My friend reminded me about Interval training (I read it before) but I think he gave me the wrong term. He called it High Impact Training. Actually its high impact sports. No such thing as High impact training... hehe.. think he got messed up.
Anyway, the problem with long distance running is the wearing out of your joints and you would only be doing aerobic training. Which improves heart rate and muscle endurance.
The other form is anaerobic exercise. Which is strength training or power training. The issue with anaerobic is that you might get muscle or ligament tear easily if you overdo it.
So the best is to combine both forms of exercise. Interval training is a form. First, we stretch and warm up and slow jog for at least 15 to 20 mins to warm up the body. After proper warming up, we sprint or run at 70-80% of your max speed for at least a min or until you reach your heart rate threshold (if have heart monitor). Then we slow jog or walk for 2 mins or until heart rate is normal and continue again. Repeat this for at least 4 times and you get to finish the run faster (now I could complete in 35- 40mins for 5km). Overall, I think its working quite well for me but really shiong. Especially after the 3rd set of sprinting. :P