How does sleep help recovery from exercise-induced muscle injuries?

Association between nighttime sleep duration and quality with low back pain in middle-aged and older Chinese adults

BACKGROUND

This study aims to investigate the association between sleep duration, sleep quality, and the risk of low back pain (LBP) among middle-aged and elderly individuals in China.

METHODS

Utilizing data from the China Health and Retirement Longitudinal Study spanning 2011 to 2020, we categorized sleep duration into long, medium, and short categories, and sleep quality into good, fair, and poor levels. LBP status was determined based on self-reported information by participants. Multivariable logistic regression analysis was employed to assess the relationship between sleep duration, sleep quality, with the risk of LBP.

RESULTS

A total of 6750 individuals were included in the longitudinal study. After 9 years of follow-up, the prevalence of LBP was 25.69 %. In the fully adjusted model, compared to individuals with medium sleep duration, those with short sleep duration had a 28 % increased risk of developing LBP (OR = 1.28, 95%CI: 1.12, 1.46). Additionally, when compared to individuals with good sleep quality, those with fair and poor sleep quality had a 35 % (OR = 1.35, 95%CI: 1.19, 1.54) and 33 % (OR = 1.33, 95%CI: 1.12, 1.58) increased risk of LBP, respectively. Joint analysis of both factors revealed that individuals with poor sleep quality and short sleep duration had the highest risk of LBP.

CONCLUSION

Among middle-aged and elderly individuals in China, short sleep duration and poor sleep quality were associated with an increased risk of LBP. Future studies should further explore the mechanisms underlying this association and validate the findings through randomized controlled trials.

How Do We Improve Sleep Quality After Total Joint Arthroplasty? A Systematic Review of Randomized Controlled Trials

BACKGROUND

Despite the importance of sleep for physiological function, rehabilitation, and recovery, sleep quality after total joint arthroplasty (TJA) remains poor. The objective of this systematic review was to identify, summarize, and evaluate postoperative interventions aimed at improving sleep quality after TJA.

METHODS

A systematic review of PubMed (MEDLINE) and Scopus (Embase, MEDLINE, COMPENDEX) from inception to April 2024 was conducted (PROSPERO ID: CRD42023447317). Randomized controlled trials on interventions to improve sleep quality were included. Sleep outcomes, including the Epworth Sleepiness Scale, Pittsburgh Sleep Quality Index, Patient-Reported Outcome Measurement Information System-Sleep Disturbance, Numeric Rating Scale sleep scores,l9 were extracted. Descriptive statistics were used to analyze the available data.

RESULTS

Of the 1,549 articles identified, seven randomized trials with a total of 840 patients were included (394 total hip arthroplasties [THA], 446 total knee arthroplasties [TKA]). Pittsburgh Sleep Quality Index was the most commonly used outcome for assessing sleep quality. Among THA studies, zolpidem, combined fascia iliaca compartment block (FICB) and dexmedetomidine (DEX), and perioperative methylprednisolone were shown to markedly improve postoperative sleep quality. Neither topical cannabidiol nor topical essential oil was found to improve postoperative sleep quality after TKA. Melatonin had no effect on sleep outcomes after TJA.

CONCLUSION

Zolpidem, FICB + DEX, and perioperative methylprednisolone are effective interventions to improve sleep quality after THA. Topical cannabis, topical essential oil, and melatonin did not improve sleep quality. No effective sleep interventions for TKA patients were identified. Improving sleep quality remains a potential therapeutic goal to improve patient satisfaction after TJA. Continued investigation on this topic is therefore necessary.

Transcranial magnetic stimulation in the assessment of acupuncture effect on exercise-induced fatigue

BACKGROUND

Acupuncture as a traditional Chinese medicine therapy relies on unique theories to alleviate fatigue. The aim of this study is to evaluate the effect of acupuncture on exercise-induced fatigue utilizing transcranial magnetic stimulation (TMS).

METHODS

A total of 20 participants with regular exercise habits were recruited for this study. All participants were randomly assigned to receive either acupuncture or sham acupuncture intervention for exercise-induced fatigue. TMS and a heart rate monitor were used to measure the amplitude and latency of motor evoked potential (MEP) as well as heart rate every 5 min over a 30-min period. The blood lactic acid (BLA) levels were measured using Lactate Scout+ at baseline, 0 min, and 30 min after fatigue. Two-way repeated measures analysis of variance was utilized to compare the differences between the effects of acupuncture method and time. Bonferroni post hoc tests were conducted to compare specific differences. Statistical significance was set at p < .05.

