I have recently discovered that when exercising or running, my safe MHR (Maximum Heart Rate) is 173bpm. Last night on my run I discovered 2 things. The first being what my MHR actually is when running. At the 2km mark in my run I stopped briefly to measure my heart rate. It was pumping nicely. I counted off 25 beats in 10 seconds x 6 = 150bpm. That’s pretty good I thought as I lowered my finger from the pulsing artery in my neck. I began to get into my run to complete it so I can measure my recovery pulse.
As I took my first few steps, I noticed the return of stinging pain in my shins. I’ve never mentioned this before in my blogs, as I didn’t think much of it, but this was different. It began at my ankle and went straight up my shin ending a couple of inches south of my knees. Both legs were experiencing the same pain. I immediatley thought, “shin splints”, but not really sure what they are, or are about. I tried to run again at a much easier pace, and was able to continue for a short distance before I was forced to stop and only continue by walking. It hurt actually more to walk than to run, so I picked up at a very easy pace. The pace ended up becoming so easy, there was really no need to measure a recovery heart rate when I got home.
I completed the run, and went through the usual cool down routines, water, stretching, breathing deep. I could hear the computer on the other side of the Family Room calling me. I wanted to learn more about what could possibly be causing this pain. I opened my Internet Explorer window, went to my default search engine “Google” and began a search for “Shin Splints”. There were quite a few returned results. I decided to look mostly at the Wikipedia site, as the others were getting a bit to medical for me to follow. So here’s what I uncovered in Wikipedia…
The function of the muscles of the anterior shin (tibialis anterior) is to dorsiflex the foot (bend the foot upwards at the ankle); other muscles here include the extensor digitorum longus muscle (long digit extender) and the extensor hallucis longus, which respectively moves the 2nd to 5th toes, and the big toe, upwards.
It might not be immediately obvious why a muscle which raises the toe can be stressed (injured) by running, because propulsion is not its function. Overstride is the reason: the stress derives from the runner landing heavily on the heel with each footstrike; thus, shin splints are a common ailment in military recruit training centers,  where recruit soldiers march extensively, by extending the leg forward and forcefully striking the boot heel on the ground. When this happens, the forefoot rapidly slaps down to the ground. Effectively, the foot, which is dorsiflexed before striking the ground, is forcefully plantarflexed, slapping the ground with the full sole of the foot.
This forceful extension (plantar flexion) of the foot causes a corresponding rapid stretching of the attached muscles. The muscle reflexes with a powerful contraction, an eccentric (off-center) contraction of the muscle that leads to soreness and possible injury of the muscle, tendon, and connective tissues.
A possible contributing cause of shin muscle pain is the relative weakness of the muscles on the front of the lower leg (the shin), compared to the relative strength of the calf muscles, at the back of the leg (the calf). Shin-muscle strengthening exercises usually are prescribed to balance the muscle-strength imbalance. The shin pain caused by medial tibial stress syndrome (shin splints) usually lasts some ten (10) days, the pain slowly diminishing as the muscle-strength imbalance is corrected. The shin pain is attributed to a forced extension of the muscle, by the opposing calf muscles.
I picked up on one of the causes, “over-striding” I have been working at improving my strides, hence improving my overall time. This, I would guess is the cause of this pain.
The good news regarding this is that it is a muscle issue and not your shin splintering or having stress ractures in it as some, including myself thought it was. A shin muscle that isn’t as developed as the calf muscles will feel the strain and will falter first. If one continues to work this group of muscles like this without proper recovery do risk eventual stress fractures in the Shin Bone. With that knowledge, I am delaying any further runs on pavement or on the trails until at least Sept 1st (giving a suggested 10 recovery period).
For now, I will head to the treadmill for a brisk walk, or maybe even a gentle run as long as the pain stays away. I am also looking into some ways to strengthen the muscles on my shins to be able to handle my return to running with longer strides. If you have any exercises or suggestions I’d love to hear them.
This is usually a good song to drive me on my run, but last night it just didn’t fit on my walk/easy pace jog 🙂