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.

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.

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.

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.

Effectiveness of motor practice in lucid dreams: a comparison with physical and mental practice.

Motor practice in lucid dreams is a form of mental rehearsal where the dreamer can consciously rehearse motor skills in the dream state while being physically asleep. A previous pilot study showed that practice in lucid dreams can improve subsequent performance. This study aimed to replicate those findings with a different task (finger-tapping) and compare the effectiveness of lucid dream practice (LDP) not only to physical but also to mental practice (MP) in wakefulness. An online experiment was completed by 68 participants within four groups: LDP group, MP group, physical practice (PP) group and control (no practice) group. Pre-test was accomplished in the evening, post-test in the next morning, while the practice was done during the night. All three practice groups significantly improved their performance from pre-test to post-test, but no significant improvements were observed for the control group. Subjective sleep quality was not affected by night practice. This study thus corroborates the previous findings that practice in lucid dreams is effective in improving performance. Its effects seem to be similar to actual PP and MP in wakefulness. Future studies should establish reliable techniques for lucid dream induction and verify the effects of LDP in sleep laboratory conditions.

Neuromuscular training in construction workers: a longitudinal controlled pilot study.

OBJECTIVE: Many accidents at construction sites are due to falls. An exercise-based workplace intervention may improve intrinsic fall risk factors. In this pilot study, we aimed at evaluating the effects of neuromuscular exercise on static and functional balance performance as well as on lower limb explosive power in construction workers. METHODS: Healthy middle-aged construction workers were non-randomly assigned to an intervention [N = 20, age = 40.3 (SD 8.3) years] or a control group [N = 20, age = 41.8 (9.9) years]. The intervention group performed static and dynamic balance and strength exercises (13 weeks, 15 min each day). Before and after the intervention and after an 8-week follow-up, unilateral postural sway, backward balancing (on 3- and 4.5-cm-wide beams) as well as vertical jump height were assessed. RESULTS: We observed a group × time interaction for postural sway (p = 0.002) with a reduction in the intervention group and no relevant change in the control group. Similarly, the number of successful steps while walking backwards on the 3-cm beam increased only in the intervention group (p = 0.047). These effects were likely to most likely practically beneficial from pretest to posttest and to follow-up test for postural sway (+12%, standardized mean difference (SMD) = 0.65 and 17%, SMD = 0.92) and backward balancing on the 3-cm beam (+58%, SMD = 0.59 and 37%, SMD = 0.40). CONCLUSIONS: Fifteen minutes of neuromuscular training each day can improve balance performance in construction workers and, thus, may contribute to a decreased fall risk.

The phenomenology of lucid dreaming: an online survey.

In lucid dreams the dreamer is aware that he or she is dreaming. Although such dreams are not that uncommon, many aspects of lucid dream phenomenology are still unclear. An online survey was conducted to gather data about lucid dream origination, duration, active or passive participation in the dream, planned actions for lucid dreams, and other phenomenological aspects. Among the 684 respondents who filled out the questionnaire, there were 571 lucid dreamers (83.5%). According to their reports, lucid dreams most often originate spontaneously in adolescence. The average lucid dream duration is about 14 minutes. Lucid dreamers are likely to be active in their lucid dreams and plan to accomplish different actions (e.g., flying, talking with dream characters, or having sex), yet they are not always able to remember or successfully execute their intentions (most often because of awakening or hindrances in the dream environment). The frequency of lucid dream experience was the strongest predictor of lucid dream phenomenology, but some differences were also observed in relation to age, gender, or whether the person is a natural or self-trained lucid dreamer. The findings are discussed in light of lucid dream research, and suggestions for future studies are provided.

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.

[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.

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.

Testing the involvement of the prefrontal cortex in lucid dreaming: a tDCS study.

