trainlog/docs/domain/anatomy_and_movement.md

Functional anatomy and movement knowledge

TRAINING KNOWLEDGE V1 separates anatomy from the exercise, its execution and its physical equipment. A muscle can move a joint, assist another mover or stabilize a segment; its role changes with posture, resistance direction and movement phase. The catalogs record qualitative roles, not force percentages, effective-set fractions or physiological measurements.

The scientific references are in catalog/science-references-v1.json. Functional entities, joint actions and authored movement conventions belong in catalog/muscles-v1.json, catalog/joint-actions-v1.json and catalog/movement-patterns-v1.json. A muscle region or muscle group is not a new anatomical muscle. Parent groups and their component muscles must not be summed as independent exposure.

Evidence and confidence

Every interpretation distinguishes established anatomy, biomechanical interpretation, EMG evidence, intervention evidence, manufacturer statements and practical inference. Anatomy explains plausible function; longitudinal training studies address adaptation. Surface EMG measures a signal affected by recording and physiological conditions. Greater amplitude does not establish greater muscle force, hypertrophy, strength improvement or universal primary muscle status. Vigotsky and colleagues

Confidence uses exactly high, moderate and uncertain. Established anatomy can have high confidence while its application to an unobserved machine variant remains uncertain. Moderate confidence is appropriate when the exercise family is clear but geometry changes secondary or stabilizing roles. Missing evidence is retained explicitly, not replaced with a commercial-name rule.

Functional muscle coverage

The catalog covers these functional distinctions:

Area	Functional distinctions
Chest	Pectoralis major, clavicular and sternocostal regions; pectoralis minor as a scapular muscle
Back and scapula	Latissimus dorsi, teres major, trapezius regions, rhomboids and serratus anterior
Shoulder	Anterior, middle and posterior deltoid; supraspinatus, infraspinatus, teres minor and subscapularis
Arms and forearms	Elbow flexors, triceps, grip/wrist flexors and extensors, pronation and supination
Trunk	Rectus abdominis, obliques, transversus abdominis, erector spinae, multifidus and quadratus lumborum
Hip	Gluteal muscles, tensor fasciae latae, iliopsoas and adductors
Thigh	Quadriceps with biarticular rectus femoris distinguished from vasti; biarticular hamstrings distinguished from biceps femoris short head
Lower leg	Gastrocnemius, soleus and tibialis anterior

Upper-limb anatomy supports shoulder, scapular, elbow and forearm distinctions. Scapular movement is not interchangeable with glenohumeral movement. Stabilizing the humeral head is not the same task as dynamically rotating the shoulder. OpenStax upper-limb anatomy

Pectoral regions share actions but differ in orientation and contribution across shoulder positions. Their existence does not establish separate isolatable “upper” and “lower” chest muscles. Deltoid regions likewise have different lines of action; the movement identifies the likely emphasis. NIH pectoralis anatomy, NIH deltoid anatomy

The hip and knee distinctions are essential: knee extension and knee flexion are different functions despite both mapping to thighs. Gastrocnemius crosses the knee and ankle; soleus does not cross the knee. Hip flexion changes the length of biarticular hamstrings but not biceps femoris short head. OpenStax lower-limb anatomy, Maeo and colleagues

Gluteus minimus abducts and stabilizes the hip. Some lower-limb textbook figure alternative text describes direction inconsistently, including minimus and adductor examples; those descriptions are not copied as anatomical truth. The NIH account corroborates the minimus classification. NIH gluteus minimus anatomy

Spinal flexion/extension and hip flexion/extension must remain separate. Abdominal-wall muscles combine movement and tension/control functions, while posterior spinal muscles contribute extension and segmental control. OpenStax spinal anatomy, OpenStax trunk anatomy, NIH abdominal-wall anatomy

Actions, patterns and stabilization

Joint actions describe motion. Their definitions include shoulder and scapular actions, elbow flexion/extension, forearm rotation, hip actions, knee actions, ankle actions and trunk flexion/extension/rotation/lateral flexion. A loaded return may reverse the visible joint motion while the same agonists control it eccentrically. OpenStax movement terminology

Horizontal/vertical push and pull, knee dominant, hip dominant and single-joint patterns are Trainlog programming conventions grounded in those actions. They are not universally standardized anatomical categories or exact torque ratios. A single-joint exercise can involve many muscles and stabilizers. A dip grouped as a vertical push is still mechanically different from an overhead press.

Trunk stabilization describes resisting an external moment while limiting motion. Anti-extension, anti-rotation and anti-lateral-flexion are task demands, not invented joint movements. Locomotion, cyclic pedaling and cyclic rowing remain distinct; a cardio profile alone does not identify the action sequence.

BODY ZONES projection

catalog/body-zones-v1.json remains the authoritative UX taxonomy. Its zones are coarser than functional anatomy. Forearm muscles fall under arms, posterior trunk muscles can relate to both back and core, and the lateral thorax/scapular function of serratus anterior does not fit a simple surface location rule. Scientific muscle-level projections explain these conventions; they do not alter persisted exercise relations.

A secondary BODY ZONE need not list every accessory or stabilizing muscle. Absence of shoulders on a row does not deny posterior-deltoid participation. Absence of thighs on hip abduction does not deny tensor fasciae latae participation. full_body is not an automatic synonym for cardio or a command to mark every zone.