Physical training and connective tissues in young mice. Biochemistry of skin.

The effect of physical training on some connective tissue components of the skin was studied in male mice of NMRI-strain. The mice to be trained and their controls were about 2-weeks-old at the beginning of the training, which took place on a 5 degree inclined treadmill 5 days a week for 3-22 weeks progressively. The final exercise bouts were 50 and 80 min for moderate programmes and 180 min for the intensive programme at a speed of 30 cm/s. At the end of each experiment skin samples from trained and control animals were taken for the analyses. We found increased concentrations of nitrogen, hexosamines and hydroxyproline in the skin of the trained mice compared to the controls. The unchanged DNA concentration suggests that the activation of synthesis occurred in a constant number of cells.