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.

Changes in the skin characteristics associated with dehydration and rehydration.

The present study aimed to test the hypothesis that changes in the dermal tissue dielectric constant (TDC) and biomechanical properties of the skin would be correlated with the indicators related to dehydration. Ten healthy adult men were enrolled in three trials: no fluid intake (DEH), ad libitum fluid intake (AL-HYD), and programmed fluid intake (P-HYD) after exercise in a randomised crossover design. The participants performed a pedalling exercise at 60% heart rate reserve until 2% body mass loss. At 120 min after exercise, an incremental exercise test was carried out. Aerobic capacity, body composition, TDC, biomechanical properties of the skin (pliability, viscoelasticity, and total recovery), and indicators related to dehydration in the serum and urine were measured before and 120 min after exercise. Higher values of the pliability and viscoelasticity, and lower value of the total recovery on the hand were demonstrated in the P-HYD trial compared to the DEH trial (all P < 0.05). Changes in the TDC were significantly correlated with changes in body mass, total body water, serum osmolarity, and hematocrit (all P < 0.05). Changes in the biomechanical properties of the hand were significantly correlated with changes in body mass, hematocrit, and urine specific gravity (all P < 0.05). The present study showed that the changes in skin characteristics correlated with the body water and dehydration-associated indicators in the serum and urine, thus suggesting that skin characteristics may be useful in the assessment of dehydration.HighlightsThis study was the first to investigate the effect of dehydration and rehydration on the TDC and biomechanical properties of the skin upon instrumental measure, and not manual testing.This study confirmed the decline in aerobic capacity by dehydration and immediate recovery with sufficient rehydration.Changes in the TDC and the biomechanical properties of the skin correlated with the body water and dehydration-associated indicators in the serum and urine.Skin characteristics may be useful in the assessment of dehydration.

Effects of Intestinal Bacterial Hydrogen Gas Production on Muscle Recovery following Intense Exercise in Adult Men: A Pilot Study.

This study aimed to examine the effects of hydrogen gas (H2) produced by intestinal microbiota on participant conditioning to prevent intense exercise-induced damage. In this double-blind, randomized, crossover study, participants ingested H2-producing milk that induced intestinal bacterial H2 production or a placebo on the trial day, 4 h before performing an intense exercise at 75% maximal oxygen uptake for 60 min. Blood marker levels and respiratory variables were measured before, during, and after exercise. Visual analog scale scores of general and lower limb muscle soreness evaluated were 3.8- and 2.3-fold higher, respectively, on the morning after treatment than that before treatment during the placebo trial, but not during the test beverage consumption. Urinary 8-hydroxy-2'-deoxyguanosine (8-OHdG) concentrations and production rates significantly increased with placebo consumption; no changes were observed with test beverage consumption. After exercise, relative blood lactate levels with H2-producing milk consumption were lower than those with placebo consumption. A negative correlation was observed between the variation of 8-OHdG and the area under the curve (AUC) of breath H2 concentrations. Lipid oxidation AUC was 1.3-fold higher significantly with H2-producing milk than with placebo consumption. Conclusively, activating intestinal bacterial H2 production by consuming a specific beverage may be a new strategy for promoting recovery and conditioning in athletes frequently performing intense exercises.

In-play optimal cooling for outdoor match-play tennis in the heat.

