The aim of this study was to assess in an in vivo rat model the effects of total starvation for 4 d on diaphragmatic strength and endurance. Twenty-four rats were divided equally into a control (CTL) group and a starved (ST) group. Diaphragmatic strength was assessed and endurance index was calculated. Starvation induced a parallel decrease in body weight and diaphragmatic weight amounting to 18% of the control group. Diaphragmatic contractility was impaired in the ST group. This reduction was associated with a significant reduction in transdiaphragmatic pressure (Pdi) for all the frequencies of stimulation, except 20 Hz, in the ST animals as compared with the CTL animals; however, no significant difference in Pdi expressed per gram of diaphragmatic mass was observed. Endurance index was 0.63 +/- 0.01 1.4 +/- 0.02 in the ST and CTL animals (p less than 0.01), respectively. We conclude that a 4-d total fast produces a reduction in diaphragmatic weight, which is associated with a decreased diaphragmatic strength and reduced endurance capacity.