Efficacy of hydrotherapy treatment for the management of chronic low back pain

AIMS

The study investigated the influence of hydrotherapy method-based McKenzie and Williams among patients with non-specific low back pain (NSLBP).

METHODS

Semi-experimental pretest-posttest with a control group design trial was conducted at Health Service Center, Qazvin, Iran. Twenty-eight NSLBP patients (16 men and 12 women, age: 42.5 ± 7 years) were recruited. Hydrotherapy program developed based on McKenzie and Williams therapy was performed individually 3 days per week for 20 sessions. Therefore, the study compared a hydrotherapy group (based on McKenzie and Williams therapy) to a control group. Participants attended a hydrotherapy program under the supervision of a hydrotherapist. The Numeric Pain Rating Scale (NPRS), Roland-Morris Disability Questionnaire (RMDQ), and Straight Leg Raise Test (SLRT) were measured at the beginning, middle, and at the end of the 20 sessions to determine pain and functionality of the patient's improvement.

RESULTS

Overall, NPRS, RMDQ, and SLRT scores were improved in hydrotherapy group in the 10th session and 20th session compared with baseline (p ≤ 0.001) and control group (p ≤ 0.001). No difference in the treatment variables between the 10th session and the 20th session was observed (p > 0.05).

CONCLUSIONS

The results indicated that the NSLBP symptom was improved after 10 sessions of hydrotherapy program developed based on McKenzie and Williams therapy.

The Complex Interaction Between the Major Sleep Symptoms, the Severity of Obstructive Sleep Apnea, and Sleep Quality

Introduction: Little information exists in the general population whether clinical presentation phenotypes of obstructive sleep apnea (OSA) differ in terms of sleep quality and comorbidities. Aim: The purpose of our study was to assess possible differences between symptomatic and asymptomatic OSA patients concerning syndrome's severity, patients' sleep quality, and comorbidities. Subjects and methods: First, in a nationwide, stratified, epidemiological survey, 4,118 Cypriot adult participants were interviewed about sleep habits and complaints. In the second stage of the survey, 264 randomly selected adults underwent a type III sleep study for possible OSA. Additionally, they completed the Greek version of Pittsburgh Sleep Quality Index (Gr-PSQI), Epworth Sleepiness Scale (ESS), Athens Insomnia Scale (AIS), and Hospital Anxiety and Depression Scale (HADS). Results: From 264 enrolled participants, 155 individuals (40 females and 115 males) were first diagnosed with OSA. Among these 155 patients, 34% had ESS ≥ 10 and 49% AIS ≥ 6. One or both symptoms present categorized the individual as symptomatic (60%) and neither major symptom as asymptomatic (40%). There were no significant statistical differences (SSDs) between the two groups (symptomatic-asymptomatic) with regard to anthropometrics [age or gender; neck, abdomen, and hip circumferences; and body mass index (BMI)]. The two groups had no differences in OSA severity-as expressed by apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and mean oxyhemoglobin saturation (SaO₂)-and in cardiometabolic comorbidities. Symptomatic patients expressed anxiety and depression more often than asymptomatics (p < 0.001) and had poorer subjective sleep quality (Gr-PSQI, p < 0.001). According to PSQI questionnaire, there were no SSDs regarding hours in bed and the use of sleep medications, but there were significant differences in the subjective perception of sleep quality (p < 0.001), sleep efficiency (p < 0.001), duration of sleep (p = 0.001), sleep latency (p = 0.007), daytime dysfunction (p < 0.001), and finally sleep disturbances (p < 0.001). Conclusion: According to our data, OSA patients reporting insomnia-like symptoms and/or sleepiness do not represent a more severe phenotype, by the classic definition of OSA, but their subjective sleep quality is compromised, causing a vicious cycle of anxiety or depression.

Cold Water Swimming-Benefits and Risks: A Narrative Review

Cold water swimming (winter or ice swimming) has a long tradition in northern countries. Until a few years ago, ice swimming was practiced by very few extreme athletes. For some years now, ice swimming has been held as competitions in ice-cold water (colder than 5 °C). The aim of this overview is to present the current status of benefits and risks for swimming in cold water. When cold water swimming is practiced by experienced people with good health in a regular, graded and adjusted mode, it appears to bring health benefits. However, there is a risk of death in unfamiliar people, either due to the initial neurogenic cold shock response or due to a progressive decrease in swimming efficiency or hypothermia.

