Overground running (running a marathon) is associated with eccentric hamstring fatigue. Eccentric hamstring fatigue may be a potential risk factor for knee injury and soft-tissue-type injuries during running. Eccentric hamstring training should therefore be introduced as an integral part of the training program of runners.
-British J Sports Med, 2006, July, BioInfoBank
MY COMMENTS: Marathoners would be well advised to spend a few minutes on eccentric hamstring work in their preparation. Eccentric strength training is done by stressing the muscle while it is lengthening rather than contracting. Here are 2 different exercises you can try.