The effect of air pollution on diurnal variation of performance in anaerobic tests, cardiovascular and hematological parameters, and blood gases on soccer players following the Yo-Yo Intermittent Recovery Test Level-1

Air pollution, a worthy opponent? How pollution levels impair athlete performance across physical, technical, and cognitive domains

INTRODUCTION

Air pollution is a global issue known to effect on human health and performance. In the context of highly skilled athletes, the influence of air pollution on players' physical and technical abilities are established, yet its effects on cognitive performance have received little consideration. This study aims to address this research gap by comprehensively examining the influence of air pollution on the performance of highly skilled athletes using a holistic approach, including both the athlete's brain and body.

METHODS

Between 2016 and 2022, a total of 799 soccer players (578 males, 221 females) belonging to a German professional first division club were measured on a battery of performance assessments, including physical, technical, and cognitive tests. The performance data were combined with the average daily concentration of three pollutants: PM10, O3 and NO2.

RESULTS

Increased levels of PM10 and O3 were primarily associated with decreased physical and technical performance, including slower sprinting times, impaired change of direction and worse speed and accuracy in the technical assessment. For instance, if the assessment test was held when PM10 levels were at 20 μg/m3, players ran an average 22 ms slower on the 30 m sprint test, 36 ms slower on the change of direction test and showed a 1 % decrease in accuracy on the technical assessment (p < .001). Furthermore, higher concentrations of NO2 negatively impacted cognitive performance across four separate tests of athletes' executive functions (p < .05).

CONCLUSION

By encompassing physical, technical, and cognitive assessments, this study highlights the multifaceted nature of performance impairments resulting from air pollution exposure in a population characterized by have exceptional abilities across all three domains. These findings underscore the widespread impact of pollution on a diverse sample of athletes and emphasize the need to consider air pollution in the broader context of its effects on human health and the environment.

The Effect of Environmental Disasters on Endocrine Status, Hematology Parameters, Body Composition, and Physical Performance in Young Soccer Players: A Case Study of the Aral Sea Region

The Aral Sea region (Uzbekistan) is infamous because of the ecological disaster characterized by the disappearance of the Aral Sea due to excessive uncontrolled water intake for agriculture needs. A new desert occurrence, soil and climate aridization led to pesticide and toxic metals environment pollution. The impact of environmental conditions in some areas of Uzbekistan on the health of soccer players is not as noticeable as, for example, the effectiveness of training, so it is not widely discussed in scientific papers. The aim of the present study was to study the features of endocrine status, hematology parameters (e.g., red blood cells (RBC) and hemoglobin (Hb)), and their influence on body composition and physical fitness performance in local young soccer players of the Aral Sea region as the territory of ecological disaster. The study involved 60 male soccer players aged from 18 to 22 years. Participants were divided into two groups: the experimental group (EG), which consisted of 30 soccer players living on the territory of the Aral ecological disaster region, and the control group (CG), which included 30 soccer players, natives of the ecologically favorable region of Uzbekistan. All volunteers had anthropometric measurements, concentrations of insulin-like growth factor-1 (IGF-1), total testosterone (TT), estradiol (E2), cortisol (C), RBC, and Hb count. Moreover, Yo-Yo Intermittent Recovery Test Level 1 (YYIRT1) and professional skills tests such as dribbling shuttle test (DSt) and goal accuracy test (GAt) were assessed. When comparing the CG group to the EG group, it was observed that the EG group exhibited statistically significantly reduced levels of TT and E2 (p < 0.05). No significant statistical difference was observed between the two groups in terms of IGF-1 and C (p > 0.05). Regarding hematological parameters, Hb, Ht, and mean corpuscular volume (MCV) were found to be significantly lower in the EG compared with the CG (p < 0.05). Moreover, the distance covered in the YYIR1 test was found to be significantly lower in soccer players within the EG compared with the CG (p < 0.05). Additionally, it was determined that there was no significant difference between the groups in terms of DSt and GAt values (p > 0.05). Lastly, significant differences were observed between the EG and CG in terms of anthropometric characteristics (diameters, skinfold, and somatotype profile) (p < 0.05). The present study showed that the changes in evaluated characteristics might result from the complex influence of endocrine-disrupting chemicals, the content of which is high in the environment of the Aral Sea region. The results obtained may help monitor the health of athletes living in an environmentally unfriendly environment.

