Im doing Aconcaqua December 2013 and wonder if people can give me tips/recommendations on increasing my cardio fitness.
I live in the South West of the UK so pretty flat nearest peaks are Brecon Beacons and Snowdonia which I am usually up every other weekend carrying 20kg and really pushing the pace.
Im also using a Personnel trainer which I always swore I would never use one as Ive always been more than motivated at working out on my cardio and love pushing myself so never needed one, but now realise I could do with all the help and that extra push I can get.
I couldnt find a Persennel trainer in these parts that has been to Altitude so chose one who specialises in endurance type training.
Even though all I do is train at cardio ie running/rowing/hill climbing interval training/tyre flips/Mountain Biking/Treadmill at max incline with 20kg pack is there anything else advice or tips people who have been their and got the T-Shirt can recommend I also do to help build the cardio up.
I also have the PowerBreathe as well which I use every day.
At 50 yr old even though I have worked out for years I realise Im no spring chicken anymore so any fitness advice is more than welcome.
I dont mind not summiting for something out of my control as that is just the luck of the draw, but it will eat me up if I dont make it due to something that is within my control and especially my fitness.

rpartington,
Here are some ideas specific to mountaineering:
http://www.alpineascents.com/denali-train.asp
http://www.mountainguides.com/rainier-training.shtml
FWIW:
another idea for cardio gain is to train for a 70.3 triathlon with a "good" and reasonable time (i.e. 6-7 hours to complete). If you do the workouts 5-6 days a week (there are lots of programs out there online), you will go to the mountain with lots of physical and mental momentum.
Each day on the mountain will not really seem like a standout/dreaded "workout", but "just another day." Your body might even crave the exercise. Just a thought.

Good luck on The Big A!
JM

rpartington - if you're really doing all that then you're training harder than I ever have and I've climbed Aconcagua twice, no problem. Pushing it on the long pack walks in the Beacons will probably do you as much good as anything else. It's not just the aerobic or physical load, it's sustaining a moderate workload both mentally and physically for 6-8hrs at a time. Training exercises like rowing, stairmachines or tyre flips are fine, but too easy to stop or slack off and too neat and clean. Get way out in the hills with a pack on your back, tired, cold and late - and know that the only way out is to just keep going 'til you're back at the car.

Most people fail on Aconcagua because they don't allow enough time to acclimatise properly - either on the mountain or on other hills just beforehand - or to wait out bad weather. And many of those that do summit on regular schedules only just make it, in no state to enjoy it, or with any margin if things go wrong.

It's a great place, take your time, enjoy it.

Apologies for the late reply, not sure why but I must have missed the notification to say I had 2 replies.
Appreciate both responses greatly.
Ive also paid out for a months rental of an Hypoxic Tent and Exercise mask, https://www.altitudecentre.com/rent/ihe-systems/ .
As I say the price this trip is costing me I dont want to get back home having not made the summit and think, hmmm I wonder if I would have made it if I had trained with this or that or paid out for this or that. Dont really want to leave anything to chance, hence why I asked the question in here and I do appreciate the responses, if nothing else they put my mind at rest that Im on the right lines with my training.

Thanks again.

Roy