Elsevier

Journal of Biomechanics

Volume 92, 19 July 2019, Pages 54-60
Journal of Biomechanics

Most marathon runners at the 2017 IAAF World Championships were rearfoot strikers, and most did not change footstrike pattern

https://doi.org/10.1016/j.jbiomech.2019.05.024Get rights and content

Abstract

The aim of this study was to analyze footstrike patterns in elite marathon runners at the 2017 IAAF World Championships. Seventy-one men and 78 women were analyzed in their respective races. Athletes’ footstrike patterns were recorded (120 Hz) at approximately 8.5, 19, 29.5 and 40 km (“Laps 1 – 4”) and categorized as either rearfoot (RFS), midfoot or forefoot striking; the latter two were classified together as non-rearfoot striking (NRFS). The most common footstrike pattern was RFS, with proportions never less than 54% of men or 67% of women at any distance. There were no sex-based differences for proportion of footstrike patterns, and there were no differences between footstrike proportions when comparing the top and bottom 50% of men finishers, or between women during Laps 1 and 2. A greater proportion of the top 50% of women maintained NRFS than amongst the bottom 50%. The proportion of RFS increased with distance run in the men’s race, although more than 75% of athletes across both marathons had consistent footstrike patterns between laps (79 RFS and 36 NRFS). As most athletes were RFS (including the top four finishing men), there appears to be no clear advantage to NRFS in marathon running. Coaches should note that it is normal for elite marathon runners to be either RFS or NRFS; however, forefoot striking was rare. The high proportion of athletes who maintained their footstrike pattern reflected individualized preferences for a given footstrike pattern.

Introduction

At 42.195 km long, the marathon is the longest running race held at the Olympic Games and International Association of Athletics Federations (IAAF) World Championships. It differs from other championship running races by being more than four times longer than the next longest race, the 10,000 m, and it is the only running race held on the road. The fatiguing nature of the marathon, with championship finishing times typically longer than 2:05:00 for men and 2:20:00 for women (IAAF, 2019a), leads to reduced running speeds in the second half and, for the world’s best athletes, success is largely a case of avoiding slowing down toward the finish, rather than speeding up (Hanley, 2016). Elite marathon runners offset fatigue to some extent through nutritional strategies (e.g., carbohydrate drinks), tactics (e.g., even pacing) and, of particular interest to biomechanists, potentially by choosing a gait mode that enhances elastic energy storage and return from lower limb muscle-tendon units.

It has been proposed that an anterior footstrike position (midfoot or forefoot striking) provides an advantage over rearfoot striking (RFS) through greater storage and release of elastic energy in the Achilles tendon and foot arches (Perl et al., 2012). Elastic strain work in the tendons and contractile components of muscles can account for about half of total mechanical work performed during running, particularly at faster speeds (Cavagna et al., 1964, Cavagna and Kaneko, 1977). This mechanism is theorized to be enhanced during forefoot striking (FFS) partly because the heel descends substantially under controlled dorsiflexion, stretching the Achilles tendon while the triceps surae acts eccentrically or isometrically, with the foot arches loaded at initial contact (Perl et al., 2012). Although a theorized enhancement of this mechanism with a midfoot striking (MFS) or FFS pattern might positively influence running economy, Kubo et al. (2015) did not find any differences in morphological or mechanical properties of the Achilles tendon between FFS, MFS and RFS, and studies comparing whole-body submaximal oxygen consumption have not found MFS or FFS to be more economical than RFS when comparing runners habituated to each footstrike pattern, or habitual versus converted strike patterns (Ardigò et al., 1995, Cunningham et al., 2010, Di Michele and Merni, 2014, Gruber et al., 2013, Ogueta-Alday et al., 2014, Perl et al., 2012). This result can be partially explained by the similarity in total lower limb mechanical work or mean power between footstrike patterns (at 16.2 km·h−1 (Stearne et al., 2014)) or a trade-off in knee versus ankle joint stiffness (Hamill et al., 2014). Interestingly, Gruber et al. (2013) found that carbohydrate oxidation rates were greater during FFS than RFS, and that FFS was less economical at running speeds of 14.4 km·h−1. Despite the theorized benefit of enhanced storage and release of elastic strain energy with an anterior footstrike, there is little evidence that one footstrike pattern results in greater whole-body running economy (Ardigò et al., 1995, Gruber et al., 2013).

