Intervention for Reducing Sleep Disturbances After a 12-Time Zone Transition.

Hoshikawa, M, Uchida, S, and Dohi, M. Intervention for reducing sleep disturbances after a 12-time zone transition. J Strength Cond Res 34(7): 1803-1807, 2020-The purpose of this study was to examine the effect of an intervention consisting of bright light exposure, sleep schedule shifts, and ramelteon on sleep disturbances after a transition of 12 time zones. Two groups, which flew from Tokyo to Rio, participated in this study. The experimental group received the treatment, whereas the control group did not receive any treatment. The experimental group members were exposed to bright light at night and their sleep-wake schedules were gradually delayed for 4 days before their flight. They also took 8 mg of ramelteon once a day for 5 days from the day of their first flight. Both groups departed Tokyo at 14:05, transiting through Frankfurt and arriving in Rio at 05:05. In Rio, it was recommended that they go to bed earlier than usual if they experienced sleepiness. Nocturnal sleep variables measured by wristwatch actigraphy and subjective morning tiredness were compared between groups. Statistical analysis revealed shorter sleep onset latencies (SOLs) in the experimental group (p < 0.01). The SOLs in Rio were 7.7 ± 2.5 minutes for the experimental group and 16.3 ± 3.7 minutes for the control group (d = 0.89, effect size: large). Sleep efficiency for the first 3 nights in Rio was 88.5 ± 1.2% for the experimental group and 82.9 ± 3.0% for the control group (p < 0.01, d = 1.09, effect size: large). These results suggest that the intervention reduced sleep disturbances in Rio. Our intervention may increase the options for conditioning methods for athletic events requiring time zone transitions.

Effects of evening partial body cryostimulation on the skin and core temperatures.

Cryostimulation is widely used to treat inflammation, rheumatism, acute soft tissue injuries, and neurodegeneration. It helps prevent injury and promotes recovery. This study aimed to examine the duration of the effects of evening partial body cryostimulation (PBC) on core and skin temperatures. Seven male athletes participated in this study. On the day of PBC, at 18:00, each athlete was exposed to PBC (approx. -180 °C) in a specially designed cabin for 3 min. On the control day, at 18:00, the participants sat still on a sofa for 10 min. On both days, bedtime was at around 23:00. Wrist and abdominal skin temperatures, except during PBC, were recorded with Thermochron thermistors after 17:30. Core temperatures were monitored with an ingestible and telemetric core body temperature sensor and a data recorder. The circadian rhythm of the core temperature was observed on both days. The core temperature at 22:30 was found to be lower on the PBC day. Wrist and abdominal skin temperatures recovered after PBC; however, the residual effects on both were different. The abdominal skin temperature at 22:30 was lower on the PBC day. Subjective sleep quality and next morning sleepiness did not differ between the conditions. These results suggested that the effects of a 3-min evening PBC session on the core and skin temperatures lasted for several hours. However, these differences did not affect the subjective sleep quality.

Effects of normobaric hypoxia equivalent to 2,000-m altitude on sleep and physiological conditions of athletes: a study using sheet-type sensor.

The purpose of this study was to evaluate the sleep and physiological conditions of athletes using a noncontact sheet-type sensor (Nemuri Monitor; Aisin Seiki Co., Ltd.). Using the sheet-type sensor, sleep parameters, heart rate (HR), and respiratory rate (RR) were monitored in 7 female intercollege level middle-distance runners, who participated in a 7-night hypoxic training camp study, in which the first night was normoxic and the next 6 nights were hypoxic. Blood oxygen saturation (SpO2) was simultaneously recorded with a pulse oximeter (Pulsox-300i; Konica Minolta Optics, Inc.). Because this was a part of a hypoxic training camp study, they underwent strenuous training during the daytime. On hypoxic night 1, acute hypoxia-induced changes, such as increases in HR, RR, and body motion during sleep, and decreases in SpO2 were observed. Until hypoxic night 6, SpO2 did not change, whereas the other parameters improved toward values that would be obtained under a normoxic night. Thus, the sheet-type sensor could be used to evaluate the sleep and physiological conditions of athletes undergoing "living-high" regimens.

