From what I've read about exercise induced anemia, it's not just heel strikes that cause it, since swimmers also get it. It has more to do with the intensity of the exercise. I developed anemia as a runner, though AFAIK I never had any issues as a long distance hiker.
When I was thruhiking, my issues with energy had a lot more to do with not getting enough fat than with the miles I was hiking. Usually a high fat meal in town did the trick to give me back the energy I lacked.