D. M. Nozdrenko, O. V. Rizun, O. O. Kalmukova,
M. Yu. Kuznietsova, N. G. Raksha, T. I. Halenova*,
O. V. Lynchak, Yu. I. Prylutskyy

Taras Shevchenko National University of Kyiv, Ukraine;
*e-mail: galenovatanya@knu.ua

Received: 23 October 2025; Revised: 12 November 2025;
Accepted: 30 January 2026; Available on-line: February 2026

Obesity has become a widespread issue across the globe, reaching epidemic proportions. Being overweight is a known risk factor for developing impairments in muscle performance. The aim of the study was to estimate mechanokinetic parameters of musculus soleus contraction in obese animals to better understand the possible impact of obesity on muscle contractile activity, tissue structure and appearance of damage markers in the blood. Experiments were carried out on 40 male white non-linear rats, divided equally into two groups. Control group were fed a standard diet for 10 weeks. Rats in the obesity group were maintained on a high-fat diet for the same time period. At the end of the experiment animals were anesthetized, musculus soleus was dissected, the ventral roots were severed from the spinal cord. Stimulation was performed by electrical impulses generated by a pulse generator. Tissue samples histological analysis was done with the use of Van Gieson’s trichrome and Sudan Black staining. Creatinine concentration, creatine phosphokinase (CPK) and lactate dehydrogenase (LDH) activity in the blood was determined. Reduction in musculus soleus maximum contraction force and muscle force impulse, prolonged relaxation time and delayed muscle return to initial state in obese animals as compared to control group were detected indicating on skeletal muscle fatigue. The appearance of intramyocellular lipid droplets and increased amount of intramuscular collagen fibers in the muscle tissue, as well as the elevated creatinine level and increased LDH and CPK activity in the blood, confirmed the impairment of muscle state in obese rat.

Keywords: contractile activity, creatinine, histological analysis, lactate­ dehydrogenase, muscle fatigue, musculus soleus, obesity, phosphokinase