I had a reader contact me about knee pain after they camped in a hammock that was so severe that it forced them off the trail early to recuperate.
This is a fairly common ailment when sleeping in a hammock and is caused by hyperextending your knees. Imagine that you’re lying in your hammock, with your feet in the middle of the sling, and your knees relaxed. Chances are that your knees are bending backwards a bit, perhaps imperceptibly so, but not at all in the way they’re intended to bend! This is what happens when you hyperextend them. I can relate to this issue because I’ve experienced it myself.
There are a couple of ways to prevent hyperextending your knees in a hammock, even asymmetric camping hammocks like the Warbonnet Blackbird where you can lie with your feet off-center of the hammock sling.
Assuming you lay flat on your back or perhaps slightly to the side, you can put a stuff sack full of clothes under the back of your knees so that they remain normally flexed at night while you sleep. This works well in warmer weather when you’re not wearing those clothes to stay warm. In colder weather, I bring a small inflatable pillow with me. Big Sky makes a nice lightweight one that I inflate and tuck under my knees. Works like a charm.
The other option is to arrange your legs differently, either curled up if you’re a side sleeper, or with the bottom of your feet pointing toward one another, so that your knees turn sideways and fall off the center of the hammock sling. However, it can be difficult to maintain these two positions at night when you’re out of it and using a pillow is much more foolproof.
The third option is to get a bridge style hammock, such as the Warbonnet Ridgerunner or the Jacks R’ Better Bear Mountain Bridge Hammock, which provide sleepers with a much flatter lay at night than a traditional gathered end hammock. Both of these hammocks are heavier than most sling style camping or backpacking tents however, although they can be much more comfortable to sleep in, especially if you’re a side sleeper.