Our goal was to address if intermittent hypobaric hypoxia (IHH) exposure can help to increase the
number of peripheral blood circulating progenitor cells and side population (SP) stem cells, in order to establish
the usefulness of this intervention for skeletal muscle repair, because these cells play a role in tissue regeneration.
Male Sprague-Dawley rats were studied in two basal states: untrained and trained and compared
with 1, 3, 7 and 14 days stages of damage recovery of trained rats that had suffered skeletal muscle injury.
Three experimental groups were studied: rats with passive recovery (CTRL); rats exposed to IHH after muscle damage
(HYP); and, trained rats that, in addition to IHH, performed light aerobic exercise sessions (EHYP). We observed an increase
in hematopoietic stem cells (HSCs) (mean = 0.153% of cells) and endothelial progenitor cells (EPCs) (mean =
0.0020 % of cells) in EHYP on day 7. Also these cells showed characteristics of more primitive progenitors in comparison
to the other experimental groups (mean = 0.107 % of cells), as deduced by retention of the promising fluorescent probe
Vybrant Dye Cycle Violet. We concluded that intermittent exposure to hypobaric hypoxia in combination with light aerobic
exercise increased the number of HSCs and EPCs on the 7th day in EHYP group, although the exercise-induced stimulus
showed a reverse effect on SP kinetics.