Are deadlifts a good exercise for the average runner..........no!
Lots of personal trainers and exercise advice sites are recommending dead lifts as a good exercise for runners etc.
As an osteopath I see the results of doing dead lifts and its frequently a lumbar disc injury. To do a dead lift your technique has to be spot on and frankly most people cannot do it correctly. I have completed UK Strength and Conditioning courses and I would not do a dead lift.
There are plenty of other good exercises to work the same muscle groups including squats and sprint training.