RESULTS

Interaction effect was observed between acupuncture method and time effect in terms of amplitude (F(1, 38) = 5.40, p < .001, η2 = 0.12) and latency (F(1, 38) = 3.78, p = .008, η2 = .09) of MEP. The application of acupuncture can promote the recovery of heart rate especially at 30 min (p < .05), but which seem insufficient to generate significant difference in BLA (F(1, 38) = 0.067, p = .797, η2 = 0.002).

CONCLUSIONS

Acupuncture can promote the increase of MEP amplitude, shorten MEP latency, and restore heart rate. Preliminary findings provide novel insights for individuals with exercise habits to alleviate fatigue and enhance sports performance.

Stress systems exacerbate the inflammatory response after corneal abrasion in sleep-deprived mice via the IL-17 signaling pathway

Sleep deprivation (SD) has a wide range of adverse health effects. However, the mechanisms by which SD influences corneal pathophysiology and its post-wound healing remain unclear. This study aimed to examine the basic physiological characteristics of the cornea in mice subjected to SD and determine the pathophysiological response to injury after corneal abrasion. Using a multi-platform water environment method as an SD model, we found that SD leads to disturbances of corneal proliferative, sensory, and immune homeostasis as well as excessive inflammatory response and delayed repair after corneal abrasion by inducing hyperactivation of the sympathetic nervous system and hypothalamic-pituitary-adrenal axis. Pathophysiological changes in the cornea mainly occurred through the activation of the IL-17 signaling pathway. Blocking both adrenergic and glucocorticoid synthesis and locally neutralizing IL-17A significantly improved corneal homeostasis and the excessive inflammatory response and delay in wound repair following corneal injury in SD-treated mice. These results indicate that optimal sleep quality is essential for the physiological homeostasis of the cornea and its well-established repair process after injury. Additionally, these observations provide potential therapeutic targets to ameliorate SD-induced delays in corneal wound repair by inhibiting or blocking the activation of the stress system and its associated IL-17 signaling pathway.

Sports and Immunity, from the recreational to the elite athlete

The pivotal role of the immune system in physical activity is well-established. While interactions are complex, they tend to constitute discrete immune responses. Moderate intensity exercise causes leukocytosis with a mild anti-inflammatory cytokine profile and immunoenhancement. Above a threshold of intensity, lactate-mediated IL-6 release causes a proinflammatory state followed by a depressed inflammatory state, which stimulates immune adaptation and longer term cardiometabolic enhancement. Exercise-related immune responses are modulated by sex, age and immunonutrition. At all ability levels, these factors collectively affect the immune balance between enhancement or overload and dysfunction. Excessive training, mental stress or insufficient recovery risks immune cell exhaustion and hypothalamic pituitary axis (HPA) stress responses causing immunodepression with negative impacts on performance or general health. Participation in sport provides additional immune benefits in terms of ensuring regularity, social inclusion, mental well-being and healthier life choices in terms of diet and reduced smoking and alcohol, thereby consolidating healthy lifestyles and longer term health. Significant differences exist between recreational and professional athletes in terms of inherent characteristics, training resilience and additional stresses arising from competition schedules, travel-related infections and stress. Exercise immunology examines the central role of immunity in exercise physiology and straddles multiple disciplines ranging from neuroendocrinology to nutrition and genetics, with the aim of guiding athletes to train optimally and safely. This review provides a brief outline of the main interactions of immunity and exercise, some influencing factors, and current guidance on maintaining immune health.

Prediction of half-marathon performance of male recreational marathon runners using nomogram

BACKGROUND

Long-distance running is a popular competitive sport. We performed the current research as to develop an easily accessible and applicable model to predict half-marathon performance in male recreational half-marathon runners by nomogram.

METHODS

Male recreational half-marathon runners in Zhejiang Province, China were recruited. A set of literature-based and panel-reviewed questionnaires were used to assess the epidemiological conditions of the recruited runners. Descriptive and binary regression analyses were done for the profiling and identification of predictors related to higher half-marathon performance (completing time ≤ 105 min). Participants were assigned to the training set (n = 141) and the testing set (n = 61) randomly. A nomogram was used to visually predict the half-marathon performance, and the receiver operating characteristic (ROC) was used to evaluate the predictive ability of the nomogram.

