Muscle Quality and Subcutaneous Adipose Tissue in the Rectus Femoris and Rectus Abdominis Muscles: Ultrasound Evaluation and Functional Correlation in Older Adults

The rectus femoris muscle was assessed using B-mode ultrasound imaging, following SARCUS group recommendations. Participants were positioned supine for 5 minutes prior to imaging to ensure fluid redistribution. A linear transducer (12 MHz) was used with neutral probe angle and minimal pressure. The anatomical landmark was the midpoint between the greater trochanter and the upper pole of the patella. Measurements included muscle thickness, pennation angle, fascicle length, echo intensity, cross-sectional area, and subcutaneous fat thickness. Images were taken in both transverse and longitudinal planes. Three measurements were taken per view to ensure accuracy.

The rectus abdominis muscle was assessed using the same ultrasound equipment and imaging protocol as for the rectus femoris. The anatomical reference point was located 3 cm lateral to the umbilicus, as per SARCUS group guidance. Images were acquired in both transverse and longitudinal planes. Measurements included muscle thickness, echo intensity, anatomical cross-sectional area, and subcutaneous fat thickness. Three measurements were taken per view to ensure reliability.

Accurate measurement of hand grip strength requires the use of a hand dynamometer (Jamar Plus) calibrated under well-defined (standardized) test conditions. Force values less than 16 Kg are considered positive.

It can be used as an indicator of the strength of the lower limb muscles. It measures the amount of time a patient needs to get up five times from a sitting position without using their arms. It will help us to affirm that the person has a probable sarcopenia. Times greater than 15 seconds are considered positive.

It is a measure used to assess a person's body weight in relation to their height. It is calculated by dividing a person's weight in kilograms by their height in meters squared (BMI = kg/m²).

Test to assess physical performance and degree of frailty consisting of 3 subtests: gait speed, balance, and lower limb strength. The maximum score is 12 points and a score ≤ 8 points indicates poor physical performance.

t is considered a fast, safe and very reliable test for sarcopenia, in a distance of 4 meters, values greater than 0.8 m/s are considered positive

A predictive test for frailty and falls, where individuals are asked to get up from a standard chair, walk to a marker 3 m away, turn around, and sit down again. Times greater than 20 seconds are considered positive.