Maximum likelihood factor analysis of the effects of chronic centrifugation on the structural development of the musculoskeletal system of the rat

At the age of 30 days female Sprague-Dawley rats were placed on a 3.66 m radius centrifuge and subsequently exposed almost continuously for 810 days to either 2.76 or 4.15 G. An age-matched control group of rats was raised near the centrifuge facility at earth gravity. Three further control groups of rats were obtained from the animal colony and sacrificed at the age of 34, 72 and 102 days. A total of 16 variables were simultaneously factor analyzed by a maximum-likelihood extraction routine and the factor loadings presented after rotation to simple structure by a varimax rotation routine. The variables include G-load, age, body mass, femoral length and cross-sectional area, inner and outer radii, density and strength at the midlength of the femur, dry weight of gluteus medius, semimenbranosus and triceps surae muscles.