title: Duration-controlled swimming exercise training induces cardiac hypertrophy in mice.
abstract: Exercise training associated with robust conditioning can be useful for the study of molecular mechanisms underlying exercise-induced cardiac hypertrophy. A swimming apparatus is described to control training regimens in terms of duration, load, and frequency of exercise. Mice were submitted to 60- vs 90-min session/day, once vs twice a day, with 2 or 4% of the weight of the mouse or no workload attached to the tail, for 4 vs 6 weeks of exercise training. Blood pressure was unchanged in all groups while resting heart rate decreased in the trained groups (8-18%). Skeletal muscle citrate synthase activity, measured spectrophotometrically, increased (45-58%) only as a result of duration and frequency-controlled exercise training, indicating that endurance conditioning was obtained. In groups which received duration and endurance conditioning, cardiac weight (14-25%) and myocyte dimension (13-20%) increased. The best conditioning protocol to promote physiological hypertrophy, our primary goal in the present study, was 90 min, twice a day, 5 days a week for 4 weeks with no overload attached to the body. Thus, duration- and frequency-controlled exercise training in mice induces a significant conditioning response qualitatively similar to that observed in humans.
authors.affiliation: Instituto do Coração, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: F S
authors.initials: FS
authors.lastname: Evangelista
authors.forename: P C
authors.initials: PC
authors.lastname: Brum
authors.forename: J E
authors.initials: JE
authors.lastname: Krieger
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D001794:Blood Pressure; D006332:Cardiomegaly / Q000209:etiology* / Q000473:pathology; D002950:Citrate (si)-Synthase / Q000378:metabolism; D006339:Heart Rate; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018482:Muscle, Skeletal / Q000201:enzymology; D010805:Physical Conditioning, Animal; D010807:Physical Endurance; D013550:Swimming; D013997:Time Factors
chemical_list: D002950:Citrate (si)-Synthase