# Characteristics of Changes in Contractile Properties of Muscle after Anaerobic Exercise
## 2 Materials and Methods
### Procedures  
The body height was measured using a stationeter and the body composition analysis was performed using a Tanita DC-360 device (Tanita Corporation, Tokyo, Japan). To ensure the accuracy of the measurements, it was ensured that the arms did not touch the torso, the shoulders were straight down, and the inner sides of the thighs were not in contact with each other. The muscle's contractile properties were assessed by tensiomyography using a TMG S2 device and TMG 3.6 software (TMG-BMC d.o.o., Ljubljana, Slovenia). The TMG parameters were measured in the superficial muscles of the dominant lower limb (in all subjects this was the right limb), in the present order: rectus femoris (RF), vastus medialis (VM), vastus lateralis (VL), soleus (SO), gluteus maximus (GT), gastrocnemius medialis (GM), and gastrocnemius lateralis (GL). The order of muscles during TMG assessments was kept constant before and after the Wingate test. The location of the sensor was determined anatomically by palpation during voluntary contraction. The sensor was aligned perpendicular to the belly muscle's thickest part halfway between the electrodes. The electrode and sensor positions were marked with a dermatological pen to ensure consistent measurement locations in consecutive assessments. Self-adhesive electrodes (5 \(\times\) 5 cm, UltraStim X, Axelgaard Manufacturing Co., Ltd., CA, USA) were placed at a distance of 2.5 cm from the sensor on both sides. The test was performed on the subject under static. The muscles rectus femoris, vastus medialis, and vastus lateralis were measured with the participant in the supine position, and the muscles gluteus maximus, gastrocnemius medialis, gastrocnemius lateralis, and soleus were measured with the participant in the prone position. No immobilization of the limb was used during the study. The proper angle of the knee joint was upheld with a triangular foam pad and a semi-circular foam cushion. The extensor muscles of the knee joint were assessed with the knee joint positioned at 120\({}^{\circ}\), while the flexor muscles were evaluated with the knee joint set at 150\({}^{\circ}\). A single rectangular monophasic pulse 1.0 ms in width, was applied. The signal magnitude began at 30 mA and was raised by 10 mA increments until Dm reached a 'plateau'. A 15-s rest period between stimulations was used to minimize the effect of fatigue. All measurements were conducted by the same skilled examiner. The curve exhibiting the greatest maximum radial displacement was selected for analysis for each assessed muscle. The collected parameters measured by the TMG method were as follows: radial muscle displacement (Dm), contraction time (Tc), deceleration time (Td), sustained contraction time (Ts), and half relaxation time (Tr). The focus was on the parameters Tc and Dm; they are the most frequently studied muscle contractile properties due to their reliability and validity [7]. The anaerobic test was the 30 s Wingate test, performed on a Cyclus 2-cycle ergometer. The test was preceded by a 5 min warm-up on the ergometer with a resistance of 2.1% of total body mass, where participants completed three 5 s sprints at minutes 2-3 and 4 with a resistance equal to 4.1% of total body mass. To eliminate the possibility of fatigue, the warm-up was followed by a rest period of 3 min. Rest was followed by the actual part  
Figure 1: Research procedures—scheme. of the test. The test subject initiated pedaling at 60 revolutions per minute (rpm) for approximately 10 s without any resistance. Then the \"3-2-1-Start!\" was counted down and the test resistance changed to that calculated from the formula 0.075 kg-kg\({}^{-1}\)[26]. The subject's goal was to achieve the highest possible pedal frequency in the shortest possible time and to maintain it throughout the 30 s test. A verbal encouragement was used during the test and the last 3 s were counted down.