ISSN:
1439-6327
Keywords:
Fatigue
;
Ammonia
;
Lactate
;
$$\dot VO_2$$ max
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary The time course of venous blood ammonia and lactate formation has been investigated on 5 separate occasions in each of two subjects. Blood was sampled from a free flowing catheter for every 30 s during a ramp bicycle test to exhaustion. In each subject blood ammonia was rapidly elevated even at work rates as low as 40–50% of $$\dot VO_2$$ max. On cessation of exercise blood concentrations fell rapidly. Lactate concentration in blood on the other hand was more slowly elevated during the test and continued to rise in the usual fashion after the completion of the work. It is suggested that ammonia may be a primary toxin during exhaustive exercise inducing changes, which ultimately become incapacitating, in essential metabolic functions. Thus fast ammonia accumulation in tissue reflected by increased blood ammonia levels may induce glycolysis and an early excessive tissue pyruvate accumulation and lactate formation. Ammonia also passes the blood brain barrier and might possibly result in the observable central nervous system symptoms of dysfunction which accompany exhaustion such as ataxia, mental confusion and syncope. These findings have important implications for the integrity of the classically accepted lactate theory of exercise fatigue.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00455182
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