Wearing long pants is always an option I suppose but seeing as how this is Thailand and it is routinely the temperature of the surface of the sun here, this isn't always going to be your best option. I had never seen these things before I moved here and started running with the Hash House Harriers but they have become a very important part of my jungle-running outfit.
You can see in the picture above that most of the people in our crew are wearing some sort of thing that goes from their shoes almost all the way to their knees and it is made of some sort of plastic-looking material. These are commonly referred to as "Gaiters" and they are meant to keep various nettles, thorns, and other wildlife out of your socks and shoes. In a lot of the territory we run it this inexpensive accessory can make a huge difference in how much you enjoy your run.
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It is possible to buy these things but for the most part we have found that the ones in the shops are simply overpriced pieces of fabric that are connected with zippers or buttons and that is exactly what our are made of as well only they are not expensive. We simply make our own and they end up costing a couple of dollars each.
Some of our members choose not to use them because they feel as though it makes them too hot when running or slows them down but these people almost always end up regretting it because there are a lot of things on our trail runs that seem to want to come along for the ride.
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Thorns, sand spurs, and various nettles are very common on our trail runs as well as trail runs around the world and once they get inside your socks (and they will do) they make a run quite uncomfortable especially if they hit that "sweet spot" that is just inside where your foot makes contact with the side of your shoe. They can be extremely difficult to remove as well and I have been through multiple pairs of socks that when looking at them and how covered with thorns and nettles they were, I just decided to throw out the socks rather than try to pick each individual thorn out. They are really effective at hitching a ride and nature has evolved these plants to be this way so that they would hitch a ride on animals in order to make a new plant somewhere else. Unfortunately for you, this amazing design on the plant's part is very uncomfortable and painful for the runner.
Gaiters prevent them from ever jumping on board in the first place and even though it may feel silly the first time you put them on, they are a crucial part of any Hasher's gear. I just had mine made for me by someone local for a couple of dollars but now I would never go trail running without them.
There's a lot of plant friends that are dying to hitch a ride in here
This isn't required gear or anything. We don't tell anyone what they have to wear and we even have some folks that walk with us wearing only sandals. These people almost always end up regretting this decision.
For me, the gaiter purchase I made is one of the best decisions I have made as far as interacting with the jungle is concerned. It improves comfort and makes the runs a lot less injury-prone. Even if your are not part of the Hash House Harriers, I strongly recommend this product if you are going to do any sort of field or trail running. If you don't have access to someone that can make them for you like we do here in Chiang Mai, they can be purchased for very little money if you shop around.
In my experience there isn't a lot of difference between the high-priced ones made by NorthFace or some other outdoor clothing designer than some generic counterpart that costs almost nothing. Just make sure it is made of some sort of material that plant life isn't capable of gripping to. It's a lot easier to enjoy your post-run beer if you are not pulling thorns out of your socks for half an hour.