Anatomy, Kinesiology, and Biomechanics
This domain tests your grasp of how the body moves. Know the planes of motion: sagittal (flexion/extension), frontal (abduction/adduction), and transverse (rotation). Understand joint actions and the prime movers for common exercises-e.g., squat targets quadriceps, glutes, hamstrings; push-up targets pectorals, anterior deltoid, triceps.
Grasp muscle roles: agonist (prime mover), antagonist (opposes), synergist (assists), and stabilizer (fixes a joint). Know muscle actions: concentric (shortening), eccentric (lengthening under load), isometric (no length change). Eccentric actions are where soreness and control often live.
Biomechanics concepts to master: leverage (classes of levers-most human joints are third-class), line of gravity and base of support for balance, and neutral spine alignment. Understand how gravity and resistance change difficulty (e.g., lever length, body position).
Traps: Questions may ask which muscle is the antagonist during a movement-don't default to the prime mover. Another trap is confusing plane with axis. Also watch for overgeneralized claims ("always keep knees behind toes")-form cues are context-dependent.
Rule of thumb: For any exercise, identify the joint action first, then the prime mover, then the opposing muscle (antagonist).
Worked example: During a biceps curl, the biceps brachii is the agonist (concentric flexion); the triceps is the antagonist; the brachialis is a synergist.