The purpose of this study was to investigate the effect of increased abdominal muscle strength on forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). Twenty-five healthy volunteers were assigned randomly to either an experimental group (n = 16) or a control group (n = 9). Peak isokinetic torque of the abdominal muscles during the performance of a trunk curl-up, FVC, and FEV1 were measured before and after a 12-session training program designed to increase abdominal muscle strength. The control group did not train. Although abdominal muscle strength increased significantly after the training program, FVC and FEV1 did not increase significantly. The correlations between abdominal muscle strength and FVC, and between abdominal muscle strength and FEV1 were low. Based on these results, abdominal muscle strengthening does not appear to be an effective means of improving FVC and FEV1 in healthy subjects.