Gut microbiota alternation with training periodization and physical fitness in Japanese elite athletes.

Introduction: The gut microbiome plays a fundamental role in host homeostasis through regulating immune functions, enzyme activity, and hormone secretion. Exercise is associated with changes in gut microbiome composition and function. However, few studies have investigated the gut microbiome during training periodization. The present study aimed to investigate the relationship between training periodization and the gut microbiome in elite athletes. Methods: In total, 84 elite athletes participated in the cross-sectional study; and gut microbiome was determined during their transition or preparation season period. Further, 10 short-track speed skate athletes participated in the longitudinal study, which assessed the gut microbiome and physical fitness such as aerobic capacity and anaerobic power in the general and specific preparation phase of training periodization. The gut microbiome was analyzed using 16S rRNA sequencing. Results: The cross-sectional study revealed significant differences in Prevotella, Bifidobacterium, Parabacteroides, and Alistipes genera and in enterotype distribution between transition and preparation season phase periodization. In the longitudinal study, training phase periodization altered the level of Bacteroides, Blautia, and Bifidobacterium in the microbiome. Such changes in the microbiome were significantly correlated with alternations in aerobic capacity and tended to correlate with the anaerobic power. Discussion: These findings suggest that periodization alters the gut microbiome abundance related to energy metabolism and trainability of physical fitness. Athlete's condition may thus be mediated to some extent by the microbiota in the intestinal environment.

A clinical survey of dehydration during winter training in elite fencing athletes.

BACKGROUND: Fencing is suggested as one of the most dangerous sporting events in terms of dehydration because of the uniform and gear covering the entire body. We aimed to elucidate the change in hydration status before and after training in elite fencing athletes in winter along with the assessment of sex and fencing style differences. METHODS: Twenty-seven elite fencing athletes (14 males and 13 females) belonging to the Japanese National Team participated in this clinical survey. Dehydration status before and after winter training was assessed using body mass change, fluid intake, urine osmolarity, urine specific gravity (USG), and sodium, potassium, chlorine, and creatinine levels. RESULTS: More than half of the participants (59.3%) drank water and tea during training. The change rate of body mass (males vs. females, 1.61±0.82% vs. 0.45±0.68%, P<0.01; foil vs. epee, 2.25±0.45% vs. 1.16±0.72%, P<0.05) and sweating rate (males vs. females, 938±251 g/h vs. 506±92 g/h, P<0.01; foil vs. epee, 1136±156 g/h vs. 796±207 g/h, P<0.05) during training showed significant differences between sexes and fencing styles. Of all participants, 66.7% were dehydrated (USG≥1.020), and 37.0% were seriously dehydrated (USG≥1.030) before training. CONCLUSIONS: Fencing athletes may be susceptible to severe dehydration before training, even in winter. Additionally, males and foil fencers appear to be at a greater risk than females and epee fencers of developing dehydration during exercise.

Chronotypes in elite Japanese athletes: assessed by the reduced Morningness-Eveningness and Munich ChronoType Questionnaires.

This study aimed to test in elite athletes the correlation between the chronotype determined by the reduced version of the Morningness-Eveningness Questionnaire (rMEQ) and that determined by the Munich ChronoType Questionnaire (MCTQ). In total, 351 elite athletes filled out the rMEQ questionnaire, 59 athletes filled out the MCTQ questionnaire, and 39 athletes filled out both questionnaires. The rMEQ score and the corrected midpoint of sleep from the MCTQ correlated weakly (|r| = 0.360, p < .05); however, some cases were mismatched. The MSFsc also weakly correlated with age (|r| = 0.374, p < .05), while rMEQ did not. Our results may suggest that the choice of questionnaire to determine chronotype should depend on the purpose and the type of sport athlete.

Postural instability at a simulated altitude of 5,000 m before and after an expedition to Mt. Cho-Oyu (8,201 m).

