Background: Neck and back pain are common musculoskeletal conditions in university students and associated with unhealthy lifestyle behaviors such as physical inactivity, unhealthy dietary habits, smoking and risky alcohol use. Cohort studies have investigated the effect of a healthy lifestyle including several lifestyle behaviors on the risk and prognosis for neck and back pain. Studies of an association between an unhealthy lifestyle and musculoskeletal conditions in university students are lacking. This study aimed to assess the association between an unhealthy lifestyle and incident activity-limiting neck/back problems (ALNBP) in university students.

Methods: Participants enrolled in the Sustainable UNiversity Life (SUN) study who did not report baseline ALNBP in the past three months were included (n = 3492). The baseline web-survey assessed unhealthy lifestyle behaviors (physical inactivity, high sitting time, meal skipping and risky use of alcohol, tobacco, and illicit drugs) with valid instruments and single-item questions. Participants with ≥ 3 unhealthy lifestyle behaviors were categorized as exposed to an unhealthy lifestyle. Responses to web-based follow-up surveys every third month until first reporting ALNBP or to the end of the one-year follow-up were used. The outcome ALNBP was defined as reporting limitations in daily activities due to a neck, low back and/or midback problem the past three months, assessed with a modified version of the Nordic Musculoskeletal Questionnaire. Crude and adjusted Cox regression models were built to assess the association between an unhealthy lifestyle and incident ALNBP, reported as a hazard rate ratio (HRR) with a 95% confidence interval (CI).

Results: Sixty percent of the participants were women, and the mean age was 24.5 ± 6.0 years. A total of 574 participants (16%) were exposed to an unhealthy lifestyle at baseline. Having an unhealthy lifestyle generated an adjusted HRR of 1.35 (95% CI 1.12, 1.63) for incident ALNBP, compared to not having an unhealthy lifestyle.

Conclusions: An unhealthy lifestyle, categorized as ≥ 3 unhealthy lifestyle behaviors, is associated with incident ALNBP in university students.

Objectives: To assess the association between (1) dietary habits and knee/shoulder injury incidence in male and female adolescent handball players and (2) menstrual dysfunction and injury incidence in females.

Methods: This study is based on seasons 2020-2022 of the Swedish Handball Cohort including 1144 participants (1703 player seasons) free from a substantial knee and shoulder injury. Participants self-reported meal frequency, meal timing, nutritional intake and menstrual function (season 2022/2023) at baseline. Weekly follow-ups throughout the season assessed training and matches, and substantial knee/shoulder injuries. Cox regression analyses estimated a hazard rate ratio (HRR) with the first event of a knee/shoulder injury (combined), with minutes of handball training and matches as the timescale.

Results: In females, adjusted analyses generated an HRR for knee/shoulder injuries of 1.46 (95% CI 1.08, 1.98) for moderate-high nutritional quality compared with low quality and an HRR of 1.38 (95% CI 1.02, 1.86) for ≥2 unfavourable dietary habits compared with 1 unfavourable dietary habit. For poor meal timing, adjusted analyses generated an HRR of 1.20 (95% CI 0.90, 1.61) compared with adequate timing in females. In males, adjusted analyses generated an HRR of 1.23 (95% CI 0.69, 2.17) for low meal frequency and an HRR of 0.83 (95% CI 0.60, 1.15) for poor meal timing.

Conclusions: In adolescent female handball players, moderate-high nutritional quality and ≥2 unfavourable dietary habits are associated with higher knee/shoulder injury incidence; whereas, no or unprecise associations were found for other dietary habits in females and males and for menstrual dysfunction in females.

BACKGROUND: There is growing awareness that back pain in adolescent soccer (European football) players is not always related to local tissue damage. Approaches taking into consideration lifestyle factors are needed. This study aimed to investigate the association between psychological distress, skipped meals, and insufficient sleep, and the occurrence of back pain among adolescent female soccer players.

HYPOTHESIS: Psychological distress, skipped meals, and insufficient sleep are associated with the occurrence of back pain.