Exergaming and Aquatic Exercises Affect Lung Function and Weight Loss in Obese Children

We investigated the effect of exergames and aquatic exercises on lung function and weight loss in obese children. Sixty-one obese male primary-school children were randomly allocated to video game, aquatic exercise, and control groups. Lung functions and anthropometric variables were measured before and after the intervention and after one month (follow-up). In the video game group, an Xbox Kinect game was played for 60 min during three sessions a week. The aquatic aerobic exercise was performed three times per week and consisted of a warm-up, main exercises, and a cool down phase. For the video game group, there was a significant reduction in body weight between (i) pre- and (ii) post-intervention and follow-up. In the aquatic exercise group, there was a significant reduction in body weight between pre- and post-intervention and between pre-intervention and follow-up. Both exercise groups improved the waist/hip ratio index compared to the control group. Forced vital capacity was significantly improved in the follow-up of the video game group and the aquatic exercise group compared to the control group. A significant improvement was found in forced expiratory volume in the first second at post-intervention and follow-up in the video game and the aquatic exercise groups. Exergames and aquatic exercises improved weight loss and lung function in obese children.

Predictive Performance Models in Long-Distance Runners: A Narrative Review

Physiological variables such as maximal oxygen uptake (VO₂max), velocity at maximal oxygen uptake (vVO₂max), running economy (RE) and changes in lactate levels are considered the main factors determining performance in long-distance races. The aim of this review was to present the mathematical models available in the literature to estimate performance in the 5000 m, 10,000 m, half-marathon and marathon events. Eighty-eight articles were identified, selections were made based on the inclusion criteria and the full text of the articles were obtained. The articles were reviewed and categorized according to demographic, anthropometric, exercise physiology and field test variables were also included by athletic specialty. A total of 58 studies were included, from 1983 to the present, distributed in the following categories: 12 in the 5000 m, 13 in the 10,000 m, 12 in the half-marathon and 21 in the marathon. A total of 136 independent variables associated with performance in long-distance races were considered, 43.4% of which pertained to variables derived from the evaluation of aerobic metabolism, 26.5% to variables associated with training load and 20.6% to anthropometric variables, body composition and somatotype components. The most closely associated variables in the prediction models for the half and full marathon specialties were the variables obtained from the laboratory tests (VO₂max, vVO₂max), training variables (training pace, training load) and anthropometric variables (fat mass, skinfolds). A large gap exists in predicting time in long-distance races, based on field tests. Physiological effort assessments are almost exclusive to shorter specialties (5000 m and 10,000 m). The predictor variables of the half-marathon are mainly anthropometric, but with moderate coefficients of determination. The variables of note in the marathon category are fundamentally those associated with training and those derived from physiological evaluation and anthropometric parameters.

Prediction of Somatotype from Bioimpedance Analysis in Elite Youth Soccer Players

The accurate body composition assessment comprises several variables, causing it to be a time consuming evaluation as well as requiring different and sometimes costly measurement instruments. The aim of this study was to develop new equations for the somatotype prediction, reducing the number of normal measurements required by the Heath and Carter approach. A group of 173 male soccer players (age, 13.6 ± 2.2 years, mean ± standard deviation; body mass index, BMI, 19.9 ± 2.5 kg/m²), members of the academy of a professional Italian soccer team participating in the first division (Serie A), participated in this study. Bioelectrical impedance analysis (BIA) was performed using the single frequency of 50 kHz and fat-free mass (FFM) was calculated using a BIA specific, impedance based equation. Somatotype components were estimated according to the Heath-Carter method. The participants were randomly split into development (n = 117) and validation groups (n = 56). New anthropometric and BIA based models were developed (endomorphy = −1.953 − 0.011 × stature²/resistance + 0.135 × BMI + 0.232 × triceps skinfold, R² = 0.86, SEE = 0.28; mesomorphy = 6.848 + 0.138 × phase angle + 0.232 × contracted arm circumference + 0.166 × calf circumference − 0.093 × stature, R² = 0.87, SEE = 0.40; ectomorphy = −5.592 − 38.237 × FFM/stature + 0.123 × stature, R² = 0.86, SEE = 0.37). Cross validation revealed R² of 0.84, 0.80, and 0.87 for endomorphy, mesomorphy, and ectomorphy, respectively. The new proposed equations allow for the integration of the somatotype assessment into BIA, reducing the number of collected measurements, the instruments used, and the time normally required to obtain a complete body composition analysis.

