71.0% of the 859 medical college students studied in this survey did not usually engage in regular physical activity, and 54.6% usually did only 1 time per week or no moderate intensity activity. During this epidemic, 50% of the medical college students had home protection days between 25 and 45 days, and over 70% had reduced or decreased the intensity, frequency, and time per physical activity; 50% spent 4 to 12 hours per day sitting on average, 4 to 12 hours per day on average using electronic devices, and 16.9% slept less than 6 hours per day.
In this survey, the overall prevalence of medical students during home protection in this NCIP epidemic was found to be 40.2% (n = 345; 95% CI 36.9%-43.4%), which is higher than normal.3,5,6 The highest prevalence was 18.4% in the neck, followed by 15.6% in the shoulder, 14.6% in the head and 11.2% in the lower back.
In an analysis of multifactorial logistic regression, it was found that sex was a risk factor for the onset of musculoskeletal pain, (OR = 1.391,95CI 1.006–1.922, p = 0.046 < 0.05), with women having a 39.1% higher risk of pain occurrence than men, which is consistent with most studies,8,9,11,15 but there are also studies showing a higher risk of developing musculoskeletal pain in individual sites in men than in women. For example, Fahad AA investigated the occurrence of musculoskeletal pain in the lower back in 1163 medical college students from five medical schools in Saudi Arabia and found that the risk was higher in men than in women.16 The reason for the difference in results may be that the overall prevalence of musculoskeletal pain and its risk factors are not the same as that of individual sites.
This study found that regular physical activity in daily life was effective in the prevention of musculoskeletal pain compared to the intensity, frequency, and time per physical activity, and that the risk of musculoskeletal pain was 64.8% higher in those with irregular physical activity in daily life than in those with regular physical activity (OR = 1.648,95CI 1.157–2.347, p = 0.006 < 0.05). A study conducted by Gidey Gomera Weleslassie et al. at Mekelle University, Ethiopia, which included 422 people, found that physical activity was effective in preventing neck and shoulder pain;12 Graciana de Azambuja et al. gave a mouse animal model a certain amount of time of swimming every day for continuous 21 days. The results showed that the prevalence of musculoskeletal pain in the experimental group was significantly lower than that in the control group without any exercise. At the same time, the levels of receptors and inflammatory factors associated with musculoskeletal pain were measured in the serum of the mice, and the results further revealed that daily swimming can effectively reduce the increase of inflammatory factors caused by persistent fatigue in the relevant areas and prevent the activation of pathways that cause musculoskeletal pain, thereby preventing the occurrence of musculoskeletal pain.17 Our study also found no correlation between changes (reductions) in intensity of physical activity, frequency of physical activity per week, time per physical activity, all three over a short period of time (median duration of home protection in this investigation was 35 days) and the occurrence of musculoskeletal pain, which is supported by similar studies.9,18
Most previous studies on the correlation between physical activity and musculoskeletal pain have focused on the intensity and frequency of physical activity, time per physical activity, or the variation of the three, and have often reached different conclusions, with major differences and controversies.9,18,19,20 A careful analysis of the methods of these studies shows that researchers tend to focus on the sum of the frequency of physical activity per week or the time per physical activity neglecting the whole distribution in seven days per week. This can lead to a large bias in the studies. Our study found that there was a strong correlation between “frequency of usual moderate intensity activity” and “regularity of physical activity in daily life” (χ2 = 154.066, p < 0.001), demonstrating that “frequency of usual moderate intensity activity” was a confounding factor, which influenced the regularity of physical activity, and then influenced the dependent variable, and whose interference could be controlled by multi-factor logistic regression analysis (OR = 0.844, 95CI 0.660–1.079, p = 0.176 > 0.05).
There was a statistical significance in differences between the average daily time spent using electronics between the musculoskeletal pain group and the group without musculoskeletal pain during home protection. Multi-factor logistic regression analysis found that it was not a correlated factor of musculoskeletal pain. Further analysis revealed that it was correlated with “regularity of physical activity in daily life” (Z= -3.648, p < 0.001), which proved to be a confounding factor. One study found that excessive use of electronic devices was associated with musculoskeletal pain, but it was not analyzed together with physical activity and other factors, and the results obtained may be biased.7,21
Less than 6 hours of sleep per day during home protection was a risk factor for musculoskeletal pain (OR = 1.474,95CI 1.020–2.131, p = 0.039 < 0.05), with a 47.4% higher risk compared to those who received 6–8 hours of adequate sleep per day. Although the interaction between sleep quality and musculoskeletal pain is now well established, the exact mechanisms involved are unclear.22 Some studies suggest that sleep deprivation causes the release of inflammatory factors that affect the regulation of the hypothalamic-pituitary-adrenal axis, reducing the secretion of dopamine and thus causing musculoskeletal pain;23 others assume that sleep deprivation causes increased sensitivity to pain sensation, decreased willingness to exercise and a range of psychological problems such as anxiety, depression and fear of pain, which are mutually reinforcing with musculoskeletal pain.24,25
This study did not further analyze the risk factors for musculoskeletal pain in each part of the body, and expanding the sample size to study their risk factors in different parts of the body would be more effective in preventing musculoskeletal pain.