Distance runners can make initial contact with the rearfoot (heel striking), midfoot or forefoot (Di Michele and Merni, 2014, Ogueta-Alday et al., 2014), with the proportion of RFS increasing over longer distances and slower recreational running speeds (Forrester and Townend, 2015, Hasegawa et al., 2007, Kasmer et al., 2014). Hayes and Caplan (2012) analyzed 181 competitive club runners at a British Miler’s Club meet of 800 m and 1500 m races (mean speeds faster than 22.90 km·h−1 for men, and 19.87 km·h−1 for women), finding that 27% of athletes were RFS, 42% MFS and 31% FFS. By contrast, at the 15 km distance in the Sapporo International half marathon race (21.095 km), the 50 highest-finishing men and the seven highest-finishing women analyzed were more likely to be MFS (37%) than slower competitors, but very few (4%) were FFS (Hasegawa et al., 2007). In the Manchester City Marathon, Larson et al. (2011) found that 93% of recreational runners (mean finishing time: 3:57:31) adopted RFS at the 32 km distance, with many switching from MFS or FFS at 10 km. Marathon runners who use MFS or FFS during the early stages might later switch to RFS (Larson et al., 2011) because this leads to longer contact times and increased economy (Gruber et al., 2013). Additionally, a shift toward RFS would be necessary as continuous FFS results in increased plantarflexor work (Baggaley et al., 2017) and can result in considerable fatigue in the contractile properties of the muscle, but not the tendon (Peltonen et al., 2012). Thus, a change in footstrike pattern during a long, submaximal run might be consistent with redistributing mechanical work to proximal leg muscles during a prolonged fatiguing run (Sanno et al., 2018). Although most recreational runners adopt RFS, the proportion of world-class marathon runners adopting MFS or FFS might be higher given the hypothesized energy return benefits (Kubo et al., 2015), their greater running speeds, and coaches’ recommendations to avoid RFS (Anderson, 2018).

Recreational and high-caliber club runners have been analyzed during good-standard races of varying distance; footstrike patterns have also been reported for laboratory testing using treadmills (Hanley and Tucker, 2018, Kubo et al., 2015) and an indoor runway (Preece et al., 2018). However, no previous research has analyzed the footstrike patterns of world-class marathon runners, or the changes that occur, as they complete a World Championship race. Measuring footstrike patterns during marathon races at World Championships ensures the highest possible ecological validity, as it allows for analysis of runners in their “natural environment”. This invaluable provision that laboratory-based studies cannot offer produces real-world data for coaches, scientists and other practitioners to base their training and applications on. The aim of this novel study was to analyze and compare footstrike patterns in elite men and women marathon runners at the 2017 IAAF World Championships at four distances throughout the race, and to compare between higher- and lower-finishing athletes. Comparisons were also made using the present study’s results with previous research on races of different lengths and athlete standards. Because the sample comprised elite marathon runners, it was hypothesized that most athletes would adopt MFS or FFS, and that the proportion of RFS would increase with distance run.

Section snippets

Participants

Data were collected as part of the London 2017 World Championships Biomechanics Project, and the use of those data was approved by the IAAF, who control the data, and locally through the institution’s research ethics procedures. Seventy-one men and 78 women were analyzed in their respective races, held on the same day and on the same course. Athletes who did not finish (27 men and 20 women) were not analyzed. Personal best (PB) and finishing times were obtained from the open-access IAAF website

Results

The mean (±1 standard deviation) PB (h:min:s) for finishers was 2:13:33 (±4:08) in the men’s race, and 2:32:53 (±7:19) in the women’s race. The mean finishing times and the percentages of PB for all finishers, and the top 50% and bottom 50% of athletes, are shown in Table 1. Overall, five men and four women ran PBs. The numbers and percentages of men and women finishers displaying each type of footstrike pattern are shown in Table 2. Because there were so few FFS athletes, their values were

Discussion

The aim of this study was to analyze and compare footstrike patterns in men and women marathon runners at the 2017 IAAF World Championships at four distances throughout the race, and to compare between higher- and lower-finishing athletes. The hypothesis that most athletes would adopt MFS or FFS (i.e., NRFS) was rejected, as the most common footstrike pattern amongst this elite cohort was RFS: its proportion was never less than 54% of all men or 67% of women. Additionally, no differences were

Declaration of Competing Interest

The authors have no conflicts of interest that are relevant to the findings of this manuscript. The data collection and initial data analysis were supported by funding provided by the IAAF as part of a wider development/education project; however, the nature of the data is purely descriptive and not associated with any governing body, commercial sector or product. No funding was provided for the writing of this manuscript. The results of the present study do not constitute endorsement by the

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