Here’s some hundred-year-old advice for selecting meat:
Beef should be a bright red and well streaked with fat.
To understand the difference between the tough and tender cuts we must be familiar with the structure of the muscle. Each muscle consists of bundles of tubes held together by connective tissues. In tough meat, the muscle tubes are thicker and there is more connective tissue present.
Exercise strengthens the muscle, and this accounts for the fact that the unexercised muscles of the young animal give us a softer meat. In the mature animal the muscles most exercised furnish a tough meat, and the less-used muscles the tender.
The tough cuts come from the neck and legs, the tender cuts from the middle of the back, the toughness increasing as the cuts approach the neck and the hind legs. The muscles of the abdomen are also tender, but they give a coarse-grained meat.
The tender cuts from the ribs and loin are the most highly prized, and therefore bring the highest price. These cuts are liked because of their tenderness although the nutritive value of the tough meat is as high or possibly even higher than the tender. We must take pains to use the cooking processes that will make the tough meats palatable.
Excerpts from Foods and Household Management : A Text-book of the Household Arts by Helen Kinne and Anna M. Cooley (1913)