Marathon Running Performance Research Articles

Wasted efforts of elite Marathon runners under a warming climate primarily due to atmospheric oxygen reduction

Meteorological conditions exert influences on sport performances via complex processes. Previous studies conventionally investigate the effects of weather conditions on marathon performance by following events held at the same places, which brings large uncertainties due to the changed participants. Via following each athlete to eliminate these uncertainties, we show that elite athletes’ marathon-running performance tends to monotonically worsen as ambient temperature rises except when it is extremely cold based on the best 16 athletes from each of the sex continents. It worsens by 0.56 (0.39 for men and 0.71 for women) min/°C when it rises beyond 15 °C. Theoretical analysis based on global marathon performance and weather observation datasets shows that more than half of this effect is mediated by reduced oxygen partial density as warmer temperature expands air and increases vapor pressure for both the men and women athletes, which is confirmed by the methods of Baron–Kenny. This atmospheric thermodynamic mechanism has not been emphasized previously. We also show that world-top athletes’ marathon performance approximately linearly worsens as ambient pressure decreases and slightly worsens as relative humidity rises if not extremely wet. These results substantially differ from the previous ones following the events instead of each athlete. Multi-variable changes in climate system are projected to slow Olympic marathon athletes by 2.51 and 1.06 min by the end of the 21st century in relative to 2020 under the high and intermediate emission scenario, respectively. Therefore, future progression of marathon performance is likely to be substantially slowed or even halted by climate changes without efficient greenhouse gas mitigation.

A simulation framework to determine optimal strength training and musculoskeletal geometry for sprinting and distance running.

Musculoskeletal geometry and muscle volumes vary widely in the population and are intricately linked to the performance of tasks ranging from walking and running to jumping and sprinting. As an alternative to experimental approaches, where it is difficult to isolate factors and establish causal relationships, simulations can be used to independently vary musculoskeletal geometry and muscle volumes, and develop a fundamental understanding. However, our ability to understand how these parameters affect task performance has been limited due to the high computational cost of modelling the necessary complexity of the musculoskeletal system and solving the requisite multi-dimensional optimization problem. For example, sprinting and running are fundamental to many forms of sport, but past research on the relationships between musculoskeletal geometry, muscle volumes, and running performance has been limited to observational studies, which have not established cause-effect relationships, and simulation studies with simplified representations of musculoskeletal geometry. In this study, we developed a novel musculoskeletal simulator that is differentiable with respect to musculoskeletal geometry and muscle volumes. This simulator enabled us to find the optimal body segment dimensions and optimal distribution of added muscle volume for sprinting and marathon running. Our simulation results replicate experimental observations, such as increased muscle mass in sprinters, as well as a mass in the lower end of the healthy BMI range and a higher leg-length-to-height ratio in marathon runners. The simulations also reveal new relationships, for example showing that hip musculature is vital to both sprinting and marathon running. We found hip flexor and extensor moment arms were maximized to optimize sprint and marathon running performance, and hip muscles the main target when we simulated strength training for sprinters. Our simulation results provide insight to inspire future studies to examine optimal strength training. Our simulator can be extended to other athletic tasks, such as jumping, or to non-athletic applications, such as designing interventions to improve mobility in older adults or individuals with movement disorders.

Small changes in thermal conditions hinder marathon running performance in the tropics

ABSTRACT We examined marathon performance of the same group of runners in relation to small changes in dry bulb temperature (Tdb) and wet bulb temperature (Twb) across 3 consecutive y, and investigated whether performance was poorer during an evening marathon compared with morning marathons. Marathon results were obtained from the 2017, 2018, and 2019 Standard Chartered Singapore Marathons. Tdb, Twb, Td, relative humidity, and absolute humidity were gathered for each marathon. K-means clustering and linear regressions were performed on 610 runners who participated in all three marathons. Analysis of the 610 runners’ marathon performance was contrasted with Tdb and Twb. Linear regressions were also performed on 190 runners filtered by percentile, yielding similar results. For clusters with similar Tdb from all runners K-means clustering, an increase in mean Twb by 1.5°C coincided with an increase in finishing time by 559 s (9.3 min) (p < 0.033). Twb hinders marathon performance more than Tdb, with each percentage rise in Tdb and Twb resulting in an increase in net time by 7.6% and 39.1%, respectively (p < 0.025). Male and female runners’ response to Tdb and Twb changes were similar (overlap in 95% confidence intervals for the respective regression coefficients). In conclusion, small variations in environmental parameters affected marathon performance, with Twb impairing marathon performance more than Tdb. Marathon performance was likely better in the morning than evening, possibly due to time of day differences, along with unfavorable Tdb that superseded training effects and the effects of lower Twb.

