Influence of muscle strength on bone strength during childhood and adolescence

In connection with the prevention of osteoporosis, paediatrics is challenged with ensuring the optimal formation of the skeletal system with maximal bone strength during childhood and youth. Biomechanical use represents the most important stimulus for activating the skeletal system. The measurement of muscle strength (grip strength) in 97 females aged 3-62 years and 71 males aged 3-61 years showed an age-dependent course. On the whole, males have greater strength with a more pronounced increase after puberty, reaching a peak maximum at 25-30 years. Females show a more moderate increase after puberty. In a pilot study, bone strength (as bone strength index - BSI) was analysed at the distal radius using peripheral quantitative computerized tomography (pQCT). BSI was calculated on the basis of the geometric data of the polar moment of resistance in combination with the cortical bone density. BSI values increase with age and reach a peak maximum at 25-30 years. There was a highly significant correlation between BSI and grip strength (r = 0.87). These relationships are especially interesting for therapeutic concepts differentiating between direct and indirect (via the muscle system) influences on the skeletal system. The non-invasive bone strength analysis in combination with muscle strength offer new perspectives for the evaluation of the functional muscle-bone unit.