STUDY DESIGN: Cohort study.

LEVEL OF EVIDENCE: Level 3.

METHODS: Swedish adolescent female soccer players aged 12 to 17 years, without back pain at baseline, were included. The exposures psychological distress, skipped meals, and insufficient sleep were assessed at baseline. The players were followed for 1 year with a weekly web-based survey, where back pain intensity was measured on a numeric rating scale (NRS) ranging from 0 to 10. The outcome back pain was defined as reporting low back pain and/or upper back/neck pain intensity of ≥4 on the NRS. Multivariable Cox proportional hazard regression analyses were performed to estimate the hazard rate ratio (HRR) with 95% CI for the association between each exposure and the outcome back pain, adjusted for age at baseline and parents' education.

RESULTS: In total, 351 players were included, and 141 players reported back pain at some point during the 1-year follow-up. The adjusted HRR for back pain was 1.79 (95% CI, 1.11-2.91) for insufficient sleep, 1.45 (95% CI, 0.97-2.17) for psychological distress, and 0.98 (95% CI, 0.61-1.59) for skipped meals.

CONCLUSION: Insufficient sleep and psychological distress are associated with the occurrence of back pain among female adolescent soccer players.

CLINICAL RELEVANCE: Our results contribute to the understanding of what may influence the occurrence of back pain in adolescence, offering potential strategies for the prevention of back pain in adolescent female soccer players.

Background: Musculoskeletal conditions impose a large burden of disability in young populations. University students are prone to neck and back pain, with potential negative impact on physical, mental, and academic functioning. In adolescent athletes, musculoskeletal injuries are common and may result in discontinued sports participation as well as impaired physical and mental health. University students and adolescent athletes tend to have unhealthy lifestyle behaviors. University students report unhealthy behaviors such as high sitting time, low physical activity levels and unhealthy dietary habits. Adolescent athletes are physically active but tend to have inadequate dietary habits in relation to their physiological demands, including insufficient intakes of total energy and carbohydrates.

Identifying modifiable risk factors for musculoskeletal conditions is the first step towards prevention, and knowledge about the role of lifestyle behaviors for these conditions is limited. The overarching purpose with this doctoral thesis was to deepen the knowledge about lifestyle behaviors and their role for the risk of musculoskeletal conditions in university students and high school athletes.

Methods, results, and conclusions: Study I and II are based on the Sustainable UNiversity Life (SUN) study, a cohort study including 4262 students at Swedish universities. The participants reported different aspects of health, lifestyle behaviors and attitudes through web-surveys every third month for one year in 2019-2021.

In Study I, the aim was to assess changes in lifestyle behaviors during the COVID-19 pandemic, compared to before, in 1877 university students (73% women, mean age 26.5 ± 6.8 years). Physical activity levels, sitting time, meal frequency and risk use of alcohol, tobacco and illicit drugs were measured at a pre-pandemic baseline and at two periods during the first six months of the pandemic, the follow-up 1 (FU1) and follow-up 2 (FU2). Population means and differences with 95% confidence interval (CI) in lifestyle behaviors were calculated with generalized estimating equations. The study found that weekly exercise decreased by -7.7 minutes (95% CI -12.6, -2.8) whereas weekly daily activities increased by 14.2 minutes (95% CI 7.9, 20.5) between the pre-pandemic baseline and FU2. Furthermore, daily sitting time decreased by -1.4 hours (95% CI -1.7, -1.2) during this period. Small changes were observed for meal frequency, whereas for risk use of alcohol, tobacco and illicit drugs, changes were only minor. The conclusion of Study I is that lifestyle behaviors in Swedish university students slightly improved during the first six months of the COVID-19 pandemic compared to before.

