Exercise and circulating hematopoietic progenitor cells (CFU-GM) in humans.

In order to determine whether the rise in blood circulating committed hematopoeitic progenitor cells (CFU-GM) was sustained long enough after exercise to be a practical adjunct to increasing stem cell yields by hemapheresis, the authors evaluated two exercise protocols in 15 normal donors. Immediately after a brief period of intense exercise, there was a significant increase in the absolute number of blood CFU-GM from 164 +/- 27 to 240 +/- 46 per ml. However, all values returned to baseline within 15 minutes. Prolonging the exercise did not enhance either the circulating CFU-GM concentration or the duration of the rise. If blood hematopoietic stem cells respond to exercise similarly, such a transient increase would not appear to be of use in stem cell harvesting.