Nightmares in Swiss elite athletes: Associated factors.

Nightmares, defined as extremely dysphoric dreams, can cause significant distress in everyday life if they occur frequently. Their aetiology is based on a disposition-stress model. As elite athletes often experience high stress levels, the present study investigated factors that might be associated with nightmare frequency in a large cohort of 2297 Swiss elite athletes (1066 women, 1231 men) with a mean age of 22.05 ± 7.53 years. In total, about 6% of the athletes reported frequent nightmares (once a week or more often). We found that well-established factors like female gender and general stress levels were related to nightmare frequency. To a smaller extent, the number of training hours, lost training days due to illness, and having early training sessions were also associated with nightmare frequency. Sport discipline was not related to nightmare frequency. An unexpected finding was the association between late alcohol intake 4 hr prior to bedtime and nightmare frequency. Our findings support the idea that stress related to practicing sports might affect nightmare frequency. Future research should study whether inventions designed for athletes suffering from frequent nightmares are beneficial for them and might even improve their athletic performance.

Sleep Difficulties in Swiss Elite Athletes.

For athletes, sleep is essential for recovery and performance. Yet, up to two-thirds of athletes report poor sleep quality. Comprehensive data across all sports disciplines on the underlying causes of sleep problems are missing. We reanalyzed a data set of N = 1004 Swiss top athletes across an extensive array of 88 sports to gain knowledge on the specific deficits in sleep health with respect to gender, sport classes, sport-related factors, and well-being. We found that 18% of athletes were affected by at least two out of five high-risk sleep factors: 9% of athletes slept less than 6 h per day, 30% were dissatisfied with their sleep, 17% showed problems falling asleep within 30 min, 18% of athletes reported difficulty maintaining sleep more than three times a week, and 6% of athletes used sleeping pills more than once a week. We found sleep health strongly linked to overall well-being and mental health (22% showed at least moderate symptoms of either depression or anxiety). Therefore, screening and treating sleep disorders might effectively improve mental health and general well-being as well as performance among athletes around the globe.

[Sleep behavior after reverse shoulder replacement in comparison to a healthy control group : An exploratory cross-sectional study]. / Schlafverhalten von Personen nach Implantation einer inversen Schulterprothese im Vergleich zu einer gesunden Kontrollgruppe : Eine explorative Querschnittsstudie.

BACKGROUND: Individuals with shoulder pathologies frequently report sleep problems. Improving sleep quality is a treatment focus of shoulder arthroplasty. So far, it is unclear whether altered anatomy and biomechanics in reversed total shoulder arthroplasty affect sleep quality in the long term. In addition to a subjective evaluation, a reliable assessment can be obtained by recording objective sleep parameters. With the help of actigraphy, body movements are registered and divided into active and inactive phases by means of threshold values. Thanks to the valid correspondence with waking and sleeping phases, the calculation of objective sleep parameters is successful. OBJECTIVES: The aims of the study were to investigate whether objective sleep parameters differ in persons with reversed total shoulder arthroplasty (RTSA) 1 year postoperatively compared to a healthy control group and to explore what the reasons are. MATERIAL AND METHODS: The present work is an exploratory cross-sectional study with one measurement time point. 29 study participants (15 in the RTSA-group, 14 in the control group) collected objective sleep parameters and body position data during seven nights using actigraphy. The Mann-Whitney-U test was used for the mean comparison of sleep parameters. In addition, reasons for wakefulness were explored. RESULTS AND CONCLUSIONS: The groups showed no significant differences in all objective sleep parameters with nearly identical sleep efficiency (p = 0.978). In the RTSA-group, 11% lay on the operated side and 65% on the back. This is just above the significance level compared to the control group with 45% in the supine position (p = 0.056). The increased use of the supine position could promote sleep-related medical conditions such as sleep apnoea and requires further research.

Changing Sleep Architecture through Motor Learning: Influences of a Trampoline Session on REM Sleep Parameters.

