Toes in the Sand: The Effects of Running on the Beach vs. Hard Surfaces

My kids compete in the Beach Blast soccer tournament in Wildwood every summer. It’s a tournament on the beach. Small 5v5 fields. Three 12-minute periods. Athletes play in their bare feet. Inevitably, someone will cut their foot on a piece of broken glass (especially when the Barefoot Country Music Fest was on the same beach the weekend before). There are a billion teams signed up. Age groups from birth to 107, I think. There are actually more than 150 fields. It’s madness. There are also a couple of notorious teams from a specific section of Philly that will remain unnamed (Fishtown) whose parents find it necessary to start drinking at 8 in the morning when they arrive and then get in fights with opposing teams’ parents. I apologize to anyone from that area who I just offended, but it’s true. Other than that, it’s really a fun weekend. Our soccer club gets discounted wristbands for the waterparks and amusement rides, or as some differentiate as the “wet rides” and the “dry rides.” We eat lousy boardwalk food and end up being there 12 hours a day for the weekend.

It got me thinking about what the implications might be for running on the sand for hours: what the possible training effects might be, and the overall benefits of just having your feet in the sand. This year there was some torrential rain halfway through the event, so some kids were running on soft sand, and some got to play on more compacted wet sand (and some had to play in pretty much a huge puddle).

It turns out there are quite a few differences between running in sand compared to running on a firmer surface. These differences can be positive or negative depending on your training and what you are trying to accomplish. There is the obvious difference of sand being softer than grass, road, or other firmer surfaces, and this may be a benefit for some.

A study in the Journal of Science and Medicine in Sport examined the impact force of running on wet, compacted sand vs. dry, uncompacted sand. Its finding: “Mean and peak impact forces were approximately 4 times greater for the wet surface while penetration, impact time and rise time were approximately 3-4 times greater for the uncompacted surface condition. The wet surface was also found to be 6 times stiffer than the uncompacted surface indicating the presence of water substantially altered surface compliance.”

There was much greater impact on the harder surface. The soft sand provides a softer landing, reduces stress on joints, and lowers the risk of injuries like stress fractures. The soft sand, however, is also less stable the softer it is. So, if you already have knee problems, the increased stability requirement of running on sand may be an issue. Another possible benefit to sand running, depending on how you look at it, is that it requires much more energy and therefore burns more calories.

A study in the European Journal of Applied Physiology compared the energetics of six elite iron men when running on sand as compared to running on grass. For the sand running trials at 8 and 11 kilometers, net aerobic energy cost (calorie burn) was significantly greater than grass running trial values. It takes more energy to run on sand. No wonder my kids are still recovering.

While these characteristics of sand running may be beneficial for some, if you are training for sport – to run faster or jump higher – these benefits turn to detriments. When sprinting on a track, ground impact forces can reach upwards of five times bodyweight. So, if you are running in sand and reducing impact forces, that is going to have the opposite of the training effect we want to get faster on the track. To get faster, we want high-impact forces so that your body can adapt to that stress to get faster. If every time your foot contacts the ground, the ground moves, you are not able to create as much force as when you are contacting a solid surface. The sand also increases ground contact time. Ground contact time refers to how long your foot is on the ground per stride. In sprinting, the longer your foot is on the ground, the slower you are going to go. Elite sprinters have a ground contact time of .07 to .11 seconds. So, running on the sand and increasing ground contact time is not good for sprint training. You won’t get faster running in the sand.

Some other benefits of beach running: If you go barefoot, you have that positive transfer of electrons. If you read my article on grounding, you know the many proven health benefits of contact with the earth. If you didn’t read the article, shame on you, you may be able to find it online on the Seven Mile Times website, 7milepub.com.

Depending on your goals, beach running may or may not be for you. Another added benefit is just enjoying the beautiful beaches of Seven Mile Beach. That’s what you’re here for anyway, right? We love the Beach Blast tournament every year. Next time, if I have to run from any overzealous parents, I’ll choose the wet, hard sand for reduced ground contact time.