Neuromuscular Electrical Stimulation and Action Observation for Healthy Aging: a Home-based Approach to Promote Sensorimotor Adaptation

Aim The purpose of study will be testing the effects of a self-administered, home-based intervention combining NMES and AO for the upper limbs in healthy elderly people on muscle strength and proprioceptive abilities. This will be done by comparing action observation-neuromuscular electrical stimulation (AO-NMES) with action observation (AO) and neuromuscular electrical stimulation (NMES) delivered alone, with the hypothesis that AO-NMES leads to higher improvement than the others. This approach could be a safe, accessible and cost-effective way to maintain or improve neuromuscular function and sensorimotor control in ageing populations. Furthermore, by preserving upper limb function, the intervention could help older adults to retain functional autonomy, reduce their risk of disability and improve their overall quality of life and well-being.

Methods

1. Participants Voluntarily participants will be recruited from the students enrolled in the 'UniGeSenior' program at the University of Genoa. The inclusion criteria are voluntarily participation, age ranges from 65 to 85 years, both male and female, sedentary. Exclusion criteria include neurological or psychiatric disorders, fractures within the past six months, orthopedic or musculoskeletal impairments, uncontrolled hypertension, and regular resistance training (at least once per week), participation in competitive sports.
2. Study design This will be a randomized, double-blind, controlled experimental trial. The study will be registered on ClinicalTrials.gov. The intervention will last four weeks, three sessions per weeks will be performed at home. The intervention will vary according to the assigned group, with all interventions delivered in parallel across the following groups: AO group, NMES group and AO-NMES group. The assignment will be done using the RAND() function in Excel, which generated random numbers that were then used to sort and allocate subjects evenly. During each session, the treatment will last 30 minutes and will include a 10-minutes warm-up phase during which the visual task will be administered, and 20 minutes of exercise phase.

Before (PRE) and after (POST) the intervention period participant will perform different kinds of assessments (see Evaluation section). 3. Intervention 3.1. Visual stimuli

The stimuli shown to the participants will change according to the group. In the AO group participants will watch a video showing different instrumental activities of daily living (IADLs), which require considerable force production, executed with the upper limbs by a woman or a man. The IADLs will involve the individual performing the following tasks:

• Moving a box forward or backward while sitting on a chair
• Lifting a box onto or bringing it down from a support while standing upright
• Placing a box onto or removing it from a shelf while standing upright
• Moving a box from left to right or right to left while sitting on a chair
• Moving a shopper from right to left or left to right while standing upright
• Placing a shopper on a shelf or taking it down from a standing position
• Holding a shopper while remaining upright The same AO task will be proposed to the AO-NMES group. Participants of the NMES group will observe changing landscapes. The visual stimuli will be administered through a tablet (Smartpad 9 Mediacom, Datamatic S.p.A, Milano, Italy) provided to the participants.