Physical Activity and Sociodemographic Profile of Brazilian People during COVID-19 Outbreak: An Online and Cross-Sectional Survey

The Coronavirus Disease 2019 (COVID-19) outbreak has created an unprecedented impact on global health and further aggravated the physical inactivity pandemic. For this reason, the understanding of sociodemographic variables in the context of physical activity levels are important for the field of public health in order to assist in relevant public health decisions. Our main aim was to characterize sociodemographic variables and physical activity levels and their association with COVID-19 aspects. We applied an online Google survey with closed questions in Brazilian people of different age and regions, both sexes and physical activity levels (n = 1.726). Our main results were that participants who had symptoms of COVID-19 had the highest percentage of level 1 of physical activity (the lowest level according to the classification used) and those who showed no symptoms had the highest percentage of levels 2 and 3 of physical activity; that is, close to the light/moderate levels of physical activity. This cross-sectional study in the Brazilian population provided important sociodemographic data and COVID-19 aspects regarding the level of physical activity. It is possible to assume that the regular practice of physical activity could positively impact health status and quality of life and be a tool in the field of public health to cope (from a physical and mental point of view) with disease scenarios that require quarantine.

Performance in 100-km Ultramarathoners-At Which Age, It Reaches Its Peak?

Nikolaidis, PT and Knechtle, B. Performance in 100-km ultramarathoners-At which age, it reaches its peak? J Strength Cond Res 34(5): 1409-1415, 2020-The number of those participating in 100-km ultramarathon has increased over the past years; however, we have limited knowledge about performance trends in this sport, and particularly, the effect of age. The aim of this study was to analyze the age when women and men runners achieve their peak performance considering 1- and 5-year age group intervals, and examining all or the fastest (i.e., top 10) participants in each age group. We analyzed 370,051 athletes (i.e., 44,601 women and 325,450 men) who finished a 100-km ultramarathon between 1959 and 2016, and studied the age of peak performance using a second-order nonlinear regression analysis. The age of peak performance was 40-44 years in women and 45-49 years in men when all finishers were analyzed, whereas it was 30-34 years in women and 35-39 years in men when the top 10 finishers were considered in 5-year age groups. When we analyzed finishers in 1-year age groups, we found the age of peak performance at 41 years in women and 45 years in men considering all finishers, and at 39 years in women and 41 years in men considering the top 10 finishers. In conclusion, the age of peak performance was younger in women than in men, which might reflect the overall younger age of women participants than men. Compared with previous studies, we observed the peak performance at an age older by ∼10 years, which could be attributed to an increase of finishers' age across calendar years. Because the knowledge of the age of peak performance is unique for each sport, coaches and fitness trainers might benefit from the findings of this study in the long-term training of their athletes.

A descriptive study on health, training and social aspects of adults that participated in ultra endurance running as youth athletes

BACKGROUND

Ultra running is popular among youth athletes (< 19 years of age), with an exponential increase in participation over the last years. If running extreme distances during such a young age has implications in adulthood is currently unknown.

METHODS

We performed a retrospective survey study investigating adults that participated in ultra endurance running as youth athletes, describing running history, health and social data. Seventyeight participants (mean age of 38.0±12.0) completed the survey.

RESULTS

Most participants were male (83.3%), white Caucasians (92.3%), originated from the USA (89.7%), were married (57.7%), with no children (52.6%), and had a university degree (79.5%). Age at first ultra was 16.1 years (± 2.3), with an average number of 3.7 ultras (± 5.5), predominantly over 50 km (1.5 ± 3.3) and 50 miles (1.21 ± 2.0). Musculoskeletal injuries occurred in 23.1% of youth athletes, and stress fractures in 6.4%. The main reason to stop running ultras were injuries (28.6%). The majority (93.6%) of youth athletes continued running into adulthood; however only 26.9% continued running ultras. Training load was significantly (p<0.001) reduced from 57.4±33.2 km/w in youth athletes to 30.1±36.8 km/w in adulthood. High risk of exercise addiction was observed in 11.5%.

