Muscle Activation When Performing the Chest Press and Shoulder Press on a Stable Bench vs. a Swiss Ball $0.00

Muscle Activation When Performing the Chest Press and Shoulder Press on a Stable Bench vs. a Swiss Ball

By: Phil Page, PHD, PT, ATC, CSCS, FACSM, LAT | Jul 31, 2019
Muscle Activation When Performing the Chest Press and Shoulder Press on a Stable Bench vs. a Swiss Ball


When exercise balls became popular in the United States in the 1980s, it was thought that their instability promoted higher activation of the back and abdominal muscles for core stabilization. Several studies have shown that the exercise ball does increase muscle activation of the abdominal muscles compared to a stable surface.

As the exercise ball increased in popularity, trainers and therapists began performing traditional resistance training exercises such as the bench press with dumbbells on an exercise ball. Theoretically, the unstable surface would increase activation of both trunk and shoulder muscles. In addition to the increased risk of injuries associated with traditional resistance training on an exercise ball, researchers began to show that using an exercise ball for extremity exercises was not as effective as once thought.

Canadian researchers (Andersen & Behm 2002) were among the first to show that performing a chest press on an exercise ball significantly decreased force output by 60%. Interestingly, the muscle activation levels remained the same between surface types despite a decrease in force output, suggesting resistance training on an unstable surface may produce less efficient muscle contractions. Subsequently, other researchers (Marshall & Murphy 2006) reported an increase in EMG levels of the deltoid and abdominals during a chest press on an exercise ball compared to a flat bench. These conflicting results may be due to the fact that these 2 studies used 75% 1RM and 60% 1RM resistances, respectively.

Researchers at Cal State Fullerton wanted to investigate the EMG levels of the arms and abdominals while performing a chest press and shoulder press on an exercise ball at 80% 1RM. They recorded EMG levels of the anterior deltoid, pectoralis major, and rectus abdominus during 4 conditions: chest press on and off and exercise ball, and overhead shoulder press on and off an exercise ball. Subjects performed 3 repetitions at 80% of their previously determined maximal strength using dumbbells. The resistance levels were the same between the stable and unstable conditions for each type of lift. Muscle activation was normalized to their maximal EMG levels during the maximal strength testing. The researchers found no significant difference between the conditions: both the exercise ball and stable surfaces produced similar muscle activation levels at the same resistance levels.

It’s important to remember that this study used higher loads than previous studies. The authors hypothesized that EMG levels would be similar between stable and unstable conditions because of the stabilization of the ball caused its deformity resulting from the subject’s body weight and resistance load. This suggests the exercise ball surface may have become more stable, comparable to a bench surface. Because the researchers did not control for the deformity of the exercise ball, more research is needed to determine if this was a reason for a lack of difference between conditions.  Based on the results of this study, the exercise ball does not increase or decrease EMG of the shoulder or trunk muscles during the chest or overhead press at high loads.

Uribe BP, et al. Muscle activation when performing the chest press and shoulder press on a stable bench vs. a Swiss ball. J Strength Cond Res. 2010 Apr;24(4):1028-33.