total beginner. I'm looking to build lung capacity and cardio-vascular fitness rather than calorie-burning. I run on a treadmill rather than road, and it's part of my gym programme which mostly consists of resistance machines. I'm a non-smoker, 5

, but only so I can get to the gym/race/work. I keep it as light as possible. If I could ditch the pack, I would. – coughie I'm training for a half Ironman, and I run once a week with my wife. She's a beginner and runs at a far slower pace than me, so

-twitch muscle fibres will not in themselves make someone a fast runner. The one thing that is consistently proven to improve fitness (and speed) is training. Generally the more you train the better you get. Less is NOT more! Don't get worked up about what your