Abstract

In an earlier study, we reported close relationships between marathon running performance and the running velocity (V) at which the onset of blood lactate accumulation (VOLBA) occurs in a group of marathon runners. Using biopsy material from the m. vastus lateralis of the same subject (n = 19), we have evaluated the relationship of VOLBA to different muscle enzyme activities together with muscle fiber composition and capillary density in the present study. The activities of lactate dehydrogenase (LDH EC 1.1.1.27), phosphofructokinase (PFK EC 2.7.1.11), and citrate synthase (CS EC 4.1.3.7) were determined. VOLBA was negatively correlated to LDH (r = -0.54) and PFKCS (r = -0.68). Using multiple regression analysis, the PFKCS ratio together with the capillary density accounted for 61 of the variation in VOBLA. Absolute training kilometrage was the most significant variable measured and accounted for 77 of the variation in VOBLA. Subjects were divided into eliterunners (n= 6) and nonelite runners ( n = 13) for an additional analysis of the relationship between VOLBA and the ratios of PFKCS or LDHCS. Significantrelationships between VOBLA and the ratios were observed only in the nonelite runners (r = -0.77 and -0.66, respectively). Verf.-Referat (gekuerzt)