Performance supplements (PS) consumed in close proximity to resistance exercise (RE) are an increasingly common product, especially among young males1, 2 and athletes3-6. The composition of PS vary widely, but the principle ingredients tend to include creatine monohydrate, caffeine, β-alanine (βA), the branched chain amino acids (BCAAs) leucine, isoleucine, and valine, as well as L-citrulline, and L-arginine. Manufacturer claims about effectiveness are often dubious and generally untested by peer-reviewed science. Of the small body of research specifically examining PS and RE training, none have used trained male subjects in conjunction with a pre- and post-exercise supplementation modality. This study sought to examine the effectiveness of two commercially available pre- and post-exercise supplements, No-Shotgun (SHOT) and NO-Synthesize (SYNTH) (Vital Pharmaceuticals, Davie, FL), respectively, at augmenting performance and muscle gains over the course of a 6-week training period. METHODS: Twenty-four, resistance trained men (age, 24.6 ± 4.9 years; height, 180.4 ± 5.5 cm; weight, 80.7 ± 8.8 kg) completed 6 weeks of periodized RE targeting muscles of the arms and shoulders, legs and core, and chest and back with three workouts per week. Resistance increased while repetitions decreased in two-week increments (week 1: 3x10, week 2: 3x6, and week 3: 3x4). Rest intervals of 60-90 seconds were constant between sets. Participants were assigned to one of two groups based upon maximal voluntary contraction of the quadriceps (Biodex) to lean mass ratio. Group 1 (n=6; Performance Supplement; PS) consumed one serving of NO-Shotgun® before each workout and one serving of NO-Synthesize® (Vital Pharmaceuticals, Inc., Davie, FL) immediately after each workout and on non-RT days. Group 2 (n= 3; Placebo; PLA) consumed a flavor-matched isocaloric maltodextrin placebo in the identical manner. Laboratory measurements included the following: body composition (dual-energy X-ray absorptiometry; DXA), circumferences of the shoulders, chest, waist, hip, and thigh, and maximal strength of the upper (chest press; CP) and lower body (leg press; LP) using one repetition maximum lifts (1RM), Anaerobic power using 30-second Wingate cycle ergometry tests, and isokinetic and isometric strength measurements. Statistical analysis was conducted using a 2x2 repeated measures analysis of variance. Significance was set at p<0.05 and all values are reported as means + standard deviation. RESULTS: Group x time interactions were observed for lean mass (LM, p = 0.017) The PS increased LM (+4.72%, p = 0.001), while the PLA group was unchanged. Both groups demonstrated similar increases in leg press and bench press. The PS group significantly increased anaerobic power (+16.22%, p = 0.002), relative anaerobic power (+9.38%, p = 0.003), average anaerobic power (+9.94%, p = 0.015), and relative average anaerobic power (+8.21%, p = 0.028), while PLA remained unchanged. Neither group showed changes in fatigue index. The supplement had no effect on training volume for any week or exercise during the 6-week training period, but may have elevated feelings of vigor in PS (p = 0.019) . CONCLUSION: Consumption of SHOT and SYNTH immediately before and after exercise during the course of a periodized exercise training program facilitated training-induced improvement in lean mass in trained males, whereas the consumption of isocaloric carbohydrate beverage did not. PS products most likely do not offer advantages in measures of muscle strength and power in this population. Sustained SHOT and SYNTH consumption has no negative effect on mood and may improve feelings of vigor, which has been shown to decrease with heavy training. Continued investigation of similar products is warranted in this and other populations.