running is not running...
You want to be lean and hard as a stone? Sprint intervals. Unless you work up to it over a meaninful amount of training time, prolonged activity over 80% of your HRM is going to munch muscle. Take a good look at long distance runners. If thats the look you want, the 'i just stumbled out of Aushwitz' look, go to town...
Now take a look at sprinters that run the 100m... JACKED! RIPPED! that might be more the visual asthetic you are looking for.. same visual comparison goes for olympic velodrome cycllists vs. ultra marathon guys... Fine, Lance is possibly the fittest guy in the world, but i dont want his body.
You want to burn fat? If you can stomach the abuse: balls to the wall high intensity interval training on an empty tank first thing in the AM or if that doesnt work for you, after your last calorie at night.. best two options.
Next up: 65%-70% of you AHR max for prolonged duration.. AGAIN A.M., empty tank...