Circadian Variability of Bioelectric Muscle Tone in Static and Dynamic Anaerobic Exercises in Men

Purpose The aim of the study was to determine the circadian variability of bioelectric muscle tone in static and dynamic exercises with the use of surface electromyography (sEMG). Methods The research sample consisted of 16 men aged 21.6±0.62 years. The tests were conducted at 02:00,10:00,18:00,22:00, included measurements of bioelectric tension (sEMG) of the vastus lateralis muscle of the right and left limbs during maximum voluntary isometric contraction (MVC), the Jumping test—vertical jump with (CMJ) and without arm swing (ACMJ), a 10-second cycle ergometer test. The tests were repeated after 24 hours. Results The level of bioelectric tension recorded during MVC did not show significant circadian variability. However, in dynamic exercises, significant variability (p<0.05) in bioelectric tension of the muscle of the left limb during the CMJ was observed between 22:00 and 18:00. A tendency to achieve higher average amplitude values was observed at 10:00 in both limbs, with the lowest values observed at 02:00 am. After 24 hours, the highest bioelectric activity was observed in both limbs at 10:00 during the CMJ, while the lowest values in the left limb at 02:00. During the ACMJ, the lowest level of bioelectric activity in the right limb was observed at 02:00. In the 10-second anaerobic test, significant variability in bioelectric tension in the left limb was shown between 18:00 (highest) and 02:00 (lowest). After 24 hours, the measurement values were generally lower. Conclusions The highest sEMG biopotential amplitude values were recorded in the evening and afternoon, while the lowest values were recorded at night time.