Today was our first filming day in London. We left our apartment in Croydon at 7 am, took the overtrain/tube into town and proceeded to walk and film all day (with a few bits of tube in-between, like for instance when we went over to Baker Street to record something special and, er, elementary. :D
I was carrying, on my back, a 2-camera studio (only one tripod, mind you), weighing about 35 pounds. I took off that kit at just about 5 pm, when we went back to our car that we'd left in Croydon and drove forever (traffic in London, sheesh) to Bristol, which we reached (after another bit of filming on top of a hill near Bath), at 10 pm.
Yes, my back hurts a bit. I also got a bruise on my collarbone. But I was able to carry this stuff and film and walk around all day. It's nothing superhuman, but it sure is tiring. And I don't know that I could do this stuff if it weren't for all the karate training I do.
So there. If you think karate is only useful to make silly movies, you're wrong. It's useful everywhere.