In the twenty years that I've been a tutor and assessor I've taught dozens of gym instructor and personal trainer courses and this is one of the most common questions I get asked. Inexperienced instructors often get seduced by the latest trends or pseudo science. Amongst the things they pick up are that machines are 'non-functional' (whatever that may mean). Free weights, in comparison, are 'functional' and work the 'core' much more. This is all well and good, but it completely misses the point since neither is better. Machines and free weights are inanimate objects; they have no character traits. They are simply objects. Only instructors can make them 'good' or 'bad'.
There are many ways that I've got this across to both personal trainers and clients. The simplest is through the use of 'they're', 'there' and 'their'. None is better or worse than the others. Their correct use (as in this very instance) is determined by just one thing: the context in which they're used.
Because I've been a trainer since 2003, I've seen at first hand the importance of not following trends or 'pseudo' science. The key is to use machines or free weights or bands or any other piece of equipment that meets just two criteria - is the choice of equipment safe; is the choice of equipment effective in the context in which you're working.
To be effective, probably the most important criteria in personal training is that the exercise is enjoyable. It matters not whether the resistance is provided by a machine or any other form of resistance such as bodyweight, bands or free weights. It might well be that free weights are indeed more 'functional' or that they work the 'core' more. However, if a client doesn't enjoy using them (for whatever reason), their use is less than likely to be successful. Teaching free weights is both a science and an art. Getting it right requires attention to detail and the ability to observe and correct technique. it takes time, time that might be put to better use by utilising the simplicity and more prescribed/determined motion of machines.
So, the long and the short of it is that free weights are not better than machines. Equally, machines are not better than free weights. Everything is determined by context. This means listening to the client rather than following any of the latest trendy ideas (I've been doing this long enough to have seen most ideas arrive, go away and then return again in another guise).
Dr. Mark Mullineaux has worked as a personal trainer in Lancaster and the South Lakes for fifteen years. He's worked as a tutor and assessor of personal trainer for Professional Fitness and Education and YMCAfit. He currently does freelance personal trainer assessing for Leeds Metropolitan University.