Effects of Nattokinase Supplementation on Strength Recovery and Muscle Damage Biomarkers Following Exercise-Induced Muscle Injury: A Pilot Study

Condition(s) studied

Investigational drug(s) / intervention(s)

Nattokinase: Participants will consume one capsule of nattokinase orally once daily, providing 2,000 FU/day, for 28 days.

Placebo: Participants will consume one matching placebo capsule orally once daily for 28 days. The placebo is matched in appearance and flavor to the nattokinase supplement.

Study summary

This pilot study aims to investigate whether 4 weeks of nattokinase supplementation (2,000 FU/day) affects recovery following exercise-induced muscle damage in healthy adult men. Approximately 12 to 16 participants aged 18 to 40 years will receive either nattokinase or a matching placebo during the supplementation period. After supplementation, participants will complete an exercise protocol designed to induce temporary muscle damage. Recovery will be evaluated using measures of muscle strength and exercise performance, muscle soreness, blood lactate, muscle oxygenation, and blood biomarkers related to muscle damage, inflammation, and oxidative stress. Measurements will be performed before and after the exercise-induced muscle damage protocol, including follow-up assessments during the recovery period. The study is intended to provide preliminary information on the potential effects of nattokinase supplementation on muscle recovery after strenuous exercise.

Eligibility

Primary outcome measure(s)

• Peak Force During Isometric Mid-Thigh Pull (IMTP) — Day 0 baseline, pre-EIMD baseline, immediately post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Peak force during the isometric mid-thigh pull (IMTP) will be measured to assess maximal isometric strength. The highest value from three trials will be used for analysis.
• Countermovement Jump (CMJ) Height — Day 0 baseline, pre-EIMD baseline, immediately post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Countermovement jump height will be measured to assess lower-limb explosive performance. The highest value from three trials will be used for analysis.
• Blood Lactate Concentration — During the Day 0, pre-EIMD, and immediately post-EIMD WAnT assessments; blood lactate will be measured before exercise, immediately after exercise, and at 3, 5, and 10 minutes post-exercise.
  Blood lactate concentration will be measured before and after the Wingate Anaerobic Test (WAnT) to assess lactate production and clearance. The WAnT will be used as a standardized high-intensity exercise stimulus.
• Muscle Oxygen Saturation (SmO₂) — Day 0 baseline, pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Muscle oxygen saturation (SmO₂) will be measured using near-infrared spectroscopy (NIRS) to assess changes in muscle oxygenation.
• Total Hemoglobin (THb) — Day 0 baseline, pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD
  Total hemoglobin (THb) will be measured using near-infrared spectroscopy (NIRS) to assess changes in local muscle blood volume.
• Subjective Muscle Soreness Using Visual Analogue Scale (VAS) — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Subjective muscle soreness will be assessed using a 100-mm visual analogue scale (VAS), ranging from no soreness to worst possible soreness.
• Subjective Muscle Soreness Using Borg CR-10 Scale — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Subjective muscle soreness will also be assessed using the Borg CR-10 scale, ranging from 0 to 10.
• Pressure Pain Threshold (PPT) — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Pressure pain threshold (PPT) will be measured at the vastus lateralis using a pressure algometer to objectively assess muscle soreness.
• Creatine Kinase (CK) Concentration — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Blood creatine kinase (CK) concentration will be measured as a marker of exercise-induced muscle damage.
• Myoglobin Concentration — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Blood myoglobin concentration will be measured as a marker of exercise-induced muscle damage.
• Lactate Dehydrogenase (LDH) Concentration — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Blood lactate dehydrogenase (LDH) concentration will be measured as a marker of exercise-induced muscle damage.
• High-Sensitivity C-Reactive Protein (hs-CRP) Concentration — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Blood high-sensitivity C-reactive protein (hs-CRP) concentration will be measured to assess the inflammatory response following EIMD.
• Interleukin-6 (IL-6) Concentration — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Blood interleukin-6 (IL-6) concentration will be measured to assess the inflammatory response following EIMD.
• Tumor Necrosis Factor-Alpha (TNF-α) Concentration — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Blood tumor necrosis factor-alpha (TNF-α) concentration will be measured to assess the inflammatory response following EIMD.
• Malondialdehyde (MDA) Concentration — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Blood malondialdehyde (MDA) concentration will be measured as a marker of oxidative stress.
• Total Antioxidant Capacity (TAC) — Pre-EIMD baseline, immediately post-EIMD, 2 hours post-EIMD, 24 hours post-EIMD, and 48 hours post-EIMD.
  Total antioxidant capacity (TAC) will be measured to assess antioxidant capacity following EIMD.

Trial sites (1)

More National Taiwan Sport University trials in Taiwan