Time of the day of exercise impact on cardiovascular disease risk factors in adults: a systematic review and meta-analysis

OBJECTIVES

To compare the effect of a single bout of morning vs. evening exercise on cardiovascular risk factors in adults.

DESIGN

Systematic review and meta-analysis.

METHODS

A systematic search of studies was conducted using PubMed and Web of Science from inception to June 2022. Selected studies accomplished the following criteria: crossover design, acute effect of exercise, blood pressure, blood glucose, and/or blood lipids as the study's endpoint, a washout period of at least 24 h, and adults. Meta-analysis was performed by analyzing: 1) separated effect of morning and evening exercise (pre vs. post); and 2) comparison between morning and evening exercise.

RESULTS

A total of 11 studies were included for systolic and diastolic blood pressure and 10 studies for blood glucose. Meta-analysis revealed no significant difference between morning vs. evening exercise for systolic blood pressure (g ∆ = 0.02), diastolic blood pressure (g ∆ = 0.01), or blood glucose (g ∆ = 0.15). Analysis of moderator variables (age, BMI, sex, health status, intensity and duration of exercise, and hour within the morning or evening) showed no significant morning vs. evening effect.

CONCLUSIONS

Overall, we found no influence of the time of the day on the acute effect of exercise on blood pressure neither on blood glucose.

A Review on Climate, Air Pollution, and Health in North Africa

PURPOSE OF REVIEW

The aim of this review is to summarize and provide clear insights into studies that evaluate the interaction between air pollution, climate, and health in North Africa.

RECENT FINDINGS

Few studies have estimated the effects of climate and air pollution on health in North Africa. Most of the studies highlighted the evidence of the link between climate and air pollution as driving factors and increased mortality and morbidity as health outcomes. Each North African country prioritized research on a specific health factor. It was observed that the health outcome from each driving factor depends on the studied area and data availability. The latter is a major challenge in the region. As such, more studies should be led in the future to cover more areas in North Africa and when more data are available. Data availability will help to explore the applicability of different tools and techniques new to the region. This review explores studies related to climate and air pollution, and their possible impacts on health in North Africa. On one hand, air quality studies have focused mainly on particulate matter exceedance levels and their long-term exposure impacts, namely, morbidity and mortality. The observed differences between the various studies are mainly due to the used exposure-response function, the studied population, background emissions, and natural emission from the Sahara Desert that characterize the region. On the other hand, climate studies have focused primarily on the impact of heat waves, vector-borne disease, and mental disorders. More than half of these studies have been on leishmaniasis disease. The review revealed unbalanced and insufficient research on health impacts from air pollution episodes and climate extremes across the region.

The Acute Effects of Exercising in Air Pollution: A Systematic Review of Randomized Controlled Trials

BACKGROUND

The acute effects of air pollution (AP) exposure during physical activity have been studied. However, comprehensive systematic reviews are lacking, particularly regarding moderate-to-vigorous physical activity (MVPA).

OBJECTIVE

Our objective was to determine the acute health- and exercise-related effects of AP exposure during a bout of MVPA in healthy individuals.

METHODS

We searched for randomized controlled trials in MEDLINE, Embase, Cochrane CENTRAL, SPORTDiscus, Agricultural and Environmental Science Database, ClinicalTrials.gov, International Standard Randomised Controlled Trial Number Registry, and the World Health Organization (WHO) International Clinical Trials Registry Platform up to July 2020 without language or date restrictions. Studies including healthy subjects engaging in a bout of MVPA while exposed to one or more of the following air pollutants were eligible: particulate matter, black carbon, carbon monoxide, nitrogen dioxide, ozone, diesel exhaust, and traffic-related air pollution (TRAP). Main outcome measures were markers of pulmonary function, symptoms, cardiovascular function, cognitive function, systemic inflammation, and exercise response. The evidence was synthesized by vote counting based on direction of effect.

RESULTS

In total, 53 studies were included in the systematic review. Studies employed a heterogeneous mix of exercise protocols, AP interventions, and measured outcomes. Pooled results suggest ozone exposure during MVPA has an adverse effect on pulmonary function (100% [95% confidence interval (CI) 88-100], p < 0.001; high-certainty evidence) and reported symptoms (88% [95% CI 69-96], p < 0.001; low-certainty evidence). The effect of exposure to carbon monoxide, nitrogen dioxide, small engine exhaust, or diesel exhaust during MVPA on health- and exercise-related outcomes is uncertain because of insufficient evidence and the low to very low certainty of available evidence.

