Study design: Case-control. Objectives: To execute an echocardiographic comparison between trained and untrained spinal cord injury (SCI) subjects, and to evaluate whether long-term heart adjustments to endurance training are comparable to those observed in able-bodied (ABL) subjects. Setting: Italy. Methods: We enrolled: (1) 17 male SCI patients (lesion level T 1 -L 3 , 34±8 years, body mass index (BMI) 23.0±2.8 kg m À2 ), 10 of whom were aerobically trained for 45 years (SCI T ); (2) 18 age-, sex-and BMI-matched ABL subjects (35 ± 6 years, BMI 23.6 ± 2.8 kg m À2 ), 10 of whom were aerobically trained for 45 years (ABL T ). Training frequency and volume were recorded by a dedicated questionnaire. All subjects underwent a trans-thoracic echocardiography; SCI subjects also performed an exhaustive incremental exercise test. Comparisons were made between ABL and SCI groups, between trained and untrained subjects within each group (analysis of variance). Results: Effects of SCI-Compared with ABL subjects, SCI patients showed lower end-diastolic volume (76±21 vs 113±23 ml, Po0.05) and ejection fraction (61±7% vs 65±5%, Po0.05). Effects of training-Compared with untrained status, the intra-ventricular septum thickness (SCI, +18%; ABL, +4%), the posterior wall thickness (SCI, +17%; ABL, +2%) and the total normalized heart mass (SCI, +48%; ABL, +5%) were higher in both SCI T and in ABL T . VO 2 peak was higher in the SCI T subgroup compared with the SCI U group. Conclusions: Heart seems to positively adapt to long-term endurance training in SCI patients. Regular exercise may therefore increase heart size, septum and posterior wall thickness, which likely contributes to improved VO 2 peak. These morphological and functional changes may reduce cardiovascular risk in SCI individuals.
INTRODUCTIONThe positive effects of endurance training on heart morphology and function are well acknowledged in able-bodied (ABL) individuals: besides the typical development of bradycardia and the improvement in coronary perfusion, cardiac morphology usually shifts toward a physiological left ventricular (LV) hypertrophy with increased mass and internal volume of the left ventricle, and improved systolic and diastolic functions (for a review, see Pavlik et al. 1 ). In ABL endurance-trained individuals, the increased stroke volume finally yields an augmented cardiac output during exercise compared with untrained subjects. 2 A previous study demonstrated a reduction in LV mass and dimension in tetraplegic subjects, 3 and a more recent study showed an altered LV diastolic function and a subclinical decrease in systolic function in spinal cord injury (SCI) individuals. 4 In these patients, the reduced venous return due to the loss of sublesional vascular sympathetic innervation and of the muscular pump may cause a reduced adaptation of stroke volume to exercise, 5 which needs to be compensated by a higher submaximal heart rate, compared with that observed in ABL subjects. 6,7 Indeed, Dela et al. 5 demonstrated a stroke volume increase of about ...