Running performance: foot power matters!

As we have stated in previous articles, two of the most important physiological determinants of running performance are excellent running efficiency (technically known as running economy) along with a high maximal oxygen uptake and the ability to use a large proportion of that oxygen for sustained periods of time (ie without the accumulation of fatiguing lactate). Running economy refers to how efficient the muscles are (in terms of oxygen usage) at producing force during sub-maximal running speeds (ie not flat out). The better the economy of the running muscles during exercise, the less oxygen is needed to propel yourself along at a given speed.

Research shows that when it comes to elite levels of performance, what really separates world-class runners from those who are ‘merely’ excellent is their extremely high levels of running economy^(1-3). Moreover, there’s a distinct relationship between running economy, maximum sustainable oxygen uptake and maximum sustainable speed; more efficient running muscles require less oxygen to maintain a given work output, meaning that higher sustainable running velocities can be achieved at maximum sustainable oxygen uptakes. And that matters because the higher the speed at which a runner can run without accumulating lactate is known to be a highly accurate method of predicting race performance⁽⁴⁾.

Foot strength and running performance

Given that the muscles of the feet are working hard to provide propulsive motion during running, it would be surprising if foot musculature and strength had no impact on running performance. And when you look at the data, it’s clear that foot muscle strength and running gait are intimately connected. For starters, research shows that runners who wear standard cushioned stiff-soled shoes with arch supports have weaker intrinsic foot muscles than runners who are habitually barefoot or wear minimalist shoes⁽⁵⁾. This is because when wearing cushioned stiff-soled shoes with arch supports, far less involvement is required from the muscles in the sole of the foot (plantar flexors).

As regular readers will know, stronger muscles and tendons tend to be more springy, which means they work more efficiently. This applies equally to the muscles in the feet and explains why training and strengthening the plantar flexor muscles with specific exercises benefits short and long-distance running performance by improving running economy^(6,7). Likewise, running in minimalist footwear is known to increase muscle thickness and cross-sectional area, and increase in toe flexion strength^(8,9). This increase in strength – along with a smoother running gait due to increased somatosensory feedback and reduced external cushioning – is believed to enhance running economy⁽¹⁰⁾.

Testing the theory

If stronger foot muscles are more efficient, could strength training them – either using specific exercises, or by performing some running in minimalist shoes – result in measurably better running performance? The good news is that a new study by a team of Polish scientists has attempted to answer this very question. Published just two weeks ago in the journal Scientific Reports, this research compared two methods of foot muscle strengthening - specific foot muscle exercises, and indirect foot muscle strengthening by training in minimalist footwear – on the ability of runners to sustain a maximal running velocity⁽¹¹⁾.

In the study, 55 long-distance, recreational runners (18 females and 37 males, aged 21–45 years) who were regularly running between 20km and 100km per week were recruited. To improve the validity of the study, runners were excluded if they had any existing diagnosed foot problems, were already using minimalist shoes or performing foot strengthening exercises, or if they had any previous history of injury or chronic pain in the last six months.

The runners were randomly divided into two groups:

·        Foot exercise group - where the participants added in specific foot strengthening exercises.

·        Minimalist shoe training group - where the participants added in some running in minimalist shoes (Vibram Five Fingers) as an alternative method of strengthening the foot muscles.

Although there was no separate control group (ie a group performing existing running training only), the runners in both groups refrained from adding in foot strengthening exercises or using minimalist shoes for the first eight weeks of the study, which meant that they performed only their normal running training during the first eight weeks and therefore served as their own controls.