DISCUSSION

The evidence is strongest for ozone, exposure to which generally induced a reduction in pulmonary function and increased symptoms during MVPA. The research related to other outcome domains remains inconclusive. Although long-term exposure to AP is proven to be hazardous, the evidence for healthy individuals to forgo MVPA during periods of high (non-ozone) pollution remains weak.

TRIAL REGISTRATION

Retrospectively registered in PROSPERO (CRD42020188280) on 10 July 2020.

Post-match recovery profile of leukocyte cell subsets among professional soccer players

This study assessed the impact of cumulative match time on the distribution of CD45+ cell subtests in the capillary blood of professional soccer players. Twenty-two males (aged 18-30 years) took part in the 36-week study. Participants playing up to 540 in cumulative match time and less than 30 min in each single match during the observation period formed the control group. White blood cell (WBC) phenotyping and creatine kinase (CK) plasma activity analyses were performed. Also, counts for WBC subsets were determined. No significant differences in the hematological parameters or lymphocyte and NK cell percentages were observed between the control and study groups. Changes in the T cell percentage were significant during weeks 11 and 30 and in Th and Tc cell percentages during weeks 2 and 26. Significant correlations were found between the cumulative match time and Th, NK, and B cell percentages; monocyte counts; and CK activity in the control group. However, for the study group, correlations were found between cumulative match time and Th, Tc, and B cell percentages; CK activity; and the CK ratio. Our study suggests that the distribution of CD45+ cells might be a useful tool for monitoring the immune status of professional soccer players.

Reliability and time-of-day effect on measures of change of direction deficit in young healthy physical education students

This study aimed to examine the reliability and the time-of-day effect of the 505 change of direction (CoD), 10-m sprint, and change of direction deficit test (CoDD). At two different time of days, 39 young diurnally active physical education male students performed different physical tests: 505 CoD, and sprint tests. Measurements were taken at two separate testing sessions, i.e. in the morning (07:00-08:30 h) and early evening (17:00-18:30 h) in a randomized and counter-balanced setting on nonconsecutive days in 21 of them (21.5 ± 1.5 y of age). The results showed that the 505 CoD test, 10-m sprint, and CoDD performances were a reliable test, and performances were better in the evening the 505 CoD, 10-m sprint, and CoDD testing provided reliable and sensitive scores. In addition, phase 2 showed that CoD, speed, and CoDD are affected by the time of day.

Respiratory Effects of Exposure to Traffic-Related Air Pollutants During Exercise

Traffic-related air pollution (TRAP) is increasing worldwide. Habitual physical activity is known to prevent cardiorespiratory diseases and mortality, but whether exposure to TRAP during exercise affects respiratory health is still uncertain. Exercise causes inflammatory changes in the airways, and its interaction with the effects of TRAP or ozone might be detrimental, for both athletes exercising outdoor and urban active commuters. In this Mini-Review, we summarize the literature on the effects of exposure to TRAP and/or ozone during exercise on lung function, respiratory symptoms, performance, and biomarkers. Ozone negatively affected pulmonary function after exercise, especially after combined exposure to ozone and diesel exhaust (DE). Spirometric changes after exercise during exposure to particulate matter and ultrafine particles suggest a decrease in lung function, especially in patients with chronic obstructive pulmonary disease. Ozone frequently caused respiratory symptoms during exercise. Women showed decreased exercise performance and higher symptom prevalence than men during TRAP exposure. However, performance was analyzed in few studies. To date, research has not identified reliable biomarkers of TRAP-related lung damage useful for monitoring athletes' health, except in scarce studies on airway cells obtained by induced sputum or bronchoalveolar lavage. In conclusion, despite partly counteracted by the positive effects of habitual exercise, the negative effects of TRAP exposure to pollutants during exercise are hard to assess: outdoor exercise is a complex model, for multiple and variable exposures to air pollutants and pollutant concentrations. Further studies are needed to identify pollutant and/or time thresholds for performing safe outdoor exercise in cities.

