Anybody carbing up right before a run or active swim?

[Duncan_K]

I don’t compete, I swim for fitness - usually 1000m three times a week.

[Blueberts]

Well, my personal experience last weekend was that I was considerably slower in ketosis, then after eating some carbs.
I swam a 50m breaststroke on a relay Friday night 2 seconds slower than I did on Sunday - even though I had a relay start.
Saturday night, I ate a pasta meal (reasonable, not overdoing it) and on Sunday, I ate some carbs.
I definitely was faster. I am think it was energy and not stroke correction, so I can only conclude that while keto may be great for endurance sports, for sprints carbs helped me. I guess you don’t burn much fat in 50 meters and it is not easy to flip over to glucose when you have been fasting and in ketosis.

[Duncan_K]

You’re probably right, for sprints where you’re giving everything you can in a short amount of time muscle glycogen is likely the best source.