To clarify the effects of altitude acclimatization on postural instability at altitudes, six female climbers stood with their eyes open or closed on a force-measuring platform under normoxia (NC) and hypobaric hypoxia, equivalent to a 5,000 m altitude (HC), before and after an expedition to Mt. Cho-Oyu (8,201 m). The expedition extended over 84 days. We recorded sways in the center of foot pressure, electromyograms (EMGs) of lower-leg muscles, blood components and arterial oxygen saturation (SpO(2)). Before the expedition, the maximum amplitude of sway with the eyes open and integrated EMG from the medial gastrocnemius increased for HC. After the expedition, red blood cell (from 423.4 ± 15.4 to 498.0 ± 24.5 × 10(4) µl(-1)), hemoglobin content (from 12.6 ± 0.32 to 14.5 ± 1.00 g/dl) and 2,3-diphosphoglycerate (from 1.93 ± 0.21 to 2.24 ± 0.34 µmol/ml) increased. The SpO(2) under HC increased from 69.2 ± 9.6 to 77.2 ± 10.0%. The maximum amplitude of sway with the eyes open decreased for HC. No difference in the sway path length and integrated EMGs was observed between NC and HC. These results suggest that acclimatization can improve the impaired postural stability on initial arrival at altitudes. However, it is still unclear how long acclimatization period is needed. Further studies are needed to reveal this point.

Physical and physiological effects on otoacoustic emissions in hypobaric hypoxia.

Tinnitus and dizziness are symptoms of acute mountain sickness. We investigated the mechanism by which high altitude (i.e. hypobaric hypoxia) affects inner ear function by measuring transient evoked otoacoustic emissions (TEOAE) and distortion product otoacoustic emissions (DPOAE) under conditions of normobaric normoxia (1,013 hPa; 760 mm Hg) and hypobaric hypoxia (540 hPa; 405 mm Hg). The possibility that air pressure effects on the eustachian tube impacted our findings was excluded by the use of tympanograms. The nonphysiological effects of hypobaric hypoxia on TEOAE and DPOAE were also assessed using an ear simulator. Under conditions of hypobaric hypoxia, both TEOAE and DPOAE levels were reduced. The amount of reduction that occurred was approximately 4 dB in the total echo power and signal-to-noise ratio of the TEOAE, and in the 2f(1) - f(2) element level of the DPOAE. Stimulus levels that were measured using an ear simulator were also reduced by approximately 4 dB under conditions of hypobaric hypoxia. These results do not indicate that stimulus levels affected TEOAE and DPOAE levels because these levels were actually only slightly affected by changes in the stimulus level. Instead, this reduction was likely due to the nonphysiological hypobaric effects of the sound pressure emitted from the tympanic membrane. We conclude that the impact of hypobaric hypoxia on cochlear function was negligible up to pressures of 540 hPa.

A Subjective Assessment of the Prevalence and Factors Associated with Poor Sleep Quality Amongst Elite Japanese Athletes.

BACKGROUND: The amount, quality, and timing of sleep are considered important for athletes' ability to train, maximize training responses, and recover. However, some research has shown that elite athletes do not obtain sufficient sleep. Based on this background, researchers recently started to assess and manage sleep in elite athletes. The purpose of this study was to clarify the prevalence of poor sleep quality and its associated factors amongst elite Japanese athletes. METHODS: Eight hundred and ninety-one candidates for the 17th Asian Games Incheon 2014, who were over 20 years old, participated in this study. They completed a questionnaire that included the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale, two-question case-finding instruments, and a checklist for sleep hygiene. Data from 817 of the 891 athletes (91.7%) with no missing values were analyzed. RESULTS: The mean time in bed was 7 h and 29 min. Two hundred and twenty-nine (28.0%) athletes showed a PSQI global score above the clinical criteria. A multiple logistic analysis revealed that sleep quality was significantly associated with five factors: "time in bed," "eating breakfast every morning," "avoiding the use of electronic devices (PC, smartphone, etc.) just before bedtime," "depressive mood", and "not thinking about troubles while in bed." Forty percent of athletes reported they had been informed by someone about "snoring loudly" and/or "leg twitching or jerking during sleep." CONCLUSIONS: The results of this study demonstrate that 28% of the athletes showed the PSQI score above the cutoff for poor sleep quality (> 5.5), which suggests that there may be a high prevalence of poor sleep quality in this population of athletes. To improve athletes' sleep, the five factors associated with sleep quality should be emphasized in athletes' sleep education. Furthermore, in medical evaluations of athletes, it may be desirable to include screening for sleep disorders.

