The influence of thermal stress on the physical and technical activities of soccer players: lessons from the 2018 FIFA World Cup in Russia

Extreme heat risk and the potential implications for the scheduling of football matches at the 2026 FIFA World Cup

Climate change is making extreme heat events more frequent and intense. This negatively impacts many aspects of society, including organised sport. As the world's most watched sporting event, the FIFA World Cup commands particular attention around the threat of extreme heat. The 2022 tournament in Qatar was moved from summer to winter in response to this threat, and now attention turns to the 2026 tournament in North America with extreme heat risk across many of the 16 host locations. We examine this risk by modelling wet bulb globe temperature (WBGT) - a widely used measure of heat stress - for the host locations using hourly meteorological data for the period 2003-2022. Our results show that 14 out of 16 host locations exceed WBGTs of 28 °C, with four (nine) exceeding this threshold more than half the time during afternoons across the mean (hottest year) of the 20 year record. This threshold is important as the level beyond which some football governing bodies recommend match delay or postponement. A climatically sound argument is therefore presented to reschedule kick-off times outside the hottest afternoon hours for the host locations with highest heat risk at which no indoor air conditioned environment exists - primarily Miami and Monterrey, but also Philadelphia, Kansas City, Boston and New York. This study highlights the need to carefully assess heat risk ahead of major sporting events to help inform any potential interventions needed in the scheduling of matches and competitions in a warming climate.

Associations Between Match Running Performance and Environmental Temperatures in 4 Professional Football Leagues

PURPOSE

This study investigated associations between environmental temperatures and match running performance in 4 professional football leagues.

METHODS

Running performance indicators including total, high-speed, and sprint distances were collated from 1610 matches from the German Bundesliga 1 and 2, Japanese J-League, and Turkish SüperLig. Environmental data for each of these matches were obtained for dry-bulb and wet-bulb globe temperatures (WBGT) retrospectively from public sources. Linear regressions were used to determine relationships between running performance indicators and both temperature and WBGT for individual leagues. Furthermore, linear mixed models were used to determine associations across all 4 leagues, accounting for differences between them as random effects. Bonferroni corrections were applied to account for multiple tests.

RESULTS

Overall, combined-league data showed that total distance (95% CI, -0.50 to 0.37; β: -0.36), number of high-speed runs (95% CI, -4.57 to 2.93; β: -0.29), high-speed distances (95% CI, -0.07 to 0.05; β: -0.28), number of sprints (95% CI, -2.72 to 2.07; β: -0.39), and sprint distances (95% CI, -0.05 to 0.03; β: -0.22) were all lower when WBGT was higher (P < .001), whereas the peak speed recorded per match (95% CI, 0.01 to 0.03; β: 0.18) was higher when WBGT was higher (P < .001). Models with temperature instead of WBGT derived similar results.

CONCLUSION

Warmer environmental conditions were associated with lower total, high-speed, and sprint distances covered. These responses may result from an increased thermoregulatory load or indirectly from an adapted individual or team-tactical pacing strategy in warmer conditions. Teams should consider strategies to counter such effects to avoid lower distances covered at high intensities that are related to success in football.

Prospective heat stress risk assessment for professional soccer players in the context of the 2026 FIFA World Cup

This study investigates the risk of severe heat stress and associated potential water losses in professional soccer players, considering as well the oxygen content of the inhaled air in the context of the 2026 FIFA World Cup. For the 16 stadiums, hourly values of biometeorological indices (adjusted Universal Thermal Climate Index - UTCI, Water loss - SW and Oxygen volume - Ov) were calculated. UTCI adjustments included modifications to activity levels, movement speeds and clothing configurations to better reflect the level of thermal stress on soccer player during a match. Ten out of the sixteen sites of the 2026 FIFA World Cup are at very high risk of experiencing extreme heat stress conditions. The highest risk of uncompensable thermal stress due to very high average hourly UTCI values above 49.5 °C and excessive water loss (> 1.5 kg/h) occur in the afternoon in stadiums located in Arlington, Houston (USA) and in Monterrey (Mexico). The results of this study will enable optimization of match schedules at individual venues, taking into account the health risks associated with extreme heat stress, but also the physiological reactions to heat potentially affecting the performance of players on the pitch.

