Effect of a Multi-Ingredient Post-Workout Dietary Supplement on Body Composition and Muscle Strength – A Randomized Controlled Trial

The aim of the current parallel randomized controlled trial was to compare the effects of ingesting a dietary supplement admixture providing carbohydrates, leucine-fortified whey protein, creatine, <i>β</i>-hydroxy-<i>β</i>-methylbutyrate, and vitamin D3 (Master Recovery 1:1, Crown Sport Nutrition, Spain), versus an isoenergetic carbohydrate-only comparator on body composition, muscle thickness, muscle strength, and performance over a 6-week resistance training program, performed three times per week, in aging, physically active individuals. Twenty participants (10 peri- and post-menopausal females and 10 males) -completed the study after being randomly assigned to one of the following groups: post-workout multi-ingredient (PWS: <i>n</i> = 10, 52.0 ± 5 years, body mass 82.0 ± 18.0 kg) or a comparator (COM: <i>n</i> = 10, 51 ± 3 years, body mass 85.9 ± 17.0 kg). Treatment consisted of ingesting 60.0 g of the assigned supplement immediately after each workout. Compared to baseline, only PWS increased fat-free mass (+1.34 ± 1.2 kg, <i>p</i> = 0.003), reduced fat mass (-1.09 ± 0.7 kg, <i>p</i> < 0.001), waist circumference (-2.5 ± 1.8 cm, <i>p</i> < 0.001), and waist-to-hip ratio (-0.03 ± 0.03 cm, <i>p</i> = 0.007). At post-intervention, waist circumference reduction was different between groups (<i>p</i> = 0.02, <i>d</i> = 1.19). Both treatments similarly improved vastus lateralis and elbow flexor thickness, medicine ball throw, and endurance performance. Although countermovement jump improved for both treatments, the PWS group showed a significantly higher performance increase compared to COM (<i>p</i> < 0.01, <i>d</i> = 1.47). Compared to ingesting carbohydrates only, the use of a targeted multi-ingredient promoted noticeable body composition outcomes and better vertical jump improvements with no further effects on hypertrophy, upper body, and endurance performance. The study was registered as a clinical trial at ClinicalTrials.gov (NCT05769088).