The purpose of this study was to compare the efficacy of four cooling interventions used for reducing physiological and perceptual strain and improving exercise performance during outdoor match-play tennis in the heat. Eight competitive tennis players played four counter-balanced simulated outdoor matches in the heat (WBGT: 28.4-32.5°C) at 24- or 48-h intervals. Each match comprised 3 sets for which the "no-ad" rule was applied to limit duration variability. Players underwent the following cooling interventions: ad libitum fluid ingestion (CON), ad libitum fluid ingestion and ice vest (VEST), total ingestion of approximately 1000 g ice slurry and ice vest (Combined: BINE), or total ingestion of approximately 400 g ice slurry and ice vest (Low-combined: L-BINE). Gastrointestinal temperature was lower in the BINE and the L-BINE trials than in the CON trial at the set-break of set 1, and these differences in gastrointestinal temperature persisted throughout the remainder of the match (p < 0.05). The ratio of moderate-high intensity activity (≥10 km/h) in set 3 was significantly higher in the L-BINE trial than that in the BINE trial (p < 0.05). In the CON and BINE trials, high intensity activity was significantly lower in set 3 compared with set 1 and 2, respectively. Cooling by optimal ice slurry ingestion and ice vest may be a more effective strategy in mitigating the development of heat strain during outdoor match-play tennis in the heat.Highlights Cooling by optimal ice slurry ingestion and ice vest may be a more effective strategy in mitigating the development of heat strain during outdoor match-play tennis in the heat.Ingesting of large amounts ice slurry may be caused the bloating and stomach discomfort, in turn declined in the ratio of moderate-high intensity activity in the second half of match-play tennis in hot outdoor environments.Future studies should not only utilize match characteristics, but also measure on-court tennis specific performance.

Mild hyperbaric oxygen for the early improvement of mood disturbance induced by high-intensity exercise.

BACKGROUND: Excessive training stress can result in decreased performance and deep fatigue due to hormonal changes. There are few available data on recovery methods for mood disturbance, especially fatigue, after high-intensity training. This study, therefore, aimed to examine the effects of mild hyperbaric oxygen at 1.3 atmospheres absolute with 31% oxygen on mood disturbance induced by high-intensity exercises. METHODS: Ten healthy adult men participated in and completed 2 trials: the control (CON) trial and the mild hyperbaric oxygen (MHO) trial. In a randomized crossover design, each subject cycled for 60 min at the physical work capacity at 75% of their maximal heart rate and were subsequently exposed to the CON and MHO conditions for 60 min as the recovery period. RESULTS: During the 20 to 40 min recovery time points, the average change ratio of heart rates was lower in the MHO trial than in CON (P<0.05). We observed that the fatigue-inertia, tension-anxiety, and total mood disturbance Profile of Mood States (POMS) scores decreased 60 min post-exercise in the MHO trial, but no differences of these scores were observed in the CON trial. There were no differences in oxidative stress, derived-reactive oxygen metabolites, and biological antioxidant potential between both trials. These results suggest that impaired mood states induced by high-intensity exercise can be improved early by MHO without any changes in oxidative stress. This improvement may be associated with decreased heart rate secondary to MHO exposure after the high intensity exercise. CONCLUSIONS: We conclude that MHO can improve mood disturbances, especially in the fatigue-inertia and tension-anxiety domains, after high-intensity exercise. This study suggest that MHO is potentially an effective recovery method for mood states after high-intensity training.

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.

The Effects of the COVID-19 Environments on Changes in Body Composition in Japanese Elite Fencing Athlete.

The Japanese government declared a state of emergency from 7 April to 25 May to limit people's movement due to the coronavirus disease (COVID-19) pandemic. This pandemic negatively affects athletes' body composition due to inactivity. Therefore, we compared the body composition data (i.e., fat-free mass (FFM) and fat mass (FM)), of 43 Japanese elite fencers (22 men, 21 women), in September 2019 for baseline, and of 21 (12 men, 9 women) who completed the following measurements in June 2020 (POST; immediately after rescinding the emergency state) and September 2020 (POST-4M; 4-months after rescinding the emergency state). Results at baseline indicate no significant differences in body compositions among fencing disciplines. We also confirmed no significant changes in body mass during the 1-year investigation period in either sex. There were no time-course changes in men's FFM and FM; however, time-course changes in women's FM were observed. Compared to the baseline, FM values were significantly higher at POST and then returned to baseline levels at POST-4M in women. In conclusion, the 2-month stay-at-home period due to COVID-19 negatively affected women's FM changes, but not their FFM or men's FM.

Beneficial Effects of Yoga Stretching on Salivary Stress Hormones and Parasympathetic Nerve Activity.