Healthy environments for athleTes (HEAT): environmental conditions along a 90 km ultra-marathon event, South Africa

This paper provides an overview of the HEAT (Healthy Environments for AthleTes) project, which aims to understand the impact of environmental conditions on athlete health and performance during major sporting events such as long-distance running, cycling, and triathlons. In collaboration with the SAFER (Strategies to reduce Adverse medical events For the ExerciseR) initiative, the HEAT project carried out a field campaign at the 2022 Comrades Marathon in the KwaZulu-Natal province of South Africa. The measurement campaign deployed seven weather stations, seven PM2.5 monitors and one spore trap along the 90 km route to capture spatially representative measurements of complex micro-climates, allergenic aerospora, and particulate matter exposure. The results indicate that runners were exposed to moderate risk heat stress conditions. Novel findings from this initial campaign shows elevated and potentially harmful PM2.5 levels at spectator areas, possibly coinciding with small fire events around the race day festivities. Our findings show values PM2.5 levels over the WHO 24-h guidelines at all stations, while 2000 µg/m3 at two stations. However, the lack of an acute exposure standard means direct health impacts cannot be quantified in the context of a sport event. The HEAT project highlights important aspects of race day monitoring; regional scale climatology has an impact on the race day conditions, the microclimatic conditions (pollution and meteorology) are not necessarily captured by proximity instruments and direct environmental measurements are required to accurately capture conditions along the route.

Can heat conditions affect the heart rate responses, perception of effort, and technical performance of young male football players during small-sided games? a comparative study

BACKGROUND

Soccer coaches often employ small-sided games (SSGs) to elicit both physiological and technical responses from players. However, numerous contextual factors can influence the outcomes of these games. This comparative study aimed to investigate how environmental temperature (< 21ºC and > 29ºC) impacts heart rate responses, perception of effort, and technical performance in young male football players during SSGs.

METHODS

This study compares temperatures below 21ºC (∼ 20.4 ± 0.4ºC) with temperatures above 29ºC (∼ 29.7 ± 0.6ºC). This repeated measures study design involved 60 male football players at a trained/developmental level, selected from under-16 and under-19 teams. It aimed to assess the effects of the 3v3 format, conducted repeatedly under conditions of 21ºC and above 29ºC. Throughout the games, mean heart rate responses (HRmean), measured via heart rate sensors; rate of perceived exertion (RPE), assessed using the CR-10 Borg scale; and successful passes and lost balls, tracked through an ad hoc observational analysis tool, were monitored.

RESULTS

No significant interactions were observed (time*age group) in meanHR (F = 0.159; p = 0.691; [Formula: see text]=0.003), RPE (F=0.646; p=0.425; [Formula: see text]=0.011), number of passes completed (F=0.204; p=0.654; [Formula: see text]=0.003), and number of lost balls (F = 0.157; p = 0.694; [Formula: see text]=0.003). Overall, significantly higher heart rate responses in mean HR (p<0.001) and RPE (p<0.001) were observed at temperatures above 29ºC, while significantly more passes were completed at temperatures below 21ºC (p<0.001).

CONCLUSIONS

Heat conditions significantly intensified the psychophysiological responses in players, concurrently leading to a significant impairment in the number of passes. Coaches should contemplate implementing mitigation strategies to avert performance declines during heat conditions when utilizing SSGs.

Key Performance Indicators Predictive of Success in Soccer: A Comprehensive Analysis of the Greek Soccer League

Previous research emphasizes the significance of key performance metrics in determining match outcomes. The purpose of this study is to enhance the understanding of success in professional soccer by analyzing the relationship between match outcomes (win, lose, draw) and various Performance Indicators extracted from the Greek soccer league, as well as to develop a regression model of success in soccer. The sample consisted of all 91 matches from the first round of the 2020-2021 season of the Greek Football League. Utilizing Kruskal-Wallis tests, significant differences were found in goals scored, shots, and shots on target, ball possession, passing metrics, touches in the penalty area, and average shot distance (p < 0.05), with winning teams having demonstrated superior performance metrics. Moreover, winning teams engaged more in positional attacks and counterattacks with shots (p < 0.05). The binary logistic regression model applied to predict match outcomes identified shots on target, counterattacks, passes metrics, offensive duels and set pieces (penalties, free kicks) as key factors influencing the likelihood of winning (p < 0.05). These findings collectively highlight the importance of effective offensive play, including goal scoring, shooting accuracy, and ball possession, in determining the outcomes of soccer matches, with the regression model offering a nuanced understanding of these relationships.

