Q+A: Why do my legs hurt two days after a long run

Q Why is it that almost exactly 48 hours after a long training run, and particularly after completing a marathon, my leg muscles hurt most? If the race is on Sunday, then I always dread Tuesday because I cannot walk down the stairs without adopting an unusual gait, and my thighs absolutely kill me!

A It sounds like a classic case of delayed onset muscle soreness (DOMS). DOMS is commonly experienced after unaccustomed strenuous exercise. The muscle tenderness usually becomes apparent the day after activity and peaks at 24 to 48 hours, subsiding over the next few days.

Over the years several theories have been proposed to explain DOMS, including muscle lactate accumulation, muscle spasms and inadequate cool-downs. However, the generally accepted explanation is that moderate to high intensity exercise causes microtrauma (small tears) in the muscle tissue.

This microtrauma causes a normal inflammatory reaction in which fluid accumulates outside the muscle cells and a slow, gradual build-up of tissue pressure ensues. This pressure soon reaches a level that stimulates nerve endings and the pain becomes perceivable. It continues to rise until around 48 hours, by which time the damaged tissue regenerates and the pain eases.

DOMS is usually worse after an unaccustomed muscle activity. Typically, it occurs in the gluteals, quadriceps and shin muscles, especially after running downhill or sprinting. It’s always advisable to cool down with slow running and stretch after exercise, but this won’t necessarily prevent DOMS if there is sufficient muscle damage.

Some athletes use non-steroidal anti-inflammatory drugs (such as ibuprofen) and ice packs or even ice baths to help reduce the inflammation.

The other important thing to remember is that while you have muscle soreness, and often for several days after it has gone, the muscles are weaker than they were, and therefore susceptible to further microtrauma.

Nick Critchley, chartered physiotherapist with Medifit medical and fitness centres