Quadriceps and more

Some recent updates, starting with the most annoying one:

1. Strained my quadriceps (or more accurately my http://en.wikipedia.org/wiki/Vastus_medialis) yesterday while running a half marathon. Took me by surprise, because this muscle group hasn't been a problem at all until now. A bit of googling tells me that "An imbalance between weak quadriceps and stronger hamstrings can also cause the injury, a condition that is common among runners". Also that it's more common for people who sit at a desk for most of their working day because the quadriceps is (unnaturally) extended for long periods of time. That's 2 out of 2 for me. I've done longer runs, but not suffered this pain before, so why now? I'm thinking that it's because this run was 11km mostly downhill, and the return was 11km mostly uphill,. And it wasn't until the last few kms that it started to hurt (at which point I switched to power walking). In other words it was more prolonged uphill than I've done before. QED. I'm pretty sure it's a minor injury, but doubtless will mean that, again, I'm going to be partially off my marathon programme and easing myself back onto it over the next couple of weeks.
2. Got my smartphone back from the repairers, so I'm back in business from a GPS / Runstatic perspective. Something very weird happened on my run yesterday though.... I'm running along, listening to music on my headphones, and suddenly the volume increases to maximum for no apparent reason. Ouch. So I dive for the volume button, bring it back to normal levels... and then it happens again. I thought maybe there was some physical pressure on the volume button on the phone, but I ruled that out. Perhaps some sweat where it shouldn't have been? After it happened about 5 times in a row, I had no choice but to unplug the headphones and listen to the sound of my breathing instead, which makes a change. Not quite so motivating, but not entirely unpleasant. I wonder if it'll happen again, and if I can work out why.
3. Moving forwards but standing still. Last week I had a full-on 100 minute interval training session on a running machine at the local gym. I don't remember ever seriously training on a running machine before. The weirdest bit was when I finished. It totally felt like I was moving forwards, even when I was standing still. Amazing how the mind plays tricks with you. Strolling back the short distance to my house it felt like being on one of those moving walkways you get at airports. Weird!