I'm a runner who had a grade 2 hamstring injury (left leg) about 5 years ago following a milder hamstring injury several weeks earlier that I didn't allow enough healing time for. Probably due to not warming up properly in prep for a hard 5K training run.
Since then, I have had a series of injuries all on my left side, including a sacral stress fracture, Achilles tendonosis (mid section) that eventually resolved w/walking boot cast & physical therapy, and then within the past year, insertional Achilles tendonosis following a mild re-injury of the same hamstring, and culminating in a 50% insertional Achilles tear in early Jan '16 during a 5K race.
It required about 2 months before I could return to any running, and I was able to adopt a heel strike running gait that avoided Achilles involvement, as long as I ran slower than about 9:00 miles (quite slow for me).
In past 2 months, I have been able to gradually increase my running pace as the tendon healed, but I was still avoiding full toe-off. Walking however, continued to be difficult since it requires more or less full use of the Achilles during the heel - toe walking gait cycle.
All during the past 1 - 2 years I also had considerable numbness in both the top and bottom of my left foot. Also symptoms of sciatica in the left leg where I continually felt the need to stretch that hamstring to relieve the perceived tension.
Then 2 weeks ago, while using a foam roller on the hamstring just prior to a 4 mile run, something quite remarkable occurred. I had read an article about the "proper" way to foam roll, which involves stopping the roller over sensitive or tight portions of the muscle and letting the roller press on that spot for about 30 seconds. So I tried this on the site of my earlier hamstring injury.
Then I proceeded to take my normal approx. 1/4 mile warm up walk to the point where I start my run. During that walk, I noticed that I suddenly had a very pronounced new "spring" in my step from the left foot and markedly increased toe-off strength, accompanied by a total lack of pain in the ankle. During the run, I noticed new strength in that calf than facilitated faster running and almost no ankle pain during or after the run.
This strength has persisted. After consultation with my podiatrist and considerable research into what could possibly have occurred to cause this spontaneous "miracle", here is what presumably happened: The extra foam roller pressure at the site of the old hamstring tear probably broke up an adhesion to the sciatic nerve, proximal to the point where it splits to form the separate tibial and common peroneal nerves.
This in turn probably opened up the nerve pathways. The tibial nerve then was enabled to restore feeling to the bottom of my foot, while the superficial branch of the peroneal nerve was enabled to restore feeling to the top of my foot as well as to restore muscle function to the peroneous longus and brevis muscles which are very important in being able to plantar flex the big toe as well as evert the foot during plantar flexion (toe off). Thus the new "spring" in my step! This also shifted some of the work of plantar flexion away from the Achilles tendon which attaches to the gastrocs and soleus.
In addition, the sciatica feeling resolved simultaneously, probably as a result of the sciatic nerve's newfound "freedom" from the hamstring muscle adhesion.
It is also quite likely that the weakened nerve, which effectively "shut off" the peroneous longus and brevis muscles, contributed to overuse of, and subsequent injuries to, the Achilles which had to take up the plantar flexion load. It may also have contributed to the sacral stress fracture, since without the "shock absorber" action of the peroneous longus muscle, my pelvic area was taking a pounding.
I can't tell you how much of a relief this spontaneous event has been, And now, I can go out for long brisk walks with no ankle pain, something I was completely unable to do prior that foam rolling session!