The Influence of Environmental Conditions on Pacing in Age Group Marathoners Competing in the "New York City Marathon".

Background: The two aspects of the influence of environmental conditions on marathon running performance and pacing during a marathon have been separately and widely investigated. The influence of environmental conditions on the pacing of age group marathoners has, however, not been considered yet. Objective: The aim of the present study was to investigate the association between environmental conditions (i.e., temperature, barometric pressure, humidity, precipitation, sunshine, and cloud cover), gender and pacing of age group marathoners in the “New York City Marathon”. Methodology: Between 1999 and 2019, a total of 830,255 finishes (526,500 males and 303,755 females) were recorded. Time-adjusted averages of weather conditions for temperature, barometric pressure, humidity, and sunshine duration during the race were correlated with running speed in 5 km-intervals for age group runners in 10 years-intervals. Results: The running speed decreased with increasing temperatures in athletes of age groups 20–59 with a pronounced negative effect for men aged 30–64 years and women aged 40–64 years. Higher levels of humidity were associated with faster running speeds for both sexes. Sunshine duration and barometric pressure showed no association with running speed. Conclusion: In summary, temperature and humidity affect pacing in age group marathoners differently. Specifically, increasing temperature slowed down runners of both sexes aged between 20 and 59 years, whereas increasing humidity slowed down runners of <20 and >80 years old.

The Role of Environmental Conditions on Master Marathon Running Performance in 1,280,557 Finishers the 'New York City Marathon' From 1970 to 2019.

Aim: This study investigated the influence of weather conditions on running performance in female and male age group runners in the largest marathon in the world, the “New York City Marathon.”Methods: The analysis included data from 1,280,557 finishers the “New York City Marathon” from the years 1970 to 2019. Linear mixed models for men and women finishers with race time (min) as dependent variable and 5-year age groups, temperature, wind and relative humidity tertiles (low, medium, high) as independent factors and finisher as random intercept was performed. Additional models with an interaction between age groups and one weather variable each were performed.Results: Temperature was positively associated with race time while wind speed and humidity were negatively associated (p < 0.001). Men were significantly greater affected wind speed and humidity than women (p < 0.001 for interaction) but not by temperature (p = 0.17 for interaction). With an average of 8 min longer race time, high temperature had the greatest effect on race time. The effect of high humidity on race time was significantly increased in 40–59 years old men and 25–65 years old women. High temperatures had an increased effect on race time in 30–64 years old men and 40–64 years old women. The inverse association between race time and high wind speed was pronounced in finishers with younger age.Conclusion: Performance was lower on days with high temperature, low humidity and low wind speed. Men seemed to benefit more from higher humidity and wind speed than women. Aged (70 +) finishers were not greater affected by high temperatures.

Effects of course design (curves and elevation undulations) on marathon running performance: a comparison of Breaking 2 in Monza and the INEOS 1:59 Challenge in Vienna

ABSTRACT Eliud Kipchoge made two attempts to break the 2-hour marathon, in Monza and then Vienna. Here we analyse only the effects of course elevation profile and turn curvatures on his performances. We used publicly available data to determine the undulations in elevation and the radii of the curves on the course. With previously developed equations for the effects of velocity, slope, and curvature on oxygen uptake, we performed simulations to quantify how much the elevation changes and curves of the Vienna course affect a runner’s oxygen uptake (at a fixed velocity) or velocity (at a fixed oxygen uptake). We estimate that, after the initial downhill benefit, the course led to an overall oxygen uptake penalty of only 0.03%. When compared to a perfectly level straight course, we estimate that the combined effects of the undulations and curves of the Vienna course incurred a penalty of just 1.37 seconds. Kipchoge ran 2:00:25 in Monza Italy. Comparison with the Monza course profile indicates a 46.2 second (1.09% oxygen uptake) advantage of Vienna’s course while the fewer curves of Vienna contributed ~ 1 second. The Vienna course was very well-chosen because it minimized the negative effects of elevation changes and curves. Abbreviations: CoT: Oxygen cost of transport; CO2: Curved rate of oxygen consumption; O2: Rate of oxygen consumption; WA: World Athletics

Lower leg muscle\u2013tendon unit characteristics are related to marathon running performance

