Application of a wireless BSN for gait and balance assessment in the elderly M.Caldara 1, 2 , P.Locatelli 1 , D.Comotti 1 , M.Galizzi 1, 3 , V.Re 1 , N.Dellerma 4 , A.Corenzi 4 , M. Pessione 3 1 Department of Engineering and Applied Sciences, University of Bergamo, Dalmine (BG), Italy 2 Human factors and Technology in Healthcare center, University of Bergamo, Italy 3 STMicroelectronics, Agrate Brianza (MB), Italy 4 Department of Clinical and Experimental Sciences, University of Brescia, Brescia, Italy Abstract— In developed countries, sedentary lifestyle is a major health risk factor. In elderly people, such mobility limitation is worsened by the reduced self-confidence and the fear of falling, leading to a further motor deterioration. This work presents an application of a wireless Body Sensor Network as a simple and easy-to-use individual motor function assessment tool for elderly. The wearable nodes have been exploited to monitor the body during the Six-Minute Walk Test and a set of stability tests. During the exercises, wearable sensors inertial data, along with the real-time orientation of the platforms, have been exploited to obtain gold-standard indicators (such as total distance) and some additional gait parameters. Stability tests consist of a series of single and double stance exercises aimed to assess the balance of the subject. This paper presents the system, the processing and the preliminary results on two subjects groups of different ages (31±6 and 70.8±7). Keywords—elderly; 6MWT; balance; stability; AHRS I. INTRODUCTION Insufficient physical activity is the 4th leading global risk for mortality in the world [1]. It is estimated to be responsible for 6% of deaths globally, after high blood pressure (13%), tobacco use (9%), high blood glucose (6%) and right before overweight and obesity (5%). As life expectancies increase and the major causes of death shift to the chronic and noncommunicable diseases (NCDs), populations are facing modern risks due to sedentary lifestyle. Moreover, the increase in the elderly population has in turn rapidly increased fall- induced injuries, which are major issues for health and social care providers in the world [2]. Falls are the most serious and frequent home accident among older people. As a matter of fact, they are the major reason for admission to hospital or a residential care setting, even when no serious injury has occurred: Heinrich et al. reported the evidence of the economic burden of falls on society [3]. The safety of walking as well as coordinating abilities depend on the single stance stability of the subject [4]. In fact, in elderly people a single stance instability situation leads to a deterioration of motor experience: the risk associated to this condition induces a lack of self-confidence in the subject, which will reduce their motor habits and change their lifestyle becoming more hypokinetic. Also, there is observational evidence that mid-life and older adults who participate in regular physical activity have reduced risk of moderate and severe functional limitations and role limitations [5]. In some cases the evidence of health benefits is strongest in older adults because the outcomes related to inactivity are more common in older adults. Pahor et al. [6] have demonstrated the potential for structured physical activity as a feasible and effective intervention to reduce the burden of disability among vulnerable older people, in spite of functional decline in late life. Furthermore, improving physical conditions and motor abilities of elderly contributes to the abatement of health and hospitalization costs. In order to prevent disability and fall-induced injuries, physical activity has to be considered as a therapeutic tool prescribed by doctors on the basis of diagnostic assessments on the patient. Such activity will have the goal to maintain and improve the motor condition of the subject, including coordination, balance, proprioception and reaction time. In this paper, a network of wearable Attitude and Heading Reference Systems (AHRS) has been exploited as a quantitative tool to assess motor performance in elderly people. Patients of different ages have been monitored during the execution of two exercises, the so-called Six-Minute Walk Test (6MWT) and a set of stability tests, in order to evaluate some gait key parameters and the balance respectively. The work reports the preliminary results of the system on two groups of subjects of different ages. II. ASSESSMENTS DESCPRITION Inactive adults of the 65 years and above age group, including those with NCDs, are likely to gain health benefits by increasing their level of physical activity. International guidelines for elderly physical activity prescription in elderly suggest to include a set of exercises aimed to improve stability. In fact, the physiological functional regression involving this category is the reason of the increase of falls, which deeply change subject's behavior even when there are no consequences. Before starting any physical exercise program, it is necessary to establish reliable methods for subjects motor assessment. Steffen et al. [7] reported reliability, validity and reference data of 4 common clinical tests, i.e. Six-Minute Walk Test, Berg Balance Scale (BBS), Timed Up & Go (TUG) and Comfortable and Fast Gait Speeds (CGS and FGS). Langley and Mackintosh provided a systematic review of published literature relevant to 17 functional balance tests [8]. In order to define a proper therapeutic set of exercises aimed to maintain and improve functional abilities, two of those assessments have been selected as diagnostic tools to evaluate motor conditions in elderly people: the 6MWT and a set of balance tests.