A jump in height of thousands of metres can do pretty odd things to the body, especially when you come from somewhere a mere 18m above sea level like Jasmin Taylor.
The 22-year-old became the first British athlete to win a Telemark World Championship medal earlier this year with bronze in the sprint race.
Hailing from Ipswich, a place notoriously hill-less, her pre-season destinations have been in Switzerland and on a French glacier where the highest altitude is 3,737m.
"It's ridiculous - living at 2,000m and training at about 3,500m is quite full-on," she told BBC Radio Suffolk.
"Sometimes it affects you worse than others. I can get nosebleeds or headaches, you get hungry a lot because you're using a lot more energy, you need to drink more.
"Just generally it's a bit more fatiguing, for anyone, but especially when you live at sea level it's definitely a shock to the system.
"There are times when it doesn't affect you at all, but certainly some days you can feel the symptoms and it pressing on you somewhat. It's bizarre."
Targets for 2016
The Telemark sprint race includes jumps, similar to ski jumps, and Taylor has quickly established herself among the world's best in the sport since competing in her first World Junior Telemark Championship in 2011.
The world number eight and British number one is determined to be crowned British Champion again this season, having missed the chance to defend her 2014 title due to other commitments.
"My goals for the coming season are 'input' goals rather than 'outcome' goals," she continued. "But of course you always want to see an improvement in timings and results.
"I'm extra intent on improving elements of my technique, fitness and mentality, which should in theory improve results but without that being the immediate process."