The human ankle joint and plantar flexor muscle–tendon unit play an important role in endurance running. It has been assumed that muscle and tendon interactions and their biomechanical behaviours depend on their morphological and architectural characteristics. We aimed to study how plantar flexor muscle characteristics influence marathon running performance and to determine whether there is any difference in the role of the soleus and gastrocnemii. The right lower leg of ten male distance runners was scanned with magnetic resonance imagining. The cross-sectional areas of the Achilles tendon, soleus, and lateral and medial gastrocnemius were measured, and the muscle volumes were calculated. Additional ultrasound scanning was used to estimate the fascicle length of each muscle to calculate the physiological cross-sectional area. Correlations were found between marathon running performance and soleus volume (r = 0.55, p = 0.048), soleus cross-sectional area (r = 0.57, p = 0.04), soleus physiological cross-sectional area (PCSA-IAAF r = 0.77, p < 0.01, CI± 0.28 to 0.94), Achilles tendon thickness (r = 0.65, p < 0.01), and soleus muscle-to-tendon ratio (r = 0.68, p = 0.03). None of the gastrocnemius characteristics were associated with marathon performance. We concluded that a larger soleus muscle with a thicker Achilles tendon is associated with better marathon performance. Based on these results, it can be concluded the morphological characteristics of the lower leg muscle–tendon unit correlate with running performance.

Influence of the Menstrual Cycle Phase on Marathon Performance in Recreational Runners

To examine the potential impact of fluctuations in sex steroid hormones across the menstrual cycle (MC) on marathon running performance of recreational female athletes. A survey questionnaire was administered to recreational, nonelite runners who had completed multiple marathons within the last 18 months. A total of 599 questionnaires were returned and deemed viable for review. From these, 185 survey participants were found to have complete information and eligibility to have their surveys used in the statistical analysis. A total of 106 women had their best marathon performance in the luteal phase (high sex steroid hormones) of the MC, and 79 had their best performance in the follicular phase (low sex steroid hormones) of the MC (responses were significantly different; z-score value = 1.11; P < .05). Recreational female runners have varying performances in the marathon across their MC phases, specifically performing better in the luteal phase of the cycle.

The Association of Aquaporin-1 Gene with Marathon Running Performance Level: a Confirmatory Study Conducted in Male Hispanic Marathon Runners

BackgroundReplication studies are essential for identifying credible associations between alleles and phenotypes. Validation of genotype-phenotype associations in the sports and exercise field is rare. An initial genetic association study suggested that rs1049305 (C > G) in the 3′ untranslated region (3′UTR) of the aquaporin-1 (AQP1) gene was associated with marathon running (MR) performance level in Hispanic males. To validate this finding, we conducted a replication analysis in an independent case-control sample of Hispanic male marathon runners (n = 1430; cases n = 713 and controls n = 717). A meta-analysis was utilized to test the extent of the association between the initial results and the present report. It also provided to test the heterogeneity (variation) between the two studies.ResultsThe replication study showed a statistically significant (p ≤ 0.05) association between rs1049305 (C > G) of the AQP1 gene and MR performance level. Association test results using a fixed effect model for the combined, original study and the present report, yielded an odds ratio = 1.28, 95% confidence interval = 1.13–1.45, p = 0.0001. The extent of the measures of heterogeneity was Tau-squared = 0, H statistic = 1, I2 statistic = 0, and Cochran’s Q test (Q = 0.29; p value 0.59), indicated the variation between studies were due to chance and not to differences in heterogeneity between the two studies. Within the limitations of the present replication, contrast of two studies and its effects on meta-analysis, the findings were robust.ConclusionThis study successfully replicated the results of Martínez et al. (Med Sportiva 13:251-5, 2009). The meta-analysis provided further epidemiological credibility for the hypothesis of association between the DNA rs1049305 (C > G) variation in the 3′UTR of the AQP1 gene and MR running performance level in Hispanics male marathon runners. It is not precluded that a linked DNA structure in the surrounding molecular neighborhood could be of influence by been part of the overly complex phenotype of MR performance level.

The Role of Environmental Conditions on Marathon Running Performance in Men Competing in Boston Marathon from 1897 to 2018.

