Yes I supplement where appropriate or needed, whether this be a pre made product or by supplementing the diet with additional naturally occurring foodstuffs which will benefit the dog if it needs it.
I have always fed a pretty well 100% natural diet.
In answer to the OP I don't use things to encourage muscle development or to help recovery as I aim for a overall good standard of health from good diet and conditioning, saying that I have used electrolytes in the past, but opt for honey and water more often if anything at all.