As a guitar coach for 25+ years, I have worked with several guitar players that were interested in weight lifting. There are similarities in process between the two. For example, there are things that are based on a progressive involvement on your part. On the guitar, you build up speed slowly by using a metronome, and in weightlifting, you increase the load over a large period of time. There are many guitarists who are a bit skeptical about weight lifting, worrying that it may negatively impact their guitar technique. There is nothing to worry about, though. On the contrary, weight training is going to help you improve your guitar playing! Let me illustrate.
First, and foremost, weight lifting is going to help you by emotionally regulating your body in general. When you are training with weights your body releases endorphins. Endorphins have a calming and pain-numbing effect that are actually quite similar to low doses of morphine! What this means is that you become more relaxed, but without taking any drugs. You become less emotionally reactive, which means you can follow your guitar practice schedule without worrying and stressing too much about what is wrong with your progression.
Second, it minimizes your chances of injury while playing guitar. That is because the muscles are much more resilient, which means you have more leeway of doing some edgier stuff on the guitar that might hurt someone who was not trained. When I was younger it was more difficult to have myself injured and I really had to overdo it. As you get older your body is not exactly the same way it used to be. You can get hurt much more easily, so it is a good idea to have some weight training in your life in order to prevent unwanted guitar-related injuries. See it as an extra protective buffer in order to try a bit more demanding techniques.
Third, it will help you develop more consistency and more discipline in general. Being consistent is extremely important, because it is going to improve your mindset. A mindset that several guitarists are in dire need of. You will not have to wait for you to be in the right time or mood. If you want to get better on the guitar, you have to practice religiously every day for a few hours and the discipline from weight training helps a lot with that. Even though it is a physical thing, it is going to help you a lot with your mindset.
Four, it is going to improve your health in general. People, who work out and use progressive resistance, are in better health overall. More healthy means more willpower and therefore more productivity. You are going to be in tune with whatever you are doing. It is going to help you with any area of your life you are concentrating on. Not just guitar playing.
So, to summarize, if you have taken the guitar playing seriously and you are going with a champion mentality (practicing for X hours a day for a few years) to achieve a really high level and see how far you are going to take, then it is going to help you have this maximum level healthwise. Being in optimal health is going to help you to fuel your guitar practice.
I hope this was helpful. You can watch the video below, where I explain this topic in more detail. If you're interested in developing your guitar skills and reaching your music goals, please check the different Elite Guitar Coaching Academy packages and how you can get private coaching from me.
Ioannis Anastassakis is a guitarist from Greece who has produced recordings in a variety of moods and styles, including flamenco and fusion.
His CD is entitled "Suspension Of Disbelief", his long-awaited rock/fusion instrumental album.