You might find this post in T-nation very interesting. A summary: a study with runners suffering from an Achilles tendon injury, healed very well by performing eccentric exercises, aka negative phases.

Eccentric exercises seem to be very useful for healing tendonitis, in several studies. More details in this answer

Additionally, you may find useful to spend some time reading Scooby's website, a fitness internet veteran. He pays himself a special attention to stretching and working out his hamstrings. See his hamstring stretch in Youtube. Note that he starts with:

You can get away without stretching almost every muscle in your body, except your hamstrings. Maintiaining hamstring flexibility is really important for every sport (...)

You might find this post in T-nation very interesting. A summary: a study with runners suffering from an Achilles tendon injury, healed very well by performing eccentric exercises, aka negative phases.

Eccentric exercises seem to be very useful for healing tendonitis, in several studies. More details in this answer

Additionally, you may find useful to spend some time reading Scooby's website, a fitness internet veteran. He pays himself a special attention to stretching and working out his hamstrings. See his hamstring stretch in Youtube. Note that he starts with:

You can get away without stretching almost every muscle in your body, except your hamstrings. Maintiaining hamstring flexibility is really important for every sport (...)