A veritable skill in its own right and if you want to do XTRI events then its one well worth acquiring. Easy to coach in person so im looking at dates to run a session. In the meantime @Karianne Lancee had the mashed quads that go along with downhills at pace so I took some video to help me explain. Big thanks to @Beppo Buchanan-Smith and Daniel for modelling. The lads got the brief and in the video the main take away is 'body alignment' but there is a big confidence element to it too. So we are showing two different methods. One is inefficient, sore and well incorrect. The other takes bottle and practice but is well 'right'. What we want to do is stand tall as always but allow gravity to lean us down the hill. If we are over cautious the brain says lean back to slow down. What happens then is you are using the quads as brakes..taking full impact on every stride. On already tired legs thats more risky than finding a nice flow..dabbing the feet frequently to cut the speed when needed. A bit like making good turns in downhill skiing. Take a look at the video and see if it makes sense then go try it. If nervy do it on the road or a grassy slope first to get the hang of it before hitting the trails.