Previous research has shown that learning procedural tasks enhances REM sleep the following night. Here, we investigate whether complex motor learning affects sleep architecture. An experiment in which twenty-two subjects either learned a motor task (trampolining) or engaged in a control task (ergometer) was carried out in a balanced within-group design. After an initial laboratory adaptation night, two experimental nights were consecutive. The results indicate that learning a motor task had an effect on REM sleep parameters and, therefore, support the hypothesis that learning a procedural skill is related to an increase in REM sleep parameters. However, the statistical effect on REM sleep is smaller than found in previous studies. One might speculate that the motor learning was not intense enough compared to other studies. For sports practice, the results suggest that REM sleep, which is particularly rich in the morning, plays an important role in motor memory consolidation. Thus, this phase should not be interrupted after complex motor skill learning sessions. In future studies, other motor tasks should be applied.

The Single Leg Heel Rise Test-A Helpful Tool for Dance Science?: A Systematic Review.

BACKGROUND: Foot and ankle injuries are the most prevalent injuries in dance. The single leg heel-rise (SLHR) test is a simple tool to assess muscular endurance of the plantar flexors of the foot and is an increasingly popular manual muscle test in various areas of dance. Although the SLHR test has shown high reliability and validity in the medical field, no uniform description of this test exists in dance. OBJECTIVE: This systematic review aimed to identify parameters, outcome measures, purposes, and existing normative values of the SLHR test in the dance field. METHODS: Following the PRISMA guidelines, the electronic databases Scopus, PubMed, SPORTDiscus, EMBASE, CINAHL, and Cochrane were searched using a predefined search strategy up to June 2022. Studies were included if they reported screening, testing, or evaluation of either muscular endurance or strength of the calf muscle-tendon unit (MUT) in dancers using the SLHR test. The methodological quality of the studies was evaluated using a modified version of the Downs and Black Quality Index. RESULTS: A total of 180 studies were identified. Twelve studies comprising a total of 427 dancers met the inclusion criteria. Key testing parameters of the SLHR test varied widely or were not reported. The average quality rating of the reviewed studies was 12.9 (range 8 to 17) out of a possible 20 points. DISCUSSION: Although commonly used in test batteries, there are no standardized parameters of the SLHR test used in the dance field. Therefore, no generally applicable normative values could be established. CONCLUSION: Key parameters such as the precise execution of the heel rises should be reported in testing protocols. For the SLHR test to be a useful tool in dance, further research on the influence of dance style, age, and injuries to the calf MTU on this test is needed.

Is healthcare a team sport? Widening our lens on interprofessional collaboration and education in sport and exercise medicine.

Effective interprofessional collaboration (IPC) has great potential to improve healthcare delivery. Therefore, students and trainees in healthcare professions should be prepared for a collaborative workforce through interprofessional education (IPE) settings. However, IPC and IPE are rarely addressed in sport and exercise medicine (SEM), although the field significantly impacts the healthcare system. Hence, we conducted a webinar to promote IPC and IPE in the Swiss SEM community. The lessons resulting from the webinar were: (1) professions involved in SEM should have opportunities to learn, with, from and about other professions in healthcare to achieve mutual respect and understanding; (2) IPC and IPE in SEM may raise awareness, value and recognition of the contributions by exercise scientists in healthcare; (3) IPC and IPE may consider collaborating with a variety of professions not traditionally integrated into healthcare but involved in broader public health and physical activity promotion. In summary, sports and exercise professions should embrace interprofessional approaches to better realise their contribution to healthcare and public health.

Muscle Oxygen Saturation Breakpoints Reflect Ventilatory Thresholds in Both Cycling and Running.

Pulmonary gas exchange analysis was compared to changes in muscle oxygen saturation as measured by near-infrared spectroscopy. First, ventilatory thresholds determined by common gas exchange analysis and breakpoints in muscle oxygen saturation were assessed for agreement during exercise with increasing intensity. Secondly, the relationship between muscle oxygen saturation as a surrogate for local oxygen extraction and peak oxygen uptake was assessed. In order to lend robustness to future NIRS testing on a broader scale, considering its potential for simple and cost-effective application, the question of a running versus a cycling modality was integrated into the design. Ten participants, of whom five were recreationally trained cyclists and five recreationally trained runners, were tested; each during a cycling test and a running test with increasing intensity to voluntary exhaustion. Muscle oxygen saturation and pulmonary gas exchange measurements were conducted. Bland-Altman analysis showed a moderate degree of agreement between both muscle oxygen saturation breakpoint 1 and muscle oxygen saturation breakpoint 2 and corresponding ventilatory threshold 1 and ventilatory threshold 2, for both cycling and running disciplines; generally speaking, muscle oxygen saturation breakpoints underestimated ventilatory thresholds. Additionally, a strong relationship could be seen between peak oxygen uptake and the minimally attained muscle oxygen saturation during cycling exercise. Muscle oxygen saturation measured using NIRS was determined to be a suitable method to assess ventilatory thresholds by finding breakpoints in muscle oxygen saturation, and muscle oxygen saturation minimum was linked to peak oxygen uptake.

