We have previously shown that short-term voluntary running for 9 days increases newly divided cells (progenitor proliferation) in the hippocampus up to 500%, whereas long-term voluntary running for 24 days paradoxically decreases by half the progenitor proliferation in the adult rat brain. A concomitant increase in stress responses was seen after long-term running only. Here we investigate the effects of different voluntary running duration on cell survival, neurogenesis and spatial memory four weeks after cessation of exercise, a time span generally accepted for progenitor maturation into functionally working neurons. Nine days of running showed increased progenitor proliferation four weeks post exercise, with increased neurogenesis ratio. In contrast, no significant changes were seen in progenitor proliferation measured four weeks after cessation of long-term running but an increase in the neurogenesis ratio. The previously observed decrease in progenitor proliferation measured directly after cessation of long-term running is thus not mirrored four weeks later, resulting in increased ratio of cell survival during the four weeks of post exercise rest. We suggest a possible compensatory mechanisms to increase cell survival of the relatively few progenitors existing during high levels of stress. In water maze test, spatial memory was significantly improved after short-term but not long-term running. These data further strengthen the beneficial role of moderate exercise and possible existence of a compensatory mechanism previously not shown, which balance the effects of decreased progenitor proliferation during post activity resting but is apparently not enough to improve spatial memory.