Whey Protein Isolate and Sappan Wood (<i>Caesalpinia sappan</i> L.) Infusion Modulates Muscle Damage and Inflammatory Biomarkers Following High-Intensity Interval Training in Sedentary Males.

High-intensity interval training (HIIT) can induce muscle damage and inflammatory responses, particularly in sedentary individuals. This study investigated the effects of whey protein isolate (WPI) combined with sappan wood ( Caesalpinia sappan L.) infusion on muscle damage and inflammation following HIIT in sedentary male individuals. This double-blind randomized controlled trial included 39 sedentary males who were allocated to three groups: WPI-sappan (n=14), WPI (n=13), and control (n=12). The participants completed treadmill-based HIIT. The WPI-sappan group received 30 g of WPI combined with a sappan wood infusion prepared from 8.3 g of sappan wood powder. The WPI group received a WPI beverage, whereas the control group consumed a carbohydrate-only drink. All beverages contained 20 g of sucrose. Supplementation was administered immediately after exercise and daily for 4 d. Serum creatine kinase (CK), lactate dehydrogenase (LDH), skeletal troponin I (sTnI), interleukin (IL)-6, and IL-10 concentrations were measured at baseline and at 24, 48, and 96 h post-exercise. Data were analyzed using repeated-measures analysis of variance. CK concentrations increased significantly after HIIT across all groups, with significant effects of time, treatment, and the time×treatment interaction ( P P =0.024), whereas IL-10 showed a significant time×treatment interaction ( P =0.010). No significant treatment effects were observed for LDH or sTnI. WPI combined with sappan wood modulated selected biomarkers of muscle damage and inflammation following HIIT in sedentary males.