Acute FeNO and Blood Pressure Responses to Air Pollution Exposure in Young Adults during Physical Activity

During physical exercise, the absorbed dose of air pollutants increases. Acute effects of exposure to air pollutants during exercise in healthy young adults remain poorly documented. The aim of this study was to assess the acute responses in fractionated exhaled nitric oxide (FeNO) and blood pressure to air pollution exposure during exercise in young adults with different physical activity levels (low or high). In this study, 76 healthy university students participating in physical activity classes (low level of physical activity) and attending sports training (high level of physical activity) completed two indoor exercise trials when air pollutant concentrations were high (exposure trial) and when the quality of the air was good (control trial). We monitored indoor particulate matter with diameter <10 µm and <2.5 µm (PM₁₀ and PM_2.5) and outdoor PM₁₀, nitric oxides (NO₂, NO_x, NO), and sulfur dioxide (SO₂) concentrations. Systolic and diastolic blood pressure (SBP and DBP), heart rate (HR), oxygen saturation (SpO₂)_, and FeNO were measured at baseline and after 45-60 min of physical activity. There were no significant differences between physiological responses to training performed under different exposure conditions in blood pressure, HR, and SpO₂. Significant positive correlations between post-exercise ΔFeNO during exposure trials and ambient air pollutants were found. FeNO increase during the exposure trial was associated with a higher physical activity level and higher outdoor PM₁₀ and NO₂ concentrations. In young and healthy adults, some differences in physiological responses to physical activity between polluted and control environments could be observed. Participants with a high physical activity level were more likely to have an increase in FeNO after exercise in a polluted environment but not after the control exercise trials.

Does red orange juice supplementation has a protective effect on performance, cardiovascular parameters, muscle damage and oxidative stress markers following the Yo-Yo Intermittent Recovery Test Level-1 under polluted air?

This study aimed to investigate the effect of red orange juice supplementation (ROJS) on performance, cardiovascular parameters, muscle damage and oxidative stress markers of athletes following exercise under polluted air. Eleven soccer players performed a Yo-Yo Intermittent Recovery Test Level-1 in polluted area (PA) and non-polluted area (NPA). Participants are invited to drink 500 ml of red orange or placebo (PLA) juice 2.5 h before the test. Blood samples were collected at rest and 3 min after each session to assess creatine kinase (CK), lactate dehydrogenase, malondialdehyde (MDA) and total antioxidant status. Our results showed that, VO_2max, heart rate and systolic blood pressure post-exercise were significantly altered by pollution with both supplements, but the damage was lowered more with ROJS than PLA. Concerning muscle damage and oxidative stress markers, orange juice supplementation blunted the effect of pollution on CK levels post-exercise (p > 0.05) and decreases significantly (p < 0.05) the MDA levels post-exercise in PA and NPA compared to PLA supplementation. In conclusion, ROJS seemed to be an appropriate strategy to reduce the risk of exposure to pollution especially on muscle damage and oxidative stress markers.

Match Performance of Soccer Teams in the Chinese Super League-Effects of Situational and Environmental Factors

To investigate the effects of situational factors (match location, strength of team and opponent) and environmental factors (relative air humidity, temperature and air quality index) on the technical and physical match performance of Chinese Soccer Super League teams (CSL). The generalized mixed modelling was employed to determine the effects by using the data of all 240 matches in the season 2015 collected by Amisco Pro^®. Increase in the rank difference would increase the number of goal-scoring related, passing and organizing related actions to a small-to-moderate extent (Effect size [ES]: 0.37–0.99). Match location had small positive effects on goal-scoring related, passing and organizing related variables (ES: 0.27–0.51), while a small negative effect on yellow card (ES = −0.35). Increment in relative air humidity and air quality index would only bring trivial or small effects on all the technical performance (ES: −0.06–0.23). Increase in humidity would decrease the physical performance at a small magnitude (ES: −0.55–−0.38). Teams achieved the highest number in the physical performance-related parameters at the temperature between 11.6 and 15.1 °C. In the CSL, situational variables had major effects on the technical performance but trivial effects on the physical performance, on the contrary, environmental factors affected mainly the physical performance but had only trivial or small impact on the technical performance.

Validity and reliability of speed tests used in soccer: A systematic review

Introduction

Speed is an important prerequisite in soccer. Therefore, a large number of tests have been developed aiming to investigate several speed skills relevant to soccer. This systematic review aimed to examine the validity and reliability of speed tests used in adult soccer players.

Methods

A systematic search was performed according to the PRISMA guidelines. Studies were included if they investigated speed tests in adult soccer players and reported validity (construct and criterion) or reliability (intraday and interday) data. The tests were categorized into linear-sprint, repeated-sprint, change-of-direction sprint, agility, and tests incorporating combinations of these skills.

