Copyright © 2017 The Academy of Geriatric Physical Therapy, APTA. Unauthorized reproduction of this article is prohibited. Journal of GERIATRIC Physical Therapy 1 Research Report INTRODUCTION Muscle tone can be defined as the continuous resting ten- sion or the resistance in response to stretching. It is an essential feature of a healthy and well-functioning muscle, which enables the production of effective and efficient movement of our limbs and provides an appropriate posi- tion of the body at rest as well as in action. 1 Consequently, inappropriate muscle tone impedes adequate movement and posture. 2 In several pathological conditions, such as stroke and cerebral palsy, muscle tone is affected. As a result, proper assessment of muscle tone is crucial from a clinical perspective in a wide range of rehabilitation domains, to aid in management of disease progression and evaluate the effect of therapeutic interventions. Currently, clinical estimation of muscle tone is commonly performed using the Modified Ashworth Scale 3 (MAS) or by manual palpation. Despite the usefulness of these tools in daily clinical practice to grade major subcategories of muscle healthy subpopulations, (a) intrarater reliability was very high and intrarater agreement was good between 2 consecutive series, (b) between days intrarater reliability was low to high and intrarater agreement was variable, (c) interrater reliability was high to very high and interrater agreement was good. In individuals with paratonia, (a) intrarater reliability was moder- ate to high and agreement was variable between series, (b) between days intrarater reliability was poor to moderate and agreement was poor, (c) interrater reliability ranged from low to high with poor agreement. Conclusions: MyotonPRO measurements of the BB muscle showed good reproducibility in both healthy subpopulations, particularly for measurements performed within the same day. In individuals with paratonia, reliability and agreement were substantially lower. MyotonPRO can be used in clinical assessment and research. However, in individuals with para- tonia, careful interpretation of results is required. Research in a larger sample of persons with paratonia at different stages of disease severity is recommended. Key Words: dementia, muscle tone, MyotonPRO, paratonia, reproducibility (J Geriatr Phys Ther 2016;00:1-10.) ABSTRACT Background and purpose: The MyotonPRO is a portable device that measures muscle tone and biomechanical muscle properties objectively. MyotonPRO has already proven to be effective in measuring muscle properties in healthy and dis- eased populations. However, to the best of our knowledge, it has never been tested in individuals suffering from paratonia, a form of hypertonia frequently accompanying dementia. The aims of the present study were to (1) compare muscle tone, elasticity, and stiffness between 3 different subpopulations of young and old healthy adults and individuals with paratonia, and (2) investigate the intra- and interrater reproducibility of MyotonPRO measurements of the biceps brachii (BB) muscle in each subpopulation. Methods: MyotonPRO measurements of muscle tone, elastic- ity, and dynamic stiffness were carried out by 2 investigators on 2 different days over the BB muscles of 54 participants (18 healthy young adults, 20 healthy older adults, and 16 older individuals with paratonia). Muscle properties were com- pared between subpopulations using ANOVA/Welch and post hoc tests. Reliability (intraclass correlation coefficient) and agreement parameters (standard error of measurement and the minimal detectable change) were calculated. Results: Statistically significant differences between sub- populations were found in all parameters, except for stiffness between healthy elderly and individuals with paratonia. In the Reproducible Measurements of Muscle Characteristics Using the MyotonPRO Device: Comparison Between Individuals With and Without Paratonia Bieke Van Deun, PT, MSc 1 ; Johannes S. M. Hobbelen, PT, PhD 2 ; Barbara Cagnie, PT, PhD 1 ; Birgit Van Eetvelde, PT, MSc 1 ; Nele Van Den Noortgate, MD, PhD 3 ; Dirk Cambier , PT, PhD 1 1 Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium. 2 Research Group Healthy Ageing, Allied Health Care and Nursing, Hanze University of Applied Sciences, Groningen, the Netherlands. 3 Department of Geriatrics, Ghent University Hospital, Ghent, Belgium. The authors declare no conflicts of interest. Address correspondence to: Bieke Van Deun, PT, MSc, Department of Rehabilitation Sciences and Physiotherapy Ghent, Campus Heymans 2B3, De Pintelaan 185, B-9000 Gent, Belgium (bieke.vandeun@ugent.be). Copyright © 2017 Academy of Geriatric Physical Therapy, APTA. Richard W. Bohannon was the Decision Editor. DOI:10.1519/JPT.0000000000000119