Changes in sleep quality of athletes under normobaric hypoxia equivalent to 2,000-m altitude: a polysomnographic study.

This study evaluated the sleep quality of athletes in normobaric hypoxia at a simulated altitude of 2,000 m. Eight male athletes slept in normoxic condition (NC) and hypoxic conditions equivalent to those at 2,000-m altitude (HC). Polysomnographic recordings of sleep included the electroencephalogram (EEG), electrooculogram, chin surface electromyogram, and electrocardiogram. Thoracic and abdominal motion, nasal and oral airflow, and arterial blood oxygen saturation (Sa(O(2))) were also recorded. Standard visual sleep stage scoring and fast Fourier transformation analyses of the EEG were performed on 30-s epochs. Subjective sleepiness and urinary catecholamines were also monitored. Mean Sa(O(2)) decreased and respiratory disturbances increased with HC. The increase in respiratory disturbances was significant, but the increase was small and subclinical. The duration of slow-wave sleep (stage 3 and 4) and total delta power (<3 Hz) of the all-night non-rapid eye movement sleep EEG decreased for HC compared with NC. Subjective sleepiness and amounts of urinary catecholamines did not differ between the conditions. These results indicate that acute exposure to normobaric hypoxia equivalent to that at 2,000-m altitude decreased slow-wave sleep in athletes, but it did not change subjective sleepiness or amounts of urinary catecholamines.

Effects of Five Nights under Normobaric Hypoxia on Sleep Quality.

PURPOSE: The purpose of this study was to evaluate the effects of five nights' sleep under normobaric hypoxia on ventilatory acclimatization and sleep quality. METHODS: Seven men initially slept for six nights under normoxia and then for five nights under normobaric hypoxia equivalent to a 2000-m altitude. Nocturnal polysomnograms (PSGs), arterial blood oxygen saturation (SpO2), and respiratory events were recorded on the first and fifth nights under both conditions. RESULTS: The hypoxic ventilatory response (HVR), hypercapnic ventilatory response (HCVR), and resting end-tidal CO2 (resting PETCO2) were measured three times during the experimental period. The duration of slow-wave sleep (SWS: stage N3) and the whole-night delta (1-3 Hz) power of nonrapid eye movement (NREM) sleep EEG decreased on the first night under hypoxia. This hypoxia-induced sleep quality deterioration on the first night was accompanied by a lower mean and minimum SpO2, a longer time spent with SpO2 below 90% (<90% SpO2 time), and more episodes of respiratory disturbance. On the fifth night, the SWS duration and whole-night delta power did not differ between the conditions. Although the mean SpO2 under hypoxia was still lower than under normoxia, the minimum SpO2 increased, and the <90% SpO2 time and number of episodes of respiratory disturbance decreased during the five nights under hypoxia. The HVR increased and resting PETCO2 decreased after five nights under hypoxia. CONCLUSIONS: The results suggest that five nights under hypoxia improves the sleep quality. This may be derived from improvements of respiratory disturbances, the minimum SpO2, and <90% SpO2 time.

Hypoxia exaggerates inspiratory accessory muscle deoxygenation during hyperpnoea.

