Mogrosides for Delayed-Onset Muscle Soreness

Eight participants will be randomly assigned to the experimental arm. They will receive oral mogroside (batch no. YTC19011823; purity >95%; mogroside V 50.56%), prepared as a 3% (g/mL) solution in warm drinking water, at 6 g per dose twice daily (12 g/day) in the morning and evening for 27 days. After 27 days, participants will perform a standardized frog-jump exercise to induce delayed-onset muscle soreness (DOMS): 10 sets of 25 consecutive jumps, with 2 minutes of rest between sets, after a 10-minute warm-up; total session approximately 34-35 minutes. They will continue the same mogroside intervention for 3 additional days after exercise. All participants will complete the same scheduled assessments. The study will be double-blind.

Eight participants will be randomly assigned to the experimental arm. They will receive oral mogroside (batch no. YTC19011823; purity >95%; mogroside V 50.56%), prepared as a 3% (g/mL) solution in warm drinking water, at 6 g per dose twice daily (12 g/day) in the morning and evening for 27 days. After 27 days, participants will perform a standardized frog-jump exercise to induce delayed-onset muscle soreness (DOMS): 10 sets of 25 consecutive jumps, with 2 minutes of rest between sets, after a 10-minute warm-up; total session approximately 34-35 minutes. They will continue the same mogroside intervention for 3 additional days after exercise. All participants will complete the same scheduled assessments. The study will be double-blind.

Eight participants will be randomly assigned to the control arm. They will receive an equal volume of warm drinking water as placebo twice daily in the morning and evening for 27 days. After 27 days, participants will perform the same standardized frog-jump exercise to induce delayed-onset muscle soreness (DOMS): 10 sets of 25 consecutive jumps, with 2 minutes of rest between sets, after a 10-minute warm-up; total session approximately 34-35 minutes. They will continue the same placebo intervention for 3 additional days after exercise. All participants will complete the same scheduled assessments. The study will be double-blind.

Eight participants will be randomly assigned to the control arm. They will receive an equal volume of warm drinking water as placebo twice daily in the morning and evening for 27 days. After 27 days, participants will perform the same standardized frog-jump exercise to induce delayed-onset muscle soreness (DOMS): 10 sets of 25 consecutive jumps, with 2 minutes of rest between sets, after a 10-minute warm-up; total session approximately 34-35 minutes. They will continue the same placebo intervention for 3 additional days after exercise. All participants will complete the same scheduled assessments. The study will be double-blind.

Subjective muscle soreness will be assessed at six time points: before the first dose of study product, before exercise, immediately after exercise, and 24, 48, and 72 hours after exercise. A 10-cm VAS ruler will be used. The side facing the participant is marked 0 at one end ("no pain") and 10 at the other ("worst imaginable pain"). Participants will move a cursor to indicate their current level of muscle soreness. The distance from the "no pain" end to the mark will be recorded as the pain score in centimeters. Higher scores indicate greater muscle soreness.

Bilateral active knee range of motion will be measured with a joint angle goniometer at six time points: before the first dose, before exercise, immediately after exercise, and 24, 48, and 72 hours after exercise. Participants will lie prone with both lower limbs extended, together, and relaxed. The goniometer axis will be placed at the lateral femoral condyle, the fixed arm along the middle of the femur, and the moving arm along the fibula. Participants will actively flex the lower leg as much as possible. The arc from the starting position to the final position of the lower leg will be recorded in degrees.

Bilateral maximal isometric muscle force will be measured with a MicroFET2 handheld dynamometer at six time points: before the first dose, before exercise, immediately after exercise, and 24, 48, and 72 hours after exercise. Participants will sit on the examination bed with arms at their sides, legs relaxed, and lower legs hanging vertically. The tester will place the dynamometer over the distal quadriceps on the front of the thigh. Participants will push the thigh upward against the tester and maintain the contraction for 8 seconds. The test will be repeated 5 times, and the maximum value will be recorded.

Bilateral thigh circumference will be measured with a soft tape measure at six time points: before the first dose, before exercise, immediately after exercise, and 24, 48, and 72 hours after exercise. Participants will lie prone on the examination bed. The circumference will be measured at the junction of the middle and lower thirds of the line between the greater trochanter of the femur and the lateral condyle. The measurement point will be marked after the first measurement to ensure the same location is used at later time points. Results will be recorded in centimeters.