Firstly the altitude. Even in the towns at the base of the slopes it may take several days to acclimatise to the altitude. Ever woken up on your first morning to find your eyes puffy? At low atmospheric pressure fluid escapes out of the blood vessels and into the tissues. Yet holiday skiers often race straight onto the slopes, where the pressure is even lower and oxygen in shorter supply.

Next take dehydration. The fluid escaping into body tissues due to this low atmospheric pressure leaves the blood vessels dehydrated. Even the very air you are breathing is dry as precipitation sucks the fluid out of the atmosphere. Dehydration can drop your blood pressure, so now the brain is being fuelled with blood at a lower pressure and containing less oxygen. This can show as mild fatigue, slight dizziness and mild shortness of breath. It's easy to just put this down to the bracing exercise, and decide to stop off at the top and heat up with a glass of mulled wine. Oops, alcohol on top of oxygen-hunger? Not good for the head, but not good for the leg muscles either.

So let's look at the muscles. How often do you spend six hours a day with your knees bent five degrees? Well, you do when you are skiing. Your quads and hamstrings muscles are working overtime, using up their stored fuel and further compromised by their low blood pressure and oxygen deficit.

Now move onto ski bindings. Those who hire skis usually benefit from an expert technician adjusting the bindings according to the height and experience of the skier. People with their own skis may adjust the bindings themselves, and make sure that they are good and tight so that the skis don't come off with every crash. Bindings are meant to come off when you crash, to save the torque stress being applied to the knees instead!

Lastly the snow. If only one could guarantee the every holiday will be blessed with good snow. With only a week's holiday, it's too bad if the snow is not optimal and holidaymakers have little option but to get out there on the slopes anyway.

Now we have the full recipe for a cruciate ligament disaster within the knee. Patchy snow with loads of bits to snare the ski on. Tight bindings to ensure that the torque of a twisted ski is transferred directly from the bindings to the cruciate ligaments inside the knee. Compromised quads and hamstrings muscles unable to protect the cruciates. All of a sudden a loud CRACK! There goes the anterior cruciate ligament and there goes the rest of the holiday!

My advice is this. If you want to enjoy the ski season book up for more than a week. Book into your local gym for a few sessions under supervision before you set off on your holiday. Then spend a couple of days acclimatising on the lower slopes and enjoying your mulled wine down there while your body rehydrates and your blood pressure adjusts to compensate for the low oxygen pressure. Your knees will be so grateful and those knee clinic back home will just have to settle back and wait for the football season!