This study evaluates the practical feasibility and potential effects of an 8-week dairy product intervention in physically active adults aged 18-39 years. Participants will consume a dairy product enriched with high protein, calcium, and vitamin D under real-life conditions. Assessments will be conducted before the intervention, after 4 weeks, and after 8 weeks, including subjective perception questionnaires, body composition analysis, and functional physical performance tests. The study aims to examine changes in physical status, functional capacity, and user experience during continuous product use.
With increasing awareness of regular exercise and health promotion, sports nutrition products have become a common supplementation choice among physically active populations. In real-world settings, these products are typically consumed continuously as part of daily life. Evaluating changes in physical status, functional physical performance, and users' subjective perceptions during actual use therefore requires research designs that closely reflect everyday living conditions. This study recruits physically active adults aged 18-39 years and conducts an 8-week intervention involving the consumption of a dairy product enriched with high protein, calcium, and vitamin D. A pre-, mid-, and post-intervention design is employed, integrating subjective perception questionnaires, body composition analysis, and functional physical performance assessments to evaluate changes in physical status, functional capacity, and subjective experiences throughout the intervention period. Through this multi-dimensional evaluation approach, the study aims to examine the practical feasibility and application value of the product in real-life settings and to provide evidence to support sports nutrition practice and future research.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
50
An 8-week high-protein, high-calcium, and vitamin D-enriched dairy intervention.
Questionnaire-based subjective assessment
Participants' subjective physical sensations, post-exercise fatigue, body image perceptions, and product use experience will be assessed using individual items from a self-administered questionnaire developed for this study. Questionnaire items may include Likert-scale items, categorical response options, and open-ended responses. Likert-scale items will be reported separately according to their original response scale, with the minimum and maximum values specified for each item. Categorical items will be reported as the number and percentage of participants selecting each response option. Open-ended responses will be summarized descriptively. No overall questionnaire total score will be calculated.
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Handgrip Strength Test
Participants performed the test in a standing position with their arms naturally hanging down. They held the handgrip dynamometer with one hand and applied maximal force continuously for at least 3 seconds. Each hand was tested three times, and the best value was recorded.
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Push-Up Test
Participants performed the push-up test on an exercise mat, with both hands placed shoulder-width apart to support the body. The fingers pointed forward, the elbows were fully extended, and the feet were approximately 10 cm apart. Male participants performed the test with support from the feet, whereas female participants performed the modified version with support from the knees. Participants were instructed to complete as many repetitions as possible while maintaining proper form. The test was terminated when the movement no longer met the required standard or could not be continued.
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Curl-Up Test
Participants lay supine on an exercise mat with both knees bent and feet flat on the floor. They performed curl-ups according to a fixed rhythm. Participants were instructed to complete as many repetitions as possible while maintaining proper form. When a participant failed to perform the movement correctly once, the examiner raised one hand and indicated the number "one." If the participant failed a second time, the examiner indicated the number "two." The test was terminated when the participant failed twice or completed 75 repetitions. If the participant was unable to maintain the required rhythm or perform the movement according to the standard criteria, the test was stopped.
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Three-Minute Progressive Step-in-Place Test
Participants performed step-in-place movements according to the instructions and raised their knees to the designated height. The test lasted for 3 minutes, with an initial cadence of 96 beats per minute, which was progressively increased each minute. During the test, heart rate was recorded using a heart rate monitor before exercise, during exercise, and during the post-exercise recovery period.
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Body weight
Body weight will be measured using the InBody 570 bioelectrical impedance analyzer (InBody, Seoul, South Korea) and reported in kilograms (kg).
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Body mass index
Body mass index (BMI) will be calculated from body weight and height and reported in kilograms per square meter (kg/m\^2).
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Body fat percentage
Body fat percentage will be measured using the InBody 570 bioelectrical impedance analyzer (InBody, Seoul, South Korea) and reported as a percentage (%).
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Fat mass
Fat mass will be measured using the InBody 570 bioelectrical impedance analyzer (InBody, Seoul, South Korea) and reported in kilograms (kg).
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Skeletal muscle mass
Skeletal muscle mass will be measured using the InBody 570 bioelectrical impedance analyzer (InBody, Seoul, South Korea) and reported in kilograms (kg).
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
Skeletal muscle percentage
Skeletal muscle percentage will be measured using the InBody 570 bioelectrical impedance analyzer (InBody, Seoul, South Korea) and reported as a percentage (%).
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.
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Waist-to-hip ratio
Waist-to-hip ratio will be measured using the InBody 570 bioelectrical impedance analyzer (InBody, Seoul, South Korea) and reported as a ratio.
Time frame: The testing time points are set as follows: before the intervention, after 4 weeks of intervention, and after 8 weeks of intervention.