This study sought to determine the influence of age on the left ventricular (LV) response to prolonged exercise (PE; 150 min). LV systolic and diastolic performance was assessed using echocardiography (ECHO) before (pre) and 60 min following (post) exercise performed at 80% maximal aerobic power in young (28 ± 4.5 years; n = 18; mean ± SD) and middle-aged (52 ± 3.9 years; n = 18) participants. LV performance was assessed using two-dimensional ECHO, including speckle-tracking imaging, to determine LV strain (LV S) and LV S rate (LV SR), in addition to Doppler measures of diastolic function. We observed a postexercise elevation in LV S (young: -19.5 ± 2.1% vs. -21.6 ± 2.1%; middle-aged: -19.9 ± 2.3% vs. -20.8 ± 2.1%; P < 0.05) and LV SR (young: -1.19 ± 0.1 vs. -1.37 ± 0.2; middle-aged: -1.20 ± 0.2 vs. -1.38 ± 0.2; P < 0.05) during recovery in both groups. Diastolic function was reduced during recovery, including the LV SR ratio of early-to-late atrial diastolic filling (SR(e/a)), in young (2.35 ± 0.7 vs. 1.89 ± 0.5; P < 0.01) and middle-aged (1.51 ± 0.5 vs. 1.05 ± 0.2; P < 0.01) participants, as were conventional indices including the E/A ratio. Dobutamine stress ECHO revealed a postexercise depression in LV S in response to increasing dobutamine dose, which was similar in both young (pre-exercise dobutamine 0 vs. 20 μg·kg(-1)·min(-1): -19.5 ± 2.1 vs. -27.2 ± 2.2%; postexercise dobutamine 0 vs. 20 μg·kg(-1)·min(-1): -21.6 ± 2.1 vs. -23.7 ± 2.2%; P < 0.05) and middle-aged participants (pre: -19.9 ± 2.3 vs. -25.3 ± 2.7%; post: -20.8 ± 2.1 vs. -23.5 ± 2.7; P < 0.05). This was despite higher noradrenaline concentrations immediately postexercise in the middle-aged participants compared with young (4.26 ± 2.7 nmol/L vs. 3.00 ± 1.4 nmol/L; P = 0.12). These data indicate that LV dysfunction is observed following PE and that advancing age does not increase the magnitude of this response.