As a runner AND a doctor (two strikes against me for Rip), I'll speak out in defense of running for mediocre lifters AND lifting for mediocre runners.
First, the heart.
The adaptations of the heart to running and weightlifting are essentially opposite, and the nature of these adaptations are pretty intuitive.
-The runner's heart has to pump more blood for a longer time. In response, the left ventricle (LV) remodels to a larger cavity,
with maybe a little increase in muscle thickness.
-The lifter's heart really doesn't have to adapt as much (due to less "time under stress" (think about your
work/rest ratio)), but it adapts to a much higher pressure load.
-in response to the pressure (not so much volume) load, the LV muscle gets thicker, and maybe the cavity grows a little.
Rowers, I figure, are somewhere in the middle of strength/endurance. I have looked EVERYWHERE to try and find articles describing
the difference in cardiac adaptations of rowers vs runners, but to no avail.
Which is better from a cardiac standpoint, between runners and and lifters? If I have read aright, probably the running, but both are a
damn sight better than the nothing that most people do.
Honestly, I suspect the rowers have us both beat, but no data to back that up.
Now, musculoskeletal.
In contrast to conventional wisdom, there is no link between osteoarthritis and running. From there, it's a bit of a leap of faith, but I think it's a
reasonable argument that running itself isn't injurious.
Runners get hurt because running BADLY is injurious (or running on bad joints is injurious).
The problem is that endurance adaptations are quick enough that your heart and lungs can write mileage or speed
checks that your legs can't cash. When you fail a lift, it's just over. You can't lift it, and you put it down. More than likely, the
only injury will be to your pride. If you try and run a distance you can't run...your form will suffer, but you can keep going.
-that = running badly, and that = injury.
I'll be honest, here. The only musculoskeletal benefit to running is that it allows you to keep running. It doesn't really have
the carryover of lifting to other activities. If you'd rather bike or stairmaster a couple of times a week for 20 minutes, that's fine. I think you
should, because I think it's good for you, and you're never going to be Kirk Karwoski
I run because I like to run, and I lift because I'm never going to be Meb Keflezighi.
I apologize if this is disjointed. I'm on call and tired. I'll try and clean it up later.