I am recovering from a TBI that happened last year. It was pretty bad, but no permanent damage.
My doctors wanted me to return to aerobic activity as soon as possible. Aerobic exercise is wonderful for healing the nervous system - gets the blood and oxygen flowing to very busy healing tissues.
A broken neck prevented much before 12 weeks, and even then the jostling I needed to avoid limited me to a bicycle trainer inside. After a few weeks it was 40 hard minutes on the trainer, which I am sure sped my recovery.
I don't understand the details of it, but the brain runs on glucose, which can be in short supply in the brain for various reasons during active healing. I would go along and suddenly get tired, which is fairly typical of TBI.
Dietary issues consisted of making sure to get enough carbs to fuel the brain adequately. I was also on a fairly specific high-fat diet for a while, as certain fats are good for nervous tissue healing. There also are issues about fat-soluble nutrients that healing tissues need.
I would second the advice to specifically talk to your physician about being cleared for exercise. Jarring is the only issue I would expect they would be worried about. I have a forefoot strike, so jarring is minimum - it was my neck bone that was the problem.
It's also prudent to ask about nutrition. If they dismiss the idea, talk to a dietician, an RD, anyway. Modern medicine is a world of specialists. Even a highly skilled neuro doctor could be sorely lacking in nutritional knowledge.
As far as time, they say to figure up to 2 years for TBI, maybe more. I was pretty much fine after 4 months, but that's really unusual. I know people who are seriously screwed up after well over a year.
It's worth a preventative trip to a psychologist too. PTSD is common, and sometimes doesn't start until after a year. I pretty much scoffed at the idea at first, but I have to work to keep the whole ordeal from bothering me.
So, get good advice, go hard, and be patient with yourself. And good luck on the mud run!
P.S. If you don't have a heart rate monitor, you might think about one. My resting heart rate went from less than 60 to ~80-90. Something to do with the TBI affecting mineral processing. It was a limiting factor for exercise for a while. Another nutritional issue.
Edited by: BEEZAUR at: 5/1/2013 (21:57)