?"It's time to face the cryptic 'cross-training' references on my marathon schedule. What should I do? There's so much choice! Whenever I run more than about 14 miles my upper body gets tired, so I know I need to develop my core strength, but what's the best

, or a perceived effort of "able to talk in short sentences", is easier to sustain, and less likely to lead to you becoming injured or stopping enjoying your runs. – VelociraptorLeave the strength training for another dayDo your core exercises as a

uphill, but running uphill all the time isn't really an option! I've seen two physios and a sports doctor, and all have suggested various abdominal/core strength exercises. They think it's perhaps a tight psoas or abdominal muscle, and have tried manually

injured. There are much better ways to improve your core strength. I've just finished 11 miles with a pack, and I probably won't be doing any exercise until Monday (three days away), when I might be able to move again! – VezzaIf you want a little more

a gait problem when I get tired. I roll my feet around more and hold my toes rigid, anticipating an uneven foot fall. Core strength exercises have helped me run more evenly. The fledgling new toenail is in good health! – Stewart Macbride

? (grasshopper1)Strength training with free weights, the Swiss ball for core stability, different types of stretch and stability exercises – all those are twice a week. And I try to fit in some time on a Nordic ski machine, elliptical trainer or aqua jogger

is the answer, because you'd be changing your natural style rhythm. However it's important to run at different speeds so that you don't develop overuse injures by always running the same style with the same range of movements. Building upper body and core