CONCLUSIONS

Most participants reported positive effects from running ultras as youth athletes (69.2%), but only 20.5% would recommend youth athletes participation in ultras. It may be prudent to be cautious about allowing general participation of youth athletes in ultra running until further evidence of its long-term effects on health and safety is available.

Effects of Plyometric Jump Training on Vertical Jump Height of Volleyball Players: A Systematic Review with Meta-Analysis of Randomized-Controlled Trial

This meta-analysis aimed to assess the effects of plyometric jump training (PJT) on volleyball players' vertical jump height (VJH), comparing changes with those observed in a matched control group. A literature search in the databases of PubMed, MEDLINE, Web of Science, and SCOPUS was conducted. Only randomized-controlled trials and studies that included a pre-to-post intervention assessment of VJH were included. They involved only healthy volleyball players with no restrictions on age or sex. Data were independently extracted from the included studies by two authors. The Physiotherapy Evidence Database scale was used to assess the risk of bias, and methodological quality, of eligible studies included in the review. From 7,081 records, 14 studies were meta-analysed. A moderate Cohen's d effect size (ES = 0.82, p <0.001) was observed for VJH, with moderate heterogeneity (I² = 34.4%, p = 0.09) and no publication bias (Egger's test, p = 0.59). Analyses of moderator variables revealed no significant differences for PJT program duration (≤8 vs. >8 weeks, ES = 0.79 vs. 0.87, respectively), frequency (≤2 vs. >2 sessions/week, ES = 0.83 vs. 0.78, respectively), total number of sessions (≤16 vs. >16 sessions, ES = 0.73 vs. 0.92, respectively), sex (female vs. male, ES = 1.3 vs. 0.5, respectively), age (≥19 vs. <19 years of age, ES = 0.89 vs. 0.70, respectively), and volume (>2,000 vs. <2,000 jumps, ES = 0.76 vs. 0.79, respectively). In conclusion, PJT appears to be effective in inducing improvements in volleyball players' VJH. Improvements in VJH may be achieved by both male and female volleyball players, in different age groups, with programs of relatively low volume and frequency. Though PJT seems to be safe for volleyball players, it is recommended that an individualized approach, according to player position, is adopted with some players (e.g. libero) less prepared to sustain PJT loads.

Performance Differences Between the Sexes in the Boston Marathon From 1972 to 2017

Knechtle, B, Di Gangi, S, Rüst, CA, and Nikolaidis, PT. Performance differences between the sexes in the Boston Marathon from 1972 to 2017. J Strength Cond Res 34(2): 566-576, 2020-The differences between the sexes in marathon running have been investigated for athletes competing in world class-level races. However, no information exists about changes in these differences since the first women officially began participating in marathons. We examined trends in participation and performance in the Boston Marathon from 1972 to 2017. A total of 371,250 different finishers (64% men) and 553,890 observations-with 187,998 (34%) being of women and 365,892 (66%) of men-were analyzed using Generalized Additive Mixed Models. The number of finishers increased over the years. Female participation started at 2.81% in 1972 and reached 45.68% in 2016. Considering all finishers, men (03:38:42 ± 00:41:43 h:min:s) were overall faster than women (04:03:28 ± 00:38:32 h:min:s) by 10.7%. Average performance worsened over the years, but the differences between the sexes decreased. For the annual 10 fastest runners, performance improved with a decrease in speed difference (18.3% overall, men: 02:13:30 ± 00:04:08 h:min:s vs. women: 02:37:42 ± 00:17:58 h:min:s). For the annual winners, performance improved with a decrease in speed difference (15.5% overall, men: 02:10:24 ± 00:03:05 h:min:s vs. women: 02:30:43 ± 00:11:05 h:min:s). For the near-elite finishers from the 21st to the 100th place and from the 101st to the 200th place, women's performance improved with a decrease in the difference to men. In summary, the trend in performance over the years depended on the methodological approach (i.e., all vs. annual 10 fastest finishers vs. annual winners), but the difference between the sexes decreased in all instances. Although men were 10.7% faster than women, the fastest men (i.e., top 10 and winners) increased the gap between men and women by an average of 18.3% for the annual 10 fastest and 15.5% for the annual winners.

