Non-invasive Brain Stimulation on Functional Capacity in Prefrail Older Adults

Fried's criteria (Frailty Phenotype) will be used. Briefly, the participant will be considered frail if he or she meets three or more of the following criteria: i) unintentional weight loss greater than 4.5 kg in the last year; ii) feeling of general exhaustion, reported by the patient himself; iii) low level of physical activity; (iv) slowness of progress; v) muscle weakness, assessed by handgrip strength. Those patients who meet one or two criteria will be considered pre-frail and those who do not meet either will be considered non-frail

The 10m Walking Test will be used to assess the speed of the walk, which records the time needed to cover the distance of 10m. The higher the walking speed, the greater the functional capacity

Neruoplasticity will be determined from the concentration of BDNF in plasma. A nurse will draw blood samples in BD Vacutainer® tubes, with EDTA as an anticoagulant. It will be centrifuged at 1500 G for 15 minutes at 4⁰ C, the supernatant (plasma) will be collected in eppendorf type tubes, which will be frozen at -80⁰ C until subsequent analysis. For the determination of BDNF levels, the ChemiKine™ BDNF Sandwich kit for ELISA (Millipore, Temecula, CA, USA) will be used, according to the manufacturer's instructions

HRV will be measured during 5 minutes at rest before intervention and during 20 minutes while performing aerobic exercise (walking). HRV will be measured with the PolarH10 band (Polar ®, Finland).

Measurement of the isometric action of the lower limb muscles will be carried out by means of a load cell (Chronojump, Spain) connected to the corresponding software (Chronojump Boscosystem). Specifically, the isometric strength of the gluteus medius, quadriceps, and hamstrings will be measured. The participant will be asked for a maximum of three repetitions with a duration of five seconds each, and a rest between them of another thirty seconds. The maximum value will be recorded, as well as the average value of each of the three repetitions, and the average will then be obtained, which will be the variable used for the subsequent data analysis. As for upper limb strength, assessed by grip strength, this will be determined by a Lafayette hand dynamometer. 3 measurements of the dominant hand will be taken and the mean will be taken for further analysis. Higher values indicate greater muscle strength

Determined using the EQ-5D instrument, a measure of self-perceived health, consisting of two parts: the EQ-5D descriptive system, which assesses five dimensions of health (i.e. mobility, self-care, usual activities, pain/discomfort, and anxiety/depression) and a visual analogue scale (VAS), in which people must estimate their general health status on a scale from 0 to 100. Higher values indicate greater quality of life.

It will be recorded with the 5 times sit to stand test (5STST). The participant must sit down and get up from a chair and the time it takes to perform the activity is timed. The higher the speed, the greater lower limb power

For this assessment, the FallSkip® tool will be used, which allows, by means of an inertial sensor incorporated in a smartphone, to record variables such as the medium-lateral and vertical displacement of the center of pressures in both dynamic and static, as well as to record the power to sit and get up from a chair and the variability of movement in a modified protocol of the Timed up and Go test. Based on the calculation of these variables, FallSkip® provides a fall risk score for each patient, ranging from very low, low, moderate, high, to very high risk, depending on the results obtained during the different test phases.

For this assessment, the FallSkip® tool will be used, which allows, by means of an inertial sensor incorporated in a smartphone, to record variables such as the medium-lateral and vertical displacement of the center of pressures in both dynamic and static, as well as to record the power to sit and get up from a chair and the variability of movement in a modified protocol of the Timed up and Go test. Based on the calculation of these variables, FallSkip® provides a fall risk score for each patient, ranging from very low, low, moderate, high, to very high risk, depending on the results obtained during the different test phases. For the dual task, a simultaneous activity will be used that will consist of numerical subtraction while walking. The higher punctuation, the better dual task functionality.