This randomized controlled trial aims to investigate the effects of a 24-week home-based progressive resistance exercise program combined with tirzepatide treatment on skeletal muscle mass, muscle quality, and functional capacity in overweight and obese individuals. A total of 108 participants initiating tirzepatide therapy will be randomized to either exercise plus pharmacotherapy or pharmacotherapy alone. The primary outcome is change in thigh muscle thickness and echo intensity assessed by ultrasonography.
Pharmacologically induced weight loss with glucagon-like peptide-1 (GLP-1)/ glucose-dependent insulinotropic polypeptide (GIP) receptor agonists such as tirzepatide is associated with significant reductions in lean body mass, raising concerns regarding muscle function and long-term outcomes. Resistance exercise is the most effective intervention to preserve muscle mass during weight loss; however, evidence combining these approaches is limited. This study is a prospective, two-center, single-blinded, randomized controlled trial designed to evaluate whether structured resistance exercise enhances muscle preservation and functional outcomes in individuals receiving tirzepatide therapy.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
108
A 24-week home-based resistance exercises using elastic band and bodyweight
Lifestyle recommendations including physical activity and nutritional advice
Change in muscle thickness
Muscle thickness of the thigh (quadriceps femoris) will be assessed using a portable ultrasound and will be presented in millimeters (mm).
Time frame: Baseline, 12 weeks, 24 weeks
Muscle echo intensity
Echo intensity will be assessed via a portable muscle ultrasonography using grayscale analysis (0-255 scale) within a standardized region of interest using ImageJ software (National Institutes of Health, USA), with higher values indicating greater intramuscular fat and fibrous tissue infiltration and thus poorer muscle quality. Assessments will include quadriceps femoris.
Time frame: Baseline, 12 weeks, 24 weeks
Muscle strength (handheld dynamometer)
Isometric muscle strength of the biceps brachii, triceps brachii, quadriceps femoris, and hamstrings will be assessed bilaterally using a Lafayette handheld dynamometer (Lafayette Instrument Company®, USA) using the make test method.
Time frame: Baseline, 12 weeks, 24 weeks
Body weight
Body weight will be assessed using bioelectrical impedance analysis and presented in kilograms (kg).
Time frame: Baseline, 12 weeks, 24 weeks
Six-minute walk test
Functional capacity will be assessed using the 6-minute walk test according to standardized procedures and the total distance will be recorded in meters.
Time frame: Baseline, 12 weeks, 24 weeks
Physical activity
Physical activity will be measured objectively using a wearable device (Garmin Vívosmart 5), time spent for light, moderate, and vigorous activity will be recorded for 7 days.
Time frame: Baseline, 12 weeks, 24 weeks
Nutritional status (3-day food record)
Dietary intake will be assessed at baseline, 12 weeks, and 24 weeks using 3-day food records (two non-consecutive weekdays and one weekend day). Prior to assessment, participants will receive standardized verbal, written, and visual instructions - including portion size estimation aids - to ensure accurate and consistent recording.
Time frame: Baseline, 12 weeks, 24 weeks
Quality of life (Short Form-36)
The Short Form-36, a validated and reliable self-reported instrument evaluating physical and mental health status across eight domains: physical functioning, role physical, bodily pain, general health, vitality, social functioning, role emotional, and mental health will be used to determine the level of quality of life. Physical and mental sub scales are scored from 0 to 100, higher scores indicate a better quality of life.
Time frame: Baseline, 12 weeks, 24 weeks
Clinical parameters (blood pressure)
Blood pressure will be measured using a sphygmomanometer at each assessment point.
Time frame: Baseline, 12 weeks, 24 weeks
Height
Height of the participants will be assessed using a stadiometer and presented in meters.
Time frame: Baseline, 12 weeks, 24 weeks
Body mass index
Body mass index will be calculated using height and weight (kg/m\^2)
Time frame: Baseline, 12 weeks, 24 weeks
Body fat percentage
Body fat percentage will be assessed using bioelectrical impedance analysis and presented in percentage (%).
Time frame: Baseline, 12 weeks, 24 weeks
Fat free mass
Fat-free mass will be assessed using bioelectrical impedance analysis and presented in kilograms.
Time frame: Baseline, 12 weeks, 24 weeks
Chair stand test
Functional capacity will be assessed using 30-second chair stand test according to standardized procedures. The number of repetitions which the participants fully raised from a chair will be recorded in numbers (n).
Time frame: Baseline, 12 weeks, 24 weeks
Self-reported physical activity
Self-reported physical activity will be determined using the International Physical Activity Questionnaire-Short Form (IPAQ-SF). Metabolic equivalent (MET) values will be calculated and participants will be categorized into inactive, moderately active, and very active based on MET values.
Time frame: Baseline, 12 weeks, 24 weeks
Grip strength
Handgrip strength will be assessed using a JAMAR dynamometer (Sammons Preston, USA) following the standardized protocol. Three maximal isometric contractions will be performed with 1-minute rest intervals, the mean of the three trials in kilograms will be used for analysis.
Time frame: Baseline, 12 weeks, 24 weeks
Clinical measures (fasting glucose)
Fasting glucose will be recorded from the medical records and will be presented in mmol/L.
Time frame: Baseline, 12 weeks, 24 weeks
Clinical parameters (lipid profile)
Total Cholesterol, LDL (Low-Density Lipoprotein) Cholesterol, HDL (High-Density Lipoprotein) Cholesterol, Triglycerides will be recorded from the medical records and presented in mmol/L.
Time frame: Baseline, 12 weeks, 24 weeks
Muscle thickness
Muscle thickness of the biceps femoris, triceps brachii, and biceps brachia will be assessed using a portable ultrasound and will be presented in millimeters (mm).
Time frame: Baseline, 12 weeks, 24 weeks
Muscle echo intensity
Echo intensity will be assessed via a portable muscle ultrasonography using grayscale analysis (0-255 scale) within a standardized region of interest using ImageJ software (National Institutes of Health, USA), with higher values indicating greater intramuscular fat and fibrous tissue infiltration and thus poorer muscle quality. Assessments will include biceps femoris, biceps brachii, and triceps brachii.
Time frame: Baseline, 12 weeks, 24 weeks
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