Triceps brachii hypertrophy is substantially greater after elbow extension training performed in the overhead versus neutral arm position
Sumiaki Maeo, Yuhang Wu, Meng Huang, Hikaru Sakurai, Yuki Kusagawa, Takashi Sugiyama, Hiroaki Kanehisa, Tadao Isaka
Abstract
ABSTRACT The biarticular triceps brachii long head (TB Long ) is lengthened more in the overhead than neutral arm position. We compared triceps brachii hypertrophy after elbow extension training performed in the overhead vs. neutral arm position. Using a cable machine, 21 adults conducted elbow extensions (90−0°) with one arm in the overhead (Overhead‐Arm) and the other arm in the neutral (Neutral‐Arm) position at 70% one‐repetition maximum (1RM), 10 reps/set, 5 sets/session, 2 sessions/week for 12 weeks. Training load was gradually increased (+5% 1RM/session) when the preceding session was completed without repetition failure. 1RM of the assigned condition and MRI‐measured muscle volume of the TB Long , monoarticular lateral and medial heads (TB Lat+Med ), and whole triceps brachii (Whole‐TB) were assessed pre‐ and post‐training. Training load and 1RM increased in both arms similarly (+62−71% at post, P = 0.285), while their absolute values/weights were always lower in Overhead‐Arm (‐34−39%, P < 0.001). Changes in muscle volume in Overhead‐Arm compared to Neutral‐Arm were 1.5‐fold greater for the TB Long (+28.5% vs. +19.6%, Cohen's d = 0.61, P < 0.001), 1.4‐fold greater for the TB Lat+Med (+14.6% vs. +10.5%, d = 0.39, P = 0.002), and 1.4‐fold greater for the Whole‐TB (+19.9% vs. +13.9%, d = 0.54, P < 0.001). In conclusion, triceps brachii hypertrophy was substantially greater after elbow extension training performed in the overhead versus neutral arm position, even with lower absolute loads used during the training.