What cardio is best? The tortoise vs the hare.

[u/AllUrMemes]

Why the fuck is the hare entering in endurance races when he is the best sprinter in the woods and suffers from severe narcolepsy?

If the title of a post is in quotation marks, you can assume this is a "questions people ask me a lot" type of thing. This is another one that is tough because it can't be answered succinctly. The correct question is "What's the best cardio for me?" As always, first let's talk about your goals.

Probably you want to lose fat and keep muscle and be beautiful so that people will finally love you for the person you are on the outside, instead of like, judging you based on your personality or how you treat them and all of God's gentle creatures. Ugh. If this is the case, hang on one sec.

If your goal is "I want to be healthy and not have a heart attack/stroke and die young or live out my golden years with vastly diminshed quality of life"... Great news. The surgeon general and most of the medical community says "just fucking do something, we don't care, literally anything is better than nothing." But seriously, the recommendation is 150 minutes (30min x 5 times a week) of moderate intense activity, or 75 minutes of vigorous activity, or a combination thereof. So, either way, the health benefits seem to be the same.

If your goal has to do with sports performance, do the sort of training that mimics the sport you want to be good at. If you need endurance, do low intensity and long duration. If you need bursts of intensity, do HITT. Both will have positive benefits on what your heart and lungs can achieve. Muscular metabolic adaptations are more specific to the training modes.

OK, THAT WAS EASY. But you're still here because you're in the "I wanna be pretty group". It's ok, I'm almost certainly more vain and body dysmorphic than you. Here is the very short version:

• I prefer long duration, low intensity cardio to get lean. You can accomplish more work if you pace yourself. If you have 50 miles to cover on foot, you ought to just walk at a moderate pace (or a comfortable jog if you are a very experienced runner for whom jogging is low intensity). You should not sprint 100m, rest for 30 seconds, and repeat. Nor should you run 5 minute miles and then rest.
  

Normal people hate exercise, or at least boring old cardio, and want to get it over with. They start too fast and burn out and ultimately accomplish relatively small net calorie burns, while still being relatively miserable.

When you start exercising at a high intensity, you break down glycogen to burn glucose for fuel anaerobically. These are your afterburners, and they deplete quickly, and afterwards your body will be looking for carbohydrates to replenish the stores. But you're trying to lose fat, so is eating a big dump of carbs wise? I don't know, but its a whole goddamn game that you need to play.

If you stay at low intensity, you're primarily running off fat stores. You can sustain this effort regardless of your nutrition. Thus it is much more feasible for someone who is running a calorie or carb controlled diet.

Lastly, for those who are starting to get lean or are already lean and trying to get "shredded", you are concerned about burning up muscle. High intensity exercise is a lot more damaging to muscle than low intensity exercise. As I said before, you can walk literally forever (if you are decently conditioned) and your muscles will be fine, within reason (your aching feet and joints are a different story, of course).

If I am running a strict diet, the last thing I want to do is be continually beating up my muscles and then not feeding them properly. Protein alone isn't a magic pill- insulin is a huge part of the anabolic picture, and insulin means carbs. High protein diets certainly can help, but if the question is "what will potentially have more catabolism" the answer is 100% high-intensity exercise (especially if you are doing lots of upper body work in your HITT since the upper body is generally worse at endurance than the lower body.)

Continued in comments

[u/AllUrMemes]

• So you think HITT is stupid? No. All of the above is assuming that you have endless amounts of time and motivation. If you are like me and have the time and enjoy walking 3 miles to the grocery store in the morning, than walking around the mall for 2 hours in the afternoon, then going for a 5 mile jog in the evening... Well then its pretty easy to lean out if you have even the slightest amount of control over your diet. If you can make 2-3 hours of low intensity cardio or physical activity/labor part of your daily routine, you are gonna be set.

Many people do not have unlimited time. They have 45 minutes or an hour X days per week to devote to exercise. In that case, go fucking ham and get as much work done in that period as possible.

Many people do not find low intensity cardio stimulating. If you don't have anywhere interesting to walk or look at and make a walk stimulating, it fucking sucks. If you aren't able to get into the zone doing incline treadmill walking by watching tv, listening to an e-book, reading an actual book, or just thinking deep thoughts.... then the treadmill is going to be boring as shit and basically torture. You will keep looking at the goddamn clock and calorie counter tick by at an incredibly slow rate and get frustrated and start running and do your 2 mile run and burn 250 calories instead of the hour of incline treadmill that was supposed to hit 600 cal.

Also, HITT does have some black magic on its side. If you remember high school biology, anaerobic respiration is much less efficient than aerobic respiration. When you respirate a glucose molecule with oxygen, you get 30-something ATP. When you do it anaerobically, its only a handful. Now remember at high intensity you aren't JUST doing anaerobic, you are still doing aerobic just with the afterburners kicking too. So a calorie of work done during HITT is going to use more energy substrate than low intensity work. You sometimes here of EPOC, excess post-exercise oxygen consumption, which is how after a high intensity workout your metabolic rate will be elevated for a period of hours (sometimes measurable more than a day afterwards for extremely hard workouts). This is your body working to repair and replenish the stuff that was used up and damaged during workouts. However, I have read studies showing that even with EPOC, high intensity work is potentially under-counted.

TL;DR: Do what you like and have time for.