The effect of a prolonged running trial on the energy cost of running (Cr) during a 60-km ultramarathon simulation at the pace of a 100-km competition was investigated in 13 men (40.8 ± 5.6 y, 70.7 ± 5.5 kg, 177.5 ± 4.5 cm) and 5 women (40.4 ± 2.3 y, 53.7 ± 4.4 kg, 162.4 ± 4.8 cm) who participated in a 60-km trial consisting of 3 consecutive 20-km laps. Oxygen uptake (VO2) at steady state was determined at constant speed before the test and at the end of each lap; stride length (SL) and frequency and contact time were measured at the same time points; serum creatine kinase (S-CPK) was measured before and at the end of the test. Cr in J · kg−1 · m−1, as calculated from VO2ss and respiratory-exchange ratio, did not increase with distance. SL significantly decreased with distance. The net increase in S-CPK was linearly related with the percentage increase of Cr observed during the trial. It is concluded that, in spite of increased S-CPK, this effort was not able to elicit any peripheral or central fatigue or biomechanical adaptation leading to any modification of Cr.
Schena, Pellegrini, Tarperi, Calabria, and Capelli are with the Dept of Neurological and Movement Sciences, and Salvagno, the School of Medicine, University of Verona, Verona, Italy. Address author correspondence to Carlo Capelli at firstname.lastname@example.org.