International Journal of Cardiology Congenital Heart Disease · Sep 27, 2026

Effects of strength training on isometric muscle strength and muscle cross-sectional area in adults with a Fontan circulation: a pilot study

By Wikner A, Bergman F, Rinnström D et al.

BACKGROUND: Adults with complex congenital heart disease, particularly those with a Fontan circulation, often have impaired muscle strength and reduced muscle mass from early age. Despite these concerns, data regarding the effects of strength training in this population is limited. AIM: To evaluate the impact of a 10-week strength training intervention on muscle strength and muscle cross-sectional area (CSA) in adults with Fontan circulation, compared to age- and sex matched controls. METHODS: Nine adults with a Fontan circulation (median age 28.9 [IQR: 23.4-35.0], 4 women) underwent a gym-based strength training program. Isometric muscle strength (elbow flexion, knee extension, grip strength), radial and tibial muscle CSA and density, and habitual physical activity (accelerometer-based and self-reported data) were measured pre- and post-intervention. Within-group changes were analysed using the Wilcoxon signed-rank test; between-group differences were assessed using the Mann Whitney U test. RESULTS: Both patients and controls demonstrated improvements in isometric elbow flexion strength (Patients: +6.2% [IQR: 2.8-17.7], p = 0.02, r = 0.77; Controls: +8.4% [IQR: 2.9-16.0], p = 0.012, r = 0.84) and tibial cross-sectional area (Patients: +5.0% [IQR: 2.7-11.4], p = 0.011, r = 0.85; Controls: +4.0% [IQR: 1.4-7.4], p = 0.018, r = 0.89). No changes were observed in isometric knee extension or grip strength. There were no differences between groups, and no adverse events occurred. CONCLUSION: This pilot study supports that strength training is safe and effective in improving muscle strength and muscle CSA in adults with a Fontan circulation. Despite the small sample size these findings are reassuring. However, confirmation in larger prospective trials is warranted. CLINICALTRIALSGOV ID: NCT05454254, https://clinicaltrials.gov.

doi.org/10.1016/j.ijcchd.2026.100716Open accessPubMed 42960030Interventions