Problematic mobile phone use (PMPU) has been described as a growing public health issue. This randomized controlled trial aimed to determine if aerobic exercise or Tai Chi Chuan as compared to the wait-list control group decreased PMPU-related symptoms; and to analyze the composition of the intestinal flora in the three study groups to explore the correlation between PMPU scores and flora species. A consecutive sample of 90 college students with PMPU was randomized to the aerobic exercise group (AE group, n = 30), the Tai Chi Chuan group (TCC group, n = 30), or the wait-list control group (WLC group, n = 30). The primary outcome was addiction symptoms, i.e., the PMPU score as assessed by the Smartphone Addiction Scale-Short Version (SAS-SV). Secondary outcomes were the emotion-related symptoms (depression, anxiety, self-esteem and self-efficacy), and physical-related symptoms (sleep quality, physical-fatigue and mental-fatigue). Intervention effects were analyzed via generalized estimated equation analysis (GEE).

Inclusion Criteria:

• (1) be 18 years or older; (2) college students; (3) fulfill the Smartphone Addiction Scale-Short Version (SAS-SV) criteria for PMPU; (4) have a low level of daily physical activity.

Exclusion Criteria:

• (1) regular practice of moderate and higher intensity exercise (Physical activity was measured using the Physical Activity Rating Scale-3 (PARS-3), which is a 3-item self-reported scale comprising intensity, duration and frequency [14]. Exercise was considered to be of more than moderate intensity when the PARS-3 scores was >42); (2) any major disease (cardiovascular disease, respiratory illness, and musculoskeletal disorder) that can affect them to participate in exercise training; (3) any gastrointestinal diseases and other diseases affecting intestinal bacteria; and (4) any severe mental illness (e.g., depression, anxiety, bipolar disorder, obsessive-compulsive disorder, eating disorder, and post-traumatic stress disorder).

Participants were recruited between February 2022 and March 2022. Participants from Anhui Medical University were recruited through promotion in academic departments and student societies as well as advertisements in social media (We-chat and QQ). The coordinator subsequently contacted potential participants via We-chat to provide them with information regarding the study; and determine their interest and eligibility.