Endothelial Function in Healthy Volunteers (NormFMD)

All the participants will be included in the only arm of this study designed to establish FMD values of reference.

FMD refers to the increase in the diameter of the brachial artery caused by hyperaemia resulting from the rapid deflation of a cuff inflated to a suprasystolic pressure. This measurement of endothelial function is carried out at the level of the microcirculation (peripheral vessels) using the non-invasive technique of measuring flow-mediated vasodilation (FMD) in the brachial artery, which is currently the gold standard for assessing vascular endothelial function in humans (Holder et al., 2021).

The diameter of the brachial artery is measured by ultrasound before and after the increase in shear stress induced by the release of the occlusion after 5 minutes. The FMD of the left brachial artery is measured in the longitudinal plane above the antecubital fossa using a high-resolution CE-marked ultrasound scanner with a 190 linear array probe operating at 7 to 12 MHz. A mechanical arm (Vascular Imaging, Amsterdam, Netherlands), fitted with micrometric screws to allow precise movement in all three dimensions, is used to ensure correct, stereotactic positioning of the probe. Once the probe is optimally positioned, images are initially recorded for 60 s and then continuously for 3 min following the resolution of forearm ischaemia, caused by inflating a blood pressure cuff to 220 mmHg for 5 min (occlusion). The images are encoded and recorded on a dedicated computer, then digitised for subsequent blinded analysis using automatic edge-detection software 197.

Muscle function will be assessed using the SARC-F questionnaire, where a score of 4 out of 5 or higher suggests the presence of sarcopenia.

Muscle function will be assessed using the SPPB test, which assesses an individual's physical performance (balance, walking speed, standing up from a chair).

Assessment of muscle strength in Kg using a dynamometer.

Body fat percentage will be measured using a bioimpedance analyser

Lean body mass percentage will be assessed using a bioimpedance analyser

Body water percentage will be assessed using a bioimpedance analyser

Quality of life will be assessed using the Pittsburgh Sleep Quality Index (PSQI), which measures sleep quality during the month preceding the interview with the participant.

The overall score (0 to 21) is calculated by adding together the sub-scores for the seven components, each of which ranges from 0 to 3 points. The higher the overall score, the greater the impairment to sleep quality. An overall score of more than 5 is an indicator of sleep disorders.

Quality of life will be assessed using the Hospital Anxiety and Depression (HAD) scale, which screens for anxiety and/or depressive disorders.

It comprises 14 items scored from 0 to 3. Seven questions relate to anxiety and seven others to the depressive dimension, thus yielding two scores (maximum score for each: 21).

A score of 7 or below indicates an absence of symptoms. A score between 8 and 10 indicates possible symptoms. A score of 11 or above indicates confirmed symptoms.

Quality of life will be assessed using 36-Item Short Form Survey (SF-36), which assesses an individual's physical and mental health based on 36 questions relating to eight aspects of health.

An index is calculated for both physical and mental health (0-100); the higher the score, the better the quality of life.

The cognitive assessment will be carried out using the MoCA test, which is a screening tool for cognitive decline that provides a comprehensive assessment of cognitive functions by examining: memory, visuospatial ability, executive functions, concentration and attention, language and spatial orientation.

A blood sample (28 mL in total) will be taken after fasting to analyse the lipid profile, certain bone markers (FGF23, vitamin D) and genetic/epigenetic markers.