Author Archives: runscribenews

Asymmetries – what is normal & how do I correct them?

We know that everyone has asymmetries associated with their running mechanics. At RunScribe, we look at Symmetry in a unique way – from both a motion & performance perspective.

By looking at symmetry using these categories, runners can start to see not only where the asymmetries lie, but how they impact performance. And with our big data comparison – we can evaluate whether your asymmetries are low, medium or high, compared against the our database of millions of footsteps. But what is unclear is understanding at what point do these asymmetries pose a problem and how should you address them?

We’re putting that question to some experts, and will publish their recommendations. Stay tuned!

How Poor are Runners at Self-Identifying Footstrike Patterns?

Running Research Junkie summarizes a number of studies that compare runner’s self-reported footstrike type to reality.

How poor are runners at self-identifying their foot strike pattern?

The Hot Topic of Cadence

Running Physio highlights misunderstood aspects of running step rate (cadence) – and what can happen when you aim for 180 steps per minute.


Pronation or Supination?

Q: Pronation or Supination – how to tell the difference with the data? – JxRx

A: Pronation excursion (FS-MP) is the measure of how much roll the foot experiences between footstrike (FS) and the point of maximum pronation (MP). MP usually occurs before contact time is on average around 300ms. Similarly Pronation Excursion MP- Toe Off (TO) is the amount of roll the foot experiences between maximum pronation and TO. So what does “roll” mean in terms of pronation/supination? One way to think about these angles is to draw a line between your mid heel and 2nd metatarsal. The roll angle is measured as the rotation around that line. Inward rotation (eversion) is negative and outward (inversion) is positive. Another way to think about it is if your foot is on the ground and you pronate, your arch tends to flatten. – RS

Correlating pronation velocity and pronation excursion?

Q: One correlation I have noticed that is pretty consistent across all of my runs is the correlation between pronation velocity and pronation excursion…Overall my rS numbers were pretty symmetrical b/w my right and left foot (which is something that I’ve been thinking about lately – whether or not it’s beneficial to strive for symmetrical biomechanics b/w my left and right side).? -Paul

A: There is indeed a strong relationship between maximum pronation velocity and pronation excursion, from both algorithm and foot-movement points of view. If you’re somebody who pronates in 50msec consistently, with reasonably low (<800deg/sec) pronation velocities, then you’ll see a very strong correlation between pronation velocity and pronation excursion. As the pronation velocities get higher (and the pronation times vary), the correlations can become less strong. In terms of symmetry, don’t be too concerned with striving for “perfect” symmetry. No one has exactly the same movement patterns on both R and L sides. However, if you have chronic injuries that tend to appear more on one side than the other it is useful to try and understand what the differences are and what might be causing them. – RS

Differences In Ground Contact Time Explain the Less Efficient Running Economy in North African Runners

Research Paper

The purpose of this study was to investigate the relationship between biomechanical variables and running economy in North African and European runners. Eight North African and 13 European male runners of the same athletic level ran 4-minute stages on a treadmill at varying set velocities. During the test, biomechanical variables such as ground contact time, swing time, stride length, stride frequency, stride angle and the different sub-phases of ground contact were recorded using an optical measurement system. Additionally, oxygen uptake was measured to calculate running economy. The European runners were more economical than the North African runners at 19.5 km · h−1, presented lower ground contact time at 18 km · h−1 and 19.5 km · h−1 and experienced later propulsion sub-phase at 10.5 km · h−1,12 km · h−1, 15 km · h−1, 16.5 km · h−1 and 19.5 km · h−1 than the European runners (P < 0.05). Running economy at 19.5 km · h−1 was negatively correlated with swing time (r = -0.53) and stride angle (r = -0.52), whereas it was positively correlated with ground contact time (r = 0.53). Within the constraints of extrapolating these findings, the less efficient running economy in North African runners may imply that their outstanding performance at international athletic events appears not to be linked to running efficiency. Further, the differences in metabolic demand seem to be associated with differing biomechanical characteristics during ground contact, including longer contact times.