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Let's Get Physical: Aerobic capacity, muscle strength, and muscle endurance in pediatric heart transplant recipients

Allan, Chantal J.1,3; Urschel, Simon1,4; Larsen, Ingrid M.1,3; Mathur, Sunita5; West, Lori J.1,4,6

doi: 10.1097/

1Pediatrics, University of Alberta, Edmonton, AB, Canada; 2Canadian National Transplant Research Program, Edmonton, AB, Canada; 3Alberta Transplant Institute, Edmonton, AB, Canada; 4Department of Medical Microbiology and Immunology, University of Alberta, Edmonton, AB, Canada; 5Department of Surgery, University of Alberta, Edmonton, AB, Canada; 6Physical Therapy, University of Toronto, Toronto, ON, Canada.

Introduction: Pediatric heart transplant recipients (pHTx) often appear to have lower physical fitness than healthy children (HC). This study assesses the aerobic capacity, muscle strength, and muscle endurance of pHTx in order to create a fitness profile for these children, and investigate clinical and lifestyle factors that may affect their fitness.

Methods: pHTx (n=3) and a control group of HC and healthy siblings (n=6) are being recruited for this study. Healthy, non-related children are selected based on age, height, and sex to reduce variability among groups. Age-specific questionnaires assess quality of life (PedsQL 4.0) and physical activity (PAQ). Anthropometry and body composition (BodPod) are measured. Aerobic capacity is assessed by six-minute walk test (6MWT). Muscle strength is measured by hand-held dynamometry of upper (deltoid), core (abdominal), and lower (quadriceps) body muscle groups. Muscle endurance of upper (push-ups), core (curl-ups), and lower (wall sit) body muscle groups is measured. Clinical data regarding transplant course, medications, physical therapy, underlying diagnosis, onset of disease, number of pre-transplant surgeries, extra-cardiac organ impairment, and cerebrovascular events is collected from patient charts.

Results: The pHTx group is age-matched with controls (pHTx=9.8±6.5 y, HC=11.4±1.4 y, p=0.72), and 6.4±7.6 y post-transplant. Preliminary data suggest that, despite comparable levels of physical activity (p=0.88), quality of life (p=0.68), and fat-free mass (p=0.63), some fitness measures are reduced in pHTx vs HC. Wall sit time is the only parameter that is significantly impaired in pHTx (p=0.02). However, the impairment in 6MWT among pHTx and HC approaches significance (p=0.08). Underlying diagnoses in pHTx include congenital heart disease (n=2) and cardiomyopathy (n=1). pHTx were receiving tacrolimus and mycophenolate mofetil, but not prednisone at the time of the study. The length of pre- and post-transplant physical therapy varied among pHTx, ranging from 0–12 weeks pre-transplant, and 0–52 weeks post-transplant.

Conclusion: Lower body muscle endurance is impaired in pHTx versus HC. Since physical activity, quality of life, and fat-free mass are matched in the study sample, muscle function is likely impaired by other factor(s). Ongoing recruitment will allow further investigation of the effect of pediatric heart transplantation on fitness, and to analyze the effects of clinical factors on fitness outcomes.

Canadian National Transplant Research Program. Astellas Pharma Canada, Inc. Women and Children's Health Research Institute. Department of Pediatrics, University of Alberta, Edmonton, Alberta, Canada.


1. Ulrich S, Hildenbrand FF, Treder U, Fischler M, Keusch S, Speich R, Fasnacht M. Reference values for the 6-minute walk test in healthy children and adolescents in Switzerland. BMC pulmonary medicine. 2013 Aug 5;13(1):49.

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