If you aren’t using multiple grip positions during elbow flexion (curls), you may be missing the opportunity for serious strength and size gains.
As it turns out, there is more than one elbow flexor muscle in the body. Everybody knows the bicep, or bicep brachii. Lesser known however, are the brachioradialis and brachialis muscles. The short and long head of the bicep brachii originate on the coracoid process of the scapula and the supraglenoid tubercle, respectively, and insert on the radial tuberosity just distal to (lower than) the elbow. The brachioradialis originates on the humerus and inserts on the radius, lower so than the bicep brachii. Finally, the brachialis originates on the anterior (front) side of the humerus and inserts on the ulna, the other of the two forearm bones.
Cutting through all the science, what this essentially means is that the body has 3 different muscles in each arm that are responsible for elbow flexion, and that the position of the grip during the elbow flexion will result in greater recruitment of specific muscles. A 2015 study by Kleiber, et al. used electromyography to measure muscle activation levels of the bicep, brachialis, and brachioradialis, during elbow flexion with the grip in neutral, pronated, and supinated position. The findings of the study were interesting in that grip position caused significant differences in muscle activation levels of the brachioradialis and brachialis but that bicep activation remained similar across all 3 grip positions. Meanwhile, both brachioradialis and brachialis muscles experienced their lowest activation levels in the supinated grip position, with brachioradialis experiencing its highest activation levels in neutral, and brachialis in pronated position. (1)
What this all means, is that in order to recruit additional muscle fibers and make your workouts more efficient, you should incorporate different grip positions to stimulate the brachioradialis and brachialis muscles. With the above research in mind, these grips can be used without sacrificing and development of the bicep, which demonstrates similar activation levels across any grip mode. Therefore, in order to maximize your strength and hypertrophy gains, use multiple grips during your workouts to recruit more muscles and reap greater benefits.
1. Kleiber T, Kunz L, Disselhorst-Klug C. Muscular coordination of biceps brachii and brachioradialis in elbow flexion with respect to hand position. Frontiers in Physiology. 2015;6:215.