Exhaustive physical exercise increases frequency of micronuclei.

Micronucleus (MN) tests were performed on PHA-stimulated blood lymphocytes of six healthy volunteers before and after two exhaustive sprints, causing lactate concentrations in the peripheral blood between 9.6 and 12.4 mmol/l. The number of micronuclei was significantly increased after 24-48 h in all six subjects. The mean of the total group increased from 37 MN per 3000 binucleated cells before exercise to 56 and 55 MN 24 and 48 h after exercise, respectively. These differences were also significant. These results indicate that exhaustive physical exercise causes severe mutations at the chromosome level in blood lymphocytes.