The purpose of this study was to examine the effects of a 12-month physical activity (PA) programme consisting in walking on muscle function in patients with COPD (Chronic Obstructive Pulmonary Disease). Forty-four men (70.3 ± 6.7 years old) diagnosed with moderate-severe COPD were recruited. The intervention group (PAG) completed a physical activity programme and the control group (COG) followed their standard treatment. Upper- and lower-limb maximum strength (1RM), lower-limb muscle power (50% and 70% 1RM) and physical activity were measured before and after 12 months. After 12 months, lower-limb maximum strength increased by 8% in the PAG (P<0.01), while it did not change in the COG. Lower-limb muscle power at 50% 1RM increased by 12% in the PAG, while it decreased by 9% in the COG (P><0.05). A physical activity programme increased muscle strength and preserved muscle power of the lower limb. ><0.01) , while it did not change in the COG. Lower-limb muscle power at 50% 1RM increased by 12% in the PAG, while it decreased by 9% in the COG (P<0.05) . A physical activity programme increased muscle strength and preserved muscle power of the lower limb.