This study investigated the effects of weather conditions on male performance during the Boston Marathon from 1897 to 2018. A total of 383,982 observations from 244,642 different finishers were analysed using Generalized Additive Mixed Models. All runners, annual top 100 finishers and annual top ten finishers were considered. Weather conditions, on race day, were: average air temperature (°C), precipitations (mm), wet-bulb globe temperature (WBGT) (°C), wind speed (km/h), wind direction (N, S, W, E) and pressure (hPa). These effects were examined in multi-variable models with spline smooth terms in function of calendar year. Temperature, when increasing by 1 °C, was related to worsened performance for all groups (i.e., by 00:01:53 h:min:sec for all finishers, p < 0.001). Wind coming from the West, compared to wind coming from other directions, was the most favourable for performance of all groups of finishers. Increasing precipitations worsened performances of top 100 (estimate 00:00:04 h:min:sec, p < 0.001) and top 10 finishers (estimate 00:00:05 h:min:sec, p < 0.001). Wind speed, when increasing by 1 km/h, was related to worsened performance for all finishers (estimate 00:00:19 h:min:sec, p < 0.001), but not for top 100 group, where performances were 00:00:09 h:min:sec faster, p < 0.001. Pressure and WBGT were examined in uni-variable models: overall, performances worsened as pressure and WBGT increased. Our findings contributed to the knowledge about the effect of weather conditions on performance level in male marathon runners.

Detecting the marathon asymmetry with a statistical signature

Lately, the sub two-hour marathon attempt in Monza was still based on the belief that constant speed is the best way of running. This idea is relayed by marathon organizers who offer pace-group leaders to help the runners to maintain a target race speed. The purposes of this study are to verify the hypotheses that 1. The mass runners try to maintain a constant speed without succeeding. 2. Marathoners run in an asymmetric way and this turns out to be visible in the speed time series. Those two points are independent of the gender, the level of performance (2h30–3h40) and the profile of the race (Paris vs Berlin). Before considering a predictive running strategy for optimizing personal marathon running performance, here we shed light on some significant statistical features by analyzing speed time series data recorded by 273 runners’ GPS. We started with looking for a trend in the speed time series. By means of Kendall’s non-parametric rank correlation coefficient we exhibited a decreasing trend in speed data, whichever the level of performance, gender (Male and Female) and race profile (Berlin and Paris marathons). Going deeper in the study we applied a systematic analysis of the asymmetry of speed via classical statistical measures of skewness. Among them the quantiles of the average speed, i.e. the proportion of the race run above or below the final average The combination of the trend and the asymmetry lead to building up a statistical signature for the speed time series which is identical regardless the level of performance, gender and race profile.

How much further for the sub-2-hour marathon?

The sub-2-hour marathon is a new barrier in endurance running performance, and it has been widely debated in the scientific community. In this review we present a mathematical model to estimate the possible year when a male could break through the sub-2-hour barrier, and also an estimation of when a female could break Paula Radcliffe’s marathon running record. Further, we present several aspects (ie, physiology, nationality, age, biomechanics, pacing, and drafting) that are associated with marathon running performance in elite runners and, finally, the possible characteristics of the male to break the sub-2-hour barrier. In summary, with the results of the developed equations, it is possible that a male athlete can break through the sub-2-hour barrier in the next decade (with Nike® Breaking2 performance 1920–2018 [NBP]: y =0.0417x2–14.18x +3,128; year of 2026; without NBP 1920–2018: y =0.045x2–15.12x +3,194; year of 2027). This marathoner will possibly have a maximal oxygen uptake >85 mL∙kg−1∙min−1 and should perform the race at a pacing higher than 85% of maximal oxygen uptake. In addition, this runner should pay more attention to strength training, endurance strength, speed training, and focus on running training at an intensity above the anaerobic threshold. Most likely, this runner originates from East Africa (especially from Ethiopia) and will have an age of ~27 years. For the females, there is poor evidence regarding the physiological profile of the female marathoner who will break Radcliffe’s record, but the available literature suggests that it will not happen any time soon.

TTN genotype is associated with fascicle length and marathon running performance.

