Turning when using a smartphone in persons with and without neurologic conditions: an observational study (Preprint)

BACKGROUND Turning during walking is a relevant and common everyday movement and it depends on a correct top-down intersegmental coordination. This could be reduced in several conditions (en-bloc turning), and an altered turning kinematics has been linked to increased risk of falls. Smartphone use has been associated with poorer balance and gait, however its effect on turning-while-walking have not been investigated yet. This study explored turning intersegmental coordination when using a smartphone in different age groups and neurologic conditions. OBJECTIVE To evaluate the effect of smartphone use on turning behavior in healthy participants of different ages and patients with various neurological diseases. METHODS Younger (age 18-60 years) and older (age >60 years) healthy participants and patients with Parkinson’s disease (PD), multiple sclerosis, subacute stroke (<4 weeks, SAS) and lower-back pain (LBP) performed turning-while-walking alone (single-task, ST) and while performing two different cognitive tasks of increasing complexity (dual-task, DT). The mobility task consisted of walking up and down a 5-meter walkway at self-selected speed, thus including 180° turns. Cognitive tasks consisted of a simple reaction time test (simple DT, SDT) and a numerical Stroop test (complex DT, CDT). General (turn duration and number of steps while turning), segmental (peak angular velocity) and intersegmental turning parameters (intersegmental turning onset latency and maximum intersegmental angle) were extracted for head, sternum and pelvis using a motion capture system and a turning detection algorithm. RESULTS One hundred twenty-one participants were enrolled. All participants, irrespective of age and neurologic disease, showed a reduced intersegmental turning onset latency and a reduced maximum intersegmental angle of both pelvis and sternum relative to head, thus indicating an en-bloc turning behavior when using a smartphone. Concerning change from ST to turning when using a smartphone, PD patients reduced their peak angular velocity the most, which was significantly different against LBP for head (P<.01). Stroke patients showed an en-bloc turning already without smartphone use. CONCLUSIONS Smartphone use during turning-while-walking may lead to en-bloc turning and thus increase fall risk across age and neurologic disease groups. This behavior is probably particularly dangerous for those groups with most pronounced changes of turning parameters during smartphone use and highest fall risk, such as PD patients. Moreover, the experimental paradigm presented here might be useful in differentiating LBP patients without and with early/prodromal PD. In SAS patients, en-bloc turning could represent a compensative strategy to overcome the newly occurring mobility deficit. Considering the ubiquitous smartphone use in daily life, this study should stimulate future studies in the area of fall risk and neurological as well as orthopedic diseases. CLINICALTRIAL German Clinical Trials Register (https://www.drks.de/drks_web/) DRKS00022998.