Effects of a 30 min nap opportunity on cognitive and short-duration high-intensity performances and mood states after a partial sleep deprivation night

This study evaluated the effects of partial-sleep-deprivation (SDN) and a 30 min nap opportunity on physical and cognitive performances and mood states. Fourteen physically active students (BMI = 232.8 ± 0.4 kg/m²) performed the reaction time, the number cancellation (i.e., assessing vigilance) and the 5-m shuttle run tests and responded to the Profile of Mood States (POMS-f) questionnaire at 18h00 after a normal-sleep (NSN) and a SDN) and after two nap conditions (Nap and no-Nap) realized between 13h00 and 13h30. Vigilance and the reaction time were better after Nap compared to no-Nap opportunity following NSN and SDN and during NSN compared to SDN only during no-Nap. Total and peak distance during the 5-m shuttle run test were higher and the fatigue index was lower during Nap compared to no-Nap condition after NSN and SDN and during NSN compared to SDN during Nap and no-Nnap. Anxiety, fatigue, confusion, and depression were lower and vigour was higher during Nap compared to no-Nap after NSN and SDN and during NSN compared to SDN during Nap and no-Nap. In conclusion, a 30-min of nap opportunity helps to overcome the negative effect of SDN on mood states as well as physical and cognitive performances.

Breaking the athletics world record in the 100 and 400 meters: an alternative method for assessment

BACKGROUND

The top 10 athletes in the International Association of Athletic Federations in 100-m and 400-m ranking for each sex were assessed for their history of race times before achieving their personal record (PR). The main goal of this study was to create a new method for optimal performance improvement rate assessment for coaches and athletes aiming the World Record.

METHODS

The difference between PR ('current' season) and the best race time in the last season was defined as the first season improvement rate (1-SIR), whereas the average improvement rate in the last and preceding seasons was the multi-season improvement rate (M-SIR). 1-SIR and M-SIR were calculated for each athlete.

RESULTS

The sex comparison for the 100 m event showed a significant difference in the M-SIR in favor of women. No statistical differences were identified for the 400 m event, with a trivial effect in both 1-SIR and M-SIR.

CONCLUSIONS

As a practical applicability, graph plots were designed to help verifying the improvement rate of athletes and to evaluate whether a long-term training strategy induced an acceptable performance improvement or whether some adjustments needed and check within the plots if the improvement rate is within the average of the top-10 athletes of their event.

Age-related participation and performance trends of children and adolescents in ultramarathon running

Participation and performance trends as well as the performance differences among sexes in ultra-endurance running have been well described in the adult population; however, less information on such trends existed in youth ultramarathoners. The aim of the present study was to investigate the age-related participation and performance trends of children and adolescent ultramarathoner runners. Data on runners, younger than 19 years of age, competing from 1960 to 2018 in distance-limited ultramarathons of 50 km, 100 km, 50 miles and 100 miles, were analysed. During this period, the number of ultramarathon participation increased, most notably among boys, most runners originated from Europe, and the 50- and 100-km race distances were the most popular. Overall, male runners were faster than female runners, except in the case of European and Oceanian origin, where girls were faster over the 50-km race. The fastest male runners originated from Africa and the fastest girls from Oceania, and the average running speed has largely decreased for both sexes over calendar years. In summary, this study was the first to report details on participation and performance trends in youth ultramarathoners competing in distance-limited ultramarathons.

