Hi Grummie the Goat.

Two things come to mind is that you may have tendonosis of archilles tendons and possibly also shin splints. Tendonosis is not really a true injury - it is a combination of age related changes in the tendon along with repetitive micro trauma. The tendon goes through an unhelpful sort of remodelling and looses it's capacity withstand force like it should.

Whatever - it sounds like you overtrained and now your lower legs are paying for it. At the young age of 43 these sorts of tissue have undergone some ageing unfortunately - it isn't the end of your running career however, just might mean you need appropriate training and it may take you a bit longer to get into shape than when you were 23. However getting the right active treatment now and building up the capacity of your muscles and remodel your tendons in a helpful direction, making them more resilient. It may be just the trick to get you running marathons

By the way have you been given a good medical go ahead for running? Not a bad idea when you hit the young age of 43. Just get checked for the big nasties like heart disease etc. Just a precaution - having an ache in your archilles tendon is annoying but dropping dead on the neighbours driveway is damn well embarrassing for everyone concerned.

Yes eccentric exercise is one of best treatments for tendonosis. However you may be worth checking you are doing it the right way to the right intensity. There are other good exercise therapy for these sorts of problems such as correcting muscle imbalances and building up both the strength and endurance of the muscles.

So go to a good MSK/sports physio and get full assessment. They should look at your running pattern on a treadmill, look at your runners and check out the state of your muscles and tendons. Physios love patients like you because you are motivated and because they can turn your problem round. So go and give it a go