I've always had a bit of a struggle with my left leg, running-wise. I wear my left shoes out long before my right. My left hip is always more annoyed at me than my right when I'm working hard. At times, I've joked that my left knee is my "health scale" and if it starts to hurt, I probably need to lose some weight. Also, my left shins and calf muscles occasionally just freak out as well. When I'm on it, I do the work to keep these imbalances in check (ART, Yoga, stretching, and functional strength).
Late last year, it got a bit out of control and I really started to struggle with a recurrent left leg issue that was possibly hamstring tendonosis, glute insertion inflammation, and/or SI joint inflammation. During this flare-up, I was slow, in more pain than I'd like, and I definitely took longer to seek solutions than I should have.
First -- ART. It works so well for me. I highly recommend trying it out.
The downside? It's a temporary solution. It fixes me, but it doesn't fix me long term. My ART professional is super knowledgeable, so he recommended lots of strength, rolling, and stretching exercises that I obviously needed. But I still found it hard to make the time and effort to do the stuff that was prescribed. And so, I was going back when things flared back up. It was a maintenance solution with a little bit of slow improvement, but not a magic bullet, for sure.
Second -- Yoga. I finally started to get back into a semi-regular practice and once I got a few workouts on the books, I noticed that my leg started to be better. (This compounded with the ART to get me into a better spot.)
Third -- Functional Strength: Side lunges. Front & back lunges with leg extensions. Clamshells. Squat-cross. Burpees. Jump rope. Skips. Leg Swings. Reasonable speed work that doesn't hurt. Making time for this stuff other than the speed is difficult for me.
Fourth -- TV/Movie Stretching. I think this is the biggest reason why I've been managing my leg so much better this Summer than I have since when I really messed it up last Fall. Frankly, it's part of the stretching that my ART professional recommended. I'd just neglected what I should be doing until I found a way to incorporate it into my night-time media consumption.
Thanks to my shoulder dislocation, I did not have a choice re: adding some quality time with shoulder/arm workouts. I experimented with weights, but after getting strong enough to max out my rotator cuff with 2.5 and 5 lb weights and my larger arm stuff with 10 lbs, I decided I didn't want to buy heavier weights. Instead, I ordered a set of resistance bands and started a habit of doing my shoulder/arm workouts to stabilize my shoulder at least 2X per week at night (although in a perfect world, 4X would be wonderful). This had a bonus of allowing me to justify some media consumption that I otherwise might have felt guilty about.
STRETCHING WITH THE RESISTANCE BANDS IS AMAZING! I hadn't planned this at all when I ordered the bands, but now, every night when I finish the shoulder/arm stuff (and some nights when I'm too lazy to do it), I add in some great stretching that the bands enable. The big ones I've been doing almost every night include seated twists seeking a bind on either side and standing bow-pose (or dancer's pose), but with a switch between which hand(s)/arm(s) holds/pulls/anchors the leg. The end result has been *much* looser hip flexors, loosening of my transverse hip movement, and very surprisingly to me, much better hamstrings & glutes, which has translated to decreased pain and a slowly increasing ability to get faster without pain.
So, there you go. My anecdotal evidence is that the foregoing makes *my* hip/hamstring/glute issues much more manageable. And this early 40s lady has been able to get faster and improve her running fitness by doing the stuff above.