Physical training and connective tissues in young mice : 1, biochemistry of long bones : 2, biochemistry of Achilles tendons

Abstract

1. The effect of physical training on collagen, ground substance and nucleic acid concentrations 1n long bones 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 training, which took place on a 5° inclined treadmill 5 days a week for 3 to 22 weeks. The duration of daily exercise was increased progressively over 3 weeks. The final daily exercise bouts were 50 and 80 minutes for moderate programs and 180 minutes for the intensive program at a speed of 30 cm/s. We found increased concentrations of nitrogen and hexosamines especially after prolonged training at both training intensities, The concentration of DNA, RNA-ribose and hydroxyproline tended to he reduced after some training programs. The hexosamine-hydroxyproline ratio was higher and the hydroxyproline-nitrogen ratio lower in the long bones of trained animals compared to the controls. We conclude that prolonged physical training contributes to maintaining a high glycosaminoglycan concentration in matured long bones.

2. Effects of physical training on collagen, ground substance and nucleic acid concentrations in Achilles tendons were 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° inclined tread­mill 5 days a week for 3 to 22 weeks. The daily duration of exercise was in­creased progressively over 3 weeks. The final daily exercise bouts were 50 and 80 minutes for moderate programs and 180 minutes for the intensive program at a speed of 30 cm/sec. We found increased concentrations of DNA, nitrogen, hexosamines, and to a lesser degree, uronic acids in the Achilles tendons of the trained mice vis a vis the controls. No difference in the concentrations of hydroxyproline and RNA-ribose was observed between the groups. The ratio of glycosamino­glycans, especially hexosamines, to hydroxyproline increased and hydroxyproline to nitrogen decreased after prolonged training. The results show that physical training during growth affects the chemical composition of Achilles tendons. Prolonged training may contribute to maintaining a high glycosaminoglycan concentration in matured tendons.