Brachialis
The brachialis is an upper-arm muscle that flexes the elbow in both pronated and supinated forearm positions.
Anatomy and function
The brachialis lies deep to the biceps brachii. It originates from the distal anterior humerus and inserts on the coronoid process and tuberosity of the ulna. It is a primary elbow flexor and can flex the elbow with the forearm pronated or supinated. Its nerve supply is mainly musculocutaneous; a radial-nerve contribution can occur.
StatPearls · Anatomy, Shoulder and Upper Limb, Brachialis Muscle · StatPearls · Musculocutaneous Nerve
What HYROX® rules establish
Elbow flexion can be involved while pulling the sled rope or completing a rowing stroke, but the HYROX® rulebook does not assign a specific force contribution to the brachialis. During the Farmers Carry, the arms must remain extended at the sides. During the Sandbag Lunges, the sandbag is supported on both shoulders. These standards do not support describing sustained elbow flexion as the defining demand of either station.
Training and interpretation
Elbow-flexion exercises load several muscles, so a split time cannot identify one weak muscle. Neutral- or pronated-grip curl variations may be selected within an individual programme, but the reviewed sources do not establish a uniquely best brachialis exercise, a universal set-and-repetition scheme, or direct transfer to a HYROX® station.
StatPearls · Anatomy, Shoulder and Upper Limb, Brachialis Muscle · ACSM · 2026 resistance-training guidance
FAQ
How is the brachialis different from the biceps?
Both flex the elbow. The biceps also contributes strongly to forearm supination, whereas the brachialis can flex the elbow across pronated and supinated positions.
StatPearls · Anatomy, Shoulder and Upper Limb, Brachialis Muscle · StatPearls · Musculocutaneous Nerve
Can a slow HYROX® split show that my brachialis is weak?
No. A station split reflects many factors and does not isolate one muscle. The current HYROX® rules and anatomy sources do not provide a diagnostic threshold for brachialis weakness.
HYROX® Singles 2026/27 · StatPearls · Anatomy, Shoulder and Upper Limb, Brachialis Muscle
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