Beyond the Miles

[This follows on from last week’s newsletter - Breaking Stride]

Power is Nothing Without Control

If I were at a CrossFit box doing a Squat or an Olympic Lift with dangerously bad form it would be reasonable for the instructor or a more experienced athlete to provide instruction to keep me safe. If your run group is like mine there’s a certain omertà, a runner's code of silence, it would be frowned upon to suggest that someone’s run form is inappropriate for their pace. Maybe that’s back to Bill -  if something is so “easy”, so “meant to be”, then questioning someone's running technique feels awkward.

You Need Running Form

Many of you will know that I am a proponent of barefoot movement and natural running techniques, but it isn’t all black or white. Take the study published in the European Journal of Sport Science by Laurent Malisoux of the Luxembourg Institute of Health, which validated that heel-striking runners hit the ground harder but get injured less in more cushioned shoes. 

On a heel strike, you get two peaks. What the researchers found was that one of the effects of soft cushioning is that it slows down that first jolt, when the lower leg abruptly decelerates, spreading it over a longer period and causing it to overlap with the second. The combination of the two impacts makes the total force appear greater, giving the impression that softer shoes produce more force. But when Malisoux used mathematical techniques to separate the first and second impacts into distinct values, he found that the first impact, the one linked to injury, was actually smaller in softer shoes.

That’s vindication for the much maligned notion that shoe cushioning can lighten the load on your joints and reduce injury risk. It’s also vindication for some of the ideas that emerged during the barefoot boom. One of the benefits of switching from heel striking (common in cushioned shoes) to midfoot or forefoot striking (common, after careful transition, in minimalist shoes) is that it delays that initial impact peak and spreads it over a longer period of time just like cushioning.

"What you don't do can be a destructive force." – Eleanor Roosevelt

As an analogy, it is a good thing that someone invents a helmet which makes hitting your head against a wall a less dangerous pastime - but why don’t you just stop hitting your head against the wall in the first place? Maybe back to my “run shaming” - some kind of 21st-century cultural right to run however you want? Even as a head-banger, there’s evidence that a couple of weeks of gait retraining, when runners are instructed to “run softer” and given feedback on the size of their impact forces, can lower injury risk. You can pick your path, but only one seems both more logical and easier to implement. After all, I run the same way in my Vivos and my Vaporflys.

Another argument can be taken from looking at the Elites. At middle and sprint distances all elite runners are forefoot strikers. This says something about which strike pattern is best for handling high levels of ground force. At 10,000m up, especially the marathon, we see increasing numbers of heel strikers. These athletes optimize their form based on their individual biomechanics and the demands of their event. During speed-work, they will revert to forefoot striking. So as a recreational runner doesn’t it make more sense to keep it simple and adopt the foot strike pattern that is most versatile across paces?

Runners Need to Strength Train

Let’s look at strength demands in more detail. Intuitively I know that running speed is basically determined by the interaction between the runner and the ground. Speed (v) = Stride Length (SL) × Stride Frequency (SF). Where stride length is influenced by the vertical and horizontal Ground Reaction Force (GRF) that propels the body forward. 

To increase speed, a runner needs to spend less time in contact with the ground, have more flight time, and/or have a higher cadence. Vertical GRF must exceed the body’s weight to achieve lift-off during each stride. In sprinting, GRF can reach 4–6 times body weight, enabling explosive lift-off and quick transitions between strides.

Horizontal GRF directly accelerates the runner forward. Faster speeds require generating higher forward force relative to body weight during the ground contact phase. For elite sprinters, horizontal GRF is maximized in a very short ground contact time. At higher speeds Vertical GRF increases to maintain sufficient lift for reduced GCT. Horizontal GRF increases to provide greater forward acceleration.

"An ounce of prevention is worth a pound of cure." – Benjamin Franklin

Running speed depends directly on the effective application of ground force. Both the magnitude of GRF and how efficiently it is applied influence stride length, frequency, and ultimately, running speed. Speed improvements involve enhancing force production, optimizing mechanics, and reducing contact time.

In a range where there is 1x Body Weight (BW) per leg whilst walking and up to 6x whilst sprinting. Let’s take the example of a series of 3-minute intervals at 5km pace. Taking my weight of 70kg and the approximate GFR of 3x BW at that pace I am in effect doing about 540 reps of single-leg 210 kg movements during each interval. That's quite some accumulated force.

If we marry that with someone new to running and whose running form and durability are only adapted to 1.5x to 2x BW there is no guarantee that their technique or strength is appropriate for these higher loads.

It would seem that as a population we lack the baseline conditioning that was taken for granted for much of human evolution. We compounded this in the 80s with the rise of cushioned running shoes which desensitizes your running gait. Combine this comfort with the jogging boom and we have a perfect storm for running injuries.

A New Resolution

Join me with a New Year's resolution. Make 2025 a year of focus on strength, mobility and running form. My strength training has been lacking in consistency but going forward my 2 to 3 times a week go-to strength work will be Squats, Deadlifts, and the Split Squat/Bulgarian Split Squat, plus Bent and Straight Knee Calf Raises. You could make it more complicated but I believe those 5 lifts hit what I need to hit. As a commitment to myself - If I don’t strength train, I won’t run! In addition, I have a 15-minute arch and foot strength circuit that I try to do almost daily on my MOBO board. Stronger more resilient feet are a big part of the equation, and for daily casual wear you won’t catch me in anything other than minimalist “barefoot” shoes.

I’ll also be looking deeper into what insights I can get from my Stryd pod. Two metrics that the Next Gen pod came with are Impact Loading Rate (ILR) and Lower Body Stress Score (LBSS). These metrics are intended to help plan recovery and monitor overuse.

Lower Body Stress Score (LBSS) is a single number to help runners understand the impact of the mechanical load experienced between a runner’s center of mass and the ground that they accumulate over their day-by-day training. A key input to LBSS is your second-by-second Impact Loading Rate (ILR), quantifying its accumulated effect to create a single number for each run.

If you track how your LBSS is trending as compared to a personal baseline, you can identify and work towards a more balanced training regimen that reduces chances for overuse. Similarly, if you are coming back from injury and want to gradually transition back to regular training, monitoring LBSS week by week can be helpful to avoid any significant increases in mechanical stress to maintain a healthy recovery.

Stryd Footpath also promises to bring the power of professional gait analysis to your everyday runs, giving you insights that were previously only accessible through specialized labs and complex equipment.

Could big data be used to predict and avoid common running injuries? It will be interesting to keep an eye on what cool stuff that Angus and the Stryd gang are doing over there in Boulder, Co.

Finding Balance and Building Resilience

Running is often romanticized as the simplest sport, but the high injury rates tell a different story. While injuries may be compounded by a combination of modern lifestyle stressors and inadequate recovery, the solution lies in a more personalized and holistic approach to training. By blending strength work, running form cues, mobility exercises, and incremental progressions, runners can reduce injury risk and improve performance.

Moreover, leveraging modern tools like Stryd’s Lower Body Stress Score (LBSS) and Impact Loading Rate (ILR) provides valuable insights into mechanical loads and recovery needs. With these metrics, runners may be able to adapt their routines to balance stress and recovery more effectively.

In 2025, let’s make a collective resolution to train smarter and not get injured. Emphasize strength, technique, and self-awareness in every step of your running journey.