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Effects of Body Position and Loading Modality on Muscle Activity and Strength in Shoulder Presses

Saeterbakken, Atle H.1; Fimland, Marius S.2,3

Journal of Strength & Conditioning Research: July 2013 - Volume 27 - Issue 7 - p 1824–1831
doi: 10.1519/JSC.0b013e318276b873
Original Research

Abstract: Saeterbakken, AH and Fimland, MS. Effects of body position and loading modality on muscle activity and strength in shoulder presses. J Strength Cond Res 27(7): 1824–1831, 2013—Little is known about the effect of performing upper-body resistance exercises with dumbbells versus barbells and standing versus seated. Therefore, this study sought to compare electromyogram activity (EMG) and one-repetition maximum (1-RM) in barbell and dumbbell shoulder presses performed seated and standing. Fifteen healthy men volunteered for 1-RM and EMG testing with a load corresponding to 80% of the 1-RM. Electromyogram activity was measured in the anterior, medial, and posterior deltoids and biceps and triceps brachii. The following EMG differences or trends were observed: For deltoid anterior: ∼11% lower for seated barbell versus dumbbell (p = 0.038), ∼15% lower in standing barbell versus dumbbell (p < 0.001), ∼8% lower for seated versus standing dumbbells (p = 0.070); For medial deltoid, ∼7% lower for standing barbell versus dumbbells (p = 0.050), ∼7% lower for seated versus standing barbell (p = 0.062), 15% lower for seated versus standing dumbbell (p = 0.008); For posterior deltoid: ∼25% lower for seated versus standing barbell (p < 0.001), ∼24% lower for seated versus standing dumbbells (p = 0.002); For biceps, ∼33% greater for seated barbell versus dumbbells (p = 0.002), 16% greater for standing barbell versus dumbbell (p = 0.074), ∼23% lower for seated versus standing dumbbells (p < 0.001); For triceps, ∼39% greater for standing barbell versus dumbbells (p < 0.001), ∼20% lower for seated versus standing barbell (p = 0.094). 1-RM strength for standing dumbbells was ∼7% lower than standing barbell (p = 0.002) and ∼10% lower than seated dumbbells (p < 0.001). In conclusion, the exercise with the greatest stability requirement (standing and dumbbells) demonstrated the highest neuromuscular activity of the deltoid muscles, although this was the exercise with the lowest 1-RM strength.

1Faculty of Teacher Education and Sport, Sogn og Fjordane University College, Sogn og Fjordane, Norway

2Department of Public Health and General Practice, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway

3Hysnes Rehabilitation Center, St. Olavs University Hospital, Trondheim, Norway

Address correspondence to Atle H. Saeterbakken, atle.saeterbakken@hisf.no.

Copyright © 2013 by the National Strength & Conditioning Association.