Last week I pulled something in my upper thigh that runs into the pelvic area. It doesn't hurt when I walk, but when I run, it is very painful. The other time I feel it is getting into the pickup when I lift my leg high, though I can do knee lifts without pain. I tried ice, heat, rest and massage and so far it still hurts, though not as badly as it did the first day. Question is - is it safe to keep up with normal walking? (I usually walk about 3 miles a day with the dog.) Is it safe to do the treadmill at a fast pace? The stationary bike didn't hurt when I tried it, so is that safe as xc while it heals?
It sounds like one of your many hip flexor muscles, and if it is not pulled too bad, you should be OK with walking and anything else that doesn't hurt. Going fast on any surface would not be a good idea because it requires your legs to swing farther and faster, which can be hard on these muscles.
Did you catch your foot on something while getting into the truck? Normally, it would be hard to pull this muscle by running, unless it is really fast, or on challenging terrain. You didn't mention an upcoming race or training program, so hopefully this injury came along at a convenient time, and you can save yourself a few miles and get some other things done while it heals. If you are kind to the injury, it should be back to normal within a couple weeks.
In the meantime, I would avoid speed work and any stretches that extend the leg too far to the rear. Familiarize yourself with the pelvic muscle group, and what muscles perform which actions, so you know where to focus any massage. Here's an interactive animation of the relevant muscles for study...
I think it may be one of the adductors, since the pain starts at the pubic area and continues to the back of the thigh. It's a hard area to ice and massage, because the painful area is deep in the thigh. I have a doctor's appointment late in the week and I'll see what he says. I hate having to spend the money for a doctor, but it isn't getting better and I want to be sure I'm not doing more damage by continuing to walk on it.
I first felt a twinge in the pubic area when running on the treadmill, but it wasn't really painful. Next day I was doing a short hilly run and two miles in the pain started. I cut the run short and tried ice and a hot bath. By that night I could barely walk. Over the next few days, with lots of ice, massage and hot baths it seemed to be getting better - until I tried to run. Or, as I said, when I'm climbing into the truck and have to lift my leg sideways.
Unfortunately, the timing was terrible. I had a race scheduled on Saturday (my first HM) and have another scheduled in six weeks. Looks like I won't be able to do either, which means no races until fall, if then. It's really frustrating.
All of the adductors, except for the Gracilis, are hip flexors, too. This helps to explain why the pain kicks in during seemingly unrelated movements. Running calls upon a larger group of muscles for flexion than other activities, in order to spread the load and rest some fibers while others are active.
The adductor/flexor most likely (as described) is the Pectineus, high and shallow on the inner thigh, right on the surface of that web from the groin. Refers pain to the hip socket. One way to distinguish it from the others is that the fibers are heavily striated, like corduroy when felt through the skin. The fibers move at roughly a 45 degree angle from groin to upper inner thigh. I would not ice this area, but the heat may help.
Try getting a thumb on it to check for sensitivity. It is not normally a sensitive muscle, despite its location. Hard to let anyone else touch, although I did work on a triathlete's in public once by her request. She said it was a recurring problem after she strained it and continued training. Not much area to work because it is a very short muscle, shown in the link I posted above.
It turns out it's probably a pelvic stress fracture. It doesn't show on x-ray, but the orthopedist is pretty sure that's the problem after examining me. He pressed on the pubic bone and I practically went through the ceiling. The pain is there when I'm on my feet but not when I'm lieing down. He manipulated my leg in all directions and there was no pain, but as soon as I'm standing on the leg, it hurts.
So, no running for a while. He did give me the okay to use a stationary bike or do water exercise. I forgot to ask about yoga, but I suppose it goes in the category of "if it hurts, don't do it."