Investigation of Respiratory Muscle Sarcopenia in Patients With Systemic Sclerosis

The diagnosis of respiratory muscle sarcopenia will also be made by combining the results of secondary measurements.

Participants included in the study:

• Hand grip strength <27 kg for men and <16 kg for women,
• Bioelectrical Impedance Analysis (Skeletal muscle mass (SMM)<20 kg for men and < 15 kg for women) the participant is diagnosed with sarcopenia. They will also be diagnosed with a frailty phenotype based on the results of the Timed Stand and Walk Test, the 4 meter walk test and the 5 Repetition Sit and Stand Test.

Patients diagnosed with sarcopenia will be diagnosed with respiratory muscle sarcopenia if respiratory muscle weakness is also detected.

The hand muscle grip strength of the individuals will be measured with a hand dynamometer. During the measurement, the position recommended by the American Association of Hand Therapists (ASHT); the participant will be in an upright sitting position and no arm support will be allowed on the sitting surface. The elbow and knee angle will be set to 90°. The wrist will be held without deviation. The measurement will be performed 3 times with an interval of 10 seconds and the highest value will be used in the study.

4MWT is a measure of walking speed, a vital sign of mobility and functionality. In older adults, walking speed is a clinical indicator of conditions such as frailty and sarcopenia. Participants were instructed to start walking at their normal speed 2 m behind the "start point" and continue until they passed the "end point". Using a stopwatch, the time taken for each participant to walk the 4 m distance between the "start" and "end" point will be measured. This will be used to calculate walking speed (distance/time).

This functional test measures the time it takes for an individual to stand up from a standard chair, walk 3 m at normal speed, turn around, walk back to the starting point and sit down. Using a stopwatch, participants test scores are recorded in seconds.

An armless chair with a straight back support and a rigid seat at a height of 48 cm from the floor will be fixed to the wall. Participants will be asked to sit on the chair and come forward in the chair until their feet are flat on the floor. Participants will be asked to do a "stand and sit" movement once with their arms crossed across their chest. The test will be terminated for those who cannot complete the task or need assistance. Those who successfully complete the first task will be asked to perform five consecutive stand and sit as fast as possible. The timing is started with the command start and stopped at the end of the fifth posture. Our participants test scores will be recorded in seconds using a stopwatch.

Intraoral pressure will be measured with a measuring device. They are easily applicable and simple measurements. Maximal voluntary inspiratory and expiratory pressures (MIP and MEP) are the most commonly used noninvasive methods to measure respiratory muscle strength. It is based on Müller (maximal inspiration) and Valsalva (maximal expiration).

Information on age, height (meter), body weight (kg), body mass index(kg/m²), gender, educational status, occupation, medication use, exercise habits and disease will be evaluated. These data will be recorded on pre-prepared forms.

Body mass and body composition will be measured using bioelectrical impedance method. The variables to be assessed are body mass index (BMI = body mass (kg)/height2 (m)2 ), fat mass (pFM) expressed as a percentage of body mass, fat-free mass (FFM) expressed in kilograms, and appendicular skeletal muscle mass (ASMM) and skeletal muscle mass (SMM) expressed in kilograms. Data will be collected with a bioelectrical impedance device and recorded on pre-prepared forms.