Analysis of potential hydration opportunities during future football tournaments based on data from the 2018 FIFA World Cup

The World Cup is traditionally held oppressive thermal conditions. Therefore, teams should follow heat strain mitigation strategies, including optimal fluid ingestion. The objective of this analysis was to assess and visually communicate match-based World Cup player hydration opportunities and behaviors. Broadcast recordings of the 2018 World Cup (June-July) were analyzed. Descriptive data were reported for match duration, the number, type, and duration of breaks, and player-initiated hydration moments, as well as environmental conditions categorized as 'no thermal stress' and 'thermal heat stress.' The median number and interquartile range of total match breaks were 7 [5-8] during official breaks, with a duration of 42 [23-72] seconds. There were 2 [1-3] player-initiated hydration moments per game, with a duration of 77 [55-100] seconds. On top of the 29% (#126) of breaks in which drinking occurred, an additional 26% (#33) of self-initiated drinking was registered with a duration of 7 [4-28] seconds without an official break. There was no significant difference (P = 0.22) in self-initiated hydration between thermal conditions. Relative percentages showed suboptimal use of substitution (14%) and VAR (38%) breaks vs. injury breaks (75%). In conclusion, football players did not sufficiently use available breaks to hydrate.

Does Prematch Neuromuscular Performance Affect Running Performance in Collegiate Elite Female Soccer?

ABSTRACT

Ishida, A, Draper, G, White, JB, and Travis, SK. Does prematch neuromuscular performance affect running performance in collegiate elite female soccer? J Strength Cond Res 37(4): 854-858, 2023-The purpose of this study was to investigate whether prematch neuromuscular performance affected match physical performance by player position in Division I collegiate female soccer. Fourteen players participated (20.7 ± 1.3 years; 165.1 ± 6.0 cm; 63.3 ± 7.0 kg) in this study. Players were selected based on being free from injuries, playing for a duration of ≥72 minutes, and match intervals were ≥2 days. Data included 73 observations ( n = 5 defenders, n = 7 midfielders, and n = 2 forward) from 14 official matches. Prematch neuromuscular performance was assessed using countermovement jump (CMJ) with polyvinyl chloride pipe on dual force plates. Countermovement jump variables included jump height (JH) and relative peak power (RPP). Match physical performance included average speed, high-speed running (HSR), and number of high accelerations and decelerations. Linear mixed model was compiled with fixed effects of loaded with fixed effect of JH, RPP, and position and random effects per individual player. In CMJ and player position model, RPP was a significant predictor for average HSR ( p = 0.003) while fixed effects of JH and position were not significant ( p = 0.15-0.86). The fixed and random effects explained 34.8 and 42.1% of variances in average HSR. In CMJ-only model, RPP significantly predicted the variances in average HSR ( p = 0.001). The fixed effects and random effects of the model explained 22.7 and 51.8% of the variance in average HSR. However, position-only was not a significant predictor for average HSR in the position-only model ( p = 0.26 and 0.33). Prematch CMJ RPP may be the greatest predictor of average HSR in collegiate female soccer.

Evaluation of the relationship between thermal comfort conditions and respiratory diseases in Amasya City, Turkey

Aim

Studies examining the relationship between thermal comfort conditions-the state of feeling insulated against atmospheric factors in the environment-and diseases have been very limited. In Turkey, which is in the transition zone of air masses in middle latitudes, thermal comfort conditions change frequently due to sudden weather changes. This study was conducted to examine the relationship between thermal comfort conditions and respiratory diseases in Amasya, an exemplary Turkish city in the Black Sea Region of Turkey.

Subject and methods

To determine the thermal comfort conditions in the study between 2017 and 2019, the PET (physiologically equivalent temperature) index obtained from the RayMan model was used for data including hourly air temperature (°C), relative humidity (%), wind velocity (m/s), and cloud cover (octa). Daily air temperature data were also obtained. The relationship between PET values and air temperature and respiratory disease hospital admissions was analyzed by Pearson correlation analysis and linear regression analysis.

Results

The results revealed a very high negative correlation between both thermal comfort conditions (PET) and air temperature and respiratory diseases (p < 0.000). The results show that with an increase of 1 °C in thermal comfort conditions (PET), hospital admissions due to respiratory diseases will decrease by approximately 64 to 67 patients. It is predicted that the number of patients will decrease by approximately 89 to 94 with an increase of 1 °C in air temperature.

Conclusion

These findings can be informative and serve as guidance for decision-makers in efforts to protect public health, for preventive medicine studies, and for studies on the effects of climate change on human health.

