This study aims to evaluate the effects of daily supplementation with room-temperature high-protein dairy products over six consecutive weeks, without altering the subjects' existing exercise habits, on muscle mass, muscle strength, and functional exercise performance in young adults aged 18-45. Furthermore, this study serves as a functional evaluation baseline for the application of room-temperature dairy products in sports nutrition.
The relationship between protein intake and muscle adaptation is well-established; however, many physically active young and middle-aged adults fail to meet the optimal protein recommendations for maximizing muscle gains. Currently, the impact of daily supplementation with shelf-stable high-protein dairy products on muscle mass, strength, and exercise performance in a real-world training environment requires further evaluation through ecologically valid research designs. This study recruited physically active adults aged 18 to 45 to participate in a 6-week high-protein dairy intervention. Utilizing a pre-, mid-, and post-test design, the study integrated subjective perception questionnaires, body composition analysis, and functional mobility tests to assess changes in physical status, functional performance, and self-reported outcomes. By employing a multi-dimensional assessment, this research aims to examine the practical feasibility and value of such products in real-life scenarios, serving as a reference for sports nutrition applications and future empirical studies.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
40
An 6-week high-protein, high-calcium, and vitamin D-enriched dairy intervention.
National Taiwan Sport University
Taoyuan, Taiwan
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 3 weeks of intervention, and after 6 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 3 weeks of intervention, and after 6 weeks of intervention.
5-Repetition Sit-to-Stand Test (5STS)
Participants performed five consecutive sit-to-stand repetitions as quickly as possible from a armless chair with arms crossed over the chest, and the total completion time (in seconds) was measured using a digital timer.
Time frame: The testing time points are set as follows: before the intervention, and after 6 weeks of intervention.
30-Second Sit-to-Stand Test (30STS)
Participants performed as many full sit-to-stand repetitions as possible within 30 seconds from a standard armless chair with arms crossed over the chest, and the total number of completed repetitions was recorded.
Time frame: The testing time points are set as follows: before the intervention, and after 6 weeks of intervention.
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Isometric Mid-Thigh Pull Test (IMTP)
Participants performed three maximum isometric effort pulls on a fixed bar over a force plate at standardized knee and hip angles for 5 seconds per trial, separated by ≥1-minute rest intervals, with the highest peak force recorded for analysis.
Time frame: The testing time points are set as follows: before the intervention, and after 6 weeks of intervention.
Countermovement Jump Test (CMJ)
Participants performed three vertical countermovement jumps on a force plate with hands fixed on the hips and 60-second rest intervals between trials, with the maximum jump height selected for final analysis.
Time frame: The testing time points are set as follows: before the intervention, and after 6 weeks of intervention.
Maximal Oxygen Consumption Test (VO² max)
Participants performed an incremental exercise protocol on a stationary cycle ergometer starting at 25W and increasing by 15W every 2 minutes at a cadence of 70 rpm until exhaustion, while heart rate and subjective rating of perceived exertion (RPE) were continuously monitored.
Time frame: The testing time points are set as follows: before the intervention, and after 6 weeks of intervention.
Time-to-Exhaustion Endurance Capacity Test (TTE)
Participants exercised at a target intensity based on their VO² max test until reaching defined volitional exhaustion criteria, with total exercise duration and mechanical work output recorded as endurance capacity indicators.
Time frame: [Time Frame: The testing time points are set as follows: before the intervention, and after 6 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 3 weeks of intervention, and after 6 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 3 weeks of intervention, and after 6 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 3 weeks of intervention, and after 6 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 3 weeks of intervention, and after 6 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 3 weeks of intervention, and after 6 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 3 weeks of intervention, and after 6 weeks of intervention.
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 3 weeks of intervention, and after 6 weeks of intervention.
Dual-Energy X-ray Absorptiometry (DXA)
Whole-body composition, as well as bone mineral density (BMD) of the AP lumbar spine, bilateral femurs, and total body, will be measured using a dual-energy X-ray absorptiometry scanner (Lunar iDXA, GE Healthcare).
Time frame: The testing time points are set as follows: before the intervention, and after 6 weeks of intervention.