“What's the best surface to run on?”
Updated: Oct 19, 2020
“What's the best surface to run on?”, “Should I run on grass, concrete or a treadmill?” are frequent questions asked by runners, and the answer is surprising to most. So read below as we delve into the effects of running on different surfaces.
An average runner will take 1,000 steps per kilometre, and with 2.5 times bodyweight in force going into the body with each step, minimizing this impact may play a role in injury prevention. Runners often think running on a softer surface like grass will “cushion” them and therefore less likely to be injured.
However, a new study by Waite et al disputes this train of thought. The authors compared peak vertical tibial acceleration (a proxy for impact forces experienced at the shin) in trained distance runners on 3 surface types (grass, asphalt, and concrete) & 3 grades (incline, decline, & level).
What did they find?
They observed that running on a softer surface (grass) actually resulted in slightly HIGHER tibial accelerations compared to a harder surface (concrete or asphalt).
Before we discuss these findings further, let’s take a slight detour to discuss what happens inside our body when we run. Our bodies are pretty amazing, and when we run on different surfaces, we subtly adapt or “tune” our muscles & tendons to absorb impacts (our in-built springs). This adaptation occurs pretty much instantaneously when we change surfaces (Ferris 1999, Nigg 2001). So when we ran across a harder surface our springs become less stiff, and the opposite occurs when running on a softer surface, so the net result is impact forces that are pretty similar across surfaces.
What do other studies have to say on this?
If we look at the findings from other studies exploring this same topic we see:
No difference in tibial acceleration (measure of impact) between running on concrete, synthetic track, natural grass, a normal treadmill, & a treadmill equipped with a cushioning underlay (Fu 2015)
Compared to running on a sandy soft surface, running on asphalt actually DECREASED the risk of tendinopathy (Knobloch 2008)
A 2003 study by Taunton et al found no relationship between injury and running surface (Taunton 2003)
Other quick points on running surface
Examining runners on a cambered surface (a slope that would be found on a road or track), Unfried et al found that muscle activity was higher on the leg closest to the gutter, so it’s worthwhile mixing things up and not always having the same leg in the gutter!
Running on grass or dirt trails provide some unexpected hazards: we’ve seen plenty a runner injure themselves tripping on a tree root or landing in a pothole, so take this into consideration.
There may be an individual response to running on different surfaces. Anecdotally, we see runners who find their symptoms worse when running on a particular surface. This reflects the observation of Dixon et al who found that only some of the runners in their study changed their knee movement when running on harder surfaces, whilst others did not (Dixon 2000). So your personal experience plays a role in determining what surface to run on.
So what should you run on?
To conclude, our bodies adapt to running on different surfaces so well, that the differences in forces to our lower limbs are likely either nil or negligible.
Whilst the research doesn’t tell us what surface is best for runners, due to the highly repetitive nature of running, it makes sense to mix things up with a variety of different surfaces. If you can find a course with a mix of asphalt, grass, crushed rock or concrete then it will help break up the monotony of running. Alternatively, run on different surfaces for different runs during your week.
If you are training for a race, take into consideration the surface on which that will be run, as you will want to spend a fair amount of your time training on this surface. But remember, like anything in running, don’t make sudden changes, gradually implement change over time!
It’s also worth noting here that the discussion on the optimal running surface also mirrors the ongoing discussion about the optimal cushioning in shoes, but we will save that one for another day....
Dixon, S. J., et al. (2000). "Surface effects on ground reaction forces and lower extremity kinematics in running." Med Sci Sports Exerc 32(11): 1919-1926.
Ferris, D. P., et al. (1999). "Runners adjust leg stiffness for their first step on a new running surface." J Biomech 32(8): 787-794.
Fu, W., et al. (2015). "Surface effects on in-shoe plantar pressure and tibial impact during running." Journal of Sport and Health Science 4(4): 384-390.
Knobloch, K., et al. (2008). "Acute and overuse injuries correlated to hours of training in master running athletes." Foot Ankle Int 29(7): 671-676.
Nigg, B. M. and J. M. Wakeling (2001). "Impact forces and muscle tuning: a new paradigm." Exerc Sport Sci Rev 29(1): 37-41.
Taunton, J. E., et al. (2003). "A prospective study of running injuries: the Vancouver Sun Run "In Training" clinics." Br J Sports Med 37(3): 239-244.
Unfried, B., et al. (2012). "What is the Influence of Cambered Running Surface on Lower Extremity Muscle Activity?" J Appl Biomech.
Waite, N., et al. (2020). "Effect of Grade and Surface Type on Peak Tibial Acceleration in Trained Distance Runners." J Appl Biomech: 1-4.