RESULTS

A total of 202 participants (median age: 49 years; higher half-marathon performance: 33.7%) were included. After multivariate analysis, three variables remained as significant predictors: longer monthly running distance [adjusted odds ratio (AOR) = 0.992, 95% confidence interval (CI): 0.988 to 0.996, p < 0.001], faster mean training pace (AOR = 2.151, 95% CI: 1.275 to 3.630, p < 0.001), and better sleep quality [the Pittsburgh Sleep Quality Index (PSQI), AOR = 2.390, 95% CI: 1.164 to 4.907, p = 0.018]. The AUC of the training and testing sets in nomogram were 0.750 and 0.743, respectively. Further ternary and linear regression analyses corroborated the primary findings.

CONCLUSIONS

This study developed a nomogram with good potential to predict the half-marathon performance of recreational runners. Our results suggest that longer monthly running distance, faster mean training pace and better sleep quality notably contribute to better half-marathon performance.

Interval training has more negative effects on sleep in adolescent speed skaters: a randomized cross controlled trial

Objective

Sleep is an essential component of athletic performance and recovery. This study aimed to investigate the effects of different types of high-intensity exercise on sleep parameters in adolescent speed skaters.

Methods

Eighteen male adolescent speed skaters underwent aerobic capacity testing, Wingate testing, and interval training in a randomized crossover design to assess strength output, heart rate, and blood lactate levels during exercise. Sleep quality after each type of exercise was evaluated using the Firstbeat Bodyguard 3 monitor.

Results

The results showed that Wingate testing and interval training led to decreased sleep duration, increased duration of stress, decreased RMSSD, and increased LF/HF ratio (p < 0.01). Conversely, aerobic capacity testing did not significantly affect sleep (p > 0.05). The impact of interval training on sleep parameters was more significant compared to aerobic capacity testing (p < 0.01) and Wingate testing (p < 0.01).

Conclusion

High-intensity anaerobic exercise has a profound impact on athletes' sleep, primarily resulting in decreased sleep duration, increased stress duration, decreased RMSSD, and increased LF/HF ratio.

Sedentary behaviour (especially accumulation pattern) has an independent negative impact on skeletal muscle size and architecture in community-dwelling older adults

Prolonged sedentary behaviour (SB) i.e. longer bouts, is suggested to have a range of negative health effects, independent of habitual light and medium-to-vigorous physical activity (LIPA or MVPA). Any effect on musculoskeletal size, architecture or morphology has seldom been reported in older adults. Moreover, no study has yet determined if any association would persist following adjustment for covariates. Therefore, the aim of the present study was to investigate the associations between SB, and properties of the Gastrocnemius Medialis (GM) muscle, in a cross-sectional sample of older adults using compositional data analysis. 105 healthy older adults (73±6y) wore a thigh mounted tri-axial accelerometer for seven consecutive days, and underwent ultrasound [e.g. muscle length (Lm), anatomical cross-sectional area (ACSA), muscle volume (VM), fascicle length (LF), & physiological cross-sectional area (PCSA)], body composition (e.g. DEXA) and health (e.g. medical history) assessments. In-unadjusted models, SB time was negatively associated with ACSA at 75% of Lm (R2adj = 0.085), VM (R2adj = 0.020), and PCSA (R2adj = 0.039). Standing was positively associated with pennation angle (R2adj = 0.110), which persisted following co-variate adjustment (R2adj = 0.296). In fully adjusted models, both SB & LIPA time were associated with ACSA at 75% of Lm (Both R2adj = 0.393). Standing and light activity time were also associated with LF, VM, & PCSA (R2adj 0.116-0.573). In fully adjusted models, SB pattern parameters (i.e. the manner in which sedentary behaviour is accumulated daily throughout waking hours such as the timing, duration and frequency of sedentary bouts), were associated with GM muscle properties (R2adj 0.156-0.564) including LM, LF, and VM. The pattern, rather than accumulated daily SB time, was associated with the size and architecture of the GM. Our results suggest that regardless of co-existing habitual physical activities, SB bouts should be kept short and frequently interrupted to offset some of the deleterious ageing-related muscle architecture characteristics changes.

Sleep duration and perceptions of sleep quality in British Army recruits during basic training - an observational analysis

Introduction

Sleep is critical to the health, wellbeing and performance of military personnel during basic training. This two-part study evaluated sleep-wake patterns and sleep disturbances in junior soldiers (JS) and infantry recruits in Autumn 2021 (study 1), and non-infantry recruits in spring 2022 (study 2).

