ◽

M. D. Haub

Keyword(s):

Power Output ◽

High Intensity ◽

Intermittent Exercise ◽

Ammonia Concentration ◽

Protein Supplementation ◽

Acid Base Balance ◽

Acid Base ◽

Plasma Ammonia ◽

Base Balance

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Effect of acetazolamide on citrate excretion in the dog

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1964.206.4.883 ◽

1964 ◽

Vol 206 (4) ◽

pp. 883-886 ◽

Cited By ~ 14

Author(s):

David P. Simpson

Keyword(s):

Metabolic Alkalosis ◽

Acid Base Balance ◽

Acid Base ◽

Marked Rise ◽

Before And After ◽

Base Balance

Clearance measurements were made on dogs in order to study the mechanism of the effect of acetazolamide on citrate excretion. Induction of metabolic alkalosis resulted in a marked rise in citrate clearance despite treatment with acetazolamide. Measurement of citrate clearances in alkalotic animals before and after acetazolamide infusion showed either no change or an increase in citrate clearance. No evidence was found that acetazolamide decreases citrate excretion when acidosis is prevented. These results are consistent with the hypothesis that changes in citrate clearance after acetazolamide administration are entirely secondary to changes in acid-base balance.

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