Validity of Recreational Marathon Runners' Self-Reported Anthropometric Data

While studies on large samples of recreational runners have often relied on participants' self-reported height and body mass, the validity of these data have not been investigated for this population. Hence, this study sought to examine the validity of self-reported anthropometric measures among recreational marathon runners. Female (n = 32) and male (n = 135) recreational marathon runners were requested to estimate their body mass and height (and we calculated their self-reported body mass index [BMI]), after which we took actual measures of their body mass and height and calculated their actual BMI. Participants' self-reported values underestimated their actual body mass by 0.65 kg (p < .001, η² = 0.222) and their actual BMI by 0.35 kg ⋅ m^-2 (p < .001, η² = 0.245). There was a significant Assessment Method × Sex Interaction for both body mass (p = .019, η² = 0.033) and BMI (p = .017, η² = 0.034), as women underestimated body mass values more than men. Participants overestimated their height by 0.44 cm (p < .001, η² = 0.075), but the interaction of sex and assessment method for height was not statistically significant. Underestimates of body mass correlated with marathon racing speed (r = .24, p = .006) and body fat percentage (r = -.29, p = .001) in men, but not in women (p > .05). The disagreement between self-reported and measured anthropometric data in the present sample was lower than has been previously reported for the general population, suggesting that marathon runners may more accurately self-perceive and/or report their anthropometric characteristics. These findings are of practical value for health professionals and researchers (e.g., nutritionists and exercise physiologists) questionnaires to recreational marathon runners.

Analysis of Cyclist's Drag on the Aero Position Using Numerical Simulations and Analytical Procedures: A Case Study

Background: Resistance acting on a cyclist is a major concern among the cycling fraternity. Most of the testing methods require previous training or expensive equipment and time-consuming set-ups. By contrast, analytical procedures are more affordable and numerical simulations are perfect for manipulating and controlling inputs. The aim of this case study was to compare the drag of a cyclist in the aero position as measured using numerical simulation and analytical procedures. Methods: An elite male cyclist (65 kg in mass and 1.72 m in height) volunteered to take part in this research. The cyclist was wearing his competition gear, helmet and bicycle. A three-dimensional model of the bicycle and cyclist in the aero position was obtained to run the numerical simulations. Computational fluid dynamics (CFD) and a set of analytical procedures were carried out to assess drag, frontal area and drag coefficient, between 1 m/s and 22 m/s, with increments of 1 m/s. The t-test paired samples and linear regression were selected to compare, correlate and assess the methods agreement. Results: No significant differences (t = 2.826; p = 0.275) between CFD and analytical procedures were found. The linear regression showed a very high adjustment for drag (R² = 0.995; p < 0.001). However, the drag values obtained by the analytical procedures seemed to be overestimated, even though without effect (d = 0.11). Conclusions: These findings suggest that drag might be assessed using both a set of analytical procedures and CFD.

The Effect of Vitamin D3 Supplementation on Hepcidin, Iron, and IL-6 Responses after a 100 km Ultra-Marathon

Deficiencies in iron and vitamin D are frequently observed in athletes. Therefore, we examined whether different baseline vitamin D₃ levels have any impact on post-exercise serum hepcidin, IL-6 and iron responses in ultra-marathon runners. In this randomized control trial, the subjects (20 male, amateur runners, mean age 40.75 ± 7.15 years) were divided into two groups: experimental (VD) and control (CON). The VD group received vitamin D₃ (10,000 UI/day) and the CON group received a placebo for two weeks before the run. Venous blood samples were collected on three occasions-before the run, after the 100 km ultra-marathon and 12 h after the run-to measure iron metabolism indicators, hepcidin, and IL-6 concentration. After two weeks of supplementation, the intervention group demonstrated a higher level of serum 25(OH)D than the CON group (27.82 ± 5.8 ng/mL vs. 20.41 ± 4.67 ng/mL; p < 0.05). There were no differences between the groups before and after the run in the circulating hepcidin and IL-6 levels. The decrease in iron concentration immediately after the 100-km ultra-marathon was smaller in the VD group than CON (p < 0.05). These data show that various vitamin D₃ status can affect the post-exercise metabolism of serum iron.

The influence of chlorine in indoor swimming pools on the composition of breathing phase of professional swimmers

OBJECTIVES

Swimming is one of the most popular forms of physical activity. Pool water is cleaned with chlorine, which - in combination with compounds contained in water - could form chloramines and trichloromethane in the swimmer's lungs. The aim of the present study was to examine the effect of swimming training in an indoor pool on the composition of swimmers' respiratory phase metabolomics, and develop a system to provide basic information about its impact on the swimmer's airway mucosa metabolism, which could help to assess the risk of secondary respiratory tract diseases i.e. sport results, condition, and health including lung acute and chronic diseases).

