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Safety
Safety

Deltoid Training Cautions (Subluxation & Rotation)

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Historical reference: its only source is the original reference manual, and some of it may be out of date. Not used for AI answers until re-sourced.

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deltoidshouldersubluxationrotationbehind-neck-pressalignment

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DefinitionA short reference note, not a full lesson.
Definition

Positioning the upper arm 45° away from the torso prevents shoulder subluxation; beware internal/external rotations; the press-behind-neck is not recommended (too much external rotation).

Detail

Safety points for deltoid training:

  • Anterior deltoid: positioning the upper arm 45 degrees away from the torso is an important safety factor to prevent subluxation of the shoulder joint. A neutral grip is a more functional movement to train this muscle (it is over-used and primarily involved in pressing).
  • Medial deltoid: ROM is 90 degrees (shoulder-joint abduction). Beware of internal and external rotations. Note the greater-tubercle / acromion-process relationship and limitation (impingement — the bones can rub against one another). This position does not allow the use of heavy weights.
  • Posterior deltoid: the most under-emphasized of the three heads; movements are rarely done properly. The key is horizontal abduction (extension). The press-behind-neck exercise is not recommended as it involves too much external rotation.

Key facts

  • Hold the upper arm 45° from the torso to prevent shoulder subluxation (anterior deltoid).
  • Medial deltoid ROM = 90° abduction; beware internal/external rotation; risk of greater-tubercle/acromion impingement; do not use heavy weights.
  • Press-behind-neck not recommended — too much external rotation.

Connections

Sources

Historical reference · reference manual (page cited)
p.276p.380p.460
Pages: 460, 276, 380.

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Atlas Connections

Anterior Deltoid
The front deltoid head; produces forward flexion, horizontal adduction, and internal rotation — primarily a pressing muscle.
External RotationClosely related
Rotation with the axis of the bone turning away from the body (e.g., the humerus turned outward).
Internal RotationClosely related
Rotation with the axis of the bone turning toward the body (e.g., the humerus turned inward).
Medial Deltoid
The middle deltoid head; the primary muscle of true shoulder abduction (90°), involving all three heads plus the supraspinatus.
Posterior Deltoid
The rear deltoid head; produces horizontal abduction, backward extension, and external rotation — the most under-emphasized deltoid head.
Behind-the-Neck Press Not RecommendedClosely related
The behind-the-neck (press behind neck) shoulder press is not recommended because it involves too much external rotation of the shoulder — the same core risk mechanism as behind-neck lat pulldown, since both are the same underlying press/pull pattern taken to a riskier angle, not a separate hazard each.
Rotator Cuff — Use Only Low Resistance
When training the rotator cuff muscles (SITS), ensure that only low resistances are used.