This study aimed to determine the effect of yoga stretching on salivary stress hormones and cardiac autonomic nervous system. To our knowledge, this study is the first to investigate changes in cardiac autonomic nervous system after yoga stretching. In this crossover design study, 10 adult men (age, 26.3 ± 2.5 years) without yoga experience participated in the rest and yoga trials for 90 min. Measurements were carried out before (pre), immediately (post), 60 min, and 120 min after rest or yoga stretching. Saliva samples were collected by chewing a sterile cotton ball at a frequency of 60 cycles per minute. Salivary cortisol and testosterone concentrations were measured using an enzyme-linked immunosorbent assay. With the subjects in the sitting position, heart rate variability was measured using pulse analyzer plus for 150 seconds. As regards rate changes, salivary testosterone level tended to increase (p = 0.088), testosterone/cortisol ratio significantly increased (p < 0.05), and cortisol level significantly decreased (p < 0.05) at 120 min after yoga stretching. The square root of the mean-squared differences of successive normal-to-normal intervals and natural logarithm high-frequency component, which are indicators of parasympathetic nerve activity, increased at 60 min (p < 0.05) and 120 min (p < 0.05) in the yoga trial, respectively. In conclusion, yoga stretching can enhance parasympathetic nerve activity and improve stress hormones. Therefore, yoga stretching may be useful to compensate for physical inactivity and increase life expectancy in the general population.

Tape stripping method is useful for the quantification of antimicrobial peptides on the human skin surface including the stratum corneum.

Antimicrobial peptides (AMPs) play an important role in innate immunity in human skin. It is known that AMPs mainly function in the stratum corneum. Therefore, AMP concentrations in the stratum corneum need to be precisely measured to clarify functional and physiological importance of AMPs in cutaneous defence. Tape stripping (TS) is a well-established method by which components in the stratum corneum can be collected. However, the usefulness of the TS method for measuring AMP concentration in human skin remains unclear. Therefore, we compared it with another popular method, skin rinsing, which had been established as a method for measuring AMP concentration in human skin. When investigated on healthy medial forearm using RNase 7, which is one of the typical AMPs, as an index, there was a significant positive correlation between RNase 7 concentrations measured by the TS method at adjacent forearm sites, demonstrating the reproducibility of the TS method. Next, a significant positive correlation was detected in RNase 7 concentrations measured using the TS and the skin rinsing method, indicating that the TS method is comparable to the skin rinsing method. Thus, we speculate that the TS method is useful for measuring AMP concentration in human skin.

Influence of acute high-intensity exercise on salivary nitric oxide levels.

This study, employing an exercise versus control crossover design, was conducted to investigate the influence of acute high-intensity exercise on salivary nitric oxide (NO) levels. Nine healthy males (aged 23.8 ± 1.4 years) performed ergometer exercise at 80%VO2peak for 60 min, whereas controls sat at rest for 60 min. Saliva samples were collected before (Pre: 0800 h) and after (Post 0-h: 0900 h, Post 1-h: 1000 h, Post 2-h: 1100 h, Post 3-h: 1200 h) the interventions. Salivary NO levels were determined by colorimetric assay. It was found that the salivary NO levels in controls were decreased (P < 0.05) at Post 0-h (-94 ± 15), Post 1-h (-80 ± 20), Post 2-h (-92 ± 34) and Post 3-h (-145 ± 39) relative to the Pre values. Under exercise conditions, salivary NO levels did not change after high-intensity ergometer exercise relative to the Pre values. Thus, the response of salivary NO levels appeared to differ between high-intensity ergometer exercise and inactivity, that exercise-related stress induces the production of salivary NO.

Assessment of Salivary Nitric Oxide Levels in Elite University Athletes in Japan: Findings From a Cross Sectional Study Design.

