Hi--I also run (6 miles 4 X weekly) and I find my legs feel like tree stumps if I run without a few carbs in my body to help out. Going for some quality veggie carbs before your workout might help. Sometimes I need a few slices of apple with peanut butter; sometimes just a cube of cheese or a broccoli floret & dip. Do a test run and see how you feel.

I'm 61 and have been an on-and-off low carber for decades. It's taken me this long to learn how my body reacts to carbs, both junky & quality. The quality ones work best! Veg & protein seem to give me the best runs.