Backpacking is one of many activities that are weight-bearing and provide resistance. Carrying a weighted backpack up and down steep trails provides a workout that can also promote flexibility, strength and balance. It can also help to build bone mass.
Unfortunately, most people have developed their bone mass by ages 18 to 19 years old. Living a sedentary lifestyle will cause a loss of bone mass over a lifetime. Also, as people get older, the chances of a fracture will increase, which could happen while hiking on a slippery trail or navigating slick rocks and logs.
Luckily, backpacking can help prevent osteoporosis as part of an overall prevention plan that includes physical activity and diet. According to the National Osteoporosis Foundation, activities that are weight bearing and high impact can help with building bones for those people who don't have a low bone mass, or are not considered frail.
While on the trail, take special care to prevent slipping and falling, and perhaps having a fracture. Wear hiking boots with a tread that can grip the trail, and carry trekking poles to maintain balance. Always keep an eye on the trail and for any obstacles.
Before hitting the trail, check with a doctor as to whether backpacking would be a good idea for combating osteoporosis. Each person is different, and if there is little bone mass, or if a person is frail, then backpacking might not be the best exercise. Also check for any other health issues that could be aggravated while backpacking.