Background: It is well established that increased internet use is related to an increased risk of musculoskeletal pain among adolescents. The relationship between internet addiction (IA), a unique condition involving severe internet overuse, and musculoskeletal pain has, however, not been reported. This study aimed to investigate the association between IA and the risk of musculoskeletal pain among Chinese college students. Methods: A cross-sectional study was conducted among 4211 Chinese college freshmen. IA status was evaluated using the 20-item Young’s Internet Addiction Test (IAT). IA was defined as internet addiction score ≥50 points. Musculoskeletal pain was assessed using a self-reported questionnaire. Multiple logistic regression analysis was performed to determine association between IA categories (normal, mild, and moderate-to-severe) and musculoskeletal pain. Results: Among all participants; neck, shoulder, elbow, wrist/hand, and low back and waist pain was reported by 29.2, 33.9, 3.8, 7.9, and 27.9%, respectively. The prevalence of IA was 17.4%. After adjusting for potential confounders, the results showed significant differences in the risk of musculoskeletal pain among different IA categories. The odds ratios (ORs) and 95% confidence intervals (CI) for neck pain with IA categories were 1.000 (reference), 1.451 (1.221, 1.725), and 1.994 (1.608, 2.473), respectively (P for trends: < 0.001). For shoulder pain, these were 1.000 (reference), 1.520 (1.287, 1.795), and 2.057 (1.664, 2.542), respectively (P for trends: < 0.001). For elbow pain, ORs (95% CIs) were 1.000 (reference), 1.627 (1.016, 2.605), and 2.341 (1.382, 3.968), respectively (P for trends: 0.001). Those for wrist/hand pain were 1.000 (reference), 1.508 (1.104, 2.060), and 2.236 (1.561, 3.202), respectively (P for trends: < 0.001). For low back and waist pain with severe IA categories, these were 1.000 (reference), 1.635 (1.368, 1.955), and 2.261 (1.813, 2.819), respectively (P for trends: < 0.001). Conclusion: This cross-sectional study showed that severe IA was associated with a higher risk of musculoskeletal pain in Chinese college freshmen. In future research, it will be necessary to explore causality regarding this relationship using interventional studies.

Skipping breakfast has been suggested to increase the risk of depressive symptoms, but there is no information regarding young adults. We aimed to investigate the relationship between the frequency of breakfast consumption and the risk of depressive symptoms among Chinese college students. We investigated a cross-sectional (n = 1060) and one-year prospective (n = 757) relationship between the frequency of breakfast consumption and the risk of depressive symptoms. The frequency of breakfast consumption was categorized into “≤1 time/week”, “2–5 times/week”, or “≥6 times/week”. Depressive symptoms were assessed using the 20-item Zung self-rating depression scale (SDS) with an SDS score of ≥50 to indicate moderate to severe depressive symptoms. In the cross-sectional analysis, the adjusted odds ratios (ORs) and 95% confidence intervals (CIs) of depressive symptoms related with the breakfast consumption categories were 1.00 (reference) for ≥6 times/week, 1.761 (95% CI: 1.131, 2.742) for 2–5 times/week, and 3.780 (95% CI: 1.719, 8.311) for ≤1 time/week (p for trend: <0.001) after adjusting for these potential confounders. Similarly, in the one-year prospective analysis, we found that 10.2% of participants was classified as having moderate to severe depressive symptoms. Multivariate logistic regressions analysis revealed a significant negative relationship between the frequency of breakfast consumption and the risk of depressive symptoms. The ORs (95% CI) for depressive symptoms with decreasing breakfast consumption frequency were 1.00 (reference) for ≥6 times/week, 2.045 (1.198, 3.491) for 2–5 times/week, and 2.722 (0.941, 7.872) for ≤1 time/week (p for trend: 0.005). This one-year prospective cohort study showed that skipping breakfast is related to increased risk of depressive symptoms among Chinese college students. Future research using interventional or experimental studies is required to explore the causal relationship between the effects of breakfast consumption and depressive symptoms.

Increased physical activity level is related to lower risk of depressive symptoms, and an inverse association between muscular strength and risk of depressive symptoms among the elderly population. However, the association among younger adults is unclear. The aim of this study was to examine the association between muscle strength, using handgrip strength as a representative of skeletal muscle strength, and the risk of depressive symptoms among Chinese female college freshman. A cross-sectional study was conducted among 867 participants aged between 16-23 years. Handgrip strength was measured with a handheld digital Smedley dynamometer, and depressive symptoms were evaluated using the 20-item Zung self-rating depression scale (SDS) with 3 cut-off points to indicate elevated depressive symptoms. We found that 10.7% of participants (17.2% or 29.2%) were classified as having moderate to severe depressive symptoms using 50 as the cut-off point. After adjusting for these potential confounders, the adjusted odds ratios for moderate-to-severe depressive symptoms across tertile of relative handgrip strength were 1.00 (reference) for tertile 1, 0.61 (95% CI: 0.35, 1.04) for tertile 2, and 0.53 (95% CI: 0.39, 0.94) for tertile 3 (P for trend: 0.024). The significant associations remained when other cut-off points (SDS 48 or 45) were used. Interactions between the handgrip strength and potential confounders for depressive symptoms in the final models were insignificant. This study showed that handgrip strength is inversely and independently related to the risk of depressive symptoms among Chinese female college freshman. These results can help with the development of an effective intervention strategy against depression. For future research, it is important to explore the causality of the effects of handgrip strength on the depressive symptoms by intervention study.