The effect of short-term cold water immersion on neuromuscular function

Thesis goal. To determine the effect of short-term CWI on neuromuscular function. Problem. Cold is encountered in various situations - at work, doing sports or merely by spending time outside in cold weather. For a long time there has been no knowledge of or research on how cold affects body functions. It is known that at lower temperatures body temperature drops due to termoregulatory mechanisms that are triggered in the process, functions of the nervous system change, psychomotor function is impaired. The effect of cold on neuromuscular functional unit and sports performance is still unclear. Research methods. Young healthy adult men participated in this study (n=8, age 24.1±3.8 y., weight 74.7±6.8 kg.). Short-term (10 min.) cold water (14±1°C) immersion in a bath up to shoulders was applied. Neuromuscular function was evaluated before and after the immersion by performing three types of jumps (squat, countermovement and drop jumps) meanwhile applying electromyography of 7 muscles (m. vastus lateralis, m. vastus medialis, m.biceps femoris, m. semimembranosus, m. tibialis anterior, m. soleus, m. gastrocnemius lateralis). The data was used to calculate the average firing frequency, RMS, maximum power, frequency at maximum power. Hypothesis. Since it was determined that cold water immersion impairs psychomotor function, slows down CNS firing frequency, has a negative effect on blood flow to tissues, and causes shiver, it is thought that even after short-term CWI neuromuscular function will be impaired: muscle firing frequency will slow down, power will be reduced. Since it is not entirely clear how cold affects functional nerve-muscle-tendon unit under different workload and circumstances (concentric, eccentric, while withstanding impact load, while trying to keep balance), it is thought that neuromuscular function after CWI under different circumstances should change differently. Results. After immersion, muscle power is decreased due to lower neural firing frequency from the CNS. However, immersion increases RMS. Power change has no tendency. This was mainly determined during the countermovement and drop jumps. The mentioned changes during the countermovement jump were most significant in G, S, TA, SM, BF, while the drop jump showed the biggest changes in VL, VM, SM ir BF. CWI increases standard data deviation and spread. Conclusions. Statistically significant changes in neuromuscular system were determined only during the countermovement and drop jumps. During the countermovement jump, S, G, TA spectrum frequency mean was reduced, VL, BF electric activity increased. During the drop jump, BF spectrum power and electric activity increased. Tendentious power increase is noticeable in VL and SM