Titin provides a molecular blueprint for muscle sarcomere assembly, and sarcomere length can vary according to titin isoform expression. If variations in sarcomere length influence muscle fascicle length, this may provide an advantage for running performance. Thus, the aim of this study was to investigate whether the titin (TTN) rs10497520 polymorphism was associated with muscle fascicle length in recreationally active men (RA; n=137) and marathon personal best time in male marathon runners (MR; n=141). Fascicle length of the vastus lateralis was assessed in vivo using B-mode ultrasonography at 50% of muscle length in RA. All participants provided either a whole blood, saliva or buccal cell sample, from which DNA was isolated and genotyped using real-time polymerase chain reaction. Vastus lateralis fascicle length was 10.4% longer in CC homozygotes, those carrying two copies of the C-allele, than CT heterozygotes (P=.003) in RA. In the absence of any TT homozygotes, reflective of the low T-allele frequency within Caucasian populations, it is unclear whether fascicle length for this group would have been smaller still. No differences in genotype frequency between the RA and MR groups were observed (P=.500), although within the MR group, the T-allele carriers demonstrated marathon personal best times 2minutes 25seconds faster than CC homozygotes (P=.020). These results suggest that the T-allele at rs10497520 in the TTN gene is associated with shorter skeletal muscle fascicle length and conveys an advantage for marathon running performance in habitually trained men.

How Biomechanical Improvements in Running Economy Could Break the 2-hour Marathon Barrier

A sub-2-hour marathon requires an average velocity (5.86m/s) that is 2.5% faster than the current world record of 02:02:57 (5.72m/s) and could be accomplished with a 2.7% reduction in the metabolic cost of running. Although supporting body weight comprises the majority of the metabolic cost of running, targeting the costs of forward propulsion and leg swing are the most promising strategies for reducing the metabolic cost of running and thus improving marathon running performance. Here, we calculate how much time could be saved by taking advantage of unconventional drafting strategies, a consistent tailwind, a downhill course, and specific running shoe design features while staying within the current International Association of Athletic Federations regulations for record purposes. Specifically, running in shoes that are 100g lighter along with second-half scenarios of four runners alternately leading and drafting, or a tailwind of 6.0m/s, combined with a 42-m elevation drop could result in a time well below the 2-hour marathon barrier.

Effects of Marathon Running on Aerobic Fitness and Performance in Recreational Runners One Week after a Race.

It is not clear whether or not recreational runners can recover aerobic fitness and performance within one week after marathon running. This study aimed to investigate the effects of running a marathon race on aerobic fitness and performance one week later. Eleven recreational runners (six men, five women) completed the race in 3 h 36 min 20 s ± 41 min 34 s (mean ± standard deviation). Before and 7 days after the race, they performed a treadmill running test. Perceived muscle soreness was assessed before the race and for the following 7 days. The magnitude of changes in the treadmill running test was considered possibly trivial for maximal oxygen uptake (O2max) (mean difference −1.2 ml/kg/min; ±90% confidence limits 2 ml/kg/min), unclear for %O2max at anaerobic threshold (AT) (−0.5; ±4.1%) and RE (0.2; ±3.5 ml/kg/km), and likely trivial for both velocity at AT and peak (−0.2; ±0.49 km/h and −0.3; ±0.28 km/h). Perceived muscle soreness increased until 3 days after the race, but there were no clear differences between the values before the race and 4–7 days after it. These results show that physiological capacity associated with marathon running performance is recovered within 7 days after a marathon run.

Relationship between age and elite marathon race time in world single age records from 5 to 93 years.

BackgroundThe aims of the study were (i) to investigate the relationship between elite marathon race times and age in 1-year intervals by using the world single age records in marathon running from 5 to 93 years and (ii) to evaluate the sex difference in elite marathon running performance with advancing age.MethodsWorld single age records in marathon running in 1-year intervals for women and men were analysed regarding changes across age for both men and women using linear and non-linear regression analyses for each age for women and men.ResultsThe relationship between elite marathon race time and age was non-linear (i.e. polynomial regression 4th degree) for women and men. The curve was U-shaped where performance improved from 5 to ~20 years. From 5 years to ~15 years, boys and girls performed very similar. Between ~20 and ~35 years, performance was quite linear, but started to decrease at the age of ~35 years in a curvilinear manner with increasing age in both women and men. The sex difference increased non-linearly (i.e. polynomial regression 7th degree) from 5 to ~20 years, remained unchanged at ~20 min from ~20 to ~50 years and increased thereafter. The sex difference was lowest (7.5%, 10.5 min) at the age of 49 years.ConclusionElite marathon race times improved from 5 to ~20 years, remained linear between ~20 and ~35 years, and started to increase at the age of ~35 years in a curvilinear manner with increasing age in both women and men. The sex difference in elite marathon race time increased non-linearly and was lowest at the age of ~49 years.

