[Incidence of complaints about heel-, knee- and back-related discomfort among Danish children, possible relation to short muscles].

Four hundred and fifty-nine children and adolescents from third, sixth and ninth classes in seven schools on Funen were questioned in 1991. Seven percent had complaints from back and knee, and 3% from the heel. When the hamstrings were so short that one knee had an extension deficit gently measured to more than 40 degrees, when the hip was flexed 90 degrees, the incidence of back pain rose significantly to 15%. Furthermore 18% had complaints from the knee and 35% from the heel when the passive range of motion of the foot was less than 0 degrees of dorsiflexion measured with the knee extended. As 75% of the boys and 35% of the girls over age ten have short hamstrings and 13% of both sexes have short Achilles tendons, it is recommended that school children be involved in a daily stretching programme in order to diminish the complaints from the extremities often seen in this group.