Correction: Aerobic Exercise Training in Post-Polio Syndrome: Process Evaluation of a Randomized Controlled Trial

• Eric L. Voorn, 
• Fieke S. Koopman, 
• Merel A. Brehm, 
• Anita Beelen, 
• Arnold de Haan, 
• Karin H. L. Gerrits, 
• Frans Nollet