Evaluation of muscle oxygenation by near infrared spectroscopy in patients with facioscapulohumeral muscular dystrophy N. Olivier a, *, J. Boissière a , E. Allart b , P. Mucci a , A. Thevenon a,b , F. Daussin a , V. Tiffreau a,b a EA 7369, URePSSS: team 1 – physical activity, muscle, health, University of Lille, 9, rue de l’Université, 59790 Ronchin, France b Neuromuscular Disorders Reference Centre, Hôpital Swynghedauw, CHRU de Lille, 59037 Lille, France Received 24 June 2015; received in revised form 1 October 2015; accepted 14 October 2015 Abstract The purpose of the study was to determine muscle metabolism adaptation to exercise in facioscapulohumeral muscular dystrophy patients (FSHD) and to study the correlation with clinical functional status (6-min walk test). 8 FSHD patients and 15 age-matched healthy controls (Controls) performed two isokinetic constant-load knee extension exercises: (1) at 20% of their maximal extensors’ peak torque (i.e. the same relative workload) and (2) at (20N·m) (the same absolute workload) for up to 4 min. All exercises consisted of rhythmic, voluntary, isokinetic, concentric contractions of the quadriceps femoris at 90°/s, whereas the flexion was performed passively at the same speed. Muscle oxygenation in the vastus lateralis was evaluated using near-infrared spectroscopy (NIRS). The FSHD patients displayed a lower maximal peak torque than controls (-41%, p < 0.05). During the two-exercise modalities, deoxygenated haemoglobin (HHb) and total haemoglobin volume (tHb) were lower in the FSHD patients (p < 0.05). The initial muscle deoxygenation time delay was shorter in the control group (FSHD: 15.1 ± 4.1 s vs. controls: 10.4 ± 2.1 s, p < 0.05). Mean response time and maximal peak torque were both correlated with functional impairment (walking endurance). The results suggest that FSHD patients present an impairment in their capacity to deliver or to use oxygen. © 2015 Elsevier B.V.All rights reserved. Keywords: Neuromuscular disease; Muscle oxygenation; Near-infrared spectroscopy; Exercise 1. Introduction Facioscapulohumeral muscular dystrophy (FSHD) is an autosomal dominant inherited muscular dystrophy and affects about 1 in 20,000 people worldwide [1]. Symptoms may develop in early childhood but generally appear after adolescence. FSHD is characterised by a progressive asymmetric muscle weakness (due to fibre degeneration) in the facial muscles, shoulder girdle and arms [2]. In addition, muscle weakness develops in other areas and the lower limbs can be affected, leading to loss of mobility in 20% of patients. Potential complications include severe muscle weakness, wheelchair use and postural problems leading to a sedentary lifestyle. Hence, the ability of patients to perform physical activity is limited and contributes to a decreased quality of life [3,4]. Understanding the mechanisms involved in the physical weakness is thus a major issue. The altered physical ability during exercise may result from a limited oxygen uptake within the active muscles in this population. Recent studies have shown an increased oxidative stress and mitochondrial dysfunction correlated to parameters of muscle function in patients affected by FSHD [5,6]. The impairment of one or more metabolic or mitochondrial pathways may result in an energy deficiency that could be a feature of muscle impairment. To investigate this hypothesis, near-infrared spectroscopy (NIRS) has been widely used for monitoring local muscle oxygenation in healthy subjects and in patients with various neuromuscular, metabolic, vascular or respiratory diseases [7–9]. More specifically in the field of neuromuscular disease, NIRS has been used almost exclusively to evaluate the muscular oxygen uptake capacity in patients with muscular metabolic disorders [10,11]. During an incremental exercise test, patients with muscular metabolic diseases display lower levels of deoxyhemoglobin (HHb) – perhaps as a result of a defect in oxygen uptake [7]. In patients * Corresponding author. EA 7369, URePSSS : team 1 – physical activity, muscle, health, University of Lille, 9, rue de l’Université, 59790 Ronchin, France. E-mail address: nicolas.olivier@univ-lille2.fr (N. Olivier). http://dx.doi.org/10.1016/j.nmd.2015.10.004 0960-8966/© 2015 Elsevier B.V.All rights reserved. ARTICLE IN PRESS Please cite this article in press as: N. Olivier, et al., Evaluation of muscle oxygenation by near infrared spectroscopy in patients with facioscapulohumeral muscular dystrophy, Neuromuscular Disorders (2015), doi: 10.1016/j.nmd.2015.10.004 Available online at www.sciencedirect.com Neuromuscular Disorders ■■ (2015) ■■–■■ www.elsevier.com/locate/nmd ScienceDirect