Lactate Threshold and Psychomotor Fatigue Threshold in Hot Conditions: Suggestions for Soccer Players Participating in the Qatar World Cup 2022

The study aimed at finding relationships between lactate threshold and psychomotor fatigue threshold during incremental exercise in thermo-neutral climate conditions and conditions for the 2022 FIFA World Cup in Qatar simulated in an environmental test chamber. The study included 24 soccer players aged 21.02 ± 3.22 years old. The following procedures were performed: The incremental exercise test to mark lactate concentration-LA (mmol·l^-1); Psychomotor test to determine choice reaction time; Designation of the lactate threshold (T_LA) and psychomotor fatigue threshold (T_PF). Climate conditions: The procedure was performed twice in the climatic chamber: (1) in thermo-neutral conditions-TNC (ambient temperature 20.5 °C and relative air humidity 58.7%), (2) after 7 days-in Qatar conditions-QC (28.5 ± 1.92 °C) and (58.7 ± 8.64%). It was confirmed that the T_PF, which reflects the highest efficiency of CNS functioning, occurs at a higher running speed than the T_LA. The temperature of 28.5 °C with 58.7% humidity, which is the lower limit of heat stress, causes the psychomotor fatigue threshold to appear at a lower running speed than in thermoneutral conditions. The data recorded in this work may help to understand the specificity of physiological and psychomotor reactions to various climatic conditions.

Responses of soccer players performing repeated maximal efforts in simulated conditions of the FIFA World Cup Qatar 2022: A holistic approach

This study aimed to assess the capacity for repeated maximal effort (RME) of soccer players in the thermo-natural conditions (NC) and in simulated conditions for the 2022 FIFA World Cup in Qatar (QSC). Twenty-four semi-professional soccer players participated in the study. The exercise test consisted of ten 6-second maximal efforts on a cycloergometer. A 90-second passive rest interval was used. The test was performed in a Weiss Technik WK-26 climate test chamber in two different conditions: 1) thermo-neutral conditions (NC-20.5°C; 58.7% humidity); and 2) simulated conditions for the 2022 World Cup in Qatar (QSC-28.5 ± 1.92°C; 58.7 ± 8.64% humidity). Power-related, physiological, psychomotor, blood, and electrolyte variables were recorded. Results showed that (1) players achieved higher peak power (max 1607,46 ± 192,70 [W] - 3rd rep), needed less time to peak power (min 0,95 ± 0,27 [s] - 3rd rep), and had a higher fatigue slope (max 218,67 ± 59,64 [W/sek] - 7th rep) in QSC than in NC (in each repetition of study protocol); (2) between the 1st repetition and subsequent repetitions a number of significants in among physiological, blood-related, and electrolyte variables were noted, but their direction was similar in both simulated conditions (e.g. V'O2/kg 37,59 ± 3,96 vs 37,95 ± 3,17 [ml/min/kg] - 3rd rep, LAC 13,16 ± 2,61 vs 14,18 ± 3,13 [mg/dl] - 10th rep or K 4,54 ± 0,29 vs 4,79 ± 0,36 [mmol/l] - 2nd rep when compare QCS and NC respectively); (3) an 8°C of temperature difference between the climatic conditions did not significantly affect the soccer players' physical and physiological responses in RME. The study results can be used in the design of training programs aimed to increase players' physiological adaptations by simulating soccer-specific conditions of play in terms of anaerobic capacity, in particular, repetitive maximal efforts. These findings will be useful during the upcoming 2022 World Cup in Qatar and in locations where high ambient temperatures are customary.

Evaluation of the Effects of Thermal Comfort Conditions on Cardiovascular Diseases in Amasya City, Turkey

Aim

Studies fall short when it comes to determining the relationship between thermal comfort and cardiovascular diseases. Studies examining the relationship between thermal comfort conditions and human health in Turkey, located in the transition zone of air masses at mid-latitudes, are quite limited. This is the first study conducted in Turkey that deals with thermal comfort conditions and CVDs, which is the leading cause of death. This study aimed to examine the relationship between thermal comfort conditions and CVDs of Amasya, a medium-sized exemplary Turkish city.

Subject and methods

To determine the thermal comfort conditions in the study area between 2014-2019, the physiologically equivalent temperature (PET) index obtained from the Rayman model, which uses hourly air temperature (ºC), relative humidity (%), wind speed (m/s), and cloud cover (octa) data, was used. The relationship between PET values and CVDs was determined by Pearson correlation analysis and linear regression analysis.

