By Kirsten Todd

Hooked on Running

 

As a coach of mature runners (most of my runners are over 40, and some are in their 60’s) my focus is on injury prevention and keeping people running well as they get older. Simple changes such as varying the surfaces you run on can have a big impact on extending your running years.

 

If you’re reading this, chances are you have at least a cursory interest in running better and staying injury free. Chances are also that you’ve read somewhere that running causes big impact forces through your body, and that you should run on soft surfaces as much as possible to reduce this impact shock. And that’s a fair enough assumption. Looking a little further into the research however, we can see that assumption does not necessarily stack up.

 

Leg Stiffness and Ground Impact

When we run, we make contact with the ground over and over again. During this impact with the ground, the muscles and tendons of the leg act like a spring. They absorb energy on impact, and release energy later in the stride.

 

Your shoes and the surfaces you run on also function as springs, absorbing and releasing energy. They also have their own unique stiffness. For example, a cricket oval will be more “springy” and less stiff, than a concrete footpath.

 

To keep itself level during running, your body needs to find a way to adjust to the differing stiffness and springiness in the different surfaces you run on. The way your body does this is to change the stiffness in your legs.

 

Your body aims to keep the stiffness in the combination of running surface, shoes and legs constant. As you can’t adjust the stiffness in your shoes as you’re running, nor the running surface you are landing on, that leaves leg stiffness as the one variant you can change as you run.

 

Leg stiffness is adjusted before each individual time you contact the ground. Your brain receives feedback from the previous stride, and uses this information, along with stored information from years of experience) anticipates the stiffness of the surface you’re about to land on and adjusts how strongly the leg muscles contract before you land. And even more amazingly, your brain will adjust leg stiffness before you step onto a new surface. So, as you step from the footpath to grass, your legs are tuned differently in mid -air to allow for the anticipated change in surface.

 

If you are running on a hard surface, your legs are less stiff than if you are running on a soft surface. And vice-versa. Softer surfaces will mean you need to run with greater leg stiffness.

 

Implications for Injury

There’s no definitive answer as to which running surface is best for injury prevention. Here are just some of the research findings on the subject, from several different studies, referenced at the end of this article.  Unfortunately, these findings don’t really leave us any the wiser

 

  1. High impact loading rates are linked to plantar fasciitis and tibial stress fractures
  2. Overall injury rates are slightly lower in runners with high impact loading rates
  3. There is no evidence that softer surfaces are more gentle to the body than harder surfaces
  4. When looking at lowering the risk of injury to feet and ankles, grass is the gentlest surface, and treadmills are the worst. Treadmills have been found to cause a 6% greater flex of the knee
  5. Running economy and running form is worse on treadmills than on grass, gravel and asphalt
  6. There is no correlation between running surface and injury rate

 

And the list of seemingly conflicting research findings could go on and on.

 

 

What Does it All Mean?

It may be better to avoid some surfaces if you have specific injuries, but overall, there appears to be no single surface that is better for injury prevention.  Using a variety of surfaces which will make different demands on the muscles in your legs and cause different degrees of knee and ankle flexion will give your legs a greater all over training benefit.

 

Make use of footpaths, asphalt (if you can find a car free zone), grass, sand, trails and synthetic surfaces. Throw a treadmill run in every now and then as well.

 

Change Your Running Surface Gradually

Like most things training related, you need to ease into any changes gradually, and only change one thing at a time. Don’t increase your training volume dramatically at the same time as you start to include more trail running in your training, or while you change into a different style of shoe. If you chose to include some soft sand running in your training-which is great for building leg strength- ease into it very very gradually to avoid injuries particularly to the calves and Achilles tendon.

 

As a rule of thumb, I tend to have my runners do their speed work on softer surfaces such as grass, or a synthetic track, and their longer slower runs can be done on the footpath. Frequently we use the grass nature strip along the side of the footpath to mix things up a bit. Be careful that you can see where you’re putting your feet to avoid pot holes and dog poo. Also, be careful of the edge of the footpath where it meets the grass. These surfaces are often at different levels, and landing on the edge of the path could cause you to sprain an ankle or wrench your knee out of whack.

 

Train on Your Race Specific Surface

If you’re training for a specific race or fun run, as you get closer to race day, increase the amount of training you do on the same surface that the race is over. If it’s a road race, increase the amount of time you spend on hard surfaces. It’s hard to get onto the road – cars are bigger than you-but if you can find a safe low or no traffic area, go for it. If your training for a trail run, including at least one trail run in your training each week is important. Trail running can be very different to road running!

 

The Bottom Line?

What you should run on is a very individual thing, depending on experience, training injuries, availability and what you’re training for.

 

Making Your Body Work as an Older Runner

As we get older we need to pay more attention to some of the things we took for granted in our miss-spent youth, such as recovery and strength training to name a couple. Over the next few months I’ll be looking at specific ways over 40’s can extend their running years. If you’d like specific and actionable strategies to keep you running like a machine, leave your details here.

 

 

About the Author

The author, Kirsten Todd, has over 15 years’ experience in the health and fitness industry. She’s on a mission to have more women astounded by their own achievements.

 

In 2007 she founded Hooked on Running, in response to the growing demand from busy women in their 30’s, 40’s and 50’s, to train smart and make the best use of their scarce training time. As a small business owner and mother of two, (and a past life working in the corporate world) she knows first-hand the juggling act that’s required to fit training around family and work commitments. She coaches women online locally, interstate and internationally, runs weekly group interval training sessions in Sydney and conducts Learn to Run training courses for running novices.

>>More blog posts by Kirsten Todd

 

 

References
  1. Pohl, M. B.; Hamill, J.; Davis, I. S., Biomechanical and Anatomic Factors Associated with a history of plantar fasciitis in female runners. Clinical Journal of Sports Medicine 2009, 19, 372-376.
  2. Nigg, B., The Role of Impact Forces and Foot Pronation: A New Paradigm. Clinical Journal of Sports Medicine 2009, (11), 2-9.
  3. Knobloch K, Yoon U, Vogt PM. Acute and overuse injuries correlated to hours of training in master running athletes. Foot Ankle Int. 2008 July;29(7) : 671-6
  4. Ferris DP, Liang K, Farley CT., Runners adjust leg stiffness for their first step on a new running surface. Journal Biomech. 1999 Aug;32(8): 787-94.
  5. Ferris DP, Liang K, Farley CT., Runners adjust leg stiffness for their first step on a new running surface. Journal Biomech. 1999 Aug;32(8): 787-94.
  6. Greenhalgh, Andrew, Jonathan Sinclair, Andrew Leat, and Nachiappan Chockalingam. “Influence of footwear choice, velocity and surfaces on tibial accelerations experienced by field hockey participants during running.” Footwear Science 4, no. 3 (2012): 213-219.