I used to run reg­u­larly but stopped when my left knee began to hurt. When I restric­ted my gym ses­sions to the cross-​trainer I was pain free, but 10 minutes after going back on the tread­mill, my knee star­ted hurt­ing again. It then made a “click­ing” sound as I walked home. What have I done and how can I make it bet­ter?

Most of us will have knee trouble at some point in our lives, often because we expect this com­plic­ated joint to with­stand all man­ner of use and abuse. Running sends large impact forces through your knees, so over time it is not so sur­pris­ing that they start to com­plain.

It sounds as though you have developed a “chronic” injury: one that appears as a res­ult of repeated stresses, some­times over a very long period, rather than arising from a par­tic­u­lar incid­ent (twist­ing your leg, knock­ing your knee etc). There is usu­ally more than one factor at work in chronic injury, com­bin­a­tions that might include your par­tic­u­lar ana­tomy, a past injury affect­ing your run­ning style, worn-​out train­ers, a change in your train­ing pat­tern, or even your genes, age, or a bit of extra weight.

At its simplest, you may have been skimp­ing on your stretch­ing routine – if you don’t reg­u­larly stretch tight muscles, this over time can cause the knee­cap to be pulled very subtly out of align­ment. Another com­mon run­ners’ prob­lem is unbal­anced leg muscles: too much outer thigh muscle devel­op­ment and not enough inner thigh, bum and ham­string strength. Again, this will upset the pre­cisely ten­sioned lig­a­ments that keep the knee mov­ing smoothly.

As we hit our 40s, “wear and tear” becomes a factor, and the shock-​absorbing knee car­til­age can start to fray and tear, without much pro­voca­tion. This is another com­mon cause of pain, dis­com­fort and a lock­ing or click­ing sen­sa­tion.

Once chronic injur­ies appear, they tend to hang around unless you take action. Rest, by itself, is rarely the answer, but neither is ignor­ing the injury or simply car­ry­ing on train­ing through pain. I sug­gest a visit to a sports physio­ther­ap­ist or osteo­path, so that they can exam­ine your life­style and your legs to try and dis­cover what has gone wrong.

A good sports physio is a detect­ive: they will always try to find out what is caus­ing the prob­lem as well as treat­ing the site of the pain or dis­com­fort. This is essen­tial if you are to return to run­ning and avoid a repeat occur­rence six months down the line. The physio may do hands-​on treat­ment such as manip­u­la­tion, mas­sage or ultra­sound, but they will almost cer­tainly also give you stretch­ing and other retrain­ing exer­cises to do at home. And don’t be sur­prised if they loc­ate the source of your trouble to your hip, back, ankle or foot: any of these could be the cul­prit.

With a good dia­gnosis and care­ful rehab­il­it­a­tion, most chronic injur­ies can be sor­ted, so don’t anti­cip­ate the worst. If you are dili­gent in fol­low­ing the therapist’s advice you should even­tu­ally be able to resume your run­ning free from pain.