Results

The study indicated a negative, high, and moderate correlation between PET values and cardiovascular diseases (p < 0.001). The results show that when PET values increase by 1 ºC, patient admissions will decrease by about 104 to 108 patients (-104.737 to -108.619 units.).

Conclusion

These results can be informative and guiding for both the protection of public health and studies on climate change and human health.

Universal Climate Thermal Index as a prognostic tool in medical science in the context of climate change: A systematic review

The assessment of the impact of meteorological factors on the epidemiology of various diseases and on human pathophysiology and physiology requires a comprehensive approach and new tools independent of currently occurring climate change. The thermal comfort index, i.e., Universal Climate Thermal Index (UTCI), is gaining more and more recognition from researchers interested in such assessments. This index facilitates the evaluation of the impact of cold stress and heat stress on the human organism and the assessment of the incidence of weather-related diseases. This work aims at identifying those areas of medical science for which the UTCI was applied for scientific research as well as its popularization among clinicians, epidemiologists, and specialists in public health management. This is a systematic review of literature found in Pubmed, Sciencedirect and Web of Science databases from which, consistent with PRISMA guidelines, original papers employing the UTCI in studies related to health, physiological parameters, and epidemiologic applications were extracted. Out of the total number of 367 papers identified in the databases, 33 original works were included in the analysis. The selected publications were analyzed in terms of determining the areas of medical science in which the UTCI was applied. The majority of studies were devoted to the broadly understood mortality, cardiac events, and emergency medicine. A significant disproportion between publications discussing heat stress and those utilizing the UTCI for its assessment was revealed.

Multi-hosting UEFA European Football Championship: Fair enough between participating teams?

PURPOSE

To describe the effects of travel distance and bio-meteorological conditions on the 2020 multi-hosting UEFA European Championship's match outcomes and progress in competition.

METHODS

Teams' basecamps, distance from match venues, match outcomes (defeat, draw and win), bio-meteorological data (ambient air temperature, relative humidity and wet bulb globe temperature) and corresponding FIFA world ranking were extracted from the official UEFA and FIFA websites, respectively; and analyzed through Chi-squared test (impact of basecamp location on match outcomes), Kruskal-Wallis test (distribution of travel distances carried out according to match outcomes and competition phases), ordinal regressions (with match outcomes and competition phases as variables of interest and FIFA ranking and venue distance as explanatory variables) and principal component analysis with the bio-meteorological conditions and match outcomes for each match.

RESULTS

Teams with basecamp near match venue improved their match outcomes. However, neither Kruskal-Wallis test (p > 0.05) nor ordinal regressions (odds ratio (OR) > 0.96, p > 0.403) identified any significant effect of travel distance on match outcomes. Besides, FIFA ranking improved the likelihood of a favorable match outcome (OR = 0.87, p = 0.001) and progression in competition (OR = 0.97, p = 0.003). Further, despite some matches were played in more stressful bio-meteorological conditions, this was not associated with match outcomes (r = -0.07 to 0.19, p > 0.188).

CONCLUSIONS

These findings cannot conclusively clarify on the effects of travel and bio-meteorological conditions on match outcomes and progress in the multi-hosting UEFA European championship, but suggest to carefully consider these variables for future multi-hosting competition to avoid any discrepancies between teams.

Characteristics of Official Wheelchair Basketball Games in Hot and Temperate Conditions

This study compared performance parameters of two wheelchair basketball games under hot (30.3 °C, 52% relative humidity) and temperate (21.6 °C, 30% relative humidity) environmental conditions and described the characteristics of wheelchair basketball. Eight wheelchair basketball players from two teams were monitored during two games using an indoor position tracking system. Total distance, mean- and peak-speed, playing-time, number of sprints, sprints per minute, heart rate and rate of perceived exertion were recorded. Additionally, athletes with a lesion level above and below T6 were compared. No measured parameter differed between the games. Across quarters (Q) mean velocity (m/s) (Q1: 1.01; Q2: 1.10; Q3: 1.18; Q4: 1.06; p < 0.001) and sprints per minute (Q1: 16; Q2: 14; Q3: 23; Q4: 14; p = 0.033) differed significantly, independent of the conditions. Descriptive statistics did not reveal differences between the groups with a lesion level below or above T6. In the present study, hot environmental conditions seemed not to have an impact on activity parameters of wheelchair basketball players. It was speculated that the game intensity and therefore metabolic heat production was too low; consequently, the athletes had a sufficient heat loss to prevent a decrease in performance during the play in hot conditions.