Smartphone Addiction and Upper Extremity Sensorimotor Performance

Nowadays, the use of digital tools among young people -particularly university students- for purposes such as communication, education, gaming, and accessing information is increasing day by day. Numerous studies have reported that smartphone addiction adversely affects mental and physical health. Smartphone users tend to hold the device with one hand while interacting with the screen with the other, typically while standing or sitting. This usage habit leads to the development of a posture known as "forward head posture," which paves the way for postural disorders. Prolonged flexion of the head and neck, combined with holding the arms extended in front of the torso during smartphone use, results in alterations to the alignment of the cervical and thoracic vertebrae. This condition is characterized by increased lordosis in the lower cervical segments and increased kyphosis in the upper thoracic segments. Maintaining a static posture for extended periods and engaging in repetitive activities are key risk factors for musculoskeletal problems, muscle shortening, and reduced joint range of motion in the neck and upper extremities. Furthermore, this can impair muscle mobility. Muscle receptors play a crucial role in detecting joint movement and position sense, which are essential for both voluntary and appropriate reflexive movements. Cervical muscles play a significant role in proprioception due to their high density of muscle spindles. Prolonged smartphone use and the maintenance of the aforementioned static posture can damage the ligaments and soft tissues surrounding the cervical joints, thereby impairing proprioception. Furthermore, considering that the shoulder girdle can be affected by the maintenance of a static posture in the cervical region, it can be inferred that shoulder joint proprioception may also be compromised.

Head posture is a fundamental factor in the organization of sensory information for the upper extremity. Coordination is defined as rhythmic, accurate, and controlled movement. There are various types of coordination, such as intersegmental, intrasegmental, and visuomotor coordination. Hand-eye coordination, a subcategory of visuomotor coordination, enables the eyes to coordinate indirectly with hand movements. A decline in hand-eye coordination has been demonstrated in individuals with smartphone addiction. Additionally, upper extremity function has been investigated in this population; difficulties in performing activities of daily living due to upper extremity symptoms and a reduction in upper extremity function have been observed. However, no studies specifically addressing upper extremity performance in individuals with smartphone addiction were found.

In light of this information, the fact that smartphone addiction facilitates the maintenance of static postures for prolonged periods -thereby leading to impaired sensorimotor function- represents a key aspect in identifying the factors affected in these individuals and, if necessary, designing appropriate exercise programs.

A review of the literature reveals that, while the impact of smartphone usage on neck position and proprioception has been examined in detail, there are very few studies investigating its relationship with shoulder joint proprioception, hand-eye coordination, and upper extremity performance. The present study was planned to address this gap in the literature.