Combining Wake-Up-Back-to-Bed with Cognitive Induction Techniques: Does Earlier Sleep Interruption Reduce Lucid Dream Induction Rate?

Lucid dreaming offers the chance to investigate dreams from within a dream and by real-time dialogue between experimenters and dreamers during REM sleep. This state of consciousness opens a new experimental venue for dream research. However, laboratory study in this field is limited due to the rarity of lucid dreamers. In a previous study, we were able to induce in 50% of the participants a lucid dream in a single sleep laboratory night by combining a wake-up-back-to-bed (WBTB) sleep routine and a mnemonic method (Mnemonic Induction of Lucid Dreams, MILD). In three experiments, we tried to replicate our earlier findings while we adapted our procedure in shortening (Exp1-3: 4.5 vs. 6 h of uninterrupted sleep in the first half of the night), simplifying (Exp2: time-based wakening vs. REM wakening in the second half of the night), and applying another induction technique (Exp3: reality testing vs. MILD). In the three conditions, four out of 15 (26%), zero out of 20 (0%), and three out of 15 (20%) participants reported a lucid dream. Compared to the original study, the earlier sleep interruption seems to reduce the lucid dream induction rate. Furthermore, without REM awakenings in the morning, lucid dream induction failed, whereas reality testing showed a lower success rate compared to MILD. Further systematic sleep laboratory studies are needed to develop reliable techniques for lucid dream research.

Critical oxygenation: Can muscle oxygenation inform us about critical power?

The power-duration relationship is well documented for athletic performance and is formulated out mathematically in the critical power (CP) model. The CP model, when applied properly, has great predictive power, e.g. pedaling at a specific power output on an ergometer the model precisely calculates the time over which an athlete can sustain this power. However, CP presents physiological inconsistencies and process-oriented problems. The rapid development of near-infrared spectroscopy (NIRS) to measure muscle oxygenation (SmO2) dynamics provides a physiological exploration of the CP model on a conceptual and empirical level. Conceptually, the CP model provides two components: first CP is defined as the highest metabolic rate that can be achieved through oxidative means. And second, work capacity above CP named W'. SmO2 presents a steady-state in oxygen supply and demand and thereby represents CP specifically at a local level of analysis. Empirically, exploratory data quickly illustrates the relationship between performance and SmO2, as shown during 3-min all-out cycling tests to assess CP. During these tests, performance and SmO2 essentially mirror each other, and both CP and W' generate solid correlation with what would be deemed their SmO2 counterparts: first, the steady-state of SmO2 correlates with CP. And second, the tissue oxygen reserve represented in SmO2, when calculated as an integral corresponds to W'. While the empirical data presented is preliminary, the proposition of a concurring physiological model to the current CP model is a plausible inference. Here we propose that SmO2 steady-state representing CP as critical oxygenation or CO. And the tissue oxygen reserve above CO would then be identified as O'. This new CO model could fill in the physiological gap between the highly predictive CP model and at times its inability to track human physiology consistently. For simplicity's sake, this would include acute changes in physiology as a result of changing climate or elevation with travel, which can affect performance. These types of acute fluctuations, but not limited to, would be manageable when applying a CO model in conjunction with the CP model. Further, modeling is needed to investigate the true potential of NIRS to model CP, with a focus on repeatability, recovery, and systemic vs local workloads.

Sleep-dependent motor memory consolidation in healthy adults: A meta-analysis.

It is widely accepted that sleep better facilitates the consolidation of motor memories than does a corresponding wake interval (King et al., 2017). However, no in-depth analysis of the various motor tasks and their relative sleep gain has been conducted so far. Therefore, the present meta-analysis considered 48 studies with a total of 53 sleep (n = 829) and 53 wake (n = 825) groups. An overall comparison between all sleep and wake groups resulted in a small effect for the relative sleep gain in motor memory consolidation (g = 0.43). While no subgroup differences were identified for differing designs, a small effect for the finger tapping task (g = 0.47) and a medium effect for the mirror tracing task (g = 0.62) were found. In summary, the meta-analysis substantiates that sleep generally benefits the consolidation of motor memories. However, to further our understanding of the mechanisms underlying this effect, examining certain task dimensions and their relative sleep gain would be a promising direction for future research.