Recent studies suggest that lucid dreaming (awareness of dreaming while dreaming) might be associated with increased brain activity over frontal regions during rapid eye movement (REM) sleep. By applying transcranial direct current stimulation (tDCS), we aimed to manipulate the activation of the dorsolateral prefrontal cortex (DLPFC) during REM sleep to increase dream lucidity. Nineteen participants spent three consecutive nights in a sleep laboratory. On the second and third nights they randomly received either 1 mA tDCS for 10 min or sham stimulation during each REM period starting with the second one. According to the participants' self-ratings, tDCS over the DLPFC during REM sleep increased lucidity in dreams. The effects, however, were not strong and found only in frequent lucid dreamers. While this indicates some preliminary support for the involvement of the DLPFC in lucid dreaming, further research, controlling for indirect effects of stimulation and including other brain regions, is needed.

Induction of lucid dreams: a systematic review of evidence.

In lucid dreams the dreamer is aware of dreaming and often able to influence the ongoing dream content. Lucid dreaming is a learnable skill and a variety of techniques is suggested for lucid dreaming induction. This systematic review evaluated the evidence for the effectiveness of induction techniques. A comprehensive literature search was carried out in biomedical databases and specific resources. Thirty-five studies were included in the analysis (11 sleep laboratory and 24 field studies), of which 26 employed cognitive techniques, 11 external stimulation and one drug application. The methodological quality of the included studies was relatively low. None of the induction techniques were verified to induce lucid dreams reliably and consistently, although some of them look promising. On the basis of the reviewed studies, a taxonomy of lucid dream induction methods is presented. Several methodological issues are discussed and further directions for future studies are proposed.

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.

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.

Sleep habits in German athletes before important competitions or games.

Sleep is generally regarded as a valuable resource for psychological and physiological well-being. Although the effects of sleep on athletic performance have been acknowledged in sport science, few studies have investigated the prevalence of sleep problems and their effects on elite athletes before a sport event. In this study, 632 German athletes from various sports were asked about their sleep habits during the night(s) before an important competition or game. The findings indicate that 65.8% of the athletes experienced poor sleep in the night(s) before a sports event at least once in their lives and a similarly high percentage (62.3%) had this experience at least once during the previous 12 months. Athletes of individual sports reported more sleep difficulties than athletes of team sports. The main sleep problem was not being able to fall asleep. Internal factors such as nervousness and thoughts about the competition were rated highest for causing sleep problems. Most athletes stated that disturbed sleep had no influence on their athletic performance; however, athletes also reported effects such as a bad mood the following day, increased daytime sleepiness, and worse performance in the competition or game. The differences between individual and team sports indicate that athletes in some sports need more help than those in other sports in managing sleep problems.

Frequency of lucid dreaming in a representative German sample.

Lucid dreams occur when a person is aware that he is dreaming while he is dreaming. In a representative sample of German adults (N = 919), 51% of the participants reported that they had experienced a lucid dream at least once. Lucid dream recall was significantly higher in women and negatively correlated with age. However, these effects might be explained by the frequency of dream recall, as there was a correlation of .57 between frequency of dream recall and frequency of lucid dreams. Other sociodemographic variables like education, marital status, or monthly income were not related to lucid dream frequency. Given the relatively high prevalence of lucid dreaming reported in the present study, research on lucid dreams might be pursued in the sleep laboratory to expand the knowledge about sleep, dreaming, and consciousness processes in general.

Frequency of nightmares and gender significantly predict distressing dreams of German athletes before competitions or games.

Important sports events are highlights and stressful situations in every athlete's career. This stress might alter the dream content of athletes and consequently evoke disturbed dreaming. In this study, the authors asked 840 German athletes from various sports about distressing dreams on the nights before an important competition or game. About 15% of the athletes stated that they experienced at least 1 distressing dream before an important competition or game during the preceding 12 months. An almost equal number of athletes reported at least 1 distressing dream in their sports career. With respect to the base rate, in about 3% of the events a distressing dream occurred. Reported dream content referred mainly to athletic failure. The main risk factor for an athlete experiencing a distressing dream before a competition appears to be the frequency of experienced nightmares in general. Future research should use diary techniques to study the impact of distressing dreams on the next-day athletic performance in a competition or game.

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.