Currently, there is a growing concern for the elderly population and for what the increase in life expectancy entails, and that is why many authors investigate about exercise protocols that delay the appearance of both cognitive and motor diseases and how to link both in your day to day. Despite this, there is still little information about training with DT tasks that improve the life of the elderly and that is why this study aims to evaluate the effect of an eight-week training program in older adults healthy, in the improvement of balance and proprioception of the knee, with the inclusion of a cognitive task performed simultaneously. We hypothesize that the inclusion of the double motor-cognitive task in the training sessions will improve the performance in the balance and proprioception tests performed with the simultaneous cognitive task after 8 weeks compared to the control group.

The study included the participation of 30 physically active older adults, who were recruited in a sports center in the community of Cataluña, between the ages of 65-85 years. Potential participants were excluded from the sample if they: i) suffered from a neurological condition such as Alzheimer's or Parkinson's disease ii) were unable to perform one or more of the parts of testing and/or iii) were undergoing pharmacological treatments likely to alter postural control and proprioception, iv) underwent lower limb joint replacement surgery. The participants were invited to take part in the study voluntarily and they were informed verbally and in writing as to the characteristics of the programme.

The study was carried out in accordance with the ethical standards set out according to the Declaration of Helsinki, and it was approved by the Ethics Committee at Ramón Llull University. All protocols applied in this research (including the management of the personal data of the participants) complied with the requirements specified in the Declaration of Helsinki of 1975 and its subsequent revisions.

The specific DT program is aimed at physically active people between 8 and 15 years old who train at the center in maintenance classes for the elderly and aim to improve their quality of life and keep them active for the functionality of their daily lives. All the study participants will be asked to sign an informed consent document that will be drafted in keeping with all applicable research ethics protocols, including a guarantee of the confidentiality of personal data and an assurance that participants can choose to abandon the study at any time.

Control group (CG), experimental group (EG) and pre-test, post-test methodology was selected. EG performed the specific DT while CG carried out the motor training.

The motor-cognitive intervention will be carried out over one year in the years (2019-2020). The first 3 months allowed investigators to recruit the participants and and observe the training sessions that the subjects did in the center. After this, the researchers designed an intervention that complemented the training that the subjects had previously carried out and were specific training for the study objectives.

This design took into account the previous experiences of the subjects' trainer and of an expert physical therapist in motor control (balance and proprioception), and a psychologist. Before starting the real intervention, test sessions of the training protocol to be developed were applied to know the level of the subjects, and thus have data that would allow us to adjust the training schedule to their needs and abilities. The conclusions drawn from this initial experience formed the scientific basis for the definitive version of motor-cognitive training.

During the fourth month, a preliminary test was carried out that included 4 balance tests, a propioceptive test and a cognitive test. The participants performed the tests in an isolated, comfortable place that did not interfere with their results. The order of the subjects and the order of the applied tests were determined randomly using a true random number generator to avoid order effects. An expert team of researchers in the field directed and controlled the tests.

Romberg test: it was the test selected to measure the motor control of the participants. Three measurement conditions were used: bipedal eyes open / eyes closed and unipedal dominant eyes open. Balance was measured on a KISTLER force platform.

Proprioception: To evaluate proprioception, the absolute repositioning error of the knee joint at 45 degrees (AEr45º) in the dominant leg was recorded. This measurement was taken with the Goniometer Pro mobile application.

Subscale of the Barcelona Test: to carry out the performance of the dual task, the subjects performed a cognitive task while their balance and proprioception were evaluated. The cognitive task came from the subscale called "categorical evocation in associations", which is found within the battery of subscales of the Revised Barcelona Test. The task consisted of mentioning the maximum number of possible words for 30 seconds belonging to the same semantic field.

In all this tests, the participants wore an orthopedic boots on both feet for the postural control measurements, helping to guarantee that the two tests (postural control and proprioception) would yield comparable results. These boots served to eliminate the effects of any initial postural control adaptations made by the toes or ankle, thus ensuring that the knee would act as the main balancing mechanism.

From October to December, the cognitive-motor training sessions were carried out in the same room in which the participants previously carried out their activities, and at the same time, thus guaranteeing the safety of the participants. An instructor will lead the session and the monitor of the activities of the participants will reinforce and help during the exercise protocol. Two sessions were held per week, on different days for each of the groups, in order not to create interferences or learning in the subjects. The duration of the sessions was thirty minutes and it was divided into a five-minute warm-up, the main part of twenty minutes and a cool down of five minutes. During the main part it was controlled that the technical execution of the exercises was carried out correctly in order to avoid injuries and favor the improvement of the balance and proprioception of the participants.

The main part consisted of a simple choreography, which progressed in the difficulty of the exercises after the sessions. It began with individual balance and proprioception exercises in the first session, in pairs in the second, trios for the third, and in groups of four for the fourth, and until the end of the protocol. The proposed exercises included walking, lateral movements, forward and backward, simple balances with both legs, and more complex when performed in the company of others, knee bends at no more than 45º to be related to the proprioception tests. For example, when performing a squat, imbalances were proposed with pairs or trios to compromise the stability of the participants, or dances such as the twist or the conga to, in addition to working on balance, promoted socialization and fun for the participants. The only difference in the training protocol between CG and EG was the inclusion of sung music in EG sessions. The objective was that at the end of the 4 sessions listening to the same music, the subjects learned pieces of the songs and that during the training they were singing them or at least memorizing them.

A post-test was carried out once the 8 weeks of the intervention protocol had ended, as was the pre-test protocol.

The Statistical Analysis will be executed using an Excel sheet and then it will be exported to the SPSS Statistics 22.0 computer program, to then carry out the different statistical tests. Initially, a normality test will be run to verify the distribution of the data and decide whether to apply parametric or nonparametric tests. The G-POWER program will be used to calculate the statistical power of the sample with a value of p <0.05 and an estimated effect size of 0.5.

Inclusion Criteria:

• Physically active older adults

Exclusion Criteria:

• Clinical disability for physical activity
• Neurological condition such as Alzheimer's or Parkinson's disease
• Subjected to drug treatments that alter the normal functioning of the nervous system
• Recent lower limb joint replacement surgery (12 months before testing)