Methods

During studies 1 and 2, validated wearable technology combined with a sleep diary was used to quantify sleep-wake indices, sleep disturbances and perceptions of sleep quality. Sleep diary data was analysed descriptively. A series of repeated-measures ANOVAs examined differences in objective sleep-wake indices. Correlation analysis determined associations between time in bed (TIB) and total sleep time (TST).

Results

Significant (p < 0.05) differences in most sleep-wake indices were observed between weeks of basic training for all cohorts. Strong positive correlations between TIB and TST were observed for each cohort across basic training (r = 0.681 - 0.970, p < 0.001), with longer TST associated with greater TIB. The mean±SD sleep duration (hours and mins [hm]) for JS (06:22 ± 00:27hm), non-infantry (05:41 ± 00:47hm) and infantry (05:46 ± 00:34hm) recruits across basic training was consistently below national recommendations. The mean±SD bed and wake times for JS (bedtime: 23:01 ± 00:32hm; awake: 05:34 ± 00:10hm), non-infantry (bedtime: 23:38 ± 01:09hm; awake: 04:47 ± 00:58hm), and infantry (bedtime: 23:13 ± 00:29hm; awake: 05:38 ± 00:26hm) recruits varied across weeks of basic training, with over 80% reporting "fairly bad" or "very bad" sleep quality and frequent periods of "dozing off" during daytime activity. The most commonly reported sleep disturbing factors identified during basic training involved: late-night military admin (e.g., ironing, boot cleaning, kit set up etc), early morning wake times, extraneous noise, light and hot room temperatures within the primary sleeping environment, bed/mattress discomfort, muscle soreness and feelings of stress and anxiety.

Discussion/Conclusion

Our findings contribute to the existing evidence that long-term sleep loss is pervasive during initial military training programmes. The average sleep durations indicate chronic and unrecoverable sleep loss which would be expected to significantly impair physical and cognitive military performance, and increase the risk of injury, illness and attrition rates during basic training. Changes in the design and scheduling of basic training programmes to enable, at the least, minimum sleep recommendations to be met, and to improve sleep hygiene in the primary sleeping environment are warranted.

Circadian rhythm in sportspersons and athletic performance: A mini review

Circadian rhythms in the physiological and behavioral processes of humans play a crucial role in the quality of living and also in the magnitude of success and failure in various endeavors including competitive sports. The rhythmic activities of the body and performance in sportspersons do have a massive impact on their every cutthroat competition. It is essential to schedule sports activities and training of players according to their circadian typology and time of peak performance for improved performance and achievement. In this review, the focus is on circadian rhythms and diurnal variations in peak athletic performance in sportspersons. Accuracy and temporal variability in peak performance in an individual could be attributed to various factors, namely chronotype, time of the day, body temperature, jetlag, hormones, and prior light exposure. Circadian rhythm of mood, alertness, T-core, and ultimately athletic performance is not only affected by sleep but also by circadian variations in hormones, such as cortisol, testosterone, and melatonin. There are, however, a few reports that are not consistent with the conclusions drawn in this review. Nevertheless, circadian rhythm and performance among sportspersons and athletes are important areas of research. This review might be useful to the managers and policymakers associated with competitive sports and athletic events.

Sleep in the Athlete

Sleep is important for not only general health but also for lowering injury risk and maintaining athletic performance. Sleep disorders are prevalent in athletes, and taking a sleep history, evaluating sleep quality, and addressing other related factors including mental health are essential in diagnosing and understanding sleep disorders. Other methods such as polysomnography, actigraphy, and sheet sensors can also be used. Treatment options for sleep disorders include sleep hygiene, cognitive behavioral therapy, medication, and addressing contributing factors. For athletes, sleep can also be affected by factors such as travel fatigue and jet lag, which should be taken into consideration.