In Study II, the aim was to assess the association between an unhealthy lifestyle and incident activity-limiting neck/back problems (ALNBP) in university students. Physical inactivity, high sitting time, meal skipping, and risky use of alcohol, tobacco and illicit drugs were combined into an unhealthy lifestyle, categorized as ≥3 unhealthy lifestyle behaviors. A total of 3492 university students (60% women, mean age 24.5 ± 6.0 years) without ALNBP the past three months at baseline were included. Cox regression models were built to assess the association between an unhealthy lifestyle and incident ALNBP, reported as a hazard rate ratio (HRR). Being exposed to an unhealthy lifestyle generated a HRR of 1.35 (95% CI 1.12 to 1.63) of ALNBP, compared to not being exposed to an unhealthy lifestyle. The conclusion of Study II is that an unhealthy lifestyle is associated with incident activity-limiting neck/back problems in university students.

Study III and IV are based on the Swedish Handball Cohort (SHC), a cohort study including 1334 adolescent handball players enrolled to a handball-profiled high school in Sweden. Participants responded to a baseline web-survey with questions about current and previous injuries, training, and dietary habits, among others, in the beginning of the handball season in 2020/2021, 2021/2022 and 2022/2023.Participants were monitored weekly throughout the handball season with questions about their amount of handball training and matches the preceding week, sleep habits, injuries, and injury consequences, among others, reported through a mobile application.

In Study III, the aim was to describe dietary habits in 1040 adolescent handball players enrolled in the SHC seasons 2020/2021 or 2021/2022 (51% males, mean age 16.6 ± 0.9 years). Differences with respect to sex and school grade were estimated with generalized linear models, generating a prevalence ratio (PR) and 95% CI. Overall, 70% and 90% of the participants met recommendations for meal frequency and meal timing, respectively, whereas adherence to recommended provision of carbohydrates was met by 17%. Sixteen percent adhered to the Nordic Nutrition Recommendations (NNR) for fruits/vegetables of ≥500 grams per week, whereas 37% adhered to the recommendations for fish/seafood of ≥2 times per week. Use of dietary supplements was reported by 28% of the participants, and 20% reported food exclusions due to other reasons than intolerances. Females reported a lower frequency of all meals, especially morning snacks and evening snacks. Also, a higher prevalence of food exclusions was observed in females, with a PR of 1.66 (95% CI 1.31to 2.01) for exclusions due to intolerances and a PR of 1.36 (95% CI 1.08, 1.64) for exclusions due to other reasons. Females also reported a higher adherence to fruits/vegetables recommendations with a PR of 2.30 (95% CI 1.98, 2.62) and use of micronutrient supplements to a larger extent with a PR of 1.72 (95% CI 1.43, 2.00), compared to their male counterparts. Small differences were observed with respect to school grade. The conclusion of Study III is that Swedish adolescent handball players’ dietary habits are somewhat in accordance with sports nutrition recommendations whereas adherence to provision of carbohydrates during matches and the NNR for fruit/vegetables and fish/seafood is low. Females seem to display more restrictive dietary habits compared to males.

In Study IV, the aim was to assess the association between dietary habits and incident knee/shoulder injuries in 1144 adolescent handball players in season 2020/2021, 2021/2022 and 2022/2023 of the SHC without a knee or shoulder injury at baseline (1703 player seasons, 53% males, mean age 16.7 ± 0.9 years). Cox regression analyses estimated a HRR with the first event of a knee/shoulder injury as the outcome. A moderate-high nutritional quality, in accordance with the NNR, generated a HRR of 1.46 (95% CI 1.08, 1.98) for knee/shoulder injuries compared to low nutritional quality in adolescent female handball players. Also, ≥2 unfavorable dietary habits in relation to sports nutrition recommendations generated a HRR of 1.38 (95% CI 1.02, 1.86) compared to 1 unfavorable dietary habit in females. For poor meal timing, adjusted analyses generated a HRR of 1.20 (95% CI 0.90, 1.61) in females, compared to adequate meal timing. In adolescent male handball players, analyses generated a HRR of 1.23 (95% CI 0.69, 2.17) for low meal frequency compared to high meal frequency and a HRR of 0.83 (95% CI 0.60, 1.15) for poor meal timing. Menstrual dysfunction was assessed in females with no use of hormonal contraceptives, as a proxy for low energy availability, however, no associations were found between menstrual dysfunction and incident injuries in these females. The conclusion of Study IV is that a moderate-high nutritional quality and having more than one unfavorable dietary habit is associated with higher rate of incident knee/shoulder injuries in adolescent female handball players, while there are no or unprecise associations for meal frequency, meal timing and menstrual dysfunction. In adolescent male handball players, there are no clear associations between dietary habits and incident injuries.

