: OWWWWWWW!!!!!!

: MY LEGS!!! I CAN'T FEEL ANYTHING BUT MY LEGS BURNING!

Hi Sean,
Warm up, stretch, exercise, stretch, cool down. Rest. Repeat.
Won't really cure the present 'burning' but it'll help, particularly in the future.

A correctly contoured seat will help too as it won't cut off the blood supply to your legs. I got a similar effect when using my trike, it's to do with leg position.
Humans usually use their legs most energetically in the upright position, walking, running, etc. so the blood vessels are adapted for this position. Arterial vessels use gravity more than other arteries so they don't 'pump' as much, while the veins have small valves to limit back-flow.
With the legs flat, the arteries don't push as much and the veins have it easy. This means the supply of food and oxygen are lessened to the legs and less oxygen to any muscles causes anaerobic use. Too much of this will cause cramps and burning muscles.

A good exercise regime will miminise the problem.

Hope this helps,
Mike Savag
South West Cork