BACKGROUND: High-intensity exercise affects the level of salivary nitric oxide (NO) with an impact on oxidative stress such as a reactive nitrogen-oxide species. However, in athletes with high-intensity training, the relationship between salivary NO levels and oxidative stress is yet to be clear. Additionally, the association of salivary NO levels and the common health disorders of athletes is unknown. Thus, the aim of this cross-sectional study was to clarify the relationship between salivary NO levels and oxidative stress, and the health/medical disorders existing in elite class university athletes. METHODS: In 250 athletes (males, 151 and females, 99) from undergraduate levels of Japanese University, we investigated the relationship between levels of salivary NO and oxidative stress markers: derived reactive oxygen species (d-ROMs) and biological antioxidant potential (BAP), and also examined that whether salivary NO levels are associated with diseases. RESULTS: There were no significant association between the levels of salivary NO and oxidative stress markers (such as d-ROM and BAP). From the questionnaire, asthma was the most prevalent as evident from medical history of the athletes. Additionally, the salivary NO levels were higher (520 ± 43 µmol/L vs. 375 ± 13 µmol/L, P < 0.05) in the asthma group (n = 9) than in the non-asthma group (n = 241). We determined the optimal cut-off value (P = 0.019) of the salivary NO levels for asthma was 425 µmol/L, with a sensitivity of 88.9% and specificity of 61.8% (area under the curve (AUC), 0.73). CONCLUSIONS: Our results suggest that the high levels of salivary NO in trained university athletes in Japan may potentially predict asthma. And this salivary NO level is not associated with markers of oxidative stress and existing diseases in athletes studied here.

Yoga stretching for improving salivary immune function and mental stress in middle-aged and older adults.

Protection against age-related immune suppression is important in elderly individuals. This study determined the effect of yoga on mucosal immune function and mental stress. Saliva samples were collected from 23 adult women (age: 60.4 ± 10.4 years) before and after 90 minutes of yoga stretching or rest to measure secretory immunoglobulin A (SIgA), cortisol, and testosterone. The SIgA concentration and secretion rate were significantly higher after yoga than before (p < .05). The cortisol concentration and secretion rate were lower and testosterone secretion rate higher after yoga (p < .05). Yoga stretching can reduce stress and enhance mucosal immune function in elderly women.

Effects of High-Intensity Endurance Exercise on Epidermal Barriers against Microbial Invasion.

For athletes, preventing infectious disease on skin is important. Examination measurement of epidermal barriers could provide valuable information on the risk of skin infections. The aim of this study was to determine the effects of high-intensity endurance exercise on epidermal barriers. Six healthy adult males (age; 22.3 ± 1.6 years) performed bicycle exercise at 75%HRmax for 60 min from 18:30 to 19:30. Skin surface samples were measured 18:30 (pre), 19:30 (post), 20:30 (60 min), and 21:30 (120 min). Secretory immunoglobulin A (SIgA) and human ß-defensin 2 (HBD-2) concentrations were measured using an enzyme-linked immunosorbent assay (ELISA). SIgA concentration at pre was significantly higher than at post, 60 min and 120 min (p < 0.05). HBD-2 concentration at post and 120 min was significantly higher than at pre (p < 0. 05). Moisture content of the stratum corneum was significantly higher at post than at pre, 60 min, and 120 min (p < 0.05). On the chest, moisture content of the stratum corneum was significantly lower at 120 min than at pre (p < 0.05). The number of staphylococci was significantly higher at post than at pre (p < 0.05), and tended to be higher at 60 min than at pre on the chest (p = 0. 08). High-intensity endurance exercise might depress the immune barrier and physical barrier and enhance the risk of skin infection. On the other hand, the biochemical barrier increases after exercise, and our findings suggest that this barrier might supplement the compromised function of other skin barriers. Key pointsThe immune barrier and physical barrier might be depressed and the risk of skin infection might be enhanced by high-intensity endurance exercise.The biochemical barrier increases after high-intensity endurance exercise and might supplement the compromised function of other skin barriers.We recommend that athletes maintain their skin surface in good condition, for example, by showering immediately after sports activities and using moisturizers.

Effects of yoga exercise on salivary beta-defensin 2.