Enhancing Sleep Quality: Assessing the Efficacy of a Fixed Combination of Linden, Hawthorn, Vitamin B1, and Melatonin

Sleep is essential for overall health, yet various sleep disorders disrupt normal sleep patterns, affecting duration, quality, and timing. This pilot study investigate the impact of a food supplement (SPINOFF®) on both sleep quality and mental well-being in 41 participants (mean age: 45.3 years). Initial assessments revealed sleep disturbances (Pittsburgh Sleep Quality Index-PSQ-mean score: 8.2) and insomnia symptoms (Insomnia Severity Index-ISI- mean score: 12.7). Mental health assessments showed psychological distress (Dass-21 Depression mean score: 4.2, Anxiety mean score: 6.9, Stress mean score: 11.6, Total mean score: 22.7). This study assessed sleep continuity using Awakenings per Night (ApN) via a smartwatch (HELO HEALTH®) and conducted the study in two phases: baseline (T0) and after 30 days of treatment (T1) (Phase A). No placebo-control was used in this study. After 30 days (Phase B), 21 patients were selected for reassessment. Eleven continued treatment for another 30 days (T2), while ten discontinued. Following the intervention, we observed remarkable improvements in sleep quality and mental distress. The SPINOFF® supplement significantly reduced the PSQI scores (22.4%), indicating enhanced sleep quality. Additionally, there was a 19.6% decrease in ISI scores, demonstrating a reduction in insomnia symptoms. Moreover, overall psychological distress decreased by 19.5% signifying improved psychological well-being. In the second phase, participants who continued treatment experienced more substantial improvements, with a mean decrease of 0.8 points in PSQI scores (±0.9) and a mean decrease of 0.9 points in ISI scores. Our findings suggest that the SPINOFF® supplement has the potential to effectively address both sleep disturbances and psychological distress in our study population.

Reliability and validity of the Chinese version of the Athens insomnia scale for non-clinical application in Chinese athletes

Purpose

This study aimed to revise and examine the reliability and validity of the Chinese version of the Athens Insomnia Scale for Non-clinical Application (AIS-NCA) among Chinese athletes. Additionally, the study tested the scale in non-athlete individuals with similar sleep management practices to further analyze its cultural specificity among Chinese athletes and make preliminary inferences about its applicability in other Chinese populations.

Methods

Four hundred twenty-six Chinese professional athletes and 779 high school students participated in this research. Both athletes and students were divided into two parallel groups for exploratory and confirmatory factor analyses. Additionally, three athlete samples and one student sample were established for reliability and validity assessments. Among athletes, the Pittsburgh Sleep Quality Index, the Epworth Sleepiness Scale, the Athlete Sleep Screening Questionnaire, and the Warwick-Edinburgh Mental Well-Being Scale were employed to evaluate convergent and discriminant validity. Re-test reliability was evaluated at intervals of 1 and 2 weeks. In the case of students, convergent and discriminant validity were tested using the Pittsburgh Sleep Quality Index and the General Self-Efficacy Scale, with re-test reliability assessed at two-week intervals.

Results

The Chinese version of the AIS-NCA consists of six items, categorized into two dimensions: sleep problems and daytime functioning. This structure explained 65.08% (athletes) and 66.22% (students) of the variance. Confirmatory factor analysis revealed good model fit, with values of χ2/df = 2.217, CFI = 0.975, AGFI = 0.929, TLI = 0.953, and RMSEA = 0.076 among athletes, and χ2/df = 3.037, CFI = 0.979, AGFI = 0.947, TLI = 0.961, and RMSEA = 0.072 among students. The scale demonstrated a reasonable degree of measurement invariance. The overall scale and two subscales exhibited strong reliability and validity among athletes. Similar results in terms of reliability and validity were also observed within the student sample.

Conclusion

The Chinese version of the AIS-NCA shows promise as an assessment tool for evaluating the sleep quality of Chinese athletes. It effectively captures both sleep-related concerns and daytime functionality within the athlete population. The scale demonstrates solid reliability and validity in professional athletes and holds potential for application across various other demographic groups in China.

Dawn of a New Dawn: Advances in Sleep Health to Optimize Performance

Optimal sleep health is a critical component to high-level performance. In populations such as the military, public service (eg, firefighters), and health care, achieving optimal sleep health is difficult and subsequently deficiencies in sleep health may lead to performance decrements. However, advances in sleep monitoring technologies and mitigation strategies for poor sleep health show promise for further ecological scientific investigation within these populations. The current review briefly outlines the relationship between sleep health and performance as well as current advances in behavioral and technological approaches to improving sleep health for performance.

Less daytime sleepiness and slow wave activity during sleep predict better physical readiness in military personnel

BACKGROUND

Military personnel must maintain physical performance despite exposure to operational stressors such as sleep loss, caloric restriction and high cognitive load. Habitual sleep and specific sleep features are positively associated with fitness and may contribute to physical performance in operational settings. Further, by affecting muscle recovery, sleep may contribute to the ability to maintain performance across multiple days of exposure to operational stressors.

