And joint stress is probably the reason that most people could not run a marathon every day for 3 weeks. The muscle energy expenditure for the TDF is off the charts--typically 8,000 calories a day, and the vast majority of that is burned in the leg muscles and respiratory system.
https://en.wikipedia.org/wiki/Sudden_arrhythmic_death_syndro...
It sounds like you've never run one. World class athletes can run an entire marathon at a sub 5m mile pace. While they could run a single mile race in 4:05 or so, it's not even remotely a low intensity effort to run a 5 minute mile, even for the fittest people on the entire planet.
Unless you've put real effort into training, 60+ year-old competitive marathoners have done a 20 minute tempo run faster than you ever have... and repeated it 7 consecutive times without rest.
Marathons are high intensity and extended efforts.
>"The definition of high intensity training is literally anything above that (lactate) threshold."
That's far from a universal definition. The phrase "high intensity training" often refers to a type of strength training popularized by the founder of Nautilus that involved lifting until muscle failure. What you're describing specifically is called anaerobic training.
In sports medicine lactate threshold/anaerobic threshold/90(ish)% of VO2max has been the de facto definition for high intensity efforts for many many years.
You'll find plenty of examples on Google Scholar (including papers criticizing people for using these thresholds to define the intensity of workouts...)
> Running is generally considered a high intensity activity
Nope. Running can be a low, medium or high intensity activity depending on how hard you run (relative to your max).
But to state that these people died because they "underprepared" is ridiculous. That's like saying you could have prevented dying from a brain tumor by doing more crossword puzzles. Just as a tumor, a congenital defect was just a bad dice throw. Exercise triggered it, but so could running to catch a bus.
but isn't the point of training to push thru the pain barrier? When do you actually stop and listen, vs when to ignore the pain and keep going?
If you know some people can run marathons, it doesn't sound crazy to think "well, I ought to be able to run for 10 minutes without any problems", but there are a lot of people who would risk seriously injuring themselves with 10 minutes of quick-pace running. Not to the point of rhabdo, probably, but certainly not a healthy experience.
It also doesn't sound crazy to think "Well, I'm in agony after two minutes, but there's no way that means I should stop. I'll never get anywhere with only two minutes of running!" But of course, 'beginner gains' are distinctive - someone who hasn't done cardio in years might be at two minutes today and six minutes next week.
The only universal answer I know to solve this is to take your first few outings in a new thing lightly. Don't even set a training plan, just go out until you're a bit uncomfortable, then stop and see how you feel the next day.
Depends on the end goal. If you can only complete two miles and you're signed up for a marathon a month from now, you're going to have to push past your comfort zones.
But if your end goal is to be able to go up a flight of stairs without heavy breathing, to sustain vitality through your older years, then no, do not push. Do just the amount of effort that will allow you to keep coming back, day after day.
If you get a stitch in your side there's no harm in pushing through, they're painful but not harmful.
If you get shin splints or your knees hurt, stop and figure out what's wrong before you damage something.
I got a lot of benefit from doing intense martial arts when I was younger but sometimes I wish I had been smarter and not just ignored pain. But again, it's a difficult decision. Some things make you tougher and some things cause problems later on.
The first thing that you should learn when doing a new exercise is what the difference between these two pains are. Then, when performing more rigorous forms of the same exercise, you can establish where you can push through the pain. Is the pain you are feeling exhaustive? Push through. Is the pain something foreign? STOP IMMEDIATELY.
This, I think, is one of the reasons why it is suggested to do a lighter exercise before engaging in the intense stuff. As well, you don't run the risk of learning the difference between the two pains too late into the exercise. In general it follows along with the trite quotes: "You have to learn to walk before you can run," and "Start slow to go fast."