Assuming you are not lactose intolerant, does milk have any specific negative effects on you during heavy exertion?
We're not talking about milk calories or fat related to weight loss. Does milk itself contain components that would affect your performance, to an extent that milk should be avoided?
For example, say someone participates in a high-school marching band where they practice drills outdoors for 6-8 hours a day, 5 days a week during practice season. This is outdoors during the summer, with temperatures in the 80s-90s Fahrenheit. I've heard that milk "curdles" in your stomach during long periods of heavy exertion and can cause nausea. This seems implausible to me.