OBJECTIVES

We examined the role of individual differences in baseline sleep on baseline physical performance and on change in physical performance throughout exposure to simulated military operational stress (SMOS).

METHODS

Military personnel (36 male, 9 female, 26.3 ± 5.3 years) completed a 5-day SMOS protocol during which they completed a tactical mobility test daily. Sleep questionnaires were administered at intake and sleep was monitored each night with polysomnography. Lasso regressions were used to identify meaningful predictors of physical performance at baseline and of change in physical performance across SMOS.

RESULTS

Better aerobic fitness, lower daytime sleepiness (Epworth Sleepiness Scale), and lower absolute slow wave activity (0.5-4 Hz) predicted better physical performance at baseline (66.1% of variance explained), but did not relate to changes in performance.

CONCLUSIONS

Collectively, higher daytime sleepiness and slow wave activity may reflect more chronic exposure to insufficient sleep and higher baseline sleep drive, which in turn led to compromised physical performance. The findings suggest that low self-report sleepiness and low objective slow wave activity may reflect two quantifiable markers of healthy sleep behaviors that have implications for operational performance.

Short sleep duration is associated with a wide variety of medical conditions among United States military service members

OBJECTIVES

This cross-sectional study investigated self-reported sleep duration and its association with a comprehensive range of clinically-diagnosed medical condition categories (CDMCs), as well as the relationship between short sleep duration (≤6 h) and demographic/lifestyle factors, among United States military service members (SMs).

METHODS

A stratified random sample of SMs (n = 20,819) completed an online questionnaire on usual daily hours of sleep and demographic/lifestyle characteristics. CDMCs for a six-month period prior to questionnaire completion were obtained from a comprehensive military electronic medical surveillance system and grouped into 33 CDMCs covering both broad and specific medical conditions. Prevalence of CDMCs was compared among three sleep duration categories (≤4, 5-6 and ≥7 h).

RESULTS

SMs reported a mean ± standard deviation of 6.3 ± 1.4 h of sleep per day. After adjustment for demographic/lifestyle characteristics, shorter sleep duration was associated with higher odds of a medical condition in 25 of 33 CDMCs, with most (n = 20) demonstrating a dose-response relationship. The five CDMCs with the largest differences between ≤4 vs ≥ 7 h sleep were: diseases of the nervous system (odds ratio [OR] = 2.9, 95% confidence interval [95%CI] = 2.4-3.4), mental/behavioral diseases (OR = 2.7, 95%CI = 2.3-3.2), diseases of the musculoskeletal system (OR = 1.9, 95%CI = 1.6-2.1), diseases of the circulatory system (OR = 1.7, 95%CI = 1.3-2.2), and diseases of the digestive system (OR = 1.6, 95%CI = 1.2-2.0). Six hours of sleep or less was independently associated with older age, less formal education, race, Hispanic ethnicity, higher body mass index, smoking, and military service branch.

CONCLUSIONS

In this young, physically active population, reporting shorter sleep duration was associated with a higher risk of multiple CDMCs.

Not Another Caffeine Effect on Sports Performance Study-Nothing New or More to Do?

The performance-enhancing potential of acute caffeine consumption is firmly established with benefits for many aspects of physical performance and cognitive function summarised in a number of meta-analyses. Despite this, there remains near exponential growth in research articles examining the ergogenic effects of caffeine. Many such studies are confirmatory of well-established ideas, and with a wealth of convincing evidence available, the value of further investigation may be questioned. However, several important knowledge gaps remain. As such, the purpose of this review is to summarise key knowledge gaps regarding the current understanding of the performance-enhancing effect of caffeine and justify their value for future investigation. The review will provide a particular focus on ten research priorities that will aid in the translation of caffeine's ergogenic potential to real-world sporting scenarios. The discussion presented here is therefore essential in guiding the design of future work that will aid in progressing the current understanding of the effects of caffeine as a performance enhancer.

