Being physically fit and being mountain fit are two very different things.
Being mountain fit will allow you to move efficiently and safely over mountainous terrain, uneven rocky surfaces and endure continuous uphill movement for hours (or days) on end.
Even if you’re doing a one-off adventure, you need to be physically prepared to go the distance, as there aren’t any quick exits from the side of a mountain.
You need a combination of strength, agility, endurance and mental grit to make sure you get to the top of the mountain with enough gas in the tank leftover to get back down safely.
On top of this, you will need a plan for acclimatisation if you are going to take on anything over a few thousand metres.
Being fit doesn’t exclude you from altitude-related illness, and it is this process that allows your body to adapt to the drop in oxygen availability.
Mountaineers achieve acclimatisation by heading up slowly and staying at moderate altitude (2,000 to 3,000 metres) for a few extra nights, then continuing a staggered ascent.
Professional mountaineers may include some pre-trek acclimatisation, using natural or artificial environments to encourage their bodies to adapt.
Although fitness won’t save you from altitude sickness, mountain climbs demand many hours of hiking, with a loaded pack, over a number of days.
Being in the best possible physical shape will help you to to meet the strenuous demands of high altitude hiking with a lower sense of effort and lower levels of fatigue.
Super-fit mountaineers and athletes also don’t expend as much oxygen – handy when there is less and less available as you climb.
As well as improving overall fitness and gaining mountaineering experience, participants in a climb should train their technical skills on indoor climbing and ice walls, prepare psychologically and try to eat well to make sure their immune system is fighting fit when the climb comes around.