Overall conclusion: This doctoral thesis sheds light on aspects of lifestyle behaviors in university students and high school athletes. Population-specific unhealthy lifestyle behaviors are common in university students and high school athletes. These behaviors seem to be of importance for the risk of musculoskeletal conditions.

Purpose: To determine the gender-specific impact of recent exposure to different forms of sexual harassment and sexual violence (SHV) on depression and anxiety symptoms three, six, and nine months later.

Methods: We recruited 2229 women and 1274 men studying at Swedish universities and followed them with web-surveys every three months over one year. We estimated mean differences (MDs) of depression and anxiety symptoms between exposed and unexposed at each follow-up, adjusting for prior SHV, prior depression and anxiety symptoms and potential confounders.

Results: For women, sexual harassment (wide subjective definition) was associated with higher symptom levels of depression (MD 1.0 [95% CI: 0.3; 1.7]) and anxiety (MD 0.8 [95% CI: 0.3; 1.4]) three months later. Unwanted sexual attention was associated with higher symptom levels of anxiety three (MD 0.5 [95% CI: 0.1; 0.8]) and six months later (MD 0.4 [95% CI: 0.0; 0.7]). Exposure to sex against ones will was associated with higher depression symptoms three (MD 1.7 [95% CI: 0.1;3.4]), and six months later (MD 3.1 [95% CI: 1.0; 5.2]). Trends indicated that associations with subsequent mental health differed between forms of SHV among women, and that most associations were more pronounced in temporal proximity to the exposures. For men, we refrain from interpreting the results since they showed high variability and were not robust to sensitivity analyses using multiple imputation to account for missing outcome data.

Conclusions: Among women, several forms of SHV were associated with higher subsequent depression and anxiety symptoms.

IMPORTANCE: Procrastination is prevalent among university students and is hypothesized to lead to adverse health outcomes. Previous cross-sectional research suggests that procrastination is associated with mental and physical health outcomes, but longitudinal evidence is currently scarce.

OBJECTIVE: To evaluate the association between procrastination and subsequent health outcomes among university students in Sweden.

DESIGN, SETTING, AND PARTICIPANTS: This cohort study was based on the Sustainable University Life study, conducted between August 19, 2019, and December 15, 2021, in which university students recruited from 8 universities in the greater Stockholm area and Örebro were followed up at 5 time points over 1 year. The present study used data on 3525 students from 3 time points to assess whether procrastination was associated with worse health outcomes 9 months later.

EXPOSURE: Self-reported procrastination, measured using 5 items from the Swedish version of the Pure Procrastination Scale rated on a Likert scale from 1 ("very rarely or does not represent me") to 5 ("very often or always represents me") and summed to give a total procrastination score ranging from 5 to 25.

MAIN OUTCOMES AND MEASURES: Sixteen self-reported health outcomes were assessed at the 9-month follow-up. These included mental health problems (symptoms of depression, anxiety, and stress), disabling pain (neck and/or upper back, lower back, upper extremities, and lower extremities), unhealthy lifestyle behaviors (poor sleep quality, physical inactivity, tobacco use, cannabis use, alcohol use, and breakfast skipping), psychosocial health factors (loneliness and economic difficulties), and general health.

