I heard from an instructor that bodybuilding causes you to have hard muscles,which are unnecessary for singing and may even hinder singing, the instructor said, though he could not explain more about the issue. Afterwards, I searched and didn't find an explanation.
How does bodybuilding or weightlifting affect a singer's voice? Does it help or negatively affect professional singing?
Body building, weight lifting etc affect the voice indirectly. A pretty important factor for voice quality is controlling the breath pressure and airway resonance actively and passively. "Passively" means "riding" on the breath and its support in the lower body. When you are training your muscles, you are losing elasticity in your breathing apparatus and consequently your breath supply.
There is also the problem that the body building posturing requires a totally different way of breathing than singing: good singing relies on a "big bag of air" around your waist. Which is exactly what you are trying to avoid when posturing.
If you want to see an example of "too much of a goodness", take a look at old "Conan the Barbarian" movies from the time where Arnold Schwarzenegger was "Mr. Universe". And particularly scenes where he is "running". It's obvious that his running muscles are quite detrimental to actually moving forward speedily.
At any rate, once bodybuilding gets to the stage where it is changing your constitution and metabolism, it will not just cause differences to your breathing but actually affect the voice itself as you have different waste products running through your body (and that's assuming that you stay off steroids).
So there are a lot of things where bodybuilding and voice building are not independent. And if you look at the faces weightlifters make: that requires serious strength in muscle groups (neck, chest, others) which you don't want to tense while singing. Making those muscles stronger and habitually tensing them is going to make control of them more tricky.
So it all boils down to an emphatic "depends".
On one hand, any type of sport can help a singer's breathing skills, but on another, some sports like body-building and weight-lifting can reduce the flexibility of some muscles. So you should be careful on muscles around your chest and neck.
I think it should be OK if you do workouts that help your muscles' flexibility around your chest and neck and also your stomach.
For assurance you can ask a physiotherapist about your workouts.
Well if you look at Chris Daughtry, does it affect his voice, obviously not, he's a singing monster and a bodybuilder. The assumption that you will get problems with your vocal technique because of too many muscles in your body sounds a bit strange. The singing "muscles" in your throat, responsible for larynx control, shortening and lengthening are muscles themselves right:-) Gaining more control over your muscles in general will help imo to get a better feel for muscles in general right, so you will get more control over your voice intuitevely. On the other hand it's logical to also work on cardiovascular strength and endurance as we need a lot of breathing muscles (here again) to maintain a solid air support from the diaphragm and learn how to expand the rib cage correctly (please don't just stick your belly out it's bad old school technique) Of course it doesn't make sense to go in absolute Schwarzenegger territory unless you want to become super huge and look like the Rock, but even so, underway you will learn by yourself how to adapt with your voice, I guarantee you with a super strong core you will work way easier with your support than before.
