We studied the effect of physical inactivity and subsequent retraining on cardiovascular risk factors in 17 young (Y; 23.4 ± 0.5 years) and 15 older adult (O; 68.1 ± 1.1 years) men who underwent 14 days of one leg immobilization followed by six weeks of training. Body weight remained unchanged. Daily physical activity decreased by 31 ± 9% (Y) and 37 ± 9% (O) (p < .001). Maximal oxygen uptake decreased with inactivity (Y) and always increased with training. Visceral fat mass decreased (p < .05) with training. Concentrations of lipids in blood were always highest in the older adults. FFA and glycerol increased with reduced activity (p < .05), but reverted with training. Training resulted in increases in HDL-C (p < .05) and a decrease in LDL-C and TC:HDL-C ratio (p < .05). A minor reduction in daily physical activity for two weeks increased blood lipids in both young and older men. Six weeks of training improved blood lipids along with loss of visceral fat.