## 1 Introduction  
The World Health Organization (WHO) defines eHealth as the electronic transfer of health resources and health care. This definition encompasses three main areas: (1) delivery and exchange of health information for health professionals and consumers through the Internet and telecommunications; (2) use of information technology and eCommerce to improve public health through education and training; and (3) practical use of electronic commerce (eBusiness) in the management of health systems. Internet and new communication technologies offer a new framework for the dissemination of information, interaction and collaboration between institutions, health professionals and users [1]. eHealth, therefore, provides new methodologies for the use of health resources such as information, money and medicines, in order to improve and streamline these resources [2]. Nowadays a form of eHealth is already in operation in developed countries for monitoring both sick and healthy patients, employing telematic equipment to log physiological signals. This equipment is mostly confined to hospitals, intensive care units (ICUs), primary and outpatient care. However, eHealth is an emerging and a promising field with great perspectives, e.g., telemedicine, which allows professionals to monitor individuals or groups of people, such as athletes, the disabled, patients with chronic illnesses, or the elderly. Also, in the case of risk groups or sectors of the population with disadvantaged economic and social situations, telemonitoring has a huge potential for analyzing pandemics, possible birth defects, phobias and other possibilities. A study about the role of eHealth in optimizing preventive care in the primary care setting has been recently published [3]. Currently, there is increasing interest in eHealth applications as the medical field is one of the most fertile areas for the use of such technology [4; 5]. There are many different electronic devices based on System-on-Chip that allow a patient or a group of patients to be monitored by gathering information on their biosignals in order to keep a check on their well-being [6]. Through the FP7 (Seventh Framework Programme) and H2020 (Horizon 2020) [7] the European Commission has funded several projects aimed at eHealth monitoring. Among different them, the most important for our purposes are eHealthMonitor, aimed at developing a platform for individualized personal healthcare services [8], and iCARDEA, aimed at designing an intelligent platform for personalized remote monitoring of cardiac patients with electronic implant devices [9]  
Other Spanish national projects, like Telemac, HELP or METABO [10; 11] have been developed in order to monitor patients with COPD (Chronic Obstructive Pulmonary Disease), Parkinson's disease or diabetes. By using several sensors, they have monitored different subjects, tracking and controlling treatments, lifestyle, physiology or physical activity, with the aim of providing and improving the information and necessary control over a disease, and ensuring a better quality-of-life for the patient, as well as increased life expectancy. The results have been positive, as monitoring has improved treatments and consequently the quality-of-life of patients [11], although the cost of these systems is high. This paper aims to provide and evaluate a system that facilitates communication between medical professionals and patients or athletes. A telemonitoring system based on an eHealth sensor board [12] has been implemented and provides follow-up on athletes and measures vital physiological parameters, such as pulse, blood pressure, electrocardiogram, electromyogram, oxygen saturation in blood, airflow, skin galvanic response, position, temperature and the parameters of interest for follow-up on athlete training or the patient.