Changes in the lower leg moment of inertia due to child's growth.

During growth the size and shape of the child's body changes. It is not clear whether the shape of a body segment changes proportionally in children between the age 5 and 18 years. The aim of this study is to describe these changes for the lower leg moment of inertia in a population of children. The segment moment of inertia describes the mass distribution along the body segment axis. The moment of inertia of the lower leg (including the foot) was measured by the free oscillation technique in 90 healthy children (61 boys and 29 girls) between and 5 and 18 years of age. The period of free oscillation was measured with and without external mass loading. The moment of inertia was calculated using a relation between the mass and the period of oscillation. A two-cylinder model of constant body density was used to predict the moment of inertia. Anthropometric measurements of length of the lower leg and foot, the circumference of the knee, ankle and foot were made. Experimental and model data of the lower leg of inertia were described by a fifth power function of body height. The experimental and model data showed high degree of convergence, confirming that the segment growth of the human body can be treated like the volume growth of a cylindrical object of constant body density. Thus it was experimentally confirmed that the lower leg segment growth between age 5 and 18 years may be considered as proportional.

[1]  R. Jensen,et al.  Body segment mass, radius and radius of gyration proportions of children. , 1986, Journal of biomechanics.

[2]  P. Rack,et al.  Response of the normal human ankle joint to imposed sinusoidal movements. , 1983, The Journal of physiology.

[3]  R. M. Alexander How Dinosaurs Ran , 1991 .

[4]  B. Blanksby,et al.  Inertial characteristics of adolescent male body segments. , 1988, Journal of biomechanics.

[5]  G L Gottlieb,et al.  Sinusoidal oscillation of the ankle as a means of evaluating the spastic patient. , 1978, Journal of neurology, neurosurgery, and psychiatry.

[6]  R. H. Cannon,et al.  Dynamics of Physical Systems , 1967 .

[7]  R K Jensen,et al.  The effect of a 12-month growth period on the body moments of inertia of children. , 1981, Medicine and science in sports and exercise.

[8]  L R Young,et al.  The relaxed oscillation technique for the determination of the moment of inertia of limb segments. , 1976, Journal of biomechanics.

[9]  Bruce A. Conway,et al.  Development of Skylab experiment T-013 crew/vehicle disturbances , 1972 .

[10]  H Hatze,et al.  A mathematical model for the computational determination of parameter values of anthropomorphic segments. , 1980, Journal of biomechanics.

[11]  G. Zahalak,et al.  A Quantitative Evaluation of the Frequency-Response Characteristics of Active Human Skeletal Muscle In Vivo , 1979 .

[12]  Archibald Vivian Hill,et al.  The dynamic constants of human muscle , 1940, Proceedings of the Royal Society of London. Series B - Biological Sciences.

[13]  David A. Winter,et al.  Biomechanics and Motor Control of Human Movement , 1990 .

[14]  R. Zernicke,et al.  Mass, center of mass, and moment of inertia estimates for infant limb segments. , 1992, Journal of biomechanics.

[15]  S. Bouisset,et al.  Experimental Determination of the Moment of Inertia of Limb Segments , 1969 .