Seniors where put on a 12 week weight training program. Some received a post-exercise protein drink. Those receiving the protein post workout did not have better results than those who did not. Also, the group with the highest protein intake had similar improvements as the group with the lowest protein intake.
It appears that even the lowest protein intake was sufficient to support anabolism. Younger individuals should be capable of greater anabolism due to higher hormone levels. Also, including carbohydrates in the post exercise drink might have improved results.