We tested whether a regular exercise regimen was associated with a change in the life span of G93A-SOD1 transgenic mice, a model of familial ALS. Regular treadmill running for 10 weeks led to a significant increase in the life span of G93A-SOD1 mice. The effect was stronger in male mice, whereas there was only a trend between exercised and sedentary female G93A-SOD1 mice. The data suggest that regular exercise has a beneficial effect on the progression of ALS.