DIFFERENCES IN UNILATERAL CHEST PRESS MUSCLE ACTIVATION ON A STABLE VERSUS UNSTABLE SURFACE WHILE HOLDING ONE VERSUS TWO DUMBBELLS

Training the bench press exercise on a traditional flat bench does not induce a level of instability as seen in sport movements and activities of daily living. Because of this, many new types of equipment have been created in an attempt to induce instability, such as the COR Bench. 15 males and 7 females between the ages of 18 and 30 were recruited for the present study, which tested two forms of instability: using one dumbbell rather than two, and lifting on the COR bench compared to a flat bench. Thusly, EMG was used to measure muscle activity in four separate conditions of unilateral bench press movements: on a flat bench with one dumbbell, on a flat bench with two dumbbells, on the COR Bench with one dumbbell, and on the COR Bench with two dumbbells. Results indicated that lifting with one dumbbell compared to two dumbbells on the flat bench significantly increased muscle activity across all four muscles being analyzed (pectoralis major, p = .005; middle trapezius, p = .008; external obliques, p = .004; and internal obliques, p = .003), but lifting with one dumbbell compared to two dumbbells on the COR Bench only significantly increased muscle activity in the middle trapezius (p = .001), external obliques(p = . 032), and internal obliques (p = .001). The only muscle to exhibit a significant increase in muscle activity when going from one dumbbell on the flat bench to one dumbbell on the COR Bench was the middle trapezius (p = .010). These results imply that the COR Bench itself does not increase muscle activity as much as switching from two dumbbells to one dumbbell, regardless of the bench being used.