ORIGINAL ARTICLE Development of a French Isometric Strength Normative Database for Adults Using Quantitative Muscle Testing Jean-Yves Hogrel, PhD, Christine A. Payan, MD, Gwenn Ollivier, PT, Véronique Tanant, PT, Shahram Attarian, MD, Annabelle Couillandre, PhD, PT, Arnaud Dupeyron, MD, Lucette Lacomblez, MD, PhD, Valérie Doppler, MD, Vincent Meininger, MD, Christine Tranchant, MD, PhD, Jean Pouget, MD, Claude Desnuelle, MD, PhD ABSTRACT. Hogrel J-Y, Payan CA, Ollivier G, Tanant V, Attarian S, Couillandre A, Dupeyron A, Lacomblez L, Doppler V, Meininger V, Tranchant C, Pouget J, Desnuelle C. Devel- opment of a French isometric strength normative database for adults using quantitative muscle testing. Arch Phys Med Re- habil 2007;88:1289-97. Objective: To establish a normative database for isometric strength measured by quantitative muscle testing (QMT) for a French adult population. Design: Measurement of maximal voluntary isometric contraction. Setting: Four clinical centers involved in neuromuscular disorders. Participants: A total of 315 healthy adults (147 men, 168 women) ages 20 to 80 years. Interventions: Not applicable. Main Outcome Measure: Isometric torque values of 14 muscle functions (13 bilaterally and neck). Results: This study led to the development of a French isometric strength normative database for adults measured by QMT. For each muscle function, predictive regression models using age, sex, and weight are proposed. Some methodologic issues concerning strength measurement are discussed. Conclusions: This database can be used to compute relative deficits in muscle strength for 27 muscle functions and also to estimate composite scores for follow-up of patients either dur- ing the natural history of their disease or during a therapeutic trial. Key Words: Isometric contraction; Muscles; Outcome as- sessment (health care); Rehabilitation. © 2007 by the American Congress of Rehabilitation Medi- cine and the American Academy of Physical Medicine and Rehabilitation A NY PATHOLOGY INVOLVING the neuromuscular sys- tem can be longitudinally investigated with 1 or several methods to follow degenerative effects on muscle strength during the natural history of the disease or to detect small changes during a therapeutic trial. As already described, 1,2 several methods may be used to assess muscle strength. De- pending on the aim of the assessment, each presents several advantages and drawbacks. Methodologic issues are funda- mental because patients present with different motor capacities, changes in strength may be fairly small over the duration of the trial, and different evaluators may be involved in different clinical centers. The term quantitative muscle testing (QMT) implies that quantification of strength is performed by a measurement de- vice or sensor. 3 It can be performed by handheld dynamome- ters, strain gauges with 1 extremity fixed to a wall-mounted frame, or isokinetic ergometers. Strain gauges have been fre- quently used in clinical trials concerning various neuromuscu- lar diseases. 4-8 Strength measurements are performed in iso- metric conditions to assess the maximal voluntary isometric contraction (MVIC) at a given position. Although muscles produce linear forces, motions at joints are generally rotary. Strength generated around joints should be measured as torque (in newton meters) because the degrees of freedom of joints are mainly rotational. When strength estimates are made, the mo- ment arm must be carefully measured. Otherwise, the repro- ducibility of measurements cannot be assessed even when anatomic reference marks are methodically respected. Accord- ing to Munsat, 9 MVIC measurement provides a “direct, repro- ducible, sensitive and practical” method to assess changes in the voluntary motor system. The reliability of QMT was ques- tioned in a report on a multicenter trial in amyotrophic lateral sclerosis (ALS). 10 The authors 10 argued that the development of precise procedures understood and applied by all the in- volved evaluators is a prerequisite to achieve consistent mea- surements. However, compared with manual muscle testing (MMT), which can require multiple training sessions to obtain acceptable reliability, a high level of agreement can be ob- tained with a single session of training in QMT. 11 Andres et al 4,12 developed standardized quantified tests known as the Tufts Quantitative Neuromuscular Exam (TQNE) for evaluating patients suffering from ALS. The TQNE in- cludes measurements of pulmonary and oropharyngeal func- tions, timed motor activities, and QMT. The different measure- ments can be combined by using z scores based on the population mean and standard deviation to produce megas- cores. The TQNE was used for instance by Munsat 13 and Conradi 14 and colleagues to assess motor disability and disease progression in ALS patients. More recently, MVIC was used in children suffering from Duchenne muscular dystrophy to as- sess the efficacy of creatine or glutamine supplementation by using QMT and MMT. 8 QMT was found to be more sensitive than MMT in detecting muscle loss of strength. From the Institut de Myologie (Hogrel, Payan, Ollivier, Couillandre, Doppler), Département de Pharmacologie Clinique (Lacomblez), Fédération des Maladies du Système Nerveux (Meininger), GH Pitié-Salpêtrière, Paris, France; Centre de Référence Maladies Neuromusculaires, Hôpital de l’Archet, Nice, France (Tanant, Desnuelles); Service de Neurologie, CHU La Timone, Marseille, France (Attarian, Pouget); and Service de Neurologie, CHU de Strasbourg, Strasbourg, France (Dupey- ron, Tranchant). Supported by the Association de Recherche sur la Sclérose Latérale Amyotro- phique and the Association Française contre les Myopathies. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated. Reprint requests to Jean-Yves Hogrel, PhD, Institut de Myologie, GH Pitié- Salpêtrière, 75651 Paris Cedex 13, France, e-mail: jy.hogrel@institut-myologie.org. 0003-9993/07/8810-11539$32.00/0 doi:10.1016/j.apmr.2007.07.011 1289 Arch Phys Med Rehabil Vol 88, October 2007