Some background, I was a 52 second/1:58 400m/800m guy in high school 14 years ago. I picked up running again (long distance) last year and worked my way down to 3 hour marathon by doing lots of slow easy distance (90 miles a week) and long tempos like 3x3 miles @ 6:40; 2x6 @ 6:40, 4x2 @ 6:40, and one 18-20 miler a week @ 7:15.
I only recently started running faster paces again and 6:30 and faster feels like I'm sprinting. During extended efforts at sub-5:45 pace I feel like I'm on the verge of throwing up and have to stop to avoid puking. Could this be because it is so hot? 80 degrees, Florida humidity, etc? What can I do to "train" this?
I train in the morning; all I have is 12oz of orange juice and 12oz of water with a pre-workout powder 30 minutes before. This has never caused me problems while running distance.
Examples:
Last week: 4x400m @ 68 seconds each with four minutes recovery. On the last one I started puking water.
Today: 2x(600-400-200) @ 5:45 min/mile pace, 5:15 min/mile pace, 4:45 min/mile pace. During the second one after a 1000m jog recovery; I puked during the 400m.
I start feeling nauseous and get the urge to puke. This doesn't happen if I just run 100-200m repeats with very long standing/walking recoveries between each like 3-4 minutes.