EN
The aim of the study was to compare changes in the force-frequency relationship of motor units (MUs) in rat medial gastrocnemius muscle, caused by treadmill training and whole body vibration training. 24 Wistar rats were studied. Rats were divided into 3 groups: treadmill training group (n=7, locomotion speed 27 cm/s, 1 km daily, 5 days weekly, for 4 weeks), whole body vibration training group (n=6, Power Plate® vibration platform, 50 Hz vibration of 2 mm amplitude, 30 s daily, 5 days weekly, for 4 weeks) and a control group n=11. Functional isolation of single MUs was achieved by electrical stimulation of ventral roots fi laments. A total of 424 MUs were studied (148 in treadmill training, 142 in vibration training and 134 in control). MUs were classifi ed as fast fatigable – FF, fast resistant – FR or S – slow. The frequency causing 60% of maximum force of MUs has decreased in FF units of both trained groups and increased in FR units. In S units the increase of the parameter was noted only in treadmill trained group. Additionally, the slope of the force-frequency curve has increased in all MUs types in the vibration training group.