Protein Distribution and Leucine Supplementation Effects on Body Composition and Performance in Tactical Athletes

This randomized controlled trial will examine the effects of within-day protein distribution and leucine supplementation on body composition, physical performance, and biomarkers of muscle damage in tactical athletes during an 8-week intensive training program. Sixty-nine healthy male participants (18-35 years) enrolled in a Ministry of Defense training course will be randomly assigned to one of three iso-caloric dietary groups providing 1.6 g/kg/day of protein: (1) evenly distributed protein across three meals (EVEN), (2) a 16-hour daily protein fasting pattern with protein concentrated at lunch and dinner (FAST), or (3) the same fasting pattern with 5 g leucine supplementation at breakfast (FAST-RESCUE). Primary outcomes include changes in lean body mass. Secondary outcomes include strength, anaerobic performance, and biochemical markers of muscle damage, including urinary titin N-terminal fragment (UTF). Assessments will be conducted at baseline, Week 5, and Week 8.