DESIGN

A group of competitive swimmers participated in the study and samples of their respiratory phase before training, immediately after training, and 2 h after training were assessed.

METHODS

Sixteen male national and international-level competitive swimmers participated in this study. Respiratory phase analysis of the indoor swimming pool swimmers was performed. Gas chromatography combined with mass spectrometry (GCMS) was used in the measurements. All collected data were transferred to numerical analysis for trends of tracking and mapping. The breathing phase was collected on special porous material and analyzed using GCMS headspace.

RESULTS

The obtained samples of exhaled air were composed of significantly different metabolomics when compared before, during and after exercise training. This suggests that exposition to indoor chlorine causes changes in the airway mucosa.

CONCLUSION

This phenomenon may be explained by occurrence of a chlorine-initiated bio-reaction in the swimmers' lungs. The obtained results indicate that chromatographic exhaled gas analysis is a sensitive method of pulmonary metabolomic changes assessment. Presented analysis of swimmers exhaled air indicates, that indoor swimming may be responsible for airway irritation caused by volatile chlorine compounds and their influence on lung metabolism.

The effect of vitamin D supplementation on serum total 25(OH) levels and biochemical markers of skeletal muscles in runners

Background

The beneficial adaptation of skeletal muscle function to strenuous exercise is partially attributable to the improvement of vitamin D status. The present study aimed to evaluate the effects of a 3-week vitamin D supplementation on serum 25(OH)D levels and skeletal muscle biomarkers (i.e. troponin, myoglobin, creatine kinase and lactic dehydrogenase) of endurance runners.

Methods

A double-blind placebo-controlled study design was used and vitamin D supplementation was compared to a non-treatment control group. Twenty-four runners, competitors of the ultra-marathons held during the National Running Championships, were randomly assigned into two groups supplemented with the dose of 2000 IU vitamin D or placebo for three weeks. All subjects participated in three exercise protocols: (a) incremental exercise test (to determine the maximum oxygen uptake and the intensity of eccentric exercise), (b) eccentric exercise before and (c) after two dietary protocols. Venous blood samples were drawn at rest, immediately after the exercise and after 1 h and 24 h of recovery in order to estimate serum 25(OH)D levels, skeletal muscle biomarkers, proinflammatory cytokines and tumor necrosis factor-alpha (TNF-α) levels. A two-way ANOVA was used to test main effects and their interactions and Pearson correlation coefficients were analyzed to determine the effects of inter-variable relationships.

Results

Significant differences between pre- and post-intervention in baseline 25(OH)D levels were observed (34.9 ± 4.7 versus 40.3 ± 4.9 ng/ml, p = 0.02) in supplemented group. A higher post intervention 25(OH)D level was observed after vitamin D diet compared to placebo (40.3 ± 4.9 versus 31.8 ± 4.2 ng/mL, respectively; p < 0.05). The vitamin D supplementation decreased post-exercise (TN max) and 1 h post-exercise troponin (p = 0.004, p = 0.03, respectively), 1 h post-exercise myoglobin concentration (p = 0.01) and TNF-α levels(p < 0.03). 24 h post exercise creatine kinase activity was significantly lower in supplemented group compared to placebo (p < 0.05). A negative correlation was observed between post exercise 25(OH)D levels and myoglobin levels (r = − 0.57; p = 0.05), and 25(OH)D levels and TNFα (r = − 0.58; p = 0.05) in vitamin D supplemented group.

Conclusions

Three weeks of vitamin D supplementation had a positive effect on serum 25(OH)D levels in endurance trained runners and it caused a marked decrease in post-exercise biomarkers levels. We concluded that vitamin D supplementation might play an important role in prevention of skeletal muscle injuries following exercise with eccentric muscle contraction in athletes.

Can the Performance Gap between Women and Men be Reduced in Ultra-Cycling?

