If you were a kid raised anytime between the 1930s and the 1970s — or raised by someone who was raised then — chances are good that you grew up with the idea that spinach was a muscle builder par excellence.If you were a kid raised anytime between the 1930s and the 1970s — or raised by someone who was raised then — chances are good that you grew up with the idea that spinach was a muscle builder par excellence.