For your marathon run, you need lightweight, breathable clothing that’s comfortable. You may have noticed that even on cooler days, most racers opt for shorts and a t-shirt or vest because once moving, you warm up quickly, so bear that in mind when choosing what to wear.
You also need to consider your underwear, as it can make a huge difference to the amount of chafing you experience when running longer distances. Like with socks, you should avoid cotton and instead look for moisture-wicking fabrics, like merino or synthetic materials, which are breathable and wick away moisture to help keep you dry and comfortable. But, the most important thing is to make sure your underwear fits you well and provides the support you need.
Post-race, you’ll want some comfortable and warm clothing to change into. A long-sleeved t-shirt or jumper and a pair of leggings are a must on cooler days as once you stop moving, you’ll soon cool down. It’s also a good idea to pack a lightweight waterproof that you can throw on if the weather takes a turn for the worse while you’re waiting for fellow runners to come in. Don’t forget to pack some spare underwear and socks too.