I recently took my first steps in natural running. About 5k on a treadmill, to be precise, in order to get a feel for the mid-foot/toe motion as opposed to my usual (very) heavy heel-strike technique. It felt great and so much lighter.
However, the very nature of this style is that the calf muscles and Achilles tendons are having to do more work. They are partly protected in a traditional running shoe as the shoe is taking over! Despite only doing 5k at a gentle pace, I suffered from some bad calf soreness over the weekend which ruled out any further running. Thankfully, it is pretty much back to normal today.
By contrast, my Achilles is just fine and I’m not surprised by this: When I first started football refereeing, I had major problems in that area, even though running was not new to me. Why? Changes of direction and speed. It’s one thing to go out for a jog where your tempo rarely changes. When refereeing, your speed and direction is constantly changing, and my Achilles did not know what hit them! It took a while to settle down, although I did not help particularly by refusing to rest properly. The end result: Strong Achilles.
I need to be more careful with the transition. Today, I intend to do a simple 5k on the treadmill (The weather outside is awful!), but most of it will be in my usual running shoes, with a bit of natural running in the my new Inov8 shoes at the end. A safe mixture. After all, I didn’t get any pain during the previous run: The DOMS came afterwards!
My calf muscles are getting more of a load in other ways too: I’m working on learning jump-rope for conditioning (via CrossFit) and being light on your toes for that necessitates calf-loading!