Smartphones, which are used quite frequently among adolescents, are becoming more and more indispensable in daily life and offer a wide variety of mobile applications for information, communication, education, and entertainment. The use of smartphones includes many user profiles such as teenagers, adults, children, working or not working. However, when looking at the smartphone user profile, it is seen that the largest proportion belongs to the young population.

With the increasing frequency of use and addiction, many physiological, psychological, and social problems are encountered today. These problems can be classified into two categories that are psychological disorders (sleep disorders, aggressive or depressive symptoms, high anxiety level, low life satisfaction, dropping out of school, and antisocial personality disorder) and physiological disorders (dry eyes, carpal tunnel syndrome, neck or back pain, postural disorders, musculoskeletal disorders, and migraine headaches). Regarding its adverse effects on physical health, especially the increase in neck pain and the decrease in daily life activities and functionality are emphasized. The effects of smartphone use on the functional level are associated with the cervical posture and the sensitivity, spasm and proprioceptive disorders in the neck circumference structures created by this posture. Smartphone addiction and computer addiction, which has similar effects, are associated with neck problems and disability in healthy young people. It has been reported that smartphone addiction in students negatively affects physical health by reducing the amount of physical activity such as walking. In the literature, an increase in muscle fatigue and increased sensitivity in cervical erector spina (CES) and upper trapezius (UT) muscles have been reported due to prolonged smartphone use. Although there are data on the negative effects of smartphone use on many physiological parameters such as pain and functional level in the literature, there is a need for studies evaluating the effect of smartphone addiction, which has emerged as an important concept in recent years.

Posture during phone use stands out as the primary cause of musculoskeletal disorders associated with smartphone use. During the use of the smartphone, the person maintains the posture in which the head is in flexion and the shoulder is in protraction for a long time to look at the device. It is known that the loads on the neck increase with the flexion of the head. This situation has effects not only on the neck musculoskeletal system but also on the shoulder and spine as it creates muscle imbalance. In current studies, it has been emphasized that posture disorder during smartphone use changes the activity of the UT muscle, CES muscle, neck extensor muscles, and hand muscles.

There are various studies in the literature on muscle activation changes, musculoskeletal system changes, and changes in daily living activities with the use of smartphones. However, it is thought that there is a need for a study that correlates smartphone addiction with musculoskeletal problems such as pain and sensitivity, muscle activation changes in the neck muscles, and changes in functional status. It is thought that the determination of physiological effects such as neck pain and muscle activations that they cause even when they do not use phones, even when they do not use telephone, are thought to be effective in terms of drawing attention to the importance of preventing them. In light of this information, our study aimed to examine the effect of smartphone addiction levels on neck pain, functional status, and muscle activation.