Final answer:
In the Overhead Squat assessment, arms falling forward indicate overactivity of the upper crossed tight muscles, a postural imbalance requiring specific exercises and stretches.
Step-by-step explanation:
The condition indicated when the arms fall forward during the Overhead Squat (OHS) assessment due to overactivity is upper crossed tight muscles (Option b). This is a result of an imbalance in muscle strength and flexibility typically characterized by tightness of the upper trapezius and levator scapula on the dorsal side, which are countered by tight pectorals on the front. These overactive muscles can pull the shoulders and arms forward during movements that require an upright posture or overhead extension, like the OHS. When correcting this postural imbalance, strengthening exercises targeting the weak, underactive muscles, and stretching the overactive, tight muscles are generally recommended.