intriguing thing, though, is this 13-day cycle of symptoms that you have noticed. There is no cycle in the body that I can think of that follows this pattern – neither tissue turnover nor hormone output. It is, I think, more likely to be caused by something

Q I’m a triathlete, and a few months ago I damaged my Achilles tendon while cycling. I tried to control the problem with rest, ice and elevation, but to no avail. It now regularly becomes inflamed and painful, and I have to have three to five days

Q I am a 50-year-old runner, and I’ve averaged 20-40 miles a week for the last 25 years. A year ago – just after completing some sit-ups – I starting getting severe back pain around my mid-spine, which extended around the chest and into the abdomen

from a stress fracture. Muscle injuries and strains may occur between the bones, but you can often run with them, unlike a stress fracture.Self-treatmentRest! You may be able to swim or cycle as long as it doesn’t provoke pain, but running – which

, particularly high-impact training like running, after a back injury, you must tread carefully (no pun intended). Start with a month of low-impact exercise, such as cycling or using an elliptical trainer in the gym, to re-develop your cardiovascular fitness

of it to die off, leaving areas of focal degeneration. In this case, the onset of pain may be more insidious and you may notice a swollen area of tendon 1-2in long, tapering at each end. Surgery may well be required.Self-treatmentYou can do a lot to both

which take the elastic strain when the knee is forced inward and hence protect the ligament from further injury. As full movement is restored, the physiotherapist will use quadriceps contractions and ultrasound with progressive cycling-type exercises

. Avoid bed rest. Movement, even crawling on hands and knees, is better than inactivity. Backs: to the future. (Real-life solutions) Real-life stories: how two runners beat back pain Injury-Proof Your Back: five sets of everyday tips to stay pain

to complete the cycle. Arteries contain muscle within their walls, and the blood in them is under much higher pressure than that within the venous system. This is particularly relevant in understanding the injury and healing cycles.Common damage:If you damage

as 'a fit bloke who runs a bit', managing a 1:06 10-miler off not much training and getting close to his goal of a sub-3:00 marathon. Last June he was out for a run when he slipped and smashed his knee on a concrete wall. "I damaged my medial knee