The purpose of this study was to elucidate inspiratory accessory muscle deoxygenation and myoelectric activity during isolated volitional hyperpnoea under hypoxic conditions. Subjects performed voluntary isocapnic hyperpnoea (tidal volume=30-40% of forced vital capacity, breathing frequency=60 breaths/min) in normoxia [inspired gas fraction (FIO2)=0.21] and hypoxia (FIO2). Muscle deoxyhemoglobin/myoglobin (Deoxy-Hb/Mb) and muscle oxygen saturation (SMO2) using near-infrared spectroscopy and surface electromyography were measured from sternocleidomastoid (SCM) and intercostal (IC) muscles. During hyperpnoea, increases in Deoxy-Hb/Mb and reductions of SMO2 in the SCM and IC muscles were larger (P<0.05) in hypoxia than those in normoxia. Under hypoxic conditions, the electromyogram increases from the SCM and IC muscles during hyperpnoea were greater than that under the normoxic conditions. These results suggest that inspiratory accessory muscle deoxygenation during isolated hyperpnoea is exaggerated in hypoxia compared with normoxia and that hypoxia has a significant impact on inspiratory accessory muscle activation.

Sleep quality under mild hypoxia in men with low hypoxic ventilatory response.

The present study evaluated whether slow-wave sleep and whole-night delta power of the non-rapid eye movement (NREM) sleep electroencephalogram (EEG) decrease during sleep at a simulated altitude of 2000 m, and whether such changes related to measures of hypoxic ventilatory response (HVR). This study consisted of two parts; in the first, HVR was measured in 41 subjects and each seven subjects with the lowest or the highest HVR were selected for the subsequent sleep study. In the second part, polysomnogram, arterial oxygen saturation (SpO2) and respiratory events are recorded on the selected subjects under normoxic and hypoxic conditions. Hypoxia decreased SpO2 and increased respiratory disturbances for both groups. The low HVR group, but not the high HVR group, showed decreases in the whole-night delta power of NREM sleep EEG under hypoxia. On the other hand, two subjects in the high HVR group, who showed relatively high apnoea indices, also showed lower SpO2 nadirs and decreases in the whole-night delta power under hypoxia. These results suggest that acute hypoxia equivalent to that at a 2000 m altitude decreases slow-wave sleep in individuals that show low HVR. However, low HVR may not be the only, but one of some factors that decrease the whole-night delta power under hypoxia. Therefore, it was not sufficient to identify individuals likely to be susceptible to deteriorated sleep quality at a simulated altitude of 2000 m only using the HVR test. Other factors, which relate to respiratory instabilities, should be taken into consideration to identify them.

Physiological responses to interval training sessions at velocities associated with VO2max.

Previous research has indicated that short-duration, high-intensity work intervals performed at velocities associated with maximal oxygen uptake (vVO2max) combined with active recovery intervals may be effective in eliciting improvements in endurance performance. This study was designed to characterize selected physiological responses to short-duration (< or = 60 seconds) interval work performed at velocities corresponding to 100% of vVO2max. Twelve men participated in 3 randomized trials consisting of treadmill running using work (W)/recovery (R) intervals of 15 seconds W/15 seconds R (15/15); 30 seconds W/15 seconds R (30/15); and 60 seconds W/15 seconds R (60/15). Work intervals were performed at 100% of vVO2max, whereas R intervals were performed at 50% of vVO2max. A fourth trial consisting of continuous work (C) at 100% of vVO2max was also performed. All subjects completed the 15/15 and 30/15 trials; however, only 5 of the 12 completed the 60/15 trial. The percentage of VO2max (mean +/- SD) during 15/15 (71.6 +/- 4.2%) was significantly lower (p < or = 0.05) than the percentages during 30/15 (84.6 +/- 4.0%), 60/15 (89.2 +/- 4.2%), or C (87.9 +/- 5.0%). Similar results were found for heart rate and perceived exertion. Blood lactate concentrations following exercise were significantly lower (p < or = 0.05) in 15/15 (7.3 +/- 2.4 mmol x L(-1)) than in the other trials. No significant differences (p > 0.05) existed among 30/15 (11.5 +/- 1.8 mmol x L(-1)), 60/15 (12.5 +/- 1.8 mmol x L(-1)) or C (12.1 +/- 1.8 mmol x L(-1)). High intensity, short-duration 2:1 W/R intervals appear to produce responses that may benefit both aerobic and anaerobic energy system development. A 4:1 W/R ratio may be an upper limit for individuals in the initial phases of interval training.