Results

In total, 90 studies covering 167 tests were included. Linear-sprint (n = 67) and change-of-direction sprint (n = 60) were studied most often, followed by combinations of the aforementioned (n = 21) and repeated-sprint tests (n = 15). Agility tests were examined fewest (n = 4). Mainly based on construct validity studies, acceptable validity was reported for the majority of the tests in all categories, except for agility tests, where no validity study was identified. Regarding intraday and interday reliability, ICCs>0.75 and CVs<3.0% were evident for most of the tests in all categories. These results applied for total and average times. In contrast, measures representing fatigue such as percent decrement scores indicated inconsistent validity findings. Regarding reliability, ICCs were 0.11–0.49 and CVs were 16.8–51.0%.

Conclusion

Except for agility tests, several tests for all categories with acceptable levels of validity and high levels of reliability for adult soccer players are available. Caution should be given when interpreting fatigue measures, e.g., percent decrement scores. Given the lack of accepted gold-standard tests for each category, researchers and practitioners may base their test selection on the broad database provided in this systematic review. Future research should pay attention to the criterion validity examining the relationship between test results and match parameters as well as to the development and evaluation of soccer-specific agility tests.

Effects of altitude on chronotype orientations in relation to cardiorespiratory and hematological quantities of college students in Ethiopia

BACKGROUND

The mechanism by which Ethiopians adapt to altitude is quite unique compared to other Highlanders with respect to increased oxygen saturation of hemoglobin. Although the effects of altitude on cardiorespiratory and hematological quantities on athletics performances are well known, but there is little information about its underlying effect on chronotype orientations.

METHODS

In this cross-sectional study 60 male college students with mean age 20±1.3 years from high and low altitude regions living in a tropical setting in Ethiopia were included. The participants' chronotype was determined using the self-administered Horne and Ostberg Morningness-Eveningness Questionnaires (MEQ). Measurements and estimations of hematological and cardiorespiratory parameters were performed from 7:00-9:00 AM, East African time zone, in order to minimize any variations that might occur in the course of the day. A multivariate binary logistic regression model was fitted to analyze the underlying chronotype predictors.

RESULTS

28 (93.9%) of participants from high altitude were mainly intermediate type (I-type) dominant with (MEQ = 42-58). While, 16 (55.2%) of participants from low altitudes were morning type (M-type) dominant chronotype with (MEQ = 59-69). Our main finding confirmed that altitude is an independent predictor of chronotype orientations of the participants (p<0.015). Thus, the results of the multivariate analysis seem to indicate that, participants from low and high altitudes may be uniquely oriented towards either M-type or I-type chronotype respectively (adjusted odds ratio [AOR] 4.772, 95% CI = 3.748-4618458). However, no significant difference on cardiorespiratory and hematological quantities between I-type and M-type chronotype of students from low altitude living in the same setting was reported (p > 0.05).

CONCLUSION

Our finding, reported for the first time that, the human chronotype varies according to the altitude, with no underlying effect of cardiorespiratory and hematological quantities.

Separate and combined effects of time of day and verbal instruction on knee extensor neuromuscular adjustments

We examined the effects of time of day and verbal instruction, separately and combined, on knee extensor neuromuscular adjustments, with special reference to rapid muscle force production capacity. Ten healthy male participants performed 4 experimental trials in counterbalanced order: morning “hard-and-fast” instruction, evening hard-and-fast instruction, morning “fast” instruction, and evening fast instruction. During each experimental trial, neuromuscular performance was assessed from the completion of 6 maximal isometric voluntary contractions (rest = 2 min) of the knee extensors with concomitant quadriceps surface electromyography recordings. For each contraction, we determined maximal voluntary force (Fmax), maximal rate of force development (RFDmax) and associated maximal electromechanical delay (EMDmax), and maximal rate of muscle activation (RMAmax). Globally, oral temperature (+2.2%), Fmax (+4.9%) and accompanying median frequency (+6.6%)/mean power frequency (+6.0%) as well as RFDmax (+13.5%) and RMAmax (+15.5%) were significantly higher in the evening than morning (p < 0.05). Conversely, evening in reference to morning values were lower for EMDmax (–4.3%, p < 0.05). Compared with a hard-and-fast instruction, RFDmax (+30.6%) and corresponding root mean square activity (+18.6%) were globally higher using a fast instruction (p < 0.05), irrespectively of the time of day. There was no significant interaction effect of time of day and verbal instruction on any parameter, except for EMDmax (p = 0.028). Despite diurnal variation in maximal or explosive force production of knee extensors and associated neuromuscular parameters, these adjustments occurred essentially independently of the verbal instruction provided.