> unless you’re on the lower end of the BMI scale

Can you clarify, do you mean lower than 'normal' range (i.e. < 18.5), or lower than the US average (i.e. < 26), or what? And is this mostly anecdotal or is there evidence to support it (the view that running is a bad exercise for people above a certain BMI)? Not challenging this, I just haven't heard it before and am intrigued. And can you clarify what you mean by "any sport with a high mobility requirement?

For best results distance runners should have a BMI on the lower end of the healthy range. If you’re serious about improving your performance over <1500m having a BMI of ~25 will be the biggest impediment. Not sure what the range is but I think your average elite marathon runner will have a BMI of 18-20.

Sport with a high mobility requirement? Things like weightlifting, gymnastics, ballet etc.

This is not a scientific argument, but if you build up conditioning safely, i think running should be excellent for you - especially if sprinting is involved. My take is that it’s a natural movement that evolution has prepared you for. Just my 2 cents.

>This is not a scientific argument, but if you build up conditioning safely, i think running should be excellent for you

the problem is that running/jogging is usually the first thing people turn to for "getting in shape" and these people are often significantly overweight. Starting off with a high impact exercise is a recipe for disaster. Put on a 50-100lb weight vest and try running around and feel the impact on your joints and back, not ideal

If you are 50lbs "overweight" your body has built the strength to carry that weight. Look at any champion powerlifter or "strongman" champion, they all look overweight. It's not all fat, it's the muscle to move that weight around as well. So it's not really the same as a normal-weight person putting on a weight vest.

But long term overweight is hard on your joints, no disupting that.

A powerlifter who skews the BMI charts is different than someone who carries 50 pounds of fat.

The powerlifter is mobile and carrying the extra weight and has the strength to do so. The fat person is sedentary and doing whatever possible to NOT carry the fat. They do not have the strength to do so.

As someone that is about 30kg overweight, no my body can't carry that weight for a run. I used to run 5km 3 times a week. That was about 15kg ago. It was okay but now my knees just can't take that punishment. My shoes can't handle it either at well over 120kg they get destroyed after a few runs.

I would consider myself above average in strength after spending most of my 20s lifting regularly but that doesn't counter the impact of being this fat. It is shocking the impact it has on your life.

Your body builds the strength necessary to support your activity level. Unless you already have an active exercise regimen, an overweight person has generally only built the strength to support walking shorter distances. So the more overweight you are, the more careful you need to be when increasing distance while running.

Alternatives like cycling and swimming are better for the knees, especially for the old and overweight.

But powerlifters still have terrible conditioning and those who do it competitively will tell you that they're uncomfortably overweight for a lot of their daily activities.

for stress on the ligaments and joints weight is one the most important factors. Be it from a weighted vest, fat, or muscle. Joints of humans are not made to carry the weight of a strongman.

Agreed. Natural movements of all types are critical. Just running long slow distances on hard surfaces can be rough on the body. Running is addictive and costless aside from your time. That's maybe why the legions (myself included) use it as their primary exercise.

Sprinting has almost nothing to do with the slow plodding runs that a typical “I want to get fit type” does.

Completely different energy systems, <90% anaerobic, and has a level of skill acquisition that distance running doesn’t have.

What you write about running isn't true. I recommend reading the book- The Big Book of Endurance Training and Racing by Phil Maffetone

What isn’t true about it?

Is that the case for cycling too?

Anecdotal. While I was in Netherlands I was quite pleasantly surprised to see so many old people, judging by their looks 70+, cycling to their daily chores. They seemed quite fit and mobile just fine to me. After a while I stopped being surprised because I realised it's a common occurrence there. So make of this what you will.

No, quite the opposite. Cycling is a very low impact activity, especially compared to running. Many runners get on a bike to develop or maintain aerobic fitness when they are healing from overuse injuries like stress fractures.

Strange opinion... no runner I ever knew nor heard of does just running, its part of whole fit regime, usually on cardio side, but its relatively easy to do some form of HIIT once achieving certain level of fitness. All runners I know do quite rigorous stretching after each run, so I'd say they have better hip mobility than average. You keep challenging your body with variation, not daily grind of exactly same exercise and 0 of anything else. It also adds fun and mental challenge.

Also, nobody overweight nor sedentary should start with running (nor do it generally), this is 101 of getting fit.

Our bodies are not that complex, but behaving stupidly ain't reaching anything good, ie I am fat and weak, everybody is running, so out of blue lets do that... and in max 3 months joints are a mess. Heck, I'd say health and fitness is one of the most important matters in each of our lives, isn't it worth spending just few hours learning about it? Resources are literally everywhere, expert physiotherapists too if one can't wade through all available info easily. Every gym has host of trainers that tailor working out to person's abilities and goals.

Running is what made us human...

It defined a large part of our genetic makeup: our (relative) lack of body hair, the way we sweat, our bone structure, the function of our leg muscles in pumping blood back to the heart, a cardiovascular system with more endurance than any other land mammal.