Question about claims of 'muscle hardening'

[Mosesport]

I'm curious as to what exactly these supplement companies are trying to say when they claim their products 'promote muscle hardening'. Are they talking about the density of the muscle? Is there science to back any of these claims? If so, how is that tested? That just seems like such a broad statement to me. Anyone able to shed some light?

 

[nattydisaster]

It depends who you ask really. For your everyday lifter, muscle hardening can be as simple as having denser muscle and/or looking more hard in the mirror (from a more dry appearance, more defined).

If you are an IFBB pro, muscle hardening means something completely different, and involves a lot more than supplements