## Body segment mass, radius and radius of gyration proportions of children

Reference | Body segment mass, radius and radius of gyration proportions of children |

Journal | J.Biomechanics, Vol.19,359-368 (1986) |

Author | R.K.Jensen |

Item | COG M I |

State | Living |

Sample number | 12 |

Sex | Male |

Age | 4-15 |

Measurement year | n/a |

Race | Caucasian |

Measurement place | n/a |

Measurement technique | Photogrammetry |

Raw data accessibility | NG |

#### (1)Definition of body segmentation

16segments:Head, Neck, Upper part of torso, Lower part of torso, Upper arm, Forearm, Hand, Thigh, Calf, Foot.

It is refered the definition of Clauser.The following definitions are original.

Head―Neck

The cut plane passes horizontally through the second vertebra.

Neck―Upper part of torso

The cut plane is located at the junction of the seventh vertebra and first thoracic vertebra.

Upper part of torso―Upper arm

The cut plane begins at the acromion, and extends to the armpit following the medial border of the deltoid muscle.

Upper part of torso―Lower part of torso

The cut plane passes horizontally through the inferior edge of the xiphoid process.

#### (2)Predictive model

- The ratio of the segment mass, center of gravity, and radii of gyration are calculated using regression equations that include age as an independent variable.

#### (3)Validation

Comparison between direct measurement of body weight and measurement by photogrammetry.

→Error: less than 4%

# Regression coefficients

## The ratio of the segment mass

The following table shows regression coefficients.

The ratio of the segment mass is expressed as a percentage of body mass

**Ex.)**

**The ratio of the head mass=0.2376-0.114×age**

## The ratio of the center of gravity

The following table shows regression coefficients.

The ratio of the COG is calculated as percentage of the segment length measured from the proximal end.

**Ex.)**

**The ratio of the COG of the head(%) =0.4833+0.0025×age**

## The ratio of the radii of gyration

The following table shows regression coefficients.

The ratio of the radius of gyration is the ratio of the semiaxis of the body segment at the center of gravity to the segment length.

**Ex.)**

**The ratio of the radius of gyration of the head =0.5748+0.0021×age**