Apparently not. Research suggests that speed might not cause as much strain on the shins as is generally believed. But experts caution that recovery days are of course still important to protect your body in other ways, so don’t consider these findings as an excuse to skip easy days.
It’s a diagnosis no runner wants to hear: stress fracture, or a small crack in the surface of bone often caused by overuse.
While there are several factors that contribute to developing stress fractures; diet, recovery, shoes, and running form. People often point a finger at training intensity. Another word of caution here though, even if we can decouple stress fractures from high intensity training, we still have the risks of muscle and tendon damage from insufficient warm-up or poor form (that becomes more problematic as we amplify intensity).
The general wisdom that slow running will put less stress on our shins could be that recovery, helps reduce your risk of injury. It seems reasonable to assume, then, that running slowly causes less strain on our legs than running fast, since we’re “active recovering” during low intensity miles.
But that might not actually be the case: According to research from the University of Maryland, fast-paced running doesn’t put any more pressure on the tibia (shin bone)—a common site of stress fractures—than easy running. Interesting, and one would have to assume that the caveat is "for a biomechanicaly correct gait".
The researchers found that it wasn’t running at fast speeds that causes the most tibial load. In fact, it was the slowest-paced running that resulted in the most strain. That’s because when the runners went easy, they took shorter strides, and thus were on the ground more often than when they were going fast. That meant that there was more opportunity for impact, since the runners were hitting the ground more often.
Running at a normal, or moderate, pace actually caused less cumulative tibia load than running the same distance in fast or slow speeds.
The researchers concluded that running fast doesn’t contribute more to cumulative tibial load than slow running—so runners shouldn’t be afraid to incorporate intervals into their training.
But as I noted earlier, picking up the pace may not increase the amount of impact our shins endure, speed does increase our exercise stress level and expose us to other injury risk. Running at high intensity demands a lot more power from our muscles and bones, which is why you should still use these sessions strategically, time them carefully and ensure that you follow them with sufficient recovery.
Apart from the injury risk associated with high intensity training, adaption (broadly the same as fitness improvement) occurs during recovery from exercise stress, not during it.
In blunt terms, high intensity efforts might not increase your risk of shin splints, but there are still a number of other risks. And if you do too many or time them badly then you are likely wasting your time - even if you don't end up injured!
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Photo by nappy: https://www.pexels.com/photo/man-wearing-white-sweater-and-black-shorts-about-to-run-936094/