Years of use (and abuse) can wear away the padding between bones. For backpackers, this can be especially severe in the back–a painful arthritic condition called spinal stenosis. Compressed vertebrae choke off blood flow to nerve roots, resulting in an aching or numbing sensation. "Legs cramp and the more you walk, the more it hurts," says Kelly, the orthopedist.
Prevent Use hiking poles to shift your body weight forward. "A forward-leaning posture will open up space for the nerve roots," Kelly says, and alleviate pain.
Soothe Pop an anti-inflammatory and sit with your back curved forward. If you can’t get relief, ditch your pack and walk slowly back to the trailhead, using hiking poles to support a comfy position.
Strengthen Abdominal muscles support the spine. Work on your six-pack with crunches. Kelly prescribes 3 sets of 8 to 12 reps every day. As you get stronger, increase resistance by doing crunches while holding a small weight (5 pounds) behind your head.