Abstract
<jats:p>Shilajit is a naturally occurring resinous exudate with centuries of documented use in Ayurvedic medicine. Its principal bioactive constituents — fulvic acid and a proprietary aromatic compound complex termed shilarathenes™, comprising urolithin metabolites, phenolic acids, and flavonoids — are proposed to enhance mitochondrial ATP synthesis, attenuate exercise-induced muscle damage, and modulate androgen biosynthesis. Prior controlled trials have demonstrated increases in testosterone and retention of muscular strength with purified shilajit, though large trials in resistance-trained populations have been absent. In this randomised, double-blind, placebo-controlled, multicenter trial (CTRI/2025/07/091323), 100 healthy males aged 21–50 years (BMI <30 kg/m²; ≥1 year of resistance training) were enrolled across four sites. Participants received 250 mg twice daily of standardised TruBlk™ Shilajit resin (≥60% fulvic acid; ≥10% shilarathenes™) or matched placebo for 90 days, and were instructed to maintain habitual training and dietary practices throughout. Primary endpoints were changes from baseline in 1RM leg press, muscle endurance, RPE, and DOMS. Secondary endpoints included VO₂max, testosterone, creatine kinase, lactate dehydrogenase, handgrip strength, and global improvement ratings. Ninety-nine participants completed the trial (99% retention). All primary outcomes showed significantly steeper improvement in the active group, assessed by treatment × time interaction: 1RM leg press (+26.0% vs +18.4%; p=0.0003, d=0.74), muscle endurance (+110.8% vs +80.5%; p=0.0017, d=0.60), RPE (p=0.002), and DOMS (p=0.036). Dominant handgrip strength showed the largest secondary effect (+12.5% vs +7.9%; p=0.0002, d=0.77). The active group also demonstrated greater reductions in creatine kinase (−33.6% vs −6.9%; p=0.030, δ=−0.26) and lactate dehydrogenase (−17.8% vs −4.2%; p=0.039, δ=−0.24), greater increases in free testosterone (+21.8% vs −2.9%; p=0.030, d=0.45) and total testosterone (+15.6% vs −3.8%; p=0.038, d=0.43), and a modest improvement in VO₂max (+3.8% vs +2.9%; p=0.032, d=0.41) compared with placebo. No adverse events were recorded in the active group. Ninety days of TruBlk™ Shilajit resin supplementation produced robust improvements in muscle strength and endurance in resistance-trained males, with moderate effect sizes for the strength outcomes. These data support TruBlk™ Shilajit resin as a safe and promising ergogenic agent meriting further clinical evaluation.</jats:p>