Blood ammonia determination in a specific field test as a method supporting talent selection in runners.

Twenty-six male runners aged 14-16 years not yet specifically trained for sprint or middle-distance running performed a field test with distances of 25 m, 75 m, and 1000 m. Before the field test they were designated as sprinters (n = 19) and middle-distance runners (n = 7) according to their self-assessment and the estimation of the coaches. Blood ammonia and lactate concentrations were measured before and after the runs, and heart rates as well as the perceived exertion were evaluated. The most remarkable finding was a significantly higher ammonia increase in the supposed sprinters after 75 m compared with the supposed middle-distance runners. The ammonia concentrations after 1000 m were considerably less pronounced in both groups and did not differ significantly. The ratio of the ammonia concentration after the 75-m and the 1000-m distance was defined as an index. A high index was typical for designated sprinters, whereas a low index was found in supposed middle-distance runners. The combination of this index and the assessment of the coaches makes it possible to recommend special training regimens.