Wake Up, Work on Dreams, Back to Bed and Lucid Dream: A Sleep Laboratory Study.

Lucid dreaming offers many opportunities to study consciousness processes. However, laboratory research in this area is limited because frequent lucid dreamers are rare. Several studies demonstrated that different methods of induction could increase the number of lucid dreams. In four field studies, a combination of a wake-up-back-to-bed (WBTB) sleep protocol and a mnemonic technique (MILD) showed promising results. To further investigate the effectiveness of this combined approach, we conducted a sleep laboratory experiment with four different conditions. The general experimental procedure was the following: Participants were awakened after 6 h of sleep from a subsequent REM period and kept awake for 30 or 60 min, during which they were asked to practice MILD or a control task (e.g., reading). Then they returned to bed for a morning sleep period. In the first condition eleven sport students, who attended a seminar on sleep and dreams, spent one night in a sleep laboratory. To avoid biases due to the seminar attendance (e.g., higher motivation), in the second condition 15 participants who did not attend the seminar were recruited. In the third condition, 14 sport students were tested with a shorter awakening period (30 min). Finally, the fourth condition served as a control condition, whereas eleven sport students slept two non-consecutive nights in a laboratory. Instead of MILD, in one night the participants read a book (fiction, unrelated to dreams), while in the other night they played a Nintendo Wii video game. In the first three conditions, six (54%), eight (53%), and five participants (36%) reported lucid dreams during the morning sleep period, whereas three, (27%), four (27%), and two participants (14%) produced PSG-verified eye signals. In contrast, in the reading condition, only one (9%) participant reported lucid dreams and no eye movements. No lucid dreams were observed in the Wii condition. The findings of the present study show that by using a combination of WBTB and MILD, lucid dreams can be effectively induced in people who are not selected for their lucid dream abilities.

Inducing lucid dreams by olfactory-cued reactivation of reality testing during early-morning sleep: A proof of concept.

The reliable induction of lucid dreams is a challenge in lucid dream research. In a previous study by our research group we were able to induce in about 50% of the participants a lucid dream in a single sleep laboratory night by combining a wake-up-back-to-bed sleep protocol and a mnemonic technique. In the present study, we extended our previous procedure by additional presentation of an odor during sleep to reactivate memory traces about reality testing. In total 16 male participants spent a single night in the sleep lab whereas the procedure induced in two participants a lucid dream (12.5%). The induction rate stays below the success rate of our previous study and therefore odor-cueing seems not a promising technique for inducing lucid dreams. Beside the odor presentation, several other methodological changes have been made, which will be discussed and hopefully help further dream engineering to improve induction techniques.

Muscle oxygen dynamics in elite climbers during finger-hang tests at varying intensities.

The aim of this study was to measure muscle oxygen saturation (SmO2) dynamics during a climbing specific task until failure in varying conditions. Our prediction was that SmO2 should be a good marker to predict task failure. Eleven elite level climbers performed a finger-hang test on a 23 mm wooden rung under four different weighted conditions, 1. body weight (BW), 2. body weight +20% (BW +20), 3. body weight -20% (BW -20) and 4. body weight -40% (BW -40), maintaining half crimp grip until voluntary exhaustion. During each trial SmO2 and time to task failure (TTF) were measured. TTF was then compared to the minimally attainable value of SmO2 (SmO2min) and time to SmO2min (TTmin). There is a considerable degree of agreement between attainable SmO2min at high intensity conditions (MBW = 21.6% ± 6.4; MBW+20 = 24.0% ± 7.0; MBW-20 = 23.0% ± 7.3). Bland-Altman plot with an a priori set equivalency interval of ±5% indicate that these conditions are statistically not different (MBW-BW + 20 = -2.4%, 95% CI [1.4, -6.2]; MBW-Bw-20 = -1.3, 95% CI [2.5, -5.1]). The fourth and lowest intensity condition (MBW -40 = 32.4% ± 8.8) was statistically different and not equivalent (MBW-BW -40 = -8.8%, 95% CI [-5.0, -12.6]). The same agreement was found between TTF and TTmin for the high intensity conditions plotted via Bland-Altman. While the rate with which oxygen was extracted and utilised changed with the conditions, the attainable SmO2min remained constant at high intensity conditions and was related to TTF.

