Pain in the leg

Answer: Muscles which ache more the second day after exercise are a common phenomenon, especially if the exercise was more strenuous than usual. The condition is known as delayed onset muscle soreness (more commonly abbreviated to DOMS) and is associated with damage, inflammation and elevated creatine kinase activity. This delayed soreness should not be confused with the transient ache sometimes felt during a bout of strenuous exercise, which is caused by the build-up of lactic acid. With regular training, adaptations appear m the muscles which significantly reduce the severity of DOMS, which is why it is less common in people who exercise regularly

The most common cause of DOMS is eccentric muscular work, which occurs when the muscle lengthens as it is being used It might happen when you lower a weight or run downhill.

Steve Bird, Department of Sport Science Canterbury Christ Church, University College, Kent

Answer: This phenomenon is called DOMS. It usually occurs after vigorous, unaccustomed exercise or overexertion. Muscle tenderness and stiffness may begin 12 to 24 hours after the exercise, gradually intensify to a peak after approximately 24 to 48 hours, and then last for anything up to seven days. We're not quite sure what causes it. Current opinion suggests it is linked to the damage of muscle fibres or connective tissue when muscles contract. After that, the tissue degenerates and dies accompanied by inflammation and oedema.

Paul Meredith, Student of physiotherapy, Cottenham, Cambridgeshire.

(New Scientist)