Muscle Properties Alterations in a Treadmill Exhaustion Protocol: Case of Study

Background: Neuromuscular function and its analysis have been widely investigated due to their relevance to sports performance, injury prevention and muscle recovery (1–3). The development of advanced technologies, such as the MyotonPRO portable device, has provided new possibilities for monitoring and understanding muscle mechanical properties. Purpose: To investigate the changes in the muscle properties of the dominant lower limb after an exhaustion treadmill running protocol using the MyotonPRO device. Methods: The sample is a male (22 years old, 1.76m and 100kg) who does regular exercise. The subject performed an incremental protocol running, which started at 8km/h and increased by 1km/h every three minutes, until exhaustion. Effort was measured using the Borg Rate of Perceived Exertion scale and the heart rate. The muscle properties of the muscles rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA) and medial gastrocnemius (GM) from the right side of the body, were measured before and after the exhaustion test. These were measured using the MyotonPRO (Myoton Ltd, Tallinn, Estonia) instrument, using a specific collection protocol (three times each muscle, without contraction, in the direction of the muscle belly, with a tap time of 15s and a 0.8s interval between each pulse). The statistical analysis starts with descriptive statistics using means±standard deviation. After that it’s applied the normality test Shapiro-Wilk. To compare two variables with normality we use paired samples T-Test and the Wilcoxon test if they’re not normal. Results: It was showed that all the muscles decreased their tone from pre to post, except for the GM. As for stiffness, all the muscles showed a decrease in its value. Relaxation and creep increased in all muscles. Elasticity, showed an increase for RF and TA and a decrease for BF and GM muscles. Of these, stiffness (sig=0.008), relaxation (sig=0.002) and creep (sig=0.002) showed statistically significant differences between the pre and post moments. Discussion and conclusions: The results found are in line with others, such as decreases in tone and stiffness in cycling athletes (1). In contrast, we’re found increases in these values in rowing athletes(3). In running, although a marathon, no differences were found in stiffness (2), which may suggest that the intensity of the effort influences muscle properties. When compared the same activity of running but with different intensities, the more intense one is the one that is going to provoke the most variances in muscle properties, being needed future investigation comparing different intensities of the same activity. Although the results cannot be generalized, they provide a basis for understanding how muscle properties respond to intense exercise, which can be used to control and adjust the training load and personalise it to each athlete, as well aspreventing injuries by looking out for signs of fatigue. Further studies are also needed to understand muscular asymmetries during running, regarding the muscular properties.