In an experiment by S.C. Glass and T. Armstrong, 15 weight –trained men performed six repetitions of a decline (-15 degrees) and an incline (30 Degrees) bench press at 70% of their one-rep max 1. EMG electrodes were placed over the upper and lower sternal pec regions and results showed that lower pec EMG activity was significantly greater during the decline press than the incline press. Yet the scientists saw no difference in EMG activity of the upper pecs between the decline and incline bench press. Greater overall pec EMG activity was noted for the decline press compared to the incline press.
Another significant finding was that involvement of the anterior deltoid, in the full range of motion in the bench press. It was noted that the anterior deltoid had a greater influence on the sticky point than the triceps. Many powerlifting coaches focus on the pecs and triceps and even the lats to strengthen the sticky point. The anterior deltoid has a significant involvement in the bench press. It was also shown that there is an insignificant contribution of the lats involvement in the actual pressing motion. Despite many powerlifting coaches and “experts” proclaiming their knowledge on the “web”, the lats do NOT play a significant role in the actual bench press itself. Biomechanically it is virtually impossible to contract the lats and press the bar in a typical bench press motion.
The researchers basically found that the decline position may recruit more muscle fibers than the incline position. One factor that might contribute to this is the fact that the test subjects were able to lift more weight in the decline position. On the other hand, it’s quite possible that other muscles contribute to the decline press; hence more weight can be lifted.
Glass, S.C. Armstrong, T. Electromyographical activity of the pectoralis muscle during incline and decline bench press. Journal of Strength and Condititoning Research 11(3); 163-167, 1997
Joaquin Calatayud, et. al., “Bench press and push-up at comparable levels of muscle activity results in similar strength gains,” Journal of Strength and Conditioning Research, DOI: 10.1519/JSC.0000000000000589