PURPOSE: Yoga stretching can be done comfortably and easily by beginners and older adults to compensate for lack of exercise or poor health maintenance. The aim of this study was to determine the effect of yoga stretching on mucosal immune functions, primarily human ß-defensin 2 (HBD-2) in saliva. METHODS: Fifteen healthy adults (age, 60.4 ± 8.0 years) participated in the study. Participants rested for 90 min on the first day and performed yoga for 90 min on the second day. Measurements were carried out before and after rest or yoga. Saliva samples were collected by chewing a sterile cotton at a frequency of 60 cycles per min. Salivary HBD-2 concentration was measured using an enzyme-linked immunosorbent assay. RESULTS: HBD-2 concentration after yoga stretching (165.4 ± 127.1 pg/mL) was significantly higher than that before yoga stretching (84.1 ± 63.4 pg/mL; p < 0.01). HBD-2 expression rate after yoga stretching (232.8 ± 192.9 pg/min) was significantly higher than that before yoga stretching (110.7 ± 96.8 pg/min; p < 0.01). HBD-2 concentration (p < 0.05) and HBD-2 expression rate (p < 0.01) at post on the second day (yoga) was significantly higher than that on the first day (rest). POMS score of anger-hostility was lower after yoga than before. CONCLUSIONS: Yoga stretching for 90 min can increase salivary HBD-2 expression in older adults. Therefore, yoga stretching might be useful for older adults and athletes to maintain their health.

Altered secretory immunoglobulin A on skin surface after intensive exercise.

The aim of this study was to determine the effects of high-intensity endurance exercise on skin immunity by estimating secretory immunoglobulin A (SIgA) and staphylococci on skin surface. Seven healthy adult men (age, 22.3 ± 2.0 years) performed bicycle exercise at 75% HRmax for 60 minutes from 2030 to 2130 hours. Secretory immunoglobulin A was obtained from 1 ml extraction liquids stirred with the microtube homogenizer in the open end of a polypropylene tube for 60 seconds. Secretory immunoglobulin A concentrations were measured using enzyme-linked immunosorbent assay. Staphylococci were harvested by pressed agar-based media against skin surface. Skin surface samples were collected from the chest and the forearm on the first day at 2030 hours (before rest, A1), 2130 hours (after rest, A2), and 2230 hours (after showering, A3); the next morning at 0700 hours (A4); on the second day at 2030 hours (before exercise, B1), 2130 hours (after exercise, B2), and 2230 hours (after showering, B3); and the next morning at 0700 hours (B4). Secretory immunoglobulin A concentration on the forearm was significantly lower at B2 (p < 0.05) and B3 (p < 0.05) than that at B1 and that on the chest at B1 tended to be higher compared with B2 (p = 0.084) and B3 (p = 0.075). The number of staphylococci was significantly higher at B2 than that at B1 (p < 0.01) and B4 (p < 0.01) on the forearm. We conclude that high-intensity endurance exercise might depress immune function and enhance infectious risk on skin surface. Coaches should encourage their athletes to take a shower and change into clean clothes immediately after sports activities and athletes should maintain a clean skin surface to decrease the infectious risk on skin surface.

Mucosal immune function comparison between amenorrheic and eumenorrheic distance runners.

This study examined the effects of amenorrhea on mucosal immune function and susceptibility to upper respiratory tract infection (URTI) in elite female distance runners. Based on their menstrual cycles during the prior year, 21 elite, collegiate, female distance runners were designated as eumenorrheic runners (ERs; n = 8; 19.9 ± 0.8 years) or amenorrheic runners (ARs; n n = 13; 20.0 ± 0.3 years). Resting saliva and blood samples were collected in the morning. The secretory immunoglobulin A (SIgA) concentration was measured using enzyme-linked immunosorbent assay. The SIgA secretion rate was calculated. Serum 17ß-estradiol concentrations and serum progesterone concentrations were measured using radioimmunoassay. Subjects reported the appearance of URTI symptoms (sore throat, headache, runny nose, coughing, or fever), if any, during the prior month. The serum estradiol concentration and salivary SIgA secretion rate were significantly lower for ARs than for ERs (p < 0.05). Serum progesterone concentration was not significantly different between groups. Higher frequencies of headache, runny nose, coughing, and fever were observed in ARs than in ERs. Results show that athletic amenorrhea with low estrogen might accelerate downregulation of mucosal immune function in athletes and enhance susceptibility to infection.