Some aspects of metabolism following a 35 km road run

The metabolism of eight men (mean: age, 26.0 years; maximal oxygen consumption, 65.0 ml.kg-1.min-1; body fat, 10.3%) was measured on counterbalanced control (baseline values for 8 h) and experimental (post 35 km run values for 8 h) days. The excess postexercise volume of oxygen consumed of 32.37 l and increase in energy used of 594 kJ during the 8 h after completion of the run were equivalent to average increases of 23.7 and 21.1%, respectively, when compared with time-matched controls. Furthermore, the oxygen uptake and energy expenditure were still elevated by 12.7 (P less than 0.0005) and 9.7% (P = 0.001), respectively, at the end of this period but the fact that they had returned to baseline 24 h after the 35 km road run contrasts with some reports in the literature that metabolism is still elevated at this time following less demanding exercise intensities. Rectal temperature was elevated by 2.3 degrees C at the end of the run but the difference had decreased to 0.2 degrees C by 7 h postexercise. The respiratory exchange ratio and changes in blood metabolites (nonesterified fatty acids, glycerol and ketone bodies) indicated a greater postexercise utilisation of fat notwithstanding a 6300 kJ meal ingested on both control and experimental days. The highest measured serum creatine kinase enzyme activity of 1151 U.l-1 (P less than 0.05) occurred 24 h postexercise, as compared with the control value of 145 U.l-1, and indicates the possibility of skeletal muscle damage.