Post exercise lymphocytopenia is a well documented phenomenon. Studies have reported exercise induced DNA damage in leucocytes and have postulated a possible link to apoptosis. Five subjects of differing fitness levels underwent a ramped treadmill test to exhaustion. Venous sampling was undertaken before, immediately post exercise, and 24 and 48 hours after exercise. Single cell gel electrophoresis showed evidence of single strand DNA breaks (as evidenced by an increase in tail moment measurements using the comet assay) in 100% oflymphocytes immediately
after exercise, and in the 24 hour and 48 hour post exercise samples. Flowcytometric analysis oflymphocytes revealed a minimal amount of both apoptosis and necrosis at all time intervals. Lymphocyte apoptosis has again been demonstrated after exercise, however the percentage of apoptosis was a maximum of 4.8% at 24 hours. These findings may in part account for the exercise induced lymphocytopenia and reduced immunity demonstrated by numerous previous other studies.
