If you want to have huge and impressive but not particularly useful muscles, the best way to do this is to lift extremely heavy weights using those machines that you find in the gym. There isn't much point thinking about buying these machines unless you have tons of space (and money) because they work very specific muscles and so you need many of them. This is because the movement is constrained or supported and so you don't use any of those smaller muscles which are needed to move things in "real life" (things don't usually move in perfectly straight lines). In fact, it is very easy to end up with severe muscle imbalances that, while they may look impressive, they could easily become injured doing real work. In fact, most body builders use free weights (that is to say, dumbells) for this reason.
If you have any doubt why you should need to do strength work while training for an Ironman just work out the number of steps you take in a Marathon and multiply that by one or two times your body weight (your impact force in running). Now imagine going to the gym for the first time and lifting 150 kilos, say, 40,000 times! Strength training in endurance events is absolutely fundamental to avoid injury and it will also improve your performance.
Muscles can also have different kinds of strengths. The muscles are made up of many fibres that are of different types. Simplifying things somewhat, there are aerobic fibres - the dark meat you get on chicken legs for example, which are good for endurance - and anaerobic fibres - the white meat of the chicken breast, which are good for explosive power. It is believed that we are endowed with a proportion of each of these fibres genetically. This doesn't mean that the day we are born, it has already been written whether we have the potential to be a Usain Bolt or a Haile Gebrselassie. Luckily, there is a third type of muscle fibre which can change from aerobic to anaerobic, or vice versa, as a function of training. This is one of the main reasons, I believe, for why so much low intensity training is necessary for a long distance event. I'm always fascinated by the fact that, as soon as you go over 400m, the bodies of the dominant athletes of that distance change dramatically from those Superman-like figures, to frankly quite weedy looking guys. But don't be deceived, those stick like legs are capable of supporting incredible loads, over and over again. This is because they have been trained to use a much higher proportion of their muscle fibres. A body builder is more interested in having big muscles - there is no penalty for weighing more in his or her sport - so, the less fibres he activates proportionally, the better: that way, his muscles must get bigger in order to cope with the stresses he puts on them. A long (or middle) distance runner must be efficient first and foremost.
The good news is that you can do a surprising amount of effective training at home with a few silly looking (and relatvely cheap) bits of kit.
The Swiss Ball
BOSU (BOth Sides Utilized)
|Is it a board, is it a ball? No, its a BOSU|
I'm starting to notice that these Scandanavians seem to be at the forefront of Sports Physiology time and time again. Both Polar and Suunto (the most popular heart rate monitors) are Finish companies. There must be some truth in what they say about that Viking blood they have.
A word on Vibrating Platforms...
Meanwhile, some athletes noticed that it did actually have a training effect. Specifically, the vibrations trick the brain into believing that the body is going out of balance or that it is about to land hard and so your brain activates your muscles in preparation. It is similar, I suppose, to electrostimulation in that your muscles (and apparently very high proportions of their fibres) are being activated without you making the mental effort to do so. The advantage of the Vibrating Platform is that you can apply it to large areas of your body at a time. For the same reason it helped the Astronauts, it is also good to strengthen or rehabilitate bones, tendons and ligaments. My coach has even written an acdademic paper demonstrating the improvement in jumping of a women's basketball team as a result of vibration training.
Still, this doesn't really fit into the category of "home gym" as it is big, bulky and very expensive (I certainly don't have one). If you are going to buy one big item, then this is a good one as very few gyms have them and they are often monopolised by people (incorrectly) thinking that they can use them to lose cellulite. By the way, don't be fooled by the cheaper models - if you are going to buy one, make sure you check the specs of frequency and amplitude of vibration.