McArdle disease (muscle glycogen phosphorylase deficiency) is a genetic condition associated with exercise intolerance, but how it affects lean mass (LM) and bone mineral content (BMC) and density (BMD) in patients is unknown. We compared these variables between McArdle patients and age/sex-matched healthy controls and assessed their potential association with physical activity (PA) levels in patients.
A case-control, cross-sectional design was used to examine LM, BMC and BMD by dual-energy X-ray absorptiometry in 136 young adults of both sexes [36 McArdle patients (33±15y) and 103 controls (34±11y)]. PA was assessed with the International Physical Activity Questionnaire (IPAQ).
McArdle patients had significantly lower LM values in whole-body and regional sites than their corresponding controls, whereas no differences were found (except for the trunk) when physically active patients (n=23) were compared with controls. All bone-related variables were significantly lower in patients than in controls (average difference of 13% for BMC and 7.6% for BMD). By contrast, no significant differences at the lumbar spine, pelvis and femur sites were found between physically active patients and controls.
We report on a previously undescribed condition in McArdle patients, poor bone health, which warrants further attention as it can occur in relatively young adults. An active lifestyle can at least partly alleviate this disorder presumably because of its beneficial effect on LM.
Correspondence Author: Ignacio Ara, PhD, GENUD Toledo Research Group, Universidad de Castilla-La Mancha, Avda Carlos III s/n, 45071 Toledo, Spain, Phone: +34 925 268 800 Ext 5543. Email: email@example.com
This study was funded by the Cátedra Real Madrid - Universidad Europea de Madrid (P2016/RM25), Fondo de Investigaciones Sanitarias (A.L., PI15/00558; G.N.G, PI15/01756 and CP14/00032, J.A. PI14/00903), the Biomedical Research Networking Centre on Frailty and Healthy Aging (CIBERFES) and FEDER funds from the European Union (CB16/10/00477). Irene Rodríguez Gómez received a PhD grant from the Universidad de Castilla-La Mancha “Contratos predoctorales para la formación de personal investigador en el marco del Plan Propio de I+D+i, cofinanciados por el Fondo Social Europeo” (2014/10340). The authors report no conflict of interest and they affirm that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by the American College of Sports Medicine.
Accepted for Publication: 16 August 2017.
© 2017 American College of Sports Medicine