This study examined a large dataset of ultra-cycling race results to investigate the sex difference in ultra-cycling performance (100 to 500 miles) according to age and race distance. Data from the time period 1996-2018 were obtained from online available database of the ultra-cycling marathon association (UMCA), including distance-limited ultra-cycling races (100, 200, 400, and 500 miles). A total of 12,716 race results were analyzed to compare the performance between men and women by calendar year, age group (18-34, 35-44, 45-59, and 60+ years), and race distance. Men were faster than women in 100 and 200 mile races, but no sex differences were identified for the 400 and 500 mile races. The performance ratio (average cycling speed_men/average cycling speed_women) was smaller in the 200 mile races compared to the 100 mile races and remained stable in the 400 and 500 mile races. In all race distances, the difference in average cycling speed between women and men decreased with increasing age. The gender gap in performance was closed in several distance-limited ultra-cycling races, such as the 400 and 500 mile races.

Subcutaneous Adipose Tissue in Female Volleyball Players: Is It Related with Performance Indices?

Background and objectives: The aim of the present study was to examine subcutaneous adipose tissue distribution in female volleyball players with regards to (a) variation by anatomical site, (b) differences among age groups and playing positions, and (c) physiological characteristics associated with performance. Materials and Methods: Participants were adolescent (n = 89, age 15.6 ± 0.9 years, mean ± standard deviation) and adult female volleyball players (n = 78, 24.8 ± 5.3 years), who performed a series of anthropometric and performance tests including skinfold thickness in 10 sites, Abalakov jump (AJ) and handgrip test (HG). Results: Chin had the smallest thickness, and iliac crest and abdomen the largest. The largest correlations of skinfold thickness were shown with regards to AJ ad HG. Coefficient of variations in skinfold thickness correlated with performance indices with small magnitude. Triceps and chin were the most frequent predictors of performance indices. The anatomical site of skinfold was near the active muscle groups related to performance in HG. Conclusions: In conclusion, performance indices such AJ and HG were related with thickness of specific skinfolds and with the variation of thickness by anatomical site (i.e., the less the variation, the better the performance). Considering the relevance of specific skinfolds (e.g., triceps and chin) for performance, their further use would be recommended for purposes of training monitoring, volleyball players’ selection and talent identification.

Age-related differences in torque in angle-specific and peak torque hamstring to quadriceps ratios in female soccer players from 11 to 18 years old: Α Cross-sectional study

The aim of this study was to evaluate and compare the hamstring (H) and quadriceps (Q) strength, bilateral difference and balance ratios in female soccer players. Ninety-three athletes from three age groups: under 13 (U13), 15 (U15) and 18 (U18) participated in the study performing isokinetic tests to measure peak torque, total work, average power and torque at 30º of thigh muscles. Conventional strength balance ratios, angle-specific balance ratio and bilateral strength difference were evaluated. There was bilateral strength difference for extensor muscles total work (p = 0.02) in U13 and flexor muscles peak torque (p = 0.02) in U15. All variables were superior in U15 than U13 (p <.05). There was no strength difference between U15 and U18. Balance ratios did not differ between sides or age groups. The study showed that although peak torque values were higher in U15 than in U13, balance ratios were similar.

Effect of Angle of View and Partial Sleep Deprivation on Distance Perception

The present study aimed to investigate the effects of intensive effort on egocentric distance perception according to different angles of view after sleep deprivation at the beginning (SDB) or at the end (SDE) of the night and after a normal sleep night (NNS). Ten male students soccer players (age 22.8 ± 1.3 years; body mass 72.0 ± 10.4 kg; body height 180.0 ± 3.0 cm) performed a repeated cycling (RS) exercise (10 × 6 s maximal cycling with 24 s in between) after SDB, SDE, and NNS. They were asked to estimate three distances (i.e. 15, 25, and 35 m) before and after RS from different angles of view [i.e. in front (0°) and in side (45° left and 45° right)]. For 35 m, distance estimation was better during NNS compared to SDB and SDE for the front and the two side angles either before or after RS (p < 0.05). Concerning 25 m, distance estimation was better after compared to before RS for the front angle during the NNS session (p < 0.05). For 15 m, distance estimation was better during NNS than SDB and SDE for the front and both side angles after RS (p < 0.05). We concluded that partial sleep deprivation negatively affected the estimation of the egocentric distance for the three angles of view either at rest or after RS exercise.