Comparing four different angles of the bench used during the narrow grip bench press, Barnett et al. (1995) found a main difference in anterior deltoid muscle activity between -18 degrees and the other steeper angles (0, 40 and 90 degrees). (strengthandconditioningresearch.com)
Comparing four different angles of the bench used during the narrow grip bench press, Barnett et al. (1995) found a main difference in triceps brachii muscle activity between -18 degrees and 0 (flat) compared with 40 and 90 degrees. (strengthandconditioningresearch.com)
• Let the dumbbells hang straight down from your shoulders with your arms perpendicular to the angle of the bench. (fitnessandpower.com)