Impact of exercise training on muscle function and ergoreflex in Fontan patients: A pilot study

Background Several studies have demonstrated persistent reduced exercise capacity in Fontan patients even after surgical intervention. The purpose of this study was to evaluate if the skeletal muscle function of these patients is abnormal, if it correlates with exercise tolerance and if it can be improved by exercise training. Methods We evaluated the functional capacity of seven patients who underwent Fontan procedure (age:16 ± 5 years, mean ± SD) and seven healthy children (19 ± 7 years) paired for age, sex, height and weight. Evaluation included pulmonary evaluation, neuromuscular function and exercise tolerance. Secondly, an 8-week exercise training program was performed by five of these patients. Results The ergoreflex contribution to absolute diastolic blood pressure was higher (12.5 ± 4.8 vs. 5.6 ± 4.2 mm Hg; p = 0.04) in Fontan patients vs. healthy subjects whereas a trend was encountered regarding the ergoreflex contribution to absolute systolic blood pressure (9.0 ± 7.0 vs. 0.4 ± 9.0 mm Hg; p = 0.09). Furthermore, time to fatigue of the non-dominant forearm muscles was shorter in Fontan patients vs. healthy subjects (431 ± 290 vs. 847 ± 347 s; p = 0.03). Following exercise training, there was a significant reduction of the ergoreflex contribution to absolute values of systolic blood pressure (9.8 ± 0.9 vs. 0.3 ± 2.7 mm Hg; p < 0.05). There was an association between muscle strength and V˙O2 peak in Fontan patients (upper limb: r = 0.895; p < 0.01; lower limb: r = 0.838; p < 0.05, respectively). Conclusions Skeletal muscle function in Fontan patients is abnormal which may have an impact in the reduced exercise tolerance encountered in these patients. Exercise training may have beneficial impacts on the skeletal muscle function in this population.