Fever Dreams: An Online Study.

In addition to a large variety of somatic symptoms, fever also affects cognition, sleep, and mood. In an online survey with 164 participants, 100 fever dream reports were submitted. Fever dreams were more bizarre and more negatively toned and included more references to health and temperature perception compared to "normal" most recent dreams - findings that are in line with the continuity hypothesis of dreaming. Future studies should follow up this line of research by conducting diary studies during naturally occurring febrile illnesses and sleep laboratory studies with experimentally induced fever. It would also be very interesting to study the effect of thermal stimulation applied during sleep on dream content. This research helps to understand subjective experiences while sleeping in an extreme condition (elevated body temperature).

Near-infrared spectroscopy-derived muscle oxygen saturation on a 0% to 100% scale: reliability and validity of the Moxy Monitor.

Near-infrared spectroscopy (NIRS) to monitor muscle oxygen saturation (SmO2) is rapidly expanding into applied sports settings. However, the technology is limited due to its inability to convey quantifiable values. A test battery to assess reliability and validity of a 0% to 100% scale modeled by a commercially available NIRS device was established. This test battery applies a commonly used technique, the arterial occlusion method (AOM) to assess repeatability, reproducibility, and face validity. A total of 22 participants completed the test battery to scrutinize the 0% to 100% scale provided by the device. All participants underwent repeated AOM tests in passive and active conditions. The SmO2 minimum and SmO2 maximum values were obtained from the AOM and were used in the subsequent analysis. Repeatability and reproducibility were tested for equivalency and Bland-Altman plots were generated. Face validity was assessed by testing SmO2 values against an a priori; defined threshold for mixed venous blood during AOM response. The device exhibits an appropriately functional 0% to 100% scale that is reliable in terms of repeatability and reproducibility. Under the conditions applied in the test battery design, the device is considered valid for application in sports.

Sleep-Related Issues for Recovery and Performance in Athletes.

The body of research that reports the relevance of sleep in high-performance sports is growing steadily. While the identification of sleep cycles and diagnosis of sleep disorders are limited to lab-based assessment via polysomnography, the development of activity-based devices estimating sleep patterns provides greater insight into the sleep behavior of athletes in ecological settings. Generally, small sleep quantity and/or poor quality appears to exist in many athletic populations, although this may be related to training and competition context. Typical sleep-affecting factors are the scheduling of training sessions and competitions, as well as impaired sleep onset as a result of increased arousal prior to competition or due to the use of electronic devices before bedtime. Further challenges are travel demands, which may be accompanied by jet-lag symptoms and disruption of sleep habits. Promotion of sleep may be approached via behavioral strategies such as sleep hygiene, extending nighttime sleep, or daytime napping. Pharmacological interventions should be limited to clinically induced treatments, as evidence among healthy and athletic populations is lacking. To optimize and manage sleep in athletes, it is recommended to implement routine sleep monitoring on an individual basis.

Recovery and Performance in Sport: Consensus Statement.

The relationship between recovery and fatigue and its impact on performance has attracted the interest of sport science for many years. An adequate balance between stress (training and competition load, other life demands) and recovery is essential for athletes to achieve continuous high-level performance. Research has focused on the examination of physiological and psychological recovery strategies to compensate external and internal training and competition loads. A systematic monitoring of recovery and the subsequent implementation of recovery routines aims at maximizing performance and preventing negative developments such as underrecovery, nonfunctional overreaching, the overtraining syndrome, injuries, or illnesses. Due to the inter- and intraindividual variability of responses to training, competition, and recovery strategies, a diverse set of expertise is required to address the multifaceted phenomena of recovery, performance, and their interactions to transfer knowledge from sport science to sport practice. For this purpose, a symposium on Recovery and Performance was organized at the Technical University Munich Science and Study Center Raitenhaslach (Germany) in September 2016. Various international experts from many disciplines and research areas gathered to discuss and share their knowledge of recovery for performance enhancement in a variety of settings. The results of this meeting are outlined in this consensus statement that provides central definitions, theoretical frameworks, and practical implications as a synopsis of the current knowledge of recovery and performance. While our understanding of the complex relationship between recovery and performance has significantly increased through research, some important issues for future investigations are also elaborated.

