Skeletal muscle accounts for approximately 50% of total lean body mass.
"We think of lean mass, most people think of it as muscle, but lean mass in our body that includes water, connective tissue, organs, as well as skeletal muscle. And about 50% of our lean mass is muscle." (said at 0:11:41)
No published records directly evaluating or quantifying the precise proportion of skeletal muscle relative to total lean body mass or fat-free mass were successfully fetched within the search limit. As a result, the specific figure of approximately 50% could not be formally verified against a fetched publication record.
Creatine was discovered in 1832.
"So, I'm fascinated that this nutrient, which was, you know, 1832 it was discovered, boring for the longest time because we thought we knew everything" (said at 1:07:48)
Although it is well documented in historical chemistry literature that French chemist Michel Eugène Chevreul discovered creatine in meat extracts in 1832 (naming it from the Greek 'kreas' for flesh), the indexed abstracts retrieved during the search focus on creatine's physiological and nutritional roles rather than its historical discovery date. Consequently, no retrieved abstract containing the verbatim historical discovery date could be cited.