Why do people hire personal trainers, when there is such an abundance of exercise knowledge on the internet?
There are many ways to answer this.
One, if a person buys a package of sessions from a personal trainer, and has scheduled an appointment and paid in advance, then that person has much greater motivation to actually get to the gym.
Two, maybe someone wants company while they work out. At the gym I go to, I listen to the personal trainers interact with their clients, and most of it consists of banter about the weather, sports, children, pets, movies, and such. These personal trainers provide a little distraction and pleasant company. Nothing wrong with that.
A third reason might be, that they hope a personal trainer will help them with technique and form. Having somebody watch you and give feedback about what your body is really doing can be extremely beneficial. Sometimes a trainer needs to physically manipulate a client's body to correct their movement pattern. However, from what I see at the gym, most personal trainers don't do enough of this. I've see lots of terrible form on display while personal trainers are chatting about the weather. So, some trainers are more diligent than others about giving clients useful feedback.
Fourth, even with the internet, there is work involved in putting together a itinerary of exercises. When I lead an exercise class, I compile exercises from a multitude of sources. A list of my sources would require a small book and I'm adding new sources every week. Some of my exercises come from scholarly research and aren't found on youtube. The average person is not going to invest this kind of time into compiling a workout itinerary. On the other hand, many personal trainers these days just copy their workouts from youtube videos. Again, what you get from a personal trainer depends on exactly who you hire and how much you are willing to pay.
We know a lot about the human body in general, such as how
- weight training tears down muscle fibres
- the body builds muscle fibres back up, better and stronger
- the body needs adequate food and rest for rebuilding muscle
- the shoulder joint is easily damaged from anterior internal rotation
- deadlifts place a lot of strain on the spine if the back muscles are not properly engaged
etc. This is information one can learn from reading books and studies online.
However, we also differ in a lot of areas, such as how
- some people have short tendons, and need to deadlift differently
- some people have shortened hip flexors
- some people sit a lot
- some people have an anterior pelvic tilt
- some people have a posterior pelvic tilt
- some people have weak hip flexors
- some people respond better to high volume training
- some people respond better to high intensity training
etc. This is information that trainers are educated on diagnosing and helping you treat, by creating workout plans specifically designed for your body in particular. Not only to get you started, but also to appropriately adjust the plan as you progress, and as you plateau.
A lot of this can be diagnosed and treated and planned for by yourself, but you would have to do a LOT more reading and studying to get there, and there's less of a guarantee of success, because you can't always trust what you read on the Internet.
So, to sum up: Hiring a personal trainer is something we do to either get help getting started, or to get a second opinion on what we're already doing.
Probably the most common reason is that many people simply don't care about how fitness works, but would like to get/stay fit. Or, they have a lot on their plate and don't have the headspace to construct fitness routines or reflect on their progress.
A decent analogy is tech support. Many people simply don't care about how computers work, or don't have time to waste researching their problem on the web. They may be intelligent people (like a doctor, say) but they would rather pay someone to solve their computer problem (indeed sometimes being given instructions over the phone/screenshare).
I have chronic illnesses and have spent a vast amount of time researching their management. But I simply don't care about analysing blood test results. I'm quite happy to pay a doctor to interpret my cell counts, thyroid function, antibodies, triglycerides, drug concentrations, liver and kidney function, etc. etc.
there is such an abundance of exercise knowledge on the internet
That is confusing different things.
Back in the day, like Aristotle back in the day, the word "knowledge" was (at least) two words:
- Episteme: scientific knowledge, or know-what
- Techne: craftsmanship, or know-how
You can get the former for free on the internet. The internet is not really an ideal medium for the second kind of knowledge. If you already have a firm base you may be able to score some pointers on Techne, but you won't be able to really get there just by e.g. watching youtube videos, no matter how well-produced.
People who hire personal trainers are angling for the second type of knowledge.
To add a personal anecdote: I can power clean/push jerk my body weight, which while not very impressive by competitive lifting standards isn't bad for a hobbyist pushing 40. I am extremely skeptical that a normal unfit person can get to that point without in-person expert help.
I will respond from my personal experience as I have started working out about a year and a half ago and I've used a personal trainer throughout and will continue to do so for the foreseeable future.
My reasons are in order from most important:
Motivation - If I have an appointment with my trainer I'm sure to go because someone is waiting for me. I will go on my own sometime but it's rare because there is always some work that needs to be done.
Correct technique and exercise choice - even if I read up online or watched videos I wouldn't be able to properly judge my technique and I probably would have trouble figuring out what exactly I should be exercising. Also I would never consider trying weights he gives me believing I couldn't manage them. And for many it would be true without a spotter anyway.
Exercise modification on the fly - One of the reasons I started exercising were shoulder pains which didn't want to go away for a couple years. My trainer was able to come up with exercises which worked around them and eventually managed to get rid of them completely. I don't have great mobility in general though so often when I get pain from some exercise which is unhealthy and related to mobility rather than the exercise my trainer comes up with a different exercise for the same muscle (group) where my lack of mobility is not a problem.
Time & variety - My trainer has a bachelor's in physical education and is working on his masters. I don't know how long it takes him to set up a session for me but I would certainly take a fair amount of extra time for each session probably half an hour or more. This way I just go to the gym say hi and than go through the exercises he prepared. Saves me time and also gives me more variety. I would certainly never consider that doing squats on a medicine ball or an exercise ball would even be a possibility and now I'm able to climb on one without using my hands.
All of these are very important for me and I'm sure without a sparring partner of some kind I wouldn't be exercising nearly as diligently or as well. So the cost of the Trainer is well covered by the results he brings.
In addition to the very good answers already present, which deal with motivation, specialized adjustments and feedback, I would also like to add that having access to an abundance of information about exercise on the internet, is not the same thing as having access to an abundance of exclusively good, complete, or unproblematic exercise information on the internet.
There is information on the internet that is really good, and will help the reader, and there is information that is a bit helpful (but often less then it seems), or that is sometimes helpful and sometimes not, or helpful in suspiciously-specific circumstances. And then there's information that might cause problems if wrongfully applied, or just be unproven or even be wrong information, or otherwise not be fit for the one researching or the suspiciously-specific circumstances that might apply to the one researching.
This isn't, by the way, me picking on the abundance of exercise information on the internets, it is true of any abundance of information on the internets, from cooking to crafting to academic analysis to career development to personal comportment. People believe things, and the act of believing doesn't come with a fact checker - and then they write down their actual beliefs and assumptions, whether the underlying cause works as they think it does, or whether these beliefs or advice work for anyone else or not.
So it does take still, and research, and prior knowledge to pick the really useful bits of information out of the minorly useful, situational, not useful, or outright wrong bits of information. Anyone can do it, sure, but it can be a nontrivial effort to do so correctly. So some people will prefer to look for someone who has the answers... like a personal trainer, who they will trust to know the actual truth and to offer them helpful knowledge.
And anyone can do it incorrectly, too, even those who are employed as personal trainers... to have that job title isn't actually a guarantee of knowledge or correctness. The choice to hire a personal trainer is about belief and confidence and assumption, as much as it is about training and research and knowledge and social factors.