Shopping in my family is not so much an activity as a sport and, as such, requires years of training. Stamina must be developed and skills honed. Vocabulary need not be extensive, though 10 meanings for "cute" are a basic requirement. Every girl must serve this apprenticeship - and look pleased to do so. I can remember one weekend with my grandmother in Chicago that was not so much "shop till you drop" as "shop till you die". By Sunday I could not walk and was wondering if the emergency services should be called. She clearly thought that at the age of 12 I should have known better. I could almost hear her thinking: no one ever said that finding the perfect rhubarb knit pantsuit would be easy.

Over the years there have been many more pitfalls and pantsuits (in America only men wear trousers). Some family members have had to be creative. Not many people know - much less are related to - someone whose version of credit control once involved keeping her Visa card in a block of ice in the freezer. "It is really great because I have to come home and then wait for the ice to melt before I can actually go back and buy. That gives me thinking time," said one of my sisters, beaming as she opened the freezer to show me her frozen plastic next to the mint chocolate-chip ice cream. Not too many years ago such behaviour might have been stigmatised. This was the period when women's magazines ran lots of articles about the dangers of shopping. We read about "retail therapy" and worried that we might be buying that extra set of towels to plug an emotional hole. It was all a bit stressful and such a relief to turn the page and read a sumptuous ad or two. This was also about the time that people who were not addicted to anything else started admitting to having a shopping problem. These "self-confessed shopaholics" spoke of "non-stop binges" and of spending thousands they did not have. Of course I was worried for them but also couldn't help wondering if perhaps freezing their credit cards might have helped.

These days no one likes to be called a shopaholic. "I really hate that label," said an acquaintance dressed top to toe in labels of another kind. "After all, it's not like I spend money on anything else." I stare at her with new interest. Such logic can only mean she has the shopping gene. Could we be related? These days my own gene only activates when I visit the family in America but this year something has changed. The shopping stakes have been raised. "Come on up and we'll go power shopping,"said another sister whose plastic is more hot than dripping. Now this is a woman who has just ordered a Lotus (no, not the flower) and my first thought was that this had something to do with engines.

"No, no, no!" But what is it then? "Power shopping is all about having direction. You know what you want and where to get it. It is goal-driven. You do not waste time." The idea is to scan and shop, shop and scan. It is an SAS-type operation: you reconnaissance the area first and plan your trip to miss the crowds. Forget Saturdays, this is more a Tuesday morning type thing. Then, when you start to shop, you need to keep moving, stay alert, remain focused. Do not allow yourself to get sidetracked: if you want a white silk blouse you do not linger over pale blue polyester. But what about impulse buying? Window shopping? My sister sighs but realises she is dealing with a slow learner. "Absolutely not. This is shopping for profess- ionals. Personal shoppers do this. Their client needs a great dress by tomorrow and they do not have time to get distracted. They do not look at shop windows. They do not have time to stop and buy a chocolate bar."

I stare. No chocolate bars? This obviously was serious stuff. "You can actually see the effect it has," says a power shopping veteran. "Their eyes start to glow as they walk towards the shop. Their whole posture changes. They walk faster and lean forward. It really is kind of exciting."

I am contemplating this while queuing at the local cafe and overhearing what I soon realise must be power coffee ordering. "I'll have one mocha cappuccino and one small, non-fat iced caramel latte, please," says a woman who looks normal but obviously isn't. "Grand mocha frappuccino for me," says the next. I thought about ordering a black coffee but quickly find something more complicated to help me prepare for power shopping. After all, I remind myself, no one ever said it was going to be easy.