P1.14. TREADMILL TRAINING VERSUS VOLUNTARY WHEEL RUNNING: EFFECTS IN CONTRACTILE PROPERTIES OF THE THREE TYPES OF MOTOR UNITS IN RAT MEDIAL GASTROCNEMIUS MUSCLE
Kacper Podgórski1, Katarzyna Kryściak1, Hanna Drzymała-Celichowska1, Joanna Śliwowska2, Jan Celichowski1
1 Poznan University of Physical Education, Department of Neurobiology, 27/39 Królowej Jadwigi St., Poznan, Poland
2 University of Life Sciences in Poznan, Department of Zoology, 71C Wojska Polskiego St., Poznan, Poland
INTRODUCTION: Various forms of physical activity differentially affect the neuromuscular system and have various impact on well-being of animals. Forced treadmill running (FTR), compared to voluntary wheel running (VWR), induces stress in rats as evidenced by elevated levels of corticosterone. This is particularly relevant to studies targeting brain structures sensitive to stress as hippocampus. Therefore, we have tested whether VWR could serve as a less stressful alternative form of training compared to FTR, while still eliciting beneficial adaptations.
AIM(S): This study was aimed to compare the effects of two distinct training forms (FTR and VWR) on proportion and contractile properties of motor units (MUs) in the medial gastrocnemius muscle.
METHOD(S): Male Wistar rats were assigned to 3 groups: control, FTR (4 weeks), VWR (4 weeks). Contractile properties and proportion of 3 MUs types: slow (S), fast fatigue-resistant (FR), fast fatigable (FF) were investigated during electrophysiological experiments. Additionally, running distances and medial gastrocnemius muscle mass were measured.
RESULTS: The fatigue resistance was significantly higher in FR MUs from rats subjected to FTR compared to VWR. Additionally, there were no significant differences in the proportion of three MUs types between the two training modalities.
CONCLUSIONS: The differences in fatigue resistance may be associated with the lower intensity and irregular pattern of VWR activity, which does not impose sustained FTR. Notably, both training modalities led to similar shifts in the proportions of S, FR and FF MUs types, indicating that muscle composition changes in a comparable manner regardless of whether the training is voluntary or forced. These results suggest that voluntary exercise may induce comparable neuromuscular adaptations while being less stressful. Thus, VWR could be considered as viable and less stressing alternative to traditional forced training protocols in experimental models.
FINANCIAL SUPPORT: National Science Centre Poland grant no. 2023/49/B/NZ9/01931 (OPUS 25)