Chronotype and Social Jetlag Influence Performance and Injury during Reserve Officers' Training Corps Physical Training

Sleep and circadian rhythms are critically important for optimal physical performance and maintaining health during training. Chronotype and altered sleep may modulate the response to exercise training, especially when performed at specific times/days, which may contribute to musculoskeletal injury. The purpose of this study was to determine if cadet characteristics (chronotype, sleep duration, and social jetlag) were associated with injury incidence and inflammation during physical training. Reserve Officers' Training Corps (ROTC) cadets (n = 42) completed the Morningness/Eveningness Questionnaire to determine chronotype, and 1-week sleep logs to determine sleep duration and social jetlag. Salivary IL-6 was measured before and after the first and fourth exercise sessions during training. Prospective injury incidence was monitored over 14 weeks of training, and Army Physical Fitness Test scores were recorded at the conclusion. Chronotype, sleep duration, and social jetlag were assessed as independent factors impacting IL-6, injury incidence, and APFT scores using ANOVAs, chi-squared tests, and the t-test where appropriate, with significance accepted at p < 0.05. Evening chronotypes performed worse on the APFT (evening = 103.8 ± 59.8 vs. intermediate = 221.9 ± 40.3 vs. morning = 216.6 ± 43.6; p < 0.05), with no difference in injury incidence. Sleep duration did not significantly impact APFT score or injury incidence. Social jetlag was significantly higher in injured vs. uninjured cadets (2:40 ± 1:03 vs. 1:32 ± 55, p < 0.05). Exercise increased salivary IL-6, with no significant effects of chronotype, sleep duration, or social jetlag. Evening chronotypes and cadets with social jetlag display hampered performance during morning APFT. Social jetlag may be a behavioral biomarker for musculoskeletal injury risk, which requires further investigation.

Development and validation of mathematical nomogram for predicting the risk of poor sleep quality among medical students

Background

Despite the increasing prevalence of poor sleep quality among medical students, only few studies have identified the factors associated with it sing methods from epidemiological surveys. Predicting poor sleep quality is critical for ensuring medical Students' good physical and mental health. The aim of this study was to develop a comprehensive visual predictive nomogram for predicting the risk of poor sleep quality in medical students.

Methods

We investigated medical Students' association with poor sleep quality at JiTang College of North China University of Science and Technology through a cross-sectional study. A total of 5,140 medical students were randomized into a training cohort (75%) and a validation cohort (25%). Univariate and multivariate logistic regression models were used to explore the factors associated with poor sleep quality. A nomogram was constructed to predict the individual risk of poor sleep quality among the medical students studied.

Results

31.9% of medical students in the study reported poor sleep quality. We performed multivariate logistic analysis and obtained the final model, which confirmed the risk and protective factors of poor sleep quality (p < 0.05). Protective factors included the absence of physical discomfort (OR = 0.638, 95% CI: 0.546-0.745). Risk factors included current drinking (OR = 0.638, 95% CI: 0.546∼0.745), heavy study stress (OR = 2.753, 95% CI: 1.456∼5.631), very heavy study stress (OR = 3.182, 95% CI: 1.606∼6.760), depressive symptoms (OR = 4.305, 95% CI: 3.581∼5.180), and anxiety symptoms (OR = 1.808, 95% CI: 1.497∼2.183). The area under the ROC curve for the training set is 0.776 and the area under the ROC curve for the validation set is 0.770, which indicates that our model has good stability and prediction accuracy. Decision curve analysis and calibration curves demonstrate the clinical usefulness of the predictive nomograms.

Conclusion

Our nomogram helps predict the risk of poor sleep quality among medical students. The nomogram used includes the five factors of drinking, study stress, recent physical discomfort, depressive symptoms, and anxiety symptoms. The model has good performance and can be used for further research on and the management of the sleep quality of medical students.

Physical Injuries, Treatment-Seeking, and Perceived Barriers to Treatment in U.S. Army Drill Sergeants

INTRODUCTION

Drill sergeants work under mentally and physically challenging conditions. The current study examined self-reported rates of physical injuries in drill sergeants; rates of treatment-seeking for injuries; perceived barriers toward treatment-seeking; and associated demographic and environmental factors.

MATERIALS AND METHODS

Drill sergeants from across all Army basic training locations completed self-report surveys from September to November of 2018. In total, 726 drill sergeants were included in analyses. Drill sergeants indicated whether they had acquired an injury during their time in the drill sergeant role and whether they had sought treatment for all such injuries. Furthermore, drill sergeants rated their agreement with a number of possible perceived barriers to treatment-seeking for physical injuries. Regression models examining each phenomenon included hours of sleep obtained per day; general- and health-specific leadership behaviors of the company command teams; unit cohesion; time as a drill sergeant; duty location; gender; military operational specialty; years in the military; previous combat deployments; and route of assignment. The study was approved by the Walter Reed Army Institute of Research Institutional Review Board.

