This study compared the ventilatory responses and exercise tidal flow-volume (Vt) loops during exercise in order to analyze the influence of gender on breathing strategy in a fit aging population. Sixteen trained elderly men (63.0+/-2.9 years) and eight peer women (62.3 +/- 5.5 years) performed an incremental test on a cycle ergometer. At 90% maximal oxygen consumption (VO2max), the women presented a significantly higher expiratory flow limitation (EFL) than the men (38 +/- 10 vs 17 +/- 8% of Vt, respectively) (P<0.01) and a lower value of expiratory reserve volume relative to forced vital capacity (FVC) compared with the men (16.8 +/- 5.3% vs 23.0 +/- 5.2%, respectively) (P<0.05). Inspiratory reserve volume relative to FVC was significantly higher in women than men at 50% (P<0.05), 70% (P<0.01) and 90%VO2max (25.2 +/- 5.4% vs 12.2 +/- 4.2%, respectively, at 90%VO2max) (P<0.01). Mechanical ventilatory constraints occurred in trained elderly men and women. However, different breathing strategies were observed relative to gender. A significantly higher EFL was measured in women, whereas men rather presented a dynamic hyperinflation. This specific breathing strategy measured in trained elderly women would induce lower ventilatory efficiency than in peer men.