SummaryLeft ventricular (LV) myocardial atrophy and diminished cardiac function have been shown to accompany chronic human tetraplegia. These changes are attributable both to physical immobilisation and abnormal autonomic circulatory regulation imposed by a spinal cord injury (SCI). To test whether exercise training increases LV mass following chronic SCI, 8 neurologically complete quadriplegic males at 2 SCI rehabilitation and research centres underwent one month of electrically-stimulated quadriceps strengthening followed by 6 months of electrically-stimulated cycling exercise. Resting M-mode and 2-D echocardiograms were measured before and after exercise training to quantify the interventricular septal and posterior wall thicknesses at end-diastole (IVST ED and PWT ED, respectively), and the LV internal dimension at end-diastole (L VI D ED). LV mass was computed from these measurements using standard cube function geometry. Results showed a 6·5% increase in LVIDED foliowing exercise training (p<0·02), with increases in IVSTED and PWTED of 17·8 (p<0·002) and 20·3% (p