In recent years having a rearfoot strike (or ‘heel-striking’ as it’s commonly called) has got a bit of a bad press. Such has been its demonisation that runners in my clinic sometimes confess it through hushed whisper, as if the foot strike gestapo are hot on their heels. Websites have emerged devoted to achieving ‘optimal running form’ by switching to forefoot, advice echoed by magazines and coaches. Despite this, switching footstrike has few proven benefits and is not without risk. Perhaps it’s time for a new view on footstrike and how to change it…
Firstly, we need to appreciate just how prevelant a rearfoot strike pattern is amongst endurance athletes. Larson et al. (2011) found that nearly 90% of runners adopt a rearfoot strike;
More recently a Brazilian study by Almieda et al. (2015) reported that 95.1% ran with rearfoot strike and under 1% with forefoot. It’s important to note that these are ‘shod’ runners (wearing shoes) rather than barefoot, but even examination of habitually barefoot runners suggest a rearfoot strike is common. A study of the Daasanach, a habitually barefoot group from northern Kenya, revealed that 72% ran with a heel-strike at endurance running speeds.
Although the data above shows considerable variation in footstrike amongst the studies, it’s fair to say that the majority of people run with a rearfoot, ‘heel-strike’ pattern. As such it is a normal finding on assessing a runner and NOT a problem! It’s also variable and changes somewhat with speed – we tend to move more towards a forefoot strike as we run faster, although again this varies between runners.
So if heel-striking is normal why change it? And if our footstrike varies with speed, why train ourselves to forefoot run at all speeds? Some people might answer, because forefoot is more efficient and reduces injury risk but does it? The research doesn’t seem to think so…
A recent study by Stearne et al. (2014) examined the implications of switching foot strike. They concluded;
“Contrary to popular claims by some in the running community, this study found no clear mechanical advantage of habitual FFS [forefoot strike] running over habitual RFS [rearfoot strike] running. Switching between RFS and FFS running techniques may have implications for injury reduction/recovery given the altered distribution in loading between joints but should be weighed against possible overall performance decrements/ improvements. Switching from a habitual RFS to an imposed FFS may be detrimental to overall performance because of an increase in both positive and negative average lower limb power, which can help explain the recent finding that imposed FFS running also requires more metabolic energy” Stearne et al. (2014)
Stearne et al. point to recent research by Gruber et al. (2013) that compared running economy between rearfoot and forefoot strike patterns. They found that forefoot was not more economical than rearfoot strike and that a rearfoot strike may confer benefits at endurance speeds. Results of these studies should be interpretted with caution as they only show immediate change and only examined a limited speed range (up to ~5m/s).
In terms of injury rate, the majority if the studies show no difference between footstrike patterns as discussed expertly here by @CraigBPayne. There’s also an important point to consider, such studies examine injury rates in habitual rearfoot or forefoot strikers, they don’t tell us what happens to our injury rates if we change our footstrike. Clinical experience would suggest a change in footstrike may increase injury risk, at least initially, due to the large change in load. I’ve seen a number of runners with calf, achilles and foot pain that coincide with switching to forefoot.
Footstrike as a continuum
Amongst the running community footstrike is often thought of as a discreet variable with 3 distinct categories – rearfoot, midfoot and forefoot strike. In reality it’s more likely to be a continuum from extreme heel-strike through to extreme forefoot strike with midfoot somewhere in the middle. The picture below shows a rough guideline as where initial contact might happen;
Biomechanical studies suggest that towards the rearfoot end of the spectrum load is higher at the hip and knee and towards the forefoot end it’s higher in the calf and foot;
Forefoot runners activate their calf muscles 11% earlier and 10% longer than rearfoot (Ahn et al. 2014). It’s estimated that runners with a forefoot strike load their achilles tendons 15% more than rearfoot runners, resulting in an increase in load equal to 47.7 times body weight per mile (Almonroeder et al. 2013). Habitual rearfoot runners place more demand in the knee joint in both sagital and frontal planes (Stearne et al. 2014), so there are pros and cons of each footstrike pattern and risks of switching from one to the other.
Perhaps it’s time to think of changing footstrike not as a leap from one category to another but rather as a progression along a continuum. Recent research helps us to build this concept. Forrester and Townend (2015) studied the effect of running speed on footstrike patterns in 102 runners. They found runners seemed to fall into 3 groups; those that were consistently rearfoot strikers, those that changed from rearfoot more towards mid, or forefoot strike with increased speed and those that were consistent forefoot strikers. If we add their findings to our continuum;
…Well, a further interesting finding was that consistent rearfoot strikers had a lower stride frequency and larger stride length compared to the other two groups. It’s interesting because stride frequency and stride length can be changed to affect footstrike. We might be able to move along the continuum, to, for example reduce load at the knee, by increasing stride frequency and reducing stride length.
Multiple studies now show this method can reduce load on the knee and hip and reduce shock absorption at impact (Schubert et al. 2014, Lenhart et al. 2014, Wilson et al. 2014) . Heiderscheit et al. (2011) also demonstrated an increase in step rate (another term for stride frequency) reduces foot inclination at initial contact, reducing footstrike angle – essentially moving along the continuum towards a more midfoot strike;
This image from @runtechnique shows some of the effects of reducing stride length. Note the difference in foot angle at footstrike;
In a nutshell what I’m saying is if you want to change footstrike, make a small, manageable change by adjusting stride frequency and stride length, rather than switching footstrike altogether. Increasing stride frequency by as little as 5-10% can significantly reduce loading while having minimal negative effects on performance.
As footsrike, stride length and stride rate vary with speed it may also be useful to examine how athletes accelerate, especially if they predominantly use increase stride length to increase speed as this may affect footstrike. More on acceleration strategy in part 2…coming soon!
Summary: Heel-striking is arguably the most common footstrike pattern amongst runners. There’s no clear advantage of switching to a forefoot strike and some evidence suggests rearfoot may even be more efficient, especially in endurance events. Each footstrike pattern has pros and cons and affects load at the hip, knee, calf and foot. Large changes in footstrike can increase load on different tissues and potentially lead to injury. Footstrike should be viewed as a continuum, rather than three separate, fixed patterns. We may move along this continuum as speed increases or by altering stride length and stride rate. A final, key question, is why do you want to change? If it’s for improved performance there may be neglible benefit, but small changes may be useful to alter load, especially at the hip and knee, which may be useful to manage injuries.
In answer to the question, “Should I switch to forefoot running?” The answer is probably, “no.”
And finally a special mention to Peter Gettings who has been instrumental in helping me gather the research needed to keep this site up to date. Thanks Peter!
Peter is a top physio and a key man to follow on Twitter – @Peter_Gettings show the man some love!