Pre-Race Dietary Carbohydrate Intake Can Independently Influence Sub-Elite Marathon Running Performance

We examined whether selected anthropometric and nutritional factors influenced field-based marathon running performance. An internet-based data collection tool allowed competitors in the 2009 London Marathon (n=257, mean ± SD age: 39 ± 8 years, finish time: 273.8 ± 59.5 min) to record a range of anthropometric, training and nutritional predictors. Multivariate statistical methods were used to quantify the change in running speed mediated by a unit change in each predictor via the 95% confidence interval for each covariate-controlled regression slope ( B). Gender ( B=1.22 to 1.95 km/h), body mass index ( B=-0.14 to -0.27 km/h), training distance ( B=0.01 to 0.04 km/h) and the amount of carbohydrate consumed the day before the race ( B=0.08 to 0.26 km/h) were significant predictors, collectively accounting for 56% of the inter-individual variability in running speed (P<0.0005). Further covariate-adjusted analysis revealed that those competitors who consumed carbohydrate the day before the race at a quantity of >7 g/kg body mass had significantly faster overall race speeds (P=0.01) and maintained their running speed during the race to a greater extent than with those who consumed <7 g/kg body mass (P=0.02). We conclude that, in addition to gender, body size and training, pre-race day carbohydrate intake can significantly and independently influence marathon running performance.

Is There a Sex Difference in the Age of Elite Marathon Runners?

The purposes of this study were to determine i) if there is a sex difference in the age of the elite marathon runners and ii) if the sex difference in performance altered across the years that women have participated in the marathon. Age at time of competition and running times of the first five placed male and female runners who competed in the seven marathons of the World Marathon Majors Series were analyzed. Data from as many years as was available online were retrieved so that 410 men and 410 women were included in the analysis. The marathons and years included the Berlin (1999-2009), Boston (2000-2009), Chicago (1997-2009), London (2001-2009), New York City (1990-2009), International Athletic Association Federation World Championship (1983, 1987, and every 2 yr from 1991), and Olympic (every 4 yr since 1984) marathons. Women were older than men (mean ± SD = 29.8 ± 4.2 vs 28.9 ± 3.8 yr), but for only two of the seven marathons, the Chicago and the London marathons (P < 0.05): the sex difference in age was not consistent across the years. There was no sex difference in age for the Berlin, Boston, New York City, World Championship, and Olympic marathons. Men were faster than women (11.6% ± 1.8%). The sex difference in running velocity varied across marathons (least for the World Championships, 10.2%) and also across years, but not systematically. This sex difference in running velocity increased from first to fifth place across all marathons. These data indicate that men and women physiologically peak at a similar age in marathon running performance. The sex difference in performance of elite marathon runners varied across years but has not systemically decreased or varied since the 1980s.

Effect of Air Pollution on Marathon Running Performance

Effect of Air Pollution on Marathon Running Performance

Effect of Air Pollution on Marathon Running Performance

Before the 2008 Olympic Games, there was concern that air pollution in Beijing would affect the performance of marathon runners. Air pollutant concentrations during marathon running and their effect on performance have not been reported. Evidence suggests that the lung function of females may be more susceptible than that of males to air pollution, but it is uncertain if this translates to decreased marathon performance. The purposes of this study were to 1) describe ambient air pollutant concentrations present during major US marathons, 2) quantify performance decrements associated with air pollutants, and 3) examine potential sex difference in performance related to air pollutants. Marathon race results, weather data, and air pollutant concentrations were obtained for seven marathons for 8-28 yr. The top three male and female finishing times were compared with the course record and contrasted with air pollutant levels and wet bulb globe temperature (WBGT). A WBGT-adjusted performance decrement was calculated, and regression analysis was used to quantify performance decrements associated with pollutants. The air pollutant concentrations of carbon monoxide, ozone, particulate matter smaller than 10 microm (PM(10)), PM(2.5), nitrogen dioxide, and sulfur dioxide ranged from 0 to 5.9 ppm, from 0 to 0.07 ppm, from 4.5 to 41.0 microg x m(-3), from 2.8 to 42.0 microg x m(-3), from 0 to 0.06 ppm, and from 0 to 0.05 ppm, respectively. After adjusting for WBGT-associated performance decrements, only PM(10) was associated with decrements in performance of women. For every 10-microg x m(-3) increase in PM(10), performance can be expected to decrease by 1.4%. The concentrations of air pollution present during marathons rarely exceed health-based national standards and levels known to affect lung function in laboratory situations. Regardless, PM(10) was significantly correlated with performance of women marathon runners.