RESULTS

In total, 38% of respondents reported acquiring an injury during their time as drill sergeants. Of those who had acquired an injury, 61% reported seeking medical help for all injuries acquired. Injuries were more likely in females (49%) than in males (34%) and less likely in drill sergeants reporting at least 6 hours of sleep (27%) versus those reporting 5 hours (40%) and 4 hours or less (43%). Reported comparisons were significant after controlling for demographic and environmental variables in regression models. The most strongly endorsed perceived barriers to treatment-seeking were "Seeking help would place too much burden on the other drill sergeants" (69%) and "Seeking help would interfere with my ability to train the recruits" (60%). Both of these perceived barriers were significantly associated with reduced treatment-seeking in injured drill sergeants, after controlling for demographic and environmental variables.

CONCLUSIONS

This study is the first to examine injury occurrence, treatment-seeking, and perceived barriers to treatment-seeking in U.S. Army drill sergeants. Building on previous studies that showed the negative effects of sleep deprivation on the safety and behavioral health of drill sergeants, the current study gives further evidence of the negative effects of such sleep deprivation, this time in the domain of physical injuries. The results suggest that pursuing strategies that allow for healthier sleep duration may contribute to injury reduction.

Relationship between circadian genes and memory impairment caused by sleep deprivation

Background

Sleep deprivation (SD)-induced cognitive impairment is highly prevalent worldwide and has attracted widespread attention. The temporal and spatial oscillations of circadian genes are severely disturbed after SD, leading to a progressive loss of their physiological rhythms, which in turn affects memory function. However, there is a lack of research on the role of circadian genes and memory function after SD. Therefore, the present study aims to investigate the relationship between circadian genes and memory function and provide potential therapeutic insights into the mechanism of SD-induced memory impairment.

Methods

Gene expression profiles of GSE33302 and GSE9442 from the Gene Expression Omnibus (GEO) were applied to identify differentially expressed genes (DEGs). Subsequently, both datasets were subjected to Gene Set Enrichment Analysis (GSEA) to determine the overall gene changes in the hippocampus and brain after SD. A Gene Oncology (GO) analysis and Protein-Protein Interaction (PPI) analysis were employed to explore the genes related to circadian rhythm, with their relationship and importance determined through a correlation analysis and a receiver operating characteristic curve (ROC), respectively. The water maze experiments detected behavioral changes related to memory function in SD rats. The expression of circadian genes in several critical organs such as the brain, heart, liver, and lungs and their correlation with memory function was investigated using several microarrays. Finally, changes in the hippocampal immune environment after SD were analyzed using the CIBERSORT in R software.

Results

The quality of the two datasets was very good. After SD, changes were seen primarily in genes related to memory impairment and immune function. Genes related to circadian rhythm were highly correlated with engagement in muscle structure development and circadian rhythm. Seven circadian genes showed their potential therapeutic value in SD. Water maze experiments confirmed that SD exacerbates memory impairment-related behaviors, including prolonged escape latencies and reduced numbers of rats crossing the platform. The expression of circadian genes was verified, while some genes were also significant in the heart, liver, and lungs. All seven circadian genes were also associated with memory markers in SD. The contents of four immune cells in the hippocampal immune environment changed after SD. Seven circadian genes were related to multiple immune cells.

Conclusions

In the present study, we found that SD leads to memory impairment accompanied by changes in circadian rhythm-related genes. Seven circadian genes play crucial roles in memory impairment after SD. Naïve B cells and follicular helper T cells are closely related to SD. These findings provide new insights into the treatment of memory impairment caused by SD.

Effect of a Recliner Chair with Rocking Motions on Sleep Efficiency

In this study, we analyze the effect of a recliner chair with rocking motions on sleep quality of naps using automated sleep scoring and spindle detection models. The quality of sleep corresponding to the two rocking motions was measured quantitatively and qualitatively. For the quantitative evaluation, we conducted a sleep parameter analysis based on the results of the estimated sleep stages obtained on the brainwave and spindle estimation, and a sleep survey assessment from the participants was analyzed for the qualitative evaluation. The analysis showed that sleep in the recliner chair with rocking motions positively increased the duration of the spindles and deep sleep stage, resulting in improved sleep quality.