From online shopping to banking and socialising, many of us live our lives partially online. But can the internet, generally considered to be an opportunity for sloth, also be used for exercise? Increasingly, it seems the answer is yes. Amid the range of weird and wonderful clips available on sites such as YouTube are videos featuring instruction in dance, yoga, pilates, tai chi and aerobics. Meanwhile, specialist health sites and sports brands, such as Nike, also offer workout video clips. Unlike usual exercise classes, there's no fee, no allotted time and the venue is wherever your computer happens to be. Many of the clips are also short and easy to follow, which makes them appear perfect for busy people, as opportunistic workouts can be done during the working day. This is, at least, the theory. To test it, we asked a very busy person who usually does no exercise to try to incorporate one online workout into each day of one working week. Caroline Melville is based in a busy office in Pollokshields, Glasgow. She is very familiar with the internet but less attached to exercise. "I use the internet for everything at work, from storing files to texting and making phone calls through a web-based phone service, as well as shopping and online journaling in my spare time," says Melville, who owns the online administration service Virtually Sorted www.virtuallysorted.com. "It's never occurred to me to use it for exercise - which I don't do anyway. I live in a second-floor flat, and climbing the stairs once or twice a day is about the extent of it." The main obstacles are that she works long hours and the nature of her work is unpredictable: she never knows what she'll be doing on any given day. "I mainly just don't have the time," says the 28-year-old. "That said, I recently met a personal trainer through work and she told me it was lazy to use lack of time as an excuse. I joked to her that if she could find me something I could do at my desk, then I would do it." To find out whether online workouts could be the solution, we gave her the following web links for a variety of workouts, including yoga, pilates and dance. Here is how she got on.

  • Day one: 15-minute desk workout from Sparkpeople.com, found at www.youtube.com/watch?v=nKCPcRcJmqc
    "I loved this. It was mainly stretching, with a bit of leaning up against the wall, half-sitting, to work the thigh muscles. It was quite gentle, but you could make it as difficult as you want it. I liked the instructor and there's a series of them, so you can do different things on different days. I didn't break a sweat. They're all more stretchy, but I suppose if you're not doing any exercise then anything is good. I got some very strange looks from colleagues in the office. I told them I'd be doing it and wore headphones so not to disturb them, but I think sitting silently at my desk while putting my hands in the air probably looked a bit odd. A couple of people said, Don't expect me to do it!' but they did have a go at the chair exercises." Verdict: 6/10
  • Day two: Three-minute Nike Rockstar workout, found at www.youtube.com/watch?v=UvUxWg5Uirg
    "None of the videos I did was particularly energetic, which is probably a good thing because you don't want to take up loads of space in your office, or jump around and bang all the ceiling tiles out in the office below - but this was something of an exception. I really liked this, and because it's so short, it makes you do it more. "I think it needs to be done a few times to get right. The first time I got it completely wrong. It's one for the more co-ordinated person, but I'm left-handed in a way that affects my entire being, so for me it was three minutes of pure silliness. It was my favourite in terms of fun and I did break a sweat." Verdict: 7/10
  • Day three: One-and-a-half minute pilates "mermaid" stretch, found at http://fitsugar.com/tags/exercise+video
    "I'd been sitting on a train all day working on my laptop and it was good to stretch out once I arrived in London. The definition in the video isn't that great, however, and I didn't like the instructor. It wasn't as great a workout as the others, but it did get the cricks out of my body." Verdict: 3/10
  • Day four: Office yoga, from 43 seconds to a minute and a half, found at www.expertvillage.com/interviews/yoga-office.htm
    "This is very do-able at your desk. The instructor in the video is actually sitting at a desk. The production wasn't great, but there were accompanying pictures and I liked that it was cut into shorter videos. This meant that I could do one exercise, then take a call, then go back and do the next bit. It's probably not the way it's designed to be used, but it works for me. I also found that it woke me up a bit, so would probably be good for a morning. At this point I found myself running out of excuses for not doing exercise." Verdict: 6/10
  • Day five: Six-minute butt workout from Sparkpeople.com, found at: http://video.google.co.uk/videoplay?docid=4705813252678683124
    "The butt workout is really fun. You have to get down on the floor, which means it's not great for the office, but it's well-produced and who doesn't need a butt workout?" Verdict: 6/10

    Overall: "Before the experiment began, I thought using exercise videos would be a repeat of my Cindy Crawford Workout video experience, which was that I watched it but didn't actually do it. I remember putting it on, sitting down and thinking, God, I'll never look like that.' "But the people in these online videos are quite normal. The programmes are also short, so I didn't have to find a spare half-hour or get changed into gym clothes, and I was really surprised at the variety, which made it difficult to get bored. "I do a lot of typing all day and my brain does need a break. Usually, I'll go and get a coffee, but doing a brief workout is much better. It gave me more energy and made me a bit fresher before starting on the next load of work. "I would say, though, that we're high-tech to the hilt in our office, with high-definition screens and a high-speed broadband connection. This means that the videos downloaded quickly with clear visuals, which made them easier to follow. Other computers might not give the same result. "In general, I can see myself doing them again, particularly the ones by Sparkpeople, which isn't something I expected to say at the end of the experiment. I think they'd yield results if I did them regularly. "The experiment has also prompted me to sign up to Nike's online Nike+ running programme, which I've been meaning to do for a long time. I've got all the kit now and hope to start soon. "It's now or never for exercise and me - I've even suggested to my colleagues that we do a tai chi one together every morning, as a sort of wake-up and team-building activity. They laughed."