I'm with OM on this one. The hardest part of backpacking for me was the endurance, not the ability to put weight on my hips. Having the leg strength to keep hiking was more important.

Doing yoga will strengthen torso musculature more effectively if that's what you're after.
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"In the beginner's mind there are many possibilities. In the expert's mind there are few." Shunryu Suzuki

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