RESULTS: The study included 3525 participants (2229 women [63%]; mean [SD] age, 24.8 [6.2] years), with a follow-up rate of 73% (n = 2587) 9 months later. The mean (SD) procrastination score at baseline was 12.9 (5.4). An increase of 1 SD in procrastination was associated with higher mean symptom levels of depression (β, 0.13; 95% CI, 0.09-0.17), anxiety (β, 0.08; 95% CI, 0.04-0.12), and stress (β, 0.11; 95% CI, 0.08-0.15), and having disabling pain in the upper extremities (risk ratio [RR], 1.27; 95% CI, 1.14-1.42), poor sleep quality (RR, 1.09, 95% CI, 1.05-1.14), physical inactivity (RR, 1.07; 95% CI, 1.04-1.11), loneliness (RR, 1.07; 95% CI, 1.02-1.12), and economic difficulties (RR, 1.15, 95% CI, 1.02-1.30) at the 9-month follow-up, after controlling for a large set of potential confounders.

CONCLUSIONS AND RELEVANCE: This cohort study of Swedish university students suggests that procrastination is associated with subsequent mental health problems, disabling pain, unhealthy lifestyle behaviors, and worse psychosocial health factors. Considering that procrastination is prevalent among university students, these findings may be of importance to enhance the understanding of students' health.

OBJECTIVES: This cross-sectional study aimed to describe dietary habits in Swedish adolescent handball players and differences with respect to sex and school grade.

METHODS: Participants in the Swedish Handball Cohort answered a web-survey assessing adherence to sports nutrition recommendations for meal frequency and meal timing, and the Nordic Nutrition Recommendations (NNR) for fruits/vegetables and fish/seafood, food exclusions and use of dietary supplements. Differences with respect to sex and school grade were estimated with generalised linear models, generating prevalence ratios (PR) with 95% CIs.

RESULTS: A total of 1040 participants (16.6±0.9 years, 51% males) were included. Overall, 70% and 90%, respectively, met recommendations for meal frequency and meal timing, whereas adherence to recommended carbohydrate intake during training/game was met by 17%. Adherence to the NNR for fruits/vegetables and fish/seafood was met by 16% and 37%, respectively. Twenty-eight per cent reported using dietary supplements. Females reported lower frequency of meals, especially morning snacks (-0.6 days/week (95% CI -0.3 to -0.9)) and evening snacks (-0.8 days/week (95% CI -0.5 to -1.1)), higher prevalence of exclusions due to intolerances (PR 1.66 (95% CI 1.31 to 2.01)) and other reasons (PR 1.36 (95% CI 1.08 to 1.64)), higher adherence to the NNR for fruits/vegetables (PR 2.30 (95% CI 1.98 to 2.62)) and use of micronutrient supplements (PR 1.72 (95% CI 1.43 to 2.00)) compared with males. Only small differences were observed between school grades.

CONCLUSIONS: Swedish adolescent handball players' dietary habits are fairly in accordance with sports nutrition recommendations but not the NNR. Females appear to display more restrictive habits than males.

Previous research shows that sleep quality may interact with some other predictors of depression, such that poor sleep could strengthen the association between these factors and depression. We aimed to determine the presence of statistical interactions between sleep quality and loneliness, risky alcohol use, perfectionistic concerns and/or physical inactivity in relation to depressive symptoms. Further, we aimed to describe the functional form of the statistical interactions and associations. We used a cross-sectional design and included 4262 Swedish university students. All measures were self-reported, sleep quality was measured with the Pittsburgh Sleep Quality Index, and depressive symptoms with the short-form Depression, Anxiety and Stress Scale. Regression models of increasing complexity (linear and non-linear, with and without interactions) were compared to determine the presence of associations and statistical interactions, and to explore the best functional form for these associations and interactions. Out-of-sample R² from repeated cross-validation was used to select the final models. We found that sleep quality was associated with depressive symptoms in all final models. Sleep quality showed a linear interaction with perfectionistic concerns in relation to depressive symptoms, such that perfectionistic concerns were more strongly associated with depressive symptoms when sleep quality was poor. Loneliness, risky alcohol use and physical inactivity were non-linearly associated with depressive symptoms but did not interact with sleep quality. We concluded that out of the four examined variables, only perfectionistic concerns interacted with sleep quality in relation to depressive symptoms. This interaction was weak and explained little of the overall variance in depressive symptoms.