A fifteen-year longitudinal study in young adults on the relation of physical activity and fitness with the development of the bone mass: The Amsterdam Growth and Health Longitudinal Study

Although positive effects of physical activity are often reported, there ar e still uncertainties about the type, intensity, duration, and frequency of these activities that are most effective for (re)modeling bone mass during youth. In the Amsterdam Growth and Health Longitudinal Study, daily physic al activity and fitness were monitored from age 13 to 29 years in a group o f 182 males and females. At a mean age of 28 years, bone mineral density (B MD) was measured at three sites with dual X-ray absorptiometry (DXA): in th e lumbar region (lumbar BMD), the femoral neck (hip BMD), and the distal ra dius (wrist BMD), Physical activity (PA) was estimated from a cross-check a ctivity interview taking in consideration all daily physical activities dur ing the last 3 months; PA was scored in two different ways: (1) metabolic p hysical activity score (METPA) by weighting the intensity (multiples of bas ic metabolic rate [METs]) and duration (minutes per week); and (2) mechanic physical activity score (MECHPA) by weighting the peak strain (ground reac tion forces as multiples of body mass) irrespective of frequency and durati on of the physical activities. Physical fitness was measured with a neuromo tor fitness test (composite of six strength, flexibility, and speed tests) and as cardiopulmonary fitness (maximal oxygen uptake). The physical activi ty and fitness scores were calculated over two age periods: during adolesce nce (13-16 years) and during adulthood (21-27 years). The standardized regr ession coefficients (corrected for gender, biological age, body composition , and calcium intake) show that weight, physical activity (both METPA and M ECHPA), and neuromotor fitness during adolescence and in young adulthood ar e significantly and positively related with the lumbar BMD (beta = 0.11-0.4 0) and hip BMD (beta = 0.18-0.26), measured at the mean age of 28 years. Th is was not the case for cardiorespiratory fitness. No significant correlati ons at all are found with wrist BMD, a bone site that is less involved in p hysical activity and fitness. It can be concluded that daily physical activ ity during adolescence and in the young adult period is significantly relat ed to the BMD at the lumbar spine and femoral neck at age 28 of males and f emales. Only neuromotor fitness and not cardiopulmonary fitness during adol escence and young adulthood is related to the BMD of males and females at a ge 28 years. (C) 2000 by Elsevier Science Inc. All rights reserved.