Changes in Subjective Sleep Quality Before a Competition and Their Relation to Competitive Anxiety.

OBJECTIVE/BACKGROUND: The aim of this study was to examine the effects of competitions on subjective sleep quality. Previous studies have been inconclusive and lack differentiated and standardized measurements of subjective sleep quality. Furthermore the temporal relation between precompetitive anxiety and sleep quality was investigated. Anxiety and nervousness associated with competitions are considered to cause sleep impairments. PARTICIPANTS: A convenience sample of N = 79 elite male athletes from various sports participated. METHODS: In a time-to-event paradigm, sleep quality and competitive anxiety were assessed via standardized self-report measurements 4 days before a competition and on the day of the competition. Univariate analyses were used to examine differences between time points. To examine cross-lagged effects between anxiety and sleep quality a latent change score model (LCSM) was specified that tested an effect of anxiety on changes in sleep quality. RESULTS: Evaluations of nocturnal sleep deteriorated significantly from 4 days before competition to the day of competition, but there were no differences regarding perceptions of the restorative value of sleep. LCSM revealed that athletes who reported more intense worry symptoms 4 days before competition also reported greater deterioration in evaluations of nocturnal sleep. CONCLUSIONS: The findings support earlier reports of impaired subjective sleep quality before competitions. Precompetitive sleep impairments appear also to be preceded by cognitive anxiety. Whereas interventions should thus address worry-cognitions associated with competition and sleep, research should address the practical importance of these perceptions of sleep impairments.

Improvement of darts performance following lucid dream practice depends on the number of distractions while rehearsing within the dream - a sleep laboratory pilot study.

In a lucid dream, the dreamer is aware of the dream state and can deliberately practice motor skills. Two field studies indicated that lucid dream practice can improve waking performance in simple motor tasks. The present pilot study investigated the effect of lucid dream practice in a controlled sleep laboratory setting, using a pre-post design with dart throwing in the evening and morning. The experimental group practiced darts in lucid dreams. Because some participants were distracted during lucid dream practice, the group was divided into lucid dreamers with few (n = 4) and many distractions (n = 5). Change of performance was compared to a physical practice group (n = 9) and a control group (n = 9), showing a significant interaction (P = .013, η2 = .368). Only the lucid dreamers with few distractions improved (18%) significantly over time (P = .005, d = 3.84). Even though these results have to be considered preliminary, the present study indicates that lucid dream practice can be an effective tool in sports practice if lucid dreamers find ways to minimise distractions during lucid dream practice. Moreover, the study emphasises the necessity to investigate lucid dream practice experiences on a qualitative level.

Heart-Rate Variability During Deep Sleep in World-Class Alpine Skiers: A Time-Efficient Alternative to Morning Supine Measurements.

BACKGROUND: It is increasingly popular to use heart-rate variability (HRV) to tailor training for athletes. A time-efficient method is HRV assessment during deep sleep. AIM: To validate the selection of deep-sleep segments identified by RR intervals with simultaneous electroencephalography (EEG) recordings and to compare HRV parameters of these segments with those of standard morning supine measurements. METHODS: In 11 world-class alpine skiers, RR intervals were monitored during 10 nights, and simultaneous EEGs were recorded during 2-4 nights. Deep sleep was determined from the HRV signal and verified by delta power from the EEG recordings. Four further segments were chosen for HRV determination, namely, a 4-h segment from midnight to 4 AM and three 5-min segments: 1 just before awakening, 1 after waking in supine position, and 1 in standing after orthostatic challenge. Training load was recorded every day. RESULTS: A total of 80 night and 68 morning measurements of 9 athletes were analyzed. Good correspondence between the phases selected by RR intervals vs those selected by EEG was found. Concerning root-mean-squared difference of successive RR intervals (RMSSD), a marker for parasympathetic activity, the best relationship with the morning supine measurement was found in deep sleep. CONCLUSION: HRV is a simple tool for approximating deep-sleep phases, and HRV measurement during deep sleep could provide a time-efficient alternative to HRV in supine position.