True, but that is in "three square meals a day and in bed by 10PM" civilian land. When you're marching 10 plus miles every day over rough terrain in temperatures of 100 degrees or more, sleeping 2 to 3 hours a night (if at all), and living off of barely nutritious rationed food, things can change rather quickly.
We had three or four women drop out during basic training due to stress fractures in their femurs and pelvises brought on by nutritional deficiency and the excessively physical work load, and that was with
three square meals a day and 6-8 hours of dedicated sleep every night. Real combat is much, much
more